issue 3 :: Spring 2006 :: www.solas-int.org solas news surface ocean - lower atmosphere study www.solas-int.org in this issue... Dimethylsulfide emission 2 in China nearshore waters Estimating ultraviolet radiation 3 in the surface ocean with SeaUV Eddy correlation measurements 4-5 of acetone air-sea fluxes over the N. Pacific Ocean International Symposium on 5 Biological and Environmental Chemistry of DMS(P) The effects of ultraviolet 6-7 radiation of DMS and DMSP biogeochemical cycling An inter-comparison of models 7 to predict DMS production and emissions from the surface ocean Role of bacteria in DMS(P) cycle 8 Photochemical mineralization 9 of chromophoric dissolved organic matter in seawater Dust storm surprise: 10-11 pollution can convert airborne iron into soluble form Focus on members of the SOLAS 12-13 Scientific Steering Committee Contributions of Black Sea 14-15 Emiliania huxleyi blooms and Saharan dust to oceanic production of atmospheric sulfur in the Northeastern Mediterranean Do marine biota control 16-17 CCN seasonality in the Southern Ocean? The science behind the 18-19 coastal studies within the RHaMBLe project Biogeochemistry of DMS 20 and DMSP in the sea-surface microlayer Release of halogens in 21 the troposphere (HitT) task team whitepaper SOLAS Special Reports 22-23 plus... • National reports from 10 SOLAS Countries • Briefs from 7 related projects University of Tokyo Ocean Research Institute student Yoko Iwamoto took this photo from the deck of the Hakuho-Maru during a cruise from 10S to 53N along 160W in the summer of 2005. In addition of marine atmospheric measurements and marine biogeochemical parameters, the group used the eddy covariance technique to attempt measurements of particle fluxes using the equipment shown at the top of the foremast. This issue of the Newsletter mainly features the activities of SOLAS Focus 1: Biogeochemical Interactions and Feedbacks Between Ocean and Atmosphere. The objective of Focus 1 is to quantify feedback mechanisms involving biogeochemical coupling across the air-sea interface, which can only be achieved by studying the ocean and atmosphere in concert. The articles in this issue demonstrate the importance of interactions among biology, chemistry and physics. Recently the Implementation Group co-chaired by Maurice Levasseur (Canada) and John Plane (UK) finished writing the Implementation Plan for Focus 1 (IMP 1) of SOLAS. It is now available as a pdf file (1.3 Mb) through the SOLAS web site. New IMP 1 co-chairs, William Miller (USA) and Mitsuo Uematsu (Japan), have recently been selected to work with the project officer Véronique Schoemann (Belgium) and the IMP 1 advisory group to reorganize and continue reviewing and discussing relevant scientific accomplishments and new scientific directions. Together, we will continue to establish and promote increased international and scientific cooperation, including field expeditions, and standardized observations and intercalibrations. We welcome input and ideas that would help promote SOLAS and Focus 1, looking forward to exciting times as research on Focus 1 science unfolds. William Miller - co-chair, IMP 1; Marine Science Department, University of Georgia Mitsuo Uematsu - co-chair, IMP 1; Ocean Research Institute, University of Tokyo Véronique Schoemann – International Project Officer, IMP 1, Université Libre de Bruxelles Welcome to the SOLAS Newsletter
Transcript
issue 3 :: Spring 2006 :: www.solas-int.orgsolas news
surface ocean - l owe r a tmosphe re s tudy www.so l a s - i n t . o rg
in this issue...Dimethylsulfide emission 2in China nearshore waters
Estimating ultraviolet radiation 3in the surface ocean with SeaUV
Eddy correlation measurements 4-5of acetone air-sea fluxes over the N. Pacific Ocean
International Symposium on 5Biological and Environmental Chemistry of DMS(P)
The effects of ultraviolet 6-7radiation of DMS and DMSP biogeochemical cycling
An inter-comparison of models 7to predict DMS production and emissions from the surface ocean
Role of bacteria in DMS(P) cycle 8
Photochemical mineralization 9of chromophoric dissolved organic matter in seawater
Dust storm surprise: 10-11pollution can convert airborne iron into soluble form
Focus on members of the SOLAS 12-13Scientific Steering Committee
Contributions of Black Sea 14-15Emiliania huxleyi blooms and Saharan dust to oceanic production of atmospheric sulfur in the Northeastern Mediterranean
Do marine biota control 16-17CCN seasonality in the Southern Ocean?
The science behind the 18-19coastal studies within the RHaMBLe project
Biogeochemistry of DMS 20and DMSP in the sea-surface microlayer
Release of halogens in 21the troposphere (HitT) task team whitepaper
SOLAS Special Reports 22-23
plus...• National reports from
10 SOLAS Countries
• Briefs from 7 related projects
University of Tokyo Ocean Research Institute student Yoko Iwamoto took this photo from the deck of theHakuho-Maru during a cruise from 10S to 53N along 160W in the summer of 2005. In addition of marineatmospheric measurements and marine biogeochemical parameters, the group used the eddy covariancetechnique to attempt measurements of particle fluxes using the equipment shown at the top of the foremast.
This issue of the Newsletter mainly featuresthe activities of SOLAS Focus 1:Biogeochemical Interactions and FeedbacksBetween Ocean and Atmosphere.
The objective of Focus 1 is to quantify feedbackmechanisms involving biogeochemical couplingacross the air-sea interface, which can only beachieved by studying the ocean andatmosphere in concert. The articles in this issuedemonstrate the importance of interactionsamong biology, chemistry and physics. Recently the Implementation Group co-chairedby Maurice Levasseur (Canada) and John Plane(UK) finished writing the Implementation Planfor Focus 1 (IMP 1) of SOLAS. It is nowavailable as a pdf file (1.3 Mb) through theSOLAS web site. New IMP 1 co-chairs, WilliamMiller (USA) and Mitsuo Uematsu (Japan), haverecently been selected to work with the project
officer Véronique Schoemann (Belgium) and the IMP 1 advisory group to reorganize andcontinue reviewing and discussing relevantscientific accomplishments and new scientificdirections. Together, we will continue toestablish and promote increased internationaland scientific cooperation, including fieldexpeditions, and standardized observations andintercalibrations. We welcome input and ideasthat would help promote SOLAS and Focus 1,looking forward to exciting times as research on Focus 1 science unfolds.
In China, huge terrestrial pollutants loadnearshore water as a result rapid economicdevelopment. As a consequence, the frequencyof red tides increase. Eutrophication stimulatesthe population size of poisonous algae resultingin higher DMS production. Therefore, more DMSmay be emitted to the atmosphere in thepolluted nearshore waters, compared with cleanwater. In addition, anthropogenic SO2 emissionsand atmospheric SO2 concentrations aredecreasing continuously in recent years underpollution control and the use of low sulfurcontaining coal and clean energy in coastalcities. However, the oxidation capacity of theambient air is enhanced due to secondary airpollution, thus more DMS could be oxidized. Thechanges in ambient air oxidation capacity andSO2 level and coastal water quality may impactthe roles of DMS in the atmosphere. Therefore,it is necessary to investigate the spatial-temporaldistribution of DMS in China nearshore waters inorder to identify the major factors related to theproduction and emission of DMS.
Qingdao nearshore waters, Jiulong Jiang Estuary,Pearl River Estuary (PRE) and adjacent northernSouth China Sea (SCS) have been selected as
study areas, as they are highly eutrophicatedwith high primary productivity. The averageconcentration of DMS in China nearshore waterswas relatively high and showed evident seasonalvariation. In Qingdao nearshore waters thehighest level of DMS concentrations wereobserved in summer with mean value of 1169.5 ngL -1 and the lowest concentration was in winter with mean value of 48.2 ngL -1. In PRE and northern SCS the highest mean DMSconcentration was 478.5 ngL -1 in spring andthe lowest value 91.3 ngL-1 in winter. In JiulongJiang Estuary and PRE, the highest concentrationof DMS was observed in the river stream. In theestuarine maximum turbidity zone, the salinity ofseawater changes greatly and the congregatedalgae emit high concentration of DMS. The phytoplankton’s DMS productivity in thethree study areas is different with their owncharacteristics. Of the physical environmentalfactors, temperature and transparency (radiation)are key factors for DMS production in Qingdaocoastal water. While salinity plays an importantrole in determining DMS productivity in JiulongJiang and Pearl River estuaries.
Based on the concentration of DMS in seawater,the sea-to-air flux of DMS can be estimated usingstagnant film model. The seasonal variation of flux was similar to that of seawater DMSconcentration. In the Qingdao coast, the highestflux was 8.00µmol m-2d -1 in summer and thelowest was only 0.14µmolm-2d -1 in winter. InPRE and northern SCS, the flux ranged from 3.4to 42.4µmolm -2 d -1 as the average of the fourcruises in 2000-2004, which was much higher inthe sea shelf than in the estuary and open sea.
1 State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of EnvironmentalSciences, Peking University, Beijing 100871, P. R. China; 2 Marine Environmental Laboratory, XiamenUniversity, Xiamen 361005, P. R. China
Prof. Min Hu is from Peking University, and her scientificresearch focuses on (1) natural emission of DMS in the easterncoastal areas of China, DMS oxidation in the atmosphere andits relationship with sulfur cycle, acid precipitation and climatechange. (2) characterizations of fine particles and its impacton air quality, regional air pollution and human health.
Figure 1: The study areas and sampling sites, 1. Qingdao nearshore waters (2001-2003); 2. Jiulong River Estuary (2001); 3. Pearl River Estuaryand Northern South China Sea (2000-2004)
Figure 2: Scientific investigation ship “Dong Fang Hong II”
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partner projects
GLOBEC (Global Ocean EcosystemDynamics) is a core project of theInternational Geosphere-BiosphereProgramme (IGBP) and is co-sponsoredby the Scientific Committee for Oceanic Research (SCOR) and theIntergovernmental OceanographicCommission (IOC) of the United Nations Educational, Scientific andCultural Organization (UNESCO).
The implementation plan was approvedin 1999, with a mandate to run untilDecember 2009. GLOBEC is thereforeentering its second phase and movinginto Integration and Synthesis (I+S), and,in 2010, GLOBEC will merge with theIntegrated Marine Biogeochemistry andEcosystem Research (IMBER) project.
In preparation for the I+S phase, theGLOBEC Scientific Steering Committee(SSC) drafted a document entitled“Blueprint to I+S” (see www.globec.orgto download) with suggestions foractivities, which were then placed on the web for comments and input from working group members, national representatives and GLOBEC researchers. A webtool was subsequently implemented to allow individual scientists to suggestworkshops, activities, and specificsynthesis outputs.
For more information on GLOBEC, seethe webpage or contact Project OfficeDirector Manuel Barange [email protected].
Can’t get enough?Additional copies - If you wish toreceive further copies of SOLAS News,subscribe a friend or your library,please contact [email protected]
solas news
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Estimating ultraviolet radiation in the surface ocean with SeaUVWilliam L. Miller and Cedric Fichot, University of Georgia, Department of Marine Science, Athens, GA, USA - contact: [email protected]
Bill Miller is the Associate Director for Marine Programs and the Director of theSapelo Island Marine Institute at the University of Georgia, USA. Following a PhDfrom the Graduate School of Oceanography at the University of Rhode Island in1990, he held a National Research Council Postdoctoral fellowship with the U.S.Environmental Protection Agency and served for 9 years as a professor ofOceanography at Dalhousie University, Canada.
High-energy ultraviolet radiation (UVR) is anatural component of the solar spectrumreaching the Earth’s surface and its potentialeffects on ecosystem function, andbiogeochemical cycling in natural waters, as well as its potential role in global change feedback scenarios have long been recognized (Zepp et al., 1998). The study of UVR as it relates to theproduction/ destruction of atmosphericallyimportant trace gases (AITGs: alkyl nitrates,halocarbons, COS, CS2, ketones, aldehydes,CO, CO2, DMS) or as a driver forphotobiological processes that directlyimpact biology in the surface ocean fallssquarely in the SOLAS domain. In almost all natural waters, chromophoric dissolvedorganic matter (CDOM) is the mainregulator of UVR and adjacent bluewavelengths, causing significant variations in both general water transparency and thevertical domain of photochemical andphotobiological processes. Clearly,operational tools to evaluate the spatial andtemporal variability of CDOM absorbance(ag(_); where wavelength is indicated insidethe parenthese) and UVR attenuation (Kd(_))in the ocean will improve our understandingand predictions of the effect of UVR on the marine environment and provide criticalinput for quantitative models describingthe air-sea exchange of AITGs in SOLAS.
Over the past twenty years, work on ocean
color has led to the development and
implementation of a number of empirical,
semi-analytical and analytical models that
permit the retrieval of inherent and
apparent optical properties from remote
sensing reflectance, Rrs(_), or normalized
water-leaving radiances, nLw(_), with
primary attention on the estimation of
biological variables such as chlorophyll and
primary productivity. Only recently has the
oceanographic community shown interest
in developing algorithms directed at CDOM
variability with relevance to the UV
radiation field. Consequently, much work
remains to fully develop and validate robust
algorithms that permit retrieval of Kd(_)
and ag(_) in the 280 - 490nm range.
Applying principal component analysis
and a multispectral classification to our
large “training dataset” ( > 320 nm,
simultaneous in situ measurements of
remote sensing reflectance, attenuation,
and CDOM absorbance, gathered over
the last 8 years in a wide range of water-
types), we have developed two improved
and “ready-to-use” algorithms (SeaUV &
SeaUVC) for estimating UV-VIS diffuse
attenuation (Kd(320-490nm)) and CDOM
absorbance (ag(320nm)) from spectrally-
resolved remote sensing reflectance in
visible wavebands. The algorithms are
optimized for application to in situ and
airborne radiometers as well as to the
current ocean color satellites SeaWiFS and
MODIS, providing estimates for Kd(_) and
ag(_) in the 320-490nm spectral range.
Using the SeaUV models, we have begun
to investigate UV attenuation dynamics in
different hydrological and biogeochemical
domains with an eye toward identifying
specific processes that dominate CDOM
variability in the various regions of the
world. An example of the dynamic
nature of UV attenuation is shown in the
accompanying global picture of Kd(320)
in July, 1999. Large “UVR attenuation
features” can be seen that reflect coastal,
riverine, bloom, and upwelling dynamics.
Continued work will be toward a
classification of the world’s oceans into a
number of distinct regions that reflect the
variability and predictability of UVR
attenuation together with dominant
regulatory processes. As these optical
tools are refined, it will become possible
to quantify the spatial and temporal
variability of UVR dependent
photochemical and photobiological
reactions. Resulting depth-resolved
models for ecosystem and
biogeochemical response to changing UV
radiation should advance SOLAS research
to a new understanding and predictability
of AITG exchange between the surface
ocean and lower atmosphere.Figure 2. Global map of downwelling attenuation at 320 nm (Kd(320) ± 15%) for July 1999.
Figure 1. Lori Ziolkowski and Jane Sherrard collectUV optical data for algorithm developmentaboard Louisiana Universities Marine Consortium(LUMCON) R/V Pelican in the Gulf of Mexico.
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Because the upper troposphere is dry, the major sources of HOx are oxygenated organiccompounds, such as acetone. In order tounderstand the reactivity of this portion of the atmosphere, studies of the global budgetof these compounds are needed. Previousfield campaigns have shown that acetoneconcentrations are significant in the uppertroposphere (Singh et al., 1995), but the sourcesof acetone are not entirely understood. The roleof the ocean in the acetone budget is particularlyin question. A large ocean source was inferredfrom aircraft measurements of acetone over the remote Pacific Ocean (Jacob et al., 2002 and references therein), but has been recentlycalled into question by measurements showingdepletion of acetone in the Pacific marineboundary layer relative to the overlying freetroposphere (Singh et al., 2004 and referencestherein). Previous budgets have ranged in theocean’s role, varying from a 21 Tg yr -1 source(Jacob et al.,2002) to a 14 Tg yr -1 sink (Singh et al., 2004). In this study, eddy correlation was used to directly measure the air-sea flux ofacetone over the North Pacific Ocean aboard the R/V Wecoma from May to July, 2004.
One Hz measurements of acetone were madeusing an atmospheric pressure chemical-ionization mass spectrometer (API-CIMS)(Eisele, 1986). Air was sampled from thebowmast at 27 slpm from 10m height through250 feet of 3/8” ID Teflon tubing.Simultaneous measurements of 3D winds andplatform angular rates and accelerations weremade to allow calculation of air-sea flux byeddy covariance (Edson et al., 1998). Seawateracetone levels are determined by analyzing anair stream continuously equilibrated withseawater pumped from the bow at a depth of5m. The measurement protocol consisted ofalternating measurements of seawater (10minute) and air (60 minutes). Flux wasdetermined by integrating the cospectrum offluctuations of the vertical wind andatmospheric acetone mixing ratio. The overalluncertainty in the flux due to low and highfrequency corrections and motion correction isestimated to be 30-40% (Edson et al., 1998).
In the western tropical Pacific Ocean,atmospheric acetone levels were 0.361 ± 0.051ppb (Fig). Air mass back-trajectories showconsistent easterly trade wind flow overequatorial waters. These levels are similar toboundary layer aircraft measurements previouslyreported for this region (Jacob et al., 2002 andreferences therein). Acetone levels were highernorthward of 25°N, with a mean of 1.04 ± 0.33ppb, reflecting continental influence. Air massback-trajectories and chemical tracers suggestthat someof the spikes in acetone observedduring this period may have been due to biomassburning over the NW Canada and Alaska.
Acetone levels in seawater exhibited adifferent pattern of variability than theatmosphere (Fig.). In the tropical waters,seawater acetone concentrations were 14.5±12.7 nM. Seawater acetone in this regionwas more variable than the atmosphericlevels. Northward of 25°N, the mean oceanlevel of acetone was 12.1 ± 3.0 nM. Theseawater concentrations of acetone measuredin this study are similar to those reportedpreviously, approximately 3 and 18 nM (Zhouand Mopper, 1997; Williams et al., 2004).
Eddy correlation measurements of acetone air-seafluxes over the N. Pacific OceanChrista Marandi, University of California, Irvine, USA - contact: [email protected]
Christa Marandi received her B.S. in Chemistry in 1998 fromGeorge Washington University. In 2000, she began work on herPhD at University of California, Irvine with Dr. Eric Saltzman. Herresearch aim is to use atmospheric pressure chemical ionizationmass spectrometry to perform eddy correlation measurementsof the air-sea flux of dimethyl sulfide and acetone.
Figure: Equatorial and North Pacific measurementsof acetone. From top: 1) Measured air-sea fluxes; 2)Air and seawater levels; 3) Sea surface temperatureand mean wind speed.
partner projects
The Global Water System Project(GWSP) addresses a central researchquestion: How are humans changingthe global water cycle, the associatedbiogeochemical cycles, and thebiological components of the globalwater system and what are the socialfeedbacks arising from these changes?
Recent activities include the developmentof a Global Water System Lexicon, aDigital Water Atlas, an internationalworkshop on ‘Governance and the GlobalWater System’, and a global study onwater indicators and on environmentalflows. The GWSP seeks to expand itsportfolio of activities and to developpartnerships with colleagues around theworld by endorsing pioneering projectsconcerned with critical questions aboutthe global water system.
You can join our network by subscribingto our newsletter ‘Global Water News’and to our emailing list. If you areinterested in getting involved with theGWSP please consult the projectwebsite at www.gwsp.org or contactthe GWSP International Project Office([email protected]).
Call for ContributionsSOLAS News is published every 6 months, and we welcome yourcomments on the content and layout.What would you like to see in your newsletter?
We need your contributions to thescientific and informational content. Do you have a meeting or activitycoming up, and would you like toinform the SOLAS Network? Do youhave a science article for publication?
We welcome contributions fromgraduate students to senior researchers,articles short and long. Send an e-mailto [email protected]
solas news
All of the acetone fluxes measured by eddycovariance in this study were negative (Fig),illustrating that the air/sea flux is uniformly into,rather than out of the ocean. In the equatorialregion the fluxes measured by eddy covariancein this region had a mean of –3.1 ± 0.9 µmolm -2 day -1. Just north of Hawaii, between 25 and 30ºN, the mean eddy covariance fluxwas -7.2 ± 3.2 µmol m -2 day -1 and at latitudesabove 30ºN the mean flux was -9.3 ± 3.7 µmolm -2 day -1. The air/sea fluxes of acetone wereconsistently larger in the mid latitudes than inthe tropics, reflecting the higher atmosphericacetone levels and higher wind speeds.
We found a strong relationship between the measured flux and the atmosphericconcentration, which we used to extrapolatethese results globally. The observed correlationsuggests that either: 1) surface acetone levelsare small compared to the atmospheric levels,and have little impact on the air-seaconcentration gradient, or 2) surface acetonelevels co-vary with the atmosphericconcentration, resulting in an air-sea gradientroughly proportional to Ca. To make thiscalculation, we use Comprehensive Ocean-Atmosphere Data Set (COADS) monthly mean1º x 1º grid wind speed, temperature andpressure. We assume acetone levels in themarine boundary layer, ranging from 400 to1000 ppt, based on this study and previouslyreported measurements (Jacob et al., 2002). Wecalculate a global air-to-sea flux of 48 Tg yr -1.
An ocean sink of this magnitude would greatlyimbalance the current atmospheric acetonebudget (Jacob et al., 2002; Singh et al., 2004).This imbalance is nearly offset by the recentreevaluation of the quantum yield for acetonephotodissociation, suggesting that theatmospheric loss due to photolysis is considerablyless than previously thought (Blitz et al., 2004).Using the revised quantum yields, we estimate a global loss rate of acetone by photolysis of 24 Tg yr -1, roughly half of the previous rate.Summing all the calculated loss rates yields a
global acetone loss rate of 101 Tgyr -1, similar tothe previous analysis, but with ocean uptakeresponsible for about half. Understanding this acetone ocean sink and its impact onatmospheric chemistry requires direct fluxmeasurements with broader seasonal and spatialcoverage, and insight into processes controllingoceanic acetone levels near the air-sea interface.
References
Blitz, M.A., D.E. Heard, and M.J. Pilling (2004),Pressure and temperature-dependent quantumyields for the photodissociation of acetonebetween 279 and 327.5 nm, Geophys. Res.Lett., 31, L06111, doi: 10.1029/2003GL018793.
Edson, J.B., et al. (1998), Direct Covarianceflux estimates from mobile platforms at sea, JAtmos. Ocean Tech., 15, 547-562.
Jacob, D.J., et al., (2002), Atmospheric budget of acetone, J. Geophys. Res., 107,doi:10.1029/2001JD000694.
Singh, H.B., M. Kanakidou, P.J. Crutzen, and D.J. Jacob (1995), High concentrations andphotochemical fate of oxygenated hydrocarbonsin the global troposphere, Nature, 378,50-54.
Singh, H.B., et al., (2004), Analysis of theatmospheric distribution, sources, and sinks ofoxygenated volatile organic chemicals basedon measurements over the Pacific duringTRACE-P, J. Geophys. Res., 109, D15S07,doi:10.1029/2003JD003883.
Williams, J., et al., (2004), Measurements oforganic species in air and seawater from thetropical Atlantic, Geophys. Res. Lett., 31,L23S06, doi:10.1029/2004GL020012.
Zhou, X., and Kenneth Mopper (1997),Photochemical production of low-molecular-weight carbonyl compounds in seawater andsurface microlayer and their air-sea exchange,Mar. Chem., 56, 201-213.
The 4th International Symposium on Biological andEnvironmental Chemistry of DMS(P) will be hosted byGill Malin and colleagues at the Laboratory for GlobalMarine and Atmospheric Chemistry (LGMAC), Schoolof Environmental Sciences (ENV), University of EastAnglia (UEA), in Norwich, UK from 2-6 May 2006.
Following the early registration deadline we areexpecting about 60 people to attend the Symposiumand there is still room for additional symposiumdelegates and poster presentations. We have receivedan excellent array of abstracts for posters and talksthat cover the whole range of research on DMS and
related compounds. The conference presentationswill range from field and laboratory studies, throughto modelling and effects of global climate change onDMS emissions. At the time of writing we arefinalising the detailed conference programme andyou will be able to find this on our web sitehttp://lgmacweb.env.uea.ac.uk/ lgmac/dmsp/ in due course.
For further information please take a look at the conference web site or if you have specificquestions email Rosie Cullington the meetingadministrator via [email protected].
International Symposium on Biological and Environmental Chemistry of DMS(P)
www.so l a s - i n t . o rg / / 05
Belgium
A SOLAS.be cluster has been acceptedfor funding by the Belgian FederalScience Policy Office. This organisesSOLAS-related research projects andconsolidates activities, including: aSOLAS.be Communication Office at theUniversité Libre de Bruxelles (ULB), anonline link with International SOLAS,data-base management, coordinationof modelling efforts, and a website.
Two new SOLAS-related projects wererecently selected for funding by thesame office: the Belcanto-III project‘Integrated study of Southern Oceanbiogeochemistry and climateinteractions in the anthropocene’, andthe PEACE project ‘Role of pelagiccalcification and export of carbonateproduction in climate change’.
Belgium remains active in coordinatingSOLAS-related meetings. The 37thInternational Liège Colloquium onOcean Dynamics was held in mid-2005at the Université de Liège and focusedon Gas Transfer At Water Surfaces. Thisfall, ULB will host a DMS ecosystemmodel intercomparison workshop.
For information on SOLAS-be, contactChristiane Lancelot ([email protected])
Denmark
A Danish carbon cycle project will be a part of a large Danish cruise(www.galathea3.dk) starting out in August this year and ending in April 2007. This will be a world wide cruise going from Denmark viaGreenland, then to India, Thailand,Australia, Antarctica, the west coast of South America to Galapagos, theWest Indies and back to Denmark. The Carbon cycle project will haveSOLAS activity, where we will measure the surface exchange of CO2 by dpCO2 method and directatmospheric CO2 fluxes.
Dr. Lise Lotte Soerensen will be leadingthe activity of CO2 air-sea exchange.
/ / 06 su r f a ce ocean - l owe r a tmosphe re s tudy
Upper-ocean foodwebs are a major source ofatmospheric dimethylsulfide (DMS), a radiativelyimportant trace gas. To date, however,fundamental gaps in our understanding of the marine sulfur cycle have prohibited usfrom fully evaluating a hypothesized negativephytoplankton-DMS-climate feedbackmechanism (e.g. Charlson et al., 1987).Emerging evidence indicates that oceanic DMSand dimethylsulfoniopropionate (DMSP, thechemical precursor to DMS) concentrations andbiogeochemical cycling rates may be stronglyregulated by physical and chemical stressfactors, including exposure to high doses ofultraviolet radiation (UVR).
To isolate and quantify the effects of UVR wehave carried out a variety of deckboard and in situ incubations in regions as diverse as theSargasso Sea, the Gulf of Maine, thecontinental shelf off of the eastern seaboardof the United States, the Southern Ocean, and
the Ross Sea. Specifically we used 35S-DMSand 35S-DMSP radioisotopes to quantify (1)DMS photochemical loss rates, (2) microbialDMS consumption rates, (3) microbialdissolved DMSP consumption rates, and (4) thepercentage DMS yield from microbial DMSPconsumption as a function of UV light doseand spectral quality (see Kiene and Linn, 2000for isotope methods). Samples were eitherincubated on deck in flowing water bathsunder a variety of long-pass optical filters oron free floating drifter arrays in the watercolumn with the light environment regulatedby the natural attenuation of light with depth.
All of our experimental results from throughoutthe world’s oceans clearly indicate that UVR hasa strong ability to structure the cycling rates(Figure). DMS photochemical loss is drivenalmost entirely by UVR with significantly higherrates observed in the Southern Oceancharacterized by high concentrations of nitrate
The effects of ultraviolet radiation of DMS and DMSP biogeochemical cyclingDierdre A. Toole1, Doris Slezak2, Ronald P. Kiene2, and David J. Kieber3 - contact: [email protected]
1 Woods Hole Oceanographic Institution, Massachusetts, USA; 2 University of South Alabama, Alabama, USA; 3 SUNY - College of Environmental Science and Forestry, New York, USA.
Dierdre Toole earned a PhD from the University of California, Santa Barbara in 2003 and carried out postdoctoral research atSUNY College of Environmental Science and Forestry and theWoods Hole Oceanographic Institution (WHOI). She is currently an assistant scientist at WHOI and continues to focus on theinteractions between light and upper-ocean organic sulfur cycling.
Figure: FDMS and DMSP biogeochemical cycling rates from within a Phaeocystis antartica bloom observed in theRoss Sea (~ -179, -77.6) on November 28 – 30th, 2005. DMS photolysis rates and the DMS yield from dissolvedDMSP consumption are normalized to full solar spectrum rates while the biological DMS and DMSP consumptionrates are normalized to dark rates. Cut-off filters are in terms of wavelength with FULL representing exposure tothe complete solar spectrum.
partner projects
In 2006, ICSU celebrates its 75thAnniversary by publishing its firstStrategic Plan. The plan has developedin close consultation with the 104National Members and the twenty-nineInternational Scientific Unions. TheICSU Interdisciplinary Bodies (includingDIVERSITAS, the InternationalGeosphere-Biosphere Programme; IGBP,the International Human DimensionsProgramme; IHDP and the WorldClimate Research Programme; WCRP)have also contributed to the planningexercise over the past few years.
The focus of the Strategic Plan is on: (i)International research collaboration,including a review of the global changeresearch programmes, participation inthe Global Earth Observation System ofSystems (GEOSS), planning for theInternational Polar Year (IPY) and a newprogramme on hazards; (ii) ensuringthat science is policy relevant and thatpolitical decisions are based on the bestavailable scientific knowledge; and (iii)ensuring the universality of science.The plan is available on www.icsu.org.For more information, [email protected].
Visit the SOLAS website athttp://www.solas-int.org
New pages include: job listings,updated national reports, SOLASstructure, the three newImplementation Plans, and much more.
From the website, you can sign upfor the monthly e-bulletin andsubscribe to SOLAS News.
The SOLAS website is meant to be acommunity resource, and wewelcome your comments about thecontent and layout. Send an e-mailto [email protected]
www.so l a s - i n t . o rg / / 07
and photochemically-reactive chromophoricdissolved organic matter. Biological DMS andDMSP consumption rates can be inhibited to as little as 10% of the dark consumption ratesat surface levels of UVR with inhibition varyingamong sites. We also have evidence of UVRinduced microbial recovery reflected in increasesin the DMS consumption rates above darkvalues in the Ross Sea and the Sargasso Sea.
While great strides have been made inmeasuring microbial and photochemical DMSand DMSP rates, at present no robust methodexists for determining in vivo production ofDMSP and DMS by phytoplankton. We mustresort to a balance of known rate processes inconjunction with known concentrationdeterminations. Unfortunately these massbalance approaches do not allow thecontributions of phytoplanktonic synthesis tobe separated from the roles of higher trophiclevels. We see the development of these typesof methods as a key goal for the sulfurcommunity over the next several years.
A variety of efforts are ongoing to developseasonally- and spatially-resolved globalbiogeochemical models to estimate the flux of
DMS to the marine boundary layer. While thesemodels all demonstrate varying degrees ofsuccess in certain geographic regions, a reviewby Belviso et al., (2004a) indicates extremelyweak correlations between empirically modeledand measured DMS concentrations in all cases.From our experimental results, we infer that thislack of agreement may be due to the failure toexplicitly include the effects of UVR on keybiogeochemical cycling rates, as well as ourinability to parameterize phytoplanktonic DMSand DMSP synthesis rates.
References
Belviso, S., et al., Comparison of globalclimatological maps of sea surface dimethylsulfide, Global Biogeochem. Cycles, 18,GB3013, doi:10.1029/2003GB002193, 2004a.
Kiene, R.P., and L.J. Linn, The fate of dissolveddimethylsulfoniopropionate (DMSP) in seawater:tracer studies using 35S-DMSP, Geochim.Cosmochim. Acta, 64, 2797-2810, 2000.
Dimethylsulfide (DMS) is a volatile organic sulfurcompound produced by biological activity in thesurface ocean. Once ventilated in the atmosphere,DMS is oxidized and implicated in a potentiallyclimate-stabilizing feedback loop (the CLAWhypothesis) that is an important focus for SOLAS. The production and emission of DMS is subject tocomplex physical, biogeochemical and ecologicalinteractions. There has been progress in modelingocean DMS distributions and dynamics; however,much work remains to build confidence these models.Following a recommendation from a discussion forumat the 2004 SOLAS Open Science Meeting 2004 inHalifax, Belgian office for Federal Science Policy andSOLAS International Project Office will sponsor aworkshop for the inter-comparison of DMS models.
Two types of data sets have been identified for thesystematic evaluation and comparison of DMSmodels: fixed-station data and data garnered fromthe various iron enrichment experiments.
The workshop organizers have proposed to use acommon simulation framework based on theGeneral Ocean Turbulence Model to ensure identicalphysical representations. In addition, the same sea-to-air DMS ventilation parameterization may beimplemented to facilitate comparison betweensurface DMS emissions from different models.
This invitation-only workshop will involve a small,well-balanced group of modelers andexperimentalists to discuss model parameterizationsin light of the results obtained by the differentmodels. Simulations will be run prior to theworkshop, and the time will be devoted tointerpretation of results and identification of keyprocesses and parameters. The product of the
workshop will be a joint publication in aninternational peer-reviewed journal. This publicationwill aim to (i) identify models convergences anddivergences with respect to the data, (ii) quantifythe impact of model differences on simulated DMSemissions to the atmosphere, and (iii) identify bestpractice in modeling DMS(P) dynamics and researchdirections for improving the models.
The workshop is scheduled for December 4-8 2006at the Universite Libre de Bruxelles in Brussels,Belgium. A planning meeting is scheduled for thenext International Symposium on Biological andEnvironmental Chemistry of DMS(P) and RelatedCompounds at the University of East Anglia (UEA), in Norwich, UK (2-6 May 2006. If you are interested, please contact the scientificcoordinator, Yvonnick Le Clainche [email protected].
Figure: Comparison of two different DMS oceanmodels (green and blue lines) against water-columnintegrated DMS data at the Bermuda time seriesstation (red line). Adapted from Le Clainche et al.2004. Can. J. Fish. Aquat. Sci., 61: 788-803.
Japan
A few months ago an important proposal “Development ofContinuous Determination Techniquesfor Marine Biogenic Carbon Cycles -BIOCARBON-” was funded.
Goals of the project are to establish the techniques of eddy covariance formaterial flux on shipboard, to developcontinuous surface seawater samplingequipment for trace metals while theship is cruising at ~15 knot, and toestablish the DOC molecular sizeseparation technique under the 10-yearGEOSS (Global Earth ObservationSystem of Systems) program by MEXT(Ministry of Education, Culture, Sports,Science and Technology), Japan. Thisproject will be supported for three years.
In March of this year, a SOLAS-Japancommittee meeting and a jointworkshop with IMBER-Japan were held at at Nagoya. We discussed the cruise schedule of research vessels for 2007-2009.
In June 2006, the Subtropical NitrogenFixation Flux Study (SNIFFS) cruise will becarried out by the SOLAS-Japan group.
Netherlands
SOLAS activities in The Netherlands are in the fields of air sea exchange ofaerosols (in particular, sea spray aerosol:source function from field campaigns,satellite remote sensing and modeling),DMS, CO2 and momentum fluxes.Several institutes work on the carboncycle with a strong participation in theEU Integrated Project CARBO-OCEAN.One institute works on nitrogen fixation.Effects of bubbles on air sea gas transferand aerosols are studied in the field andthough laboratory experiments. Manyactivities are closely related to IMBER.Re-vitalization and organization ofSOLAS activities in The Netherlands hasbeen started up this spring. Responseswere received from 10 individuals from8 different institutes and likely thereare more interested parties.
In early May 2006, we will hold aworkshop of Netherlands SOLAS/IMBER/GEOTRACES in conjuction with theSOLAS SSC meeting in Amsterdam.
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Role of bacteria in DMS(P) cycleSree S. Kumar, Usha Chinchkar, Shanta Nair, P. A. Loka Bharathi and D. Chandramohan - contact: [email protected]
National Institute of Oceanography, Dona Paula. Goa. India. 403 004
Sree Kumar is a Marine Biology post graduate and in the finalyear of her PhD in ‘Study of the Role of Microbes as Sourceand Sink of Dimethyl Sulphide in Coastal Waters’ at theNational Institute of Oceanography, Goa, India. She isinterested in studying about marine microbes and their role invarious bigeochemical cycles in the marine environment.
Dimethyl sulphide (DMS) was reported inoceanic waters by Lovelock et al., (1972). Itsprecursor Dimethyl sulfoniopropionate (DMSP)is ubiquitous in the euphotic zone especially in regions dominated by phytoplankton. The biogeochemical importance of DMSP isbased on its bacterial (Wolfe et al., 1999) oralgal mediated (Steinke et al., 2002) enzymaticcleavage to acrylic acid and dimethyl sulphide(DMS). Dissolved DMSP can satisfy 1-15% ofthe total bacterial carbon and virtually all of thebacterial sulfur demand (Kiene et al., 2000;Simo et al., 2002). Bacteria play an importantrole in the cycling of sulfur and their role inthe conversion of DMSP to DMS is important.The coastal ecosystems, especially tidallyinfluenced estuaries are biogeochemicallyactive zones. The estuarine region alsoharbours high DMSP concentrations, as theyare highly productive areas. Although theimportance of estuarine systems in determiningthe coastal DMS(P) cycle has been covered,studies pertaining to tropical areas are sparse.Hence this work examines the temporalvariation in DMSP levels in Dona Paula waters.It also examines the influence of the differentphysiological groups of bacteria in DMSutilization. Knowledge of the abundance,physiology of the bacteria involved in DMS(P)cycle are vital in understanding thedynamics of these compounds.
The Dona Paula Bay, Goa (Fig.) is located onthe west coast of India at the terminus ofZuari estuary. Sampling was carried out oncein a month during receding high tide.Samples were analyzed for Total Viable Count
(TVC) (Kogure et al., 1984), ‘DMS’ and‘DMSP’ utilizers (Visscher et al., 1991), TDLO(Thiobacillus denitrificans like organisms) (Loka Bharathi, 1989), SRB (Sulphate ReducingBacteria) (Loka Bharathi and Chandramohan,1985) and Heterotrophs respectively.
DMSP averaged high during monsoon (13.4± 2 nmol L-1) with peaks in post -monsoon months of Nov (13.2 nmol L-1) andDec (15.1nmol L-1). DMS averaged high inpost - monsoon (9.5 ± 9 nmol L-1) with apeak in November (22.2 ± 2 nmol L-1).
Total viable count (TVC) of bacterialpopulation varied from 0.01 to 3.87 x 106
cells L-1. Average Most Probable number(MPN) of bacteria utilizing DMSP were 2.4 x 103 , 7.5 x 103 , 6.7 x 103 cells L-1,DMS utilizers were 1.6 x 102, 4.6 x 102,2.9 x 102 cells L-1 during pre-monsoon ,monsoon and post-monsoon respectively. A positive coupling between TVC and DMSand DMSP utilizers during pre and postmonsoon may suggest the response of thebacteria to the available substrates.
Utilization of DMS by different physiologicalgroups of bacteria isolated from the field weremonitored in the laboratory to grade theirmetabolic potential towards the substrate. The utilization rate day for TDLO was 0.6 nmol L -1 day-1, for heterotrophs 0.4 nmol L-1 and SRB was 0.3 nmol L-1 day -1.On per cell basis, the values were 0.6, 0.43,and 0.23 fmol cell -1 day-1 for TDLO,heterotrophs and SRB respectively.
References
Bharathi P. A. L, and D.Chandramohan. 1985.Indian Journal of Marine Science.14. 182-191.
Bharathi P. A. L. 1989. The occurrence ofdenitrifying colourless sulphur-oxidisingbacteria in marine waters and sediments asshown by the agar shake technique. FEMSMicrobiol. Ecol. 62: 335-342.
Kiene, R.P., L.J. Linn, and J. A. Bruton,2000. New and important roles for DMSPin marine microbial communities. J. SeaRes. 43 : 209-224.
Kogure K, Simidu U, Taga N (1984) Animproved direct viable count method foraquatic bacteria. Arch Hydrobiol 102: 117-122.
Lovelock, J. E., R.J. Maggs, and R.A.Rasmussen, 1972. Atmosphericdimethylsulfide and the natural sulfur cycle.Nature, 237:452-453.
Simo S.D., C. Archer Pedros-Alio, L. Gilpin,and C.E. Stelfox-Widdicompe. 2002.Coupled dynamics of dimethylsulphoniopropionate and dimethyl sulphidecycling and the microbial food web insurface waters of the North Atlantic.Limnol. Oceanogr. 47 : 53-61.
Steinke, M., G. Malin, D. A. Stephen, H.B.Peter, and P.S. Liss. 2002. DMS productionin a coccolithophorid bloom: evidence forthe importance of dinoflagellate DMSPLyases. Aquat. Microb. Ecol. 26 : 259-270.
Visscher, P.T., P Quist, and H. Gemerden Van.1991. Methylated sulphur compounds inmicrobial mats: In situ concentrations &metabolism by a colourless sulphur bacterium.Appl. Environ. Microbiol . 57 :1758–1763.
Wolfe, G.V., M. Levasseur, G. Cantin, andS. Michaud. 1999. Microbial consumptionand production of dimethyl sulphide (DMS)in the Labrador Sea. Aquat. Microb. Ecol.18 : 197-205.
Yoch, D.C., 2002. Dimethylsulphoniopropionate: Its sources, role in the marine food web, and biologicaldegradation to dimethyl sulphide. Appl.Environ. Microbiol. 68 : 5804 – 5815.
Figure: Study site
Photochemical mineralization of chromophoric dissolved organic matter in seawaterEmily M. White1, David J. Kieber1, and Kenneth Mopper2 - 1 Chemistry Department, State University of New York, College of Environmental Science andForestry, Syracuse, NY, USA; 2 Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, USA - contact: [email protected]
Emily White is a PhD student in Chemistry at the StateUniversity of New York, College of Environmental Science and Forestry. Her research focuses on the photochemistry ofdissolved organic matter. Emily is currently completing herdissertation on the photochemical production of dissolvedinorganic carbon in estuarine and marine waters.
Chromophoric dissolved organic matter(CDOM) plays an important role in theemission of trace gases from the ocean to theatmosphere. CDOM in the surface oceanabsorbs UV radiation, resulting in theproduction of a variety of climatically-relevanttrace gases (e.g., CO, COS, CS2, CH3I, andalkenes). Photochemical degradation ofCDOM also influences the bioavailability ofdissolved organic carbon and the opticalproperties of seawater which indirectly controlthe cycling of these trace gases. Therefore, a better understanding of CDOMphotochemistry is needed to quantitativelypredict trace gases emissions on a global scale.
Photochemical mineralization of CDOMresults in the production of significantamounts of dissolved inorganic carbon (DIC)as CO2. While the importance of this processto the marine carbon cycle has beenrecognized (e.g., Miller and Zepp 1995;Johannessen and Miller 2001), DICphotoproduction rates have not beendetermined in seawater. Estimates for theglobal oceanic flux of photochemicallyproduced CO2 range from 2.7 PgC yr -1
(Mopper and Kieber 2000) to ~12 PgC yr-1
(Johannessen 2000). In order to betterconstrain the magnitude of this flux, we havedetermined CO2 photoproduction rates andinvestigated the relationship between opticalproperties (i.e., CDOM character and
concentration) and CDOM photoreactivity ina variety of waters. Estuaries and othercoastal areas are of particular importance dueto large inputs of terrestrial organic matter.
We employed a highly sensitive analyticalsystem to measure CO2 photoproductionrates in the Northwest Atlantic Ocean andalong the salinity gradient of the DelawareEstuary. Prior to irradiation, ambient DIC wasstripped from acidified, 0.2 µm-filtered watersamples. After adjustment back to the originalpH, the resulting low DIC samples (< 0.5µmolC L-1) were pneumatically transferred togas-tight quartz tubes and exposed tosunlight in a circulating water bath.
Within the estuary, rates of photochemicalCO2 production were highest at thefreshwater end member (1.43 ± 0.04 µmolC L-1 h -1 at S = 0.09) and decreased non-linearlywith salinity to 0.15 ± 0.07 µmolC L-1 h-1
near the mouth of the bay. Differences inphotoreactivity along the salinity gradient werelargely due to the dilution of terrestrial CDOM,resulting in a constant CO2 photoproductionefficiency throughout the estuary. Based onour results, we estimate a loss of 1-5 % ofdissolved organic carbon (DOC) per day byphotochemical mineralization of CDOM insurface water of the estuary. With a flushingtime on the order of 100 days, photo-chemistry can account for a significant lossof organic carbon within the estuary.
Photochemical mineralization rates werecomparatively lower in Northwest AtlanticOcean, ranging from 0.020 to 0.130 µmol L -1 h -1 at open ocean and coastalstations, respectively. CO2 photoproductionwas dependent on the CDOM absorbance,quantified by the absorption coefficient at300 nm (a300). Our preliminary work withcoastal and open ocean waters indicates aturnover of 0.1-0.4% DOC per day in thecoastal surface ocean.
The efficiency of CO2 photoproduction (ratesnormalized to a300) differed with water typeaccording to the following trend: riverine >estuarine > oceanic. This suggests thatdifferences in CDOM character (i.e., terrestrialversus marine origin) must be consideredwhen using measurements of CDOM topredict photochemical production rates.
Acknowledgements
This study was based on work supported bythe National Science Foundation ChemicalOceanography Program (OCE-9711206, OCE-0196220 and OCE-0096426 to KM; OCE-9711174 and OCE-0096413 to DJK) andNASA Headquarters under the Earth SystemScience Fellowship Grant (NGT5-30431, EMW).
ReferencesJohannessen, S. C., 2000. A photochemicalsink for dissolved organic carbon in theocean. Ph.D. thesis. Dalhousie University.
Johannessen S. C., and W. L. Miller. 2001.Quantum yield for the photochemicalproduction of dissolved inorganic carbon inseawater. Marine Chemistry 76: 271-283
Miller, W. L., and R. G. Zepp., 1995.Photochemical production of dissolvedinorganic carbon from terrestrial organicmatter: Significance to the oceanic organiccarbon cycle. Geophysical Research Letters22: 417-420.
Mopper, K., and D. J. Kieber., 2000. Marine photochemistry and its impact oncarbon cycling, p. 101-129. In S. de Mora,S. Demers and M. Vernet [eds.], Effects ofUV Radiation in the Marine Environment.Cambridge Environmental Chemistry Series. University Press.
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
RiverineEstuarineOceanic
Figure: CO2 photoproduction rates in riverine, estuarine, and oceanic waters. Error bars denote thestandard deviation of replicate analyses of multiple light and dark treatments.
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Iron (Fe) is one of the nutrients needed byphytoplankton to carry out photosynthesis.The availability of Fe might limitphytoplankton productivity in large areas ofthe remote ocean, particularly in high-nitratelow-chlorophyll (HNLC) regions. The HNLCwaters comprise a large traction of the world’socean, and thus the supply of Fe to thesurface waters of the ocean may play a keyrole in regulating ocean productivity, theatmospheric CO2 concentration and climate(Jickells et al., 2005 and references therein).Since Fe is one of the most abundantelements in the Earth’s crust, atmospherictransport and deposition of mineral dust isbelieved to be the dominant source of new(not acquired via nutrient recycling) Fe to theremote ocean. While mostly soluble Fe isbioavailable, virtually all the Fe found at thesource regions is in a crystalline Fe-III form,highly insoluble in seawater (Jickells et al.,2005). Thus for phytoplankton to utilize theFe deposited in mineral dust, some fraction ofthe Fe must be mobilized during transport inthe atmosphere. The fraction of dissolved Fein airborne mineral dust (DIF) is uncertain.Previous estimates of DIF generally range fromless than 0.01% to more than 90%. Such alarge range, if used in global models, wouldchange ocean waters from being everywherestrongly Fe limited to Fe saturated (c.f., Funget al., 2000).
We have proposed an “acid-mobilization” as aprimary mechanism for the formation of solubleFe in mineral dust. The hypothesized mechanisminvolved acidification of dust by sulfur dioxide(SO2), an acidic trace gas emitted from industrialfacilities and power plants, and the subsequentdissolution of the Fe contained in acidic mineralaerosols (Meskhidze et al., 2003).
To further explore the combination of processesthat act to solubilize Fe in mineral dust along itsatmospheric trajectory we developed aLagrangian equilibrium model and used it tosimulate the chemical evolution of Fe duringdocumented episodes of Asian dust advectionover the North Pacific Ocean (NPO). The majorobjective of this research was to find out howvariations in anthropogenic air pollution andmineral dust may affect iron solubilizationduring the plume’s transport over the ocean.The model calculations were combined withremotely sensed data from space-borneplatforms to identify specific mineral dust eventsfrom East Asia, track their trajectories across thePacific Ocean, estimate the likely input ofbioavailable Fe to the surface waters of the NPOduring these dust events and determine if thepassage of these dust plumes across the Oceancan be correlated with the occurrence of achlorophyll-a pulse. Modeling results were quiteunexpected; for large dust storms that carriedvast amounts of mineral dust model predictednegligible amounts of dissolved Fe, while
Dust storm surprise: Pollution can convert airborne iron into soluble formNicholas Meskhidze1, Athanasios Nenes1,2 and William L. Chameides3 - contact: [email protected]
1. School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta GA, 30332; 2. Schoolof Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, 30332; 3. ChiefScientist, Environmental Defense, 257 Park Avenue South, New York, NY 10010
Nicholas Meskhidze completed his PhD in 2003 inatmospheric chemistry at Georgia Institute of Technology,where he is currently employed as a research scientist withAthanasios Nenes. His primary research interest is incomprehensive understanding of the mechanisms responsiblefor iron mobilization in mineral dust.
Figure 1: MODIS-observed [Chl a] over the NPO for the period of (a) 30 March to 6 April, 2001 and (b) 15 to 22April, 2001. The black color over the ocean denotes the missing data due to clouds, and the thin white lines indicatethe coastal boundary. The arrow indicates the location of an enhanced-[Chl a] patch (Meskhidze et al., 2005).
partner projects
The International Union of Geodesy andGeophysics (IUGG) is the internationalorganization dedicated to advancing,promoting, and communicatingknowledge of the Earth system, itsspace environment, and the dynamicalprocesses causing change.
Through its constituent Associations,Commissions, and services, IUGG convenesinternational assemblies and workshops,undertakes research, assemblesobservations, gains insights, coordinatesactivities, liaises with other scientific bodies,plays an advocacy role, contributes to education, and works to expandcapabilities and participation worldwide.
Data, information, and knowledgegained are made openly available forthe benefit of society.
IUGG Associations and UnionCommissions encourage scientificinvestigation of Earth science andespecially interdisciplinary aspects. The Associations of relevance to SOLASinclude the domains of Meteorology andAtmospheric Science (IAMAS) and thePhysical Sciences of the Ocean (IAPSO).
The IUGG will be holding its nextGeneral Assembly, entitled “Earth: OurChanging Planet,” in July of 2007, inPerugia, Italy. For more information,see http://www.iugg.org
Photo CreditsPg 2 (portrait) - Yuan LiuPg 2 (ship) - Min HuPg 3 (deck) - R. PowellPg 4 - Adam O’ConnorPg 6 - Andrew HallPg 8 - Sheikh Ali KarimPg 9 - Emily WhitePg 12 (Tim Jickells) - Tim JickellsPg 13 (Paty Matrai) - Fran ScannellPg 13 (Isabel Cacho) - Ben De MolPg 14 - Devrim TezcanPg 16 - Daniel FranksPg 18 - Margaret FowlerPg 21 - Thomas Scholl
solas news
www.so l a s - i n t . o rg / / 11
calculations showed that in small dust plumes0.5 - 10 % of mineral-Fe can be in dissolvedform. The differing results were attributed tothe ratio of dust to SO2 prior to the plumesdeparture from the continent. Because largestorms contain a higher proportion of calciumcarbonate they are highly alkaline and theamount of SO2 typically encountered in mostindustrial cities of China is not high enough toacidify mineral dust and initialize Fe dissolution.As small plumes get relatively easily acidified,the percentage of soluble Fe in small dustplumes can be many orders of magnitudehigher than large dust storms. The estimatedchange in phytoplankton population inferredfrom the model-calculated inputs of bioavailableFe for two historic dust transport episodes wasconsistent with the satellite-measured surfaceocean chlorophyll-a [Chl a] concentrations inthe NPO. Fig. 1a shows that the chlorophyll-aconcentration after the passage of small dustplume increased by more than an order ofmagnitude above the background level, whilethe large storm that deposited massive amountsof dust to HNLC waters of NPO showed noincreased phytoplankton activity (Fig.1b)(Meskhidze et al., 2005). Therefore, ourresearch showed that the recipe of addingpollution to mineral dust from East Asia mayactually enhance ocean productivity and, in sodoing, draw down atmospheric carbon dioxide.Thus, China’s current plans to reduce sulfurdioxide emissions, which will have far-reachingbenefits for the environment and health of thepeople of China, may have the unintendedconsequence of exacerbating global warming.
References
Fung, I.Y., S.K. Meyn, I. Tegen, S.C. Doney,J.G. John, and J.K.B. Bishop (2000), Ironsupply and demand in the upper ocean,Global Biogeochem. Cy., 14, 281-295.
Jickells, T. D., Z. S. An, K. K. Andersen, A. R.Baker, G. Bergametti, N. Brooks, J. J. Cao, P. W.Boyd, R. A. Duce, K. A. Hunter, H. Kawahata,N. Kubilay, J. laRoche, P. S. Liss, N. Mahowald,J. M. Prospero, A. J. Ridgwell, I. Tegen, R. Torres(2005), Global iron connections between desertdust, ocean biogeochemistry, and climate,Science, 308, 67-71.
Meskhidze, N., W. L. Chameides, A. Nenes, and G. Chen (2003), Iron mobilization in mineraldust: Can anthropogenic SO2 emissions affectocean productivity?, Geophys. Res. Lett., 30(21),2085, doi:10.1029/ 2003GL018035.
Meskhidze, N., W. L. Chameides, and A. Nenes(2005), Dust and pollution: A recipe forenhanced ocean fertilization?, J. Geophys. Res.,110, D03301, doi:10.1029/2004JD005082.
Areas that require more research:
• Full exploration of the significance of acidmobilization mechanism on a global carboncycle and climate.
• What fraction of bioavailable Fe in dustplumes mixed with high concentrations ofindustrial and power plant pollutants mayhave an anthropogenic origin?
• How and to what extent are the Femediated phytoplankton blooms affectingcloud properties?
A local artist creates the Hawaiian style SOLAS logo in the Waikiki International Marketplace. Go to page 22 to see the finished version, and to find out about SOLAS sessions held at theAGU/ASLO/TOS Ocean Sciences Meeting, Honolulu February 20-24, 2006.
Norway
Norway’s most significant connection to SOLAS science is through the EU-sponsored CARBOOCEAN programme(http://www.carboocean.org/). Much of the Norwegian component of thismultinational programme is conducted atthe Bjerknes Centre of Climate Research(BCCR) which has been nominated as aCentre of Excellence by the NorwegianResearch Council (NRC). Additionalwork of interest to SOLAS is the BCCRcontribution to the NRC projectCABANERA (Carbon flux and ecosystemfeedback in the northern Barents Sea inthe era of climate change;http://www.nfh.uit.no/cabanera/). BBCR also has joined the EUR-OCEANS(European Network of Excellence forOcean Ecosystem Analysis) network andhas developed a Marie Curie Training Siteon the role of ice-ocean-atmosphereprocesses in high latitude climate change.
The SOLAS liason for the InternationalPolar Year (IPY) is also located at BCCR([email protected]). For more information on SOLAS-Norway, contact the SOLAS NationalRepresentative, Abdirahman Omar([email protected]).
China (Taipei)
Three SOLAS-relevant research projectsare on-going: Asian Dust Storms andtheir Impact on Taiwan and Vicinity(ADS), Long-Term Observation andResearch of the East China Sea (LORECS),and South-East Asia Time-series Study(SEATS). The ADS project has beenconducting field surveys since 2002 andwill continue until 2010. LORECS wasinitiated in 2000 and aims to understandbiogeochemical cycles in the East ChinaSea under natural conditions and todetect changes induced by humanactivities. The response of phytoplanktonto dust storms in spring is one focus ofLORECS, which has close links with ADS.The SEATS project began in 1998 withseasonal cruises and moored instrumentsin the northern South China Sea. The intent of SEATS is to investigatebiogeochemical responses to physicalforcings at different time scales: short-term (typhoons), seasonal (monsoons)and inter-annual oscillations (ENSO). The standing National SteeringCommittee includes: Gwo-ChingGong ([email protected]),Kon-Kee Liu ([email protected]), andWu-Ting Tsai ([email protected]).
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The Scientific Steering Committe would like to extend a warm welcome tonew members Sergey Gulev and Isabel Cacho, and also a grateful farewell and sincere thanks to departing members Peter Schlosser and Elsa Cortijo.
Peter Schlosser is Vinton Professor of Earth and Environmental Engineering and Professor of Earth and Environmental Sciences at Columbia University, New York. He is also a Senior ResearchScientist at the Lamont-Doherty Earth Observatory and Associate Director of the Earth Institute at Columbia University. He received an MS from Heidelberg in 1981 and a PhD in 1985. Peter’sresearch focuses on water systems, primarily in oceans and groundwater including problemscaused by human impact. His studies of the hydrosphere utilize natural and anthropogenic tracesubstances such as radiocarbon, oxygen-18, radioactive hydrogen and its decay product He-3, aswell as measurement of noble gases. Schlosser’s ocean research concerns water circulation in theocean surface, movement into the deep ocean, and circulation patterns within the deep ocean, aswell as gas exchange at the air-sea interface. Current research also is directed toward explorationof mixing and gas exchange in river and estuary environments. Schlosser presently chairs theScience Steering Committee of the SEARCH program (Study of Environmental Arctic Change).
Elsa Cortijo is a CNRS research scientist in palaeoclimatology in the Palaeoceanographyteam at Laboratoire des Sciences du Climat et de l’Environnement in Gif-sur-Yvette(France), a laboratory of the Institut Pierre Simon Laplace (LSCE/IPSL). She is a specialist inmicropaleontology, and in geochemistry measurements on foraminifera shells, used toreconstruct the hydrological characteristics of water masses. During her pHD-thesis, sheworked on quantifying the North Atlantic hydrological changes during rapid climaticvariability in glacial times in terms of temperature and salinity, allowing for quantitativemodel reconstructions of the so-called Heinrich Events. Her recent research has focused on palaeoceanography during the interglacial periods, to understand the relationshipsbetween orbital forcing, sea level changes and ocean circulation changes. She is 37 years old and has published about 40 scientific papers. She was the head of thepaleoceanography team for several years and is currently associate director of LSCE.
...and thank you
Sergey Gulev’s primary research interests are in air-sea interaction processes and their role inclimate. He received an MSc degree from Moscow State University in 1980, and worked atthe State Oceanographic Institution; first as a Junior, then Senior Research Scientist, andbecame Head of the Marine Meteorology Lab in 1988. He joined the P.P. Shirshov Instituteof Oceanology of the Russian Academy of Science as the Head of the Air-Sea Interactionand Climate Laboratory. Over the course of the past decade, Sergey has conducted researchon the global analysis of ocean waves for basin-scale estimates of wind-wave interaction, inclimate diagnostics of synoptic activity of the atmosphere, and in ocean general circulationmodeling. He holds a position as Professor of Oceanography and Meteorology at MoscowState University. From 1996 to 2001, Sergey served as co-chair of WCRP/SCOR WorkingGroup on intercomparison and validation of ocean-atmosphere flux fields. Since 2001Sergey has been a member of the Joint Steering Committee of the WCRP.
Isabel Cacho graduated in Geology from the Universitat de Barcelona (Spain) in 1992. She was introduced to the research of ancient oceanography (paleoceanography) duringher Mater thesis performed in collaboration between the Universitat de Barcelona and the Universtität zu Kiel (Germany). During her PhD she was captivated by the study of past rapid climatic variability in the Mediterranean region by the analysis of molecularbiomarkers; the thesis was presented in the University of Barcelona in 2000. During 2000-2003 she moved to the fresher and stimulating atmosphere of Cambridge University(United Kingdom) where she broadened her geochemical training applied to thereconstruction of past sea water properties. Currently, she is a researcher in the Universitatde Barcelona working on paleoceanograpical reconstructions from different regions butmostly in the Eastern Equatorial Pacific, Mediterranean Sea and North Atlantic Ocean.
Welcome...
Sergey Gulev
Isabel Cacho
Peter Schlosser
Elsa Cortijo
www.so l a s - i n t . o rg / / 13
Tim JickellsTim Jickells was born and raised in Barry in South Wales. He then went to ReadingUniversity to do a degree in chemistry and subsequently to Southampton University foran MSc in Oceanography. He worked for the Clyde River Purification Board in Glasgow,and then Tim moved to a position at the Bermuda Biological Station before accepting aposition in the School of Environmental Sciences at the University of East Anglia. Timholds the position of Professor and Director of the Laboratory for Global Marine andAtmospheric Chemistry. His research interests include coastal nutrient cycling andatmospheric inputs to the oceans and their effects.
In each issue of SOLAS news, we give you the chance to meet some ofthe members of the SOLAS Scientific Steering Committee. This issue, we meet distinguished members from 4 continents.
Barry HuebertBorn in Nebraska, Barry Huebert is the son of a preacher, and as a child, Barry’s family movedevery few years all over the central US. He graduated from Occidental College with a degreein Chemistry in 1967 and from Northwestern University with a PhD in Physical Chemistry in1970. His concern about air pollution initiated his work on analytical methods for measuringatmospheric trace species, and several mentors taught him to continually challenge theassumption that results faithfully represent atmospheric concentrations. He is proudest ofthose projects that have improved our ability to measure concentrations and fluxes. Barrynow spends most of the year in Kailua, Hawaii with his wife and Shetland sheepdog. He alsospends part of the year in Colorado Springs, the home of his two grandkids. Barryspends his free time cooking for friends, gardening, and trying to rationalize spendinglarge sums of money on photographic equipment and large prints that don’t sell.
Paty Matrai Paty Matrai is a Senior Research Scientist at the Bigelow Laboratory for Ocean Sciences.She studied nutrient cycling in an upwelling system for her BS in Marine Biology fromthe Universidad de Concepción, Chile, and her MS from Scripps (SIO) focused onphytoplankton species distributions along an open ocean-to-coastal gradient. Paty alsoobtained her PhD from Scripps, with a study on organic sulfur cycling in marine waters.She served on the faculty at the Rosenstiel School of Marine and Atmospheric Sciencesat the University of Miami, and has been at Bigelow since 1995.
Paty’s current research is focused on biological production and consumption of organicsulfur and halogenated compounds of climatic relevance and their environmentalcontrols in various oceanic environments. This has led into research on the precursorsand controls of the production of new atmospheric particles in the Arctic, the role ofthe physiological ecology of phytoplankton and associated foodweb on carbon andsulfur cycling, and the inclusion of such biogenic rates and controls in climate models.
Mitsuo Uematsu Dr. Mitsuo Uematsu was born in Osaka, Japan. He received his PhD in Geochemistry fromHokkaido University, Japan in 1980. He then worked on the Sea/Air Exchange (SEAREX)Program at the Center for Atmospheric Chemistry at the Graduate School of Oceanography(GSO), the University of Rhode Island (URI) as a Research Associate from 1980 to 1987. Mits then joined the new Department of Marine Science and Technology at Hokkaido TokaiUniversity until 1997. He is currently a Professor at the Center for International Cooperation,Ocean Research Institute, at the University of Tokyo. Mits’ major research interests includethe long-range transport of natural and anthropogenic substances over the ocean, andmarine aerosol properties and their impact on marine environment. He serves as Vice-President of the Oceanographic Society of Japan and as a Chairperson of SOLAS-Japan.
/ / 14 su r f a ce ocean - l owe r a tmosphe re s tudy
Even though biologically produced gases inthe surface ocean are known to play animportant role in the global climate system,the relation between marine productivityand MSA (methanesulfonate) and non-sea-salt (nss) sulfate concentrations, used asatmospheric proxies for DMS, is notquantified explicitely so far. Yet anotherlimitation in our understanding of marineproductivity and climate connection is thelack of knowledge on the natural variabilityof DMS in marine ecosystems. Studies atocean time series sites are particularlyvaluable to comprehend the impact ofcompeting biotic and abiotic processes onDMS emissions to the atmosphere and toassess the fraction of DMS converted
ultimately to SO2 and MSA. Moreover,atmospheric inputs of dust likely modulatebiological production in the oceans and, inturn, modify the exchanges of climaticallyimportant trace gases between theatmosphere and oceans. Temporal andspatial variability of atmospheric dusttransport and deposition to the oceanhowever remains as an issue of activescientific research.
Being highly oligotrophic and limited withnutrient supply from rivers, Saharan-basedmineral dust transport and depositionconstitute an essential component of thebiogeochemical cycles of the EasternMediterranean ocean-atmosphere system.The atmospheric input of nutrients
Contributions of Black Sea Emiliania huxleyi blooms and Saharan dust to oceanic production ofatmospheric sulfur in the Northeastern MediterraneanNilgün Kubilay and Temel Oguz, Institute of Marine Sciences, Middle East Technical University, PO Box 28,Erdemli, 33731, Mersin-Turkey; Contact: [email protected], Personal Web Page:ttp://www.ims.metu.edu.tr/cv/kubilaynilgun/nil_cv.htm
Nilgün Kubilay is an Associate Professor in the Institute ofMarine Sciences of Middle East Technical University, Turkey. Herwork primarily involves studying chemical and optical propertiesof aerosols using observations through various instrumentationand aerosol samples collected on top of the 20m tall towerwithin the institute campus, situated on the Turkish coast.
Figure: Distributions of (a) aerosol methanesulfonate (MSA in ng m-3) and, (b) non-sea-salt (nss) sulfateconcentrations (in µg m-3) in samples collected during January 1996 to December 1999 at Erdemli (Turkey) and Finokalia (Crete) shown by blue and red circles, respectively.
partner projects
The Global Land Project Science Planand Implementation Strategy waspublished in 2005 and released at theInternational Human Dimensions Project(IHDP) Open Meeting in Bonn, duringwhich GLP was formally launched aftera handover from Land Use and CoverChange (LUCC) to GLP. GLP wasprovided interim leadership with Dennis Ojima and Richard Aspinall. The Science Steering Committee forGLP has been established and begun to develop an operational programme.The scientific challenges of GLP willneed the integrated efforts of both the Global Change and TerrestrialEcosystems (GCTE) and LUCC networksand communities operating within thenew GLP framework. GLP will alsoreach out to a wider spectrum ofdisciplines and networks to explore theconcepts associated with the dynamicsof land systems, consequences of land-system change, and integration ofanalysis and modelling for evaluation ofland sustainability. Close collaborationwith other Core Projects of theInternational Geosphere-BiosphereProgramme (IGBP) and IHDP will also bean important priority.
Call for ContributionsSOLAS News is published every six months, and we welcome yourcomments onthe content and layout.What would you like to see in your newsletter?
We need your contributions to thescientific and informational content. Do you have a meeting or activitycoming up, and would you like toinformthe SOLAS Network? Do youhave a science article for publication?
We welcome contributions fromgraduate students to senior researchers,articles short and long. Send an e-mailto [email protected]
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(primarily phosphate) acts as the mosteffective external source of nutrientspromoting biological production during the summer and autumn. The episodicdust events, particularly pronounced duringMarch-May period, further contribute tonew production on local and event scales.Our measurements, simultaneous withthose performed at a coastal site innorthern Crete during 1999-2000, indicatethat the atmospheric dissolved inorganicphosphate supplies 20 to 38% of the totalphosphate used for the new production inthe Eastern Mediterranean.
A four-year-long time series on aerosol MSA and nss-sulfate concentrations (Fig.)further revealed unexpectedly high biogenicsulfate production over this very poorlyproductive sea, and points to a very efficientocean-atmosphere coupling of sulfur cycle aswell as significant lateral transports over theregion. The measurements at Erdemlisuggest high (>150 ngm-3) MSAconcentrations during June-July of each year.Even monthly mean values of ~100 ngm-3
of the entire data set exceed significantlymany of those measured globally. The biogenically-derived monthly mean nss-sulfate concentrations of ~6 µgm-3 arethree-to-five times larger than the thosemeasured in open ocean regions and twiceas large asthose measured in continentalEurope originating from anthropogenicsources. The enhanced summer atmosphericsulfur cycling appears to be a basinwideevent in the Eastern Mediterranean as similar level concentrations are measured in Crete and Israel.
Analysis of the air mass back trajectory andthe SeaWiFS data suggests that the majorityof the biogenic contribution is originatedfrom the persistent summer coccolith-ophorid Emiliania huxleyi blooms developedin the Black Sea. The sulfate aerosolswhich are generated as a byproduct ofDMS oxidation in the atmosphere arecarried southward to the EasternMediterranean by the prevailing northerlylow-level boundary layer transport. Thisprocess occurs approximately from the mid-May to the end of September.
Prior to the initiation of the summer Black Sea-originated MSA and nss-sulfateintrusions, the Eastern Mediterraneanencounters its own local oceanic productionof MSA through occasional fertilization by Saharan dust transport events. Such fertilization episodes follow wet
deposition of Saharan dust particles, and are repeated two or three times per monthduring the April-May period, and accountsfor episodic, strong weekly changes in MSAconcentrations from their background valuesof ~50-75 ngm-3 to ~100-150 ngm-3
following the wet deposition events.
In summary, the Eastern Mediterranean is arelatively closed system connected with twoadjacent major sources regions (the BlackSea and Sahara) through efficientatmospheric transports. Very strongsignature of the ocean-atmosphere sulfurcycling makes it an ideal environment tocarry out more detailed studies to exploreand quantify many processes ofbiogeochemical coupling across the air-seainterface from oceanic, atmospheric, andclimate perspectives which are relevant toobjectives of the SOLAS Program.
Further Reading
Bonnet, S., Guieu, C., Chiaverini, J., Ras, J.,Stock, A., 2005. Effect of atmosphericnutrients on the autotrophic communities in a low nutrient, low chlorophyll system.Limnology and Oceanography 50 (6),1810-1819.
Cokacar, T., Oguz, T., Kubilay, N., 2004.Satellite-detected early summercoccolithophore blooms and theirinterannual variability in the Black Sea.Deep Sea Research I 51, 1017-1031.
Kubilay, N., Koçak, M., Çokacar, T., Oguz,T., Kouvarakis, G., Mihalopoulos, N., 2002.Influence of Black Sea and local biogenicactivity on the seasonal variation of aerosolsulfur species in the eastern Mediterraneanatmosphere. Global Biogeochemical Cycles16 (4), doi: 10.1029/2002GB001880.
Kubilay, N., Oguz, T., Koçak, M., Torres, O., 2005. Ground-based assessment ofTotal Ozone Mapping Spectrometer (TOMS) data for dust transport over thenortheastern Mediterranean. GlobalBiogeochemical Cycles 19, GB1022,doi:10.1029/2004GB002370.
Markaki, Z., Oikonomou, K., Kocak, M.,Kouvarakis, G., Chaniotaki, A., Kubilay, N.,Mihalopoulos, N., 2003. Atmosphericdeposition of inorganic phosphorus in theLevantine Basin, eastern Mediterranean:Spatial and temporal variability and its rolein seawater productivity. Limnology andOceanography 48 (4), 1557-1568
Russia
In Russia, SOLAS activities are currentlydeveloping at P.P. Shirshov Institute of Oceanology (IORAS), the MainGeophysical Observatory (MGO), and the Moscow State University (MSU). The Sea-air interaction laboratory (SAIL)at IORAS develops the analysis of globalwave and wind data, available fromVOS, satellites and numerical modeling.
The main objective is to quantitativelyestimate the impact of wind waves on air-sea energy and mass exchanges, and inparticular, on the gas fluxes between theocean and the atmosphere. SAIL/IORASis also developing methodologies forthe creating global and regional ocean-atmosphere surface flux fields and forestimation of sampling errors in surfacefluxes. MGO (Prof. Bortkovsky group)during the last years developed model of air-sea gas exchange which wassuccessfully used for computations of air-sea fluxes of CO2 and O2 in differentocean regions. Using this model andnumerical simulations with a climatemodel, MGO developed estimates ofclimatic CO2 and O2 fluxes in severalareas of Gulf Stream and Kuroshio zonesand projected these estimates on the mid and late 21st century. This allowed for theassessment of the role of mean windspeed changes in modification of oceanicCO2 uptake under anthropogenicwarming. The Radiochemical Laboratory of the Chemical Department of MSU (Prof. Sapozhnikov group) develops theanalysis of different metals in the surfaceocean layer using field observations in the Northwest Pacific and Black sea. MSU designs sophisticated laboratory and field equipment for analyzingmetals in the ocean.
New Zealand
The main findings of the NZ-SOLASexperiment ‘FeCycle’ are nowpublished in a special section of Global Biogeochemical Cycles - in theDecember 2005 edition and are alsoavailable on the AGU website as PDFs.
We have a voyage entitled “N-Cycle”taking place in the subtropical watermass NW of New Zealand in March2006. We will attempt to quantify therelative importance of N supply to theupper ocean via N fixation, atmosphericN deposition and internal wave activity.
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DMS is produced in the upper ocean withinvolvement of the whole planktonic foodweb, and a fraction of it is ventilated fromthe oceans to the atmosphere. Once in theatmosphere DMS undergoes a sequence ofoxidative reactions through interactionmainly with the hydroxyl radical (OH),giving rise to a range of products. Amongthem, non-sea-salt sulfate (nss-SO4) and, toa lesser extent, methanesulfonate (MSA) areof particular interest because of theirpotential role to form cloud condensationnuclei (CCN). MSA and SO4 particles arehighly hygroscopic and mainly occur in thesubmicron size fraction, ranging between0.1 and 1 um in diameter, which is theoptimal size range for CCN.
It has been postulated that DMS regulatesCCN formation and therefore that it has aclimatic role (the CLAW hypothesis).Globally, DMS emissions represent between25% and 35% of the estimatedanthropogenic sulfur emissions (65 TgS/yr)but they can account for essentially all nss-SO4 in vast regions of the remote oceans.The Southern Ocean (SO) atmosphere isregarded as one of the most unpollutedover the world, and therefore, it is the mostappropriate region for testing the validity ofthe CLAW hypothesis, or at least some oftheir central statements.
Optical sensors on satellites (e.g. NASA’sSeaWiFS and MODIS) offer the possibility of making quasi-synoptic, reliable and with high spatial resolution simultaneousmeasurements of ocean and atmosphericvariables at large scales. With such newmethodology and data, it is possible toinvestigate if the connection betweenmarine microbiota and CCN found in local studies also holds at larger spatialscales that are relevant for potential climate regulation.
A three-year time series set (from January2002 to December 2004) of monthly meansof satellite-derived chlorophyll and CCN, aswell as model outputs of OH, rainfallamount and wind speed for the SouthernOcean (40S - 60S) has been analyzed inorder to explain CCN seasonality.Chlorophyll is used as a proxy for oceanicDMS emissions since both climatologicalaqueous DMS and atmospheric MSAconcentrations are tightly coupled withchorophyll seasonality over the SouthernOcean. OH is included as the mainatmospheric oxidant of DMS to produceCCN, and rainfall amount as the main lossfactor for CCN through aerosol scavenging.Wind speed is used as a proxy for sea saltparticles production.
The CCN concentration seasonality ischaracterized by a clear pattern of highervalues during austral-summer and lowervalues during austral-winter. Linear andmultiple regression analyses reveal highsignificant correlations between CCN andthe product chlorophyll*OH (in phase) andrainfall amount (in anti-phase). Also, CCNconcentrations are anti-correlated withwind speed, which shows very littlevariability and a slight wintertime increase,in agreement with the sea salt seasonalityreported in the literature. Finally, thefraction of the total aerosol optical depthcontributed by small particles (ETA) exhibitsa seasonality with a 3.5 fold increase fromaustral-winter to austral-summer.
The biogenic contribution to CCN isestimated to vary between 35% (winter)and 80% (summer). Sea salt particles,although contributing an important fractionof the CCN burden, do not play a role incontrolling CCN seasonality over the SO.These findings support the central role ofbiogenic DMS emissions in controlling not
Do marine biota control CCN seasonality in the Southern Ocean?S. M. Vallina1, R. Sim1 and S. Gass2 - contact: [email protected]
1 Institut de Ciéncies del Mar - Consejo Superior de Investigaciones Cientficas (ICM - CSIC),Barcelona, Spain.(2) Goddard Earth Science and Technology Center (GEST), Universitiy ofMaryland, Baltimore County, Baltimore, Maryland, USA.
solas sponsor Sergio M. Vallina is a PhD student in Oceanography at the Institut de Ciéncies del Mar de Barcelona (ICM - CSIC). His main research is focused on globaldimethylsulfide (DMS) dynamics and its relationships to Cloud Condensation Nuclei (CCN) using satelliteimages, statistical analysis and modelling.
The Scientific Committee on OceanicResearch (SCOR) is one of the fourinternational co-sponsors of SOLAS.SCOR has been encouraginginternational cooperation in oceansciences since its formation by theInternational Council of Science in 1957.SCOR is currently sponsoring severalactivities related to SOLAS interests:
Second Symposium on The Ocean in a High-CO2 World—SCOR, theIntergovernmental OceanographicCommission, and the InternationalGeosphere-Biosphere Programme arebeginning planning for this symposium,to be held in late 2007 or early 2008.
SCOR has approved the Science Plan forGEOTRACES, which is an internationalstudy of the global marine biogeochemicalcycles of trace elements and their isotopes.GEOTRACES cruises are planned as part of the International Polar Year andGEOTRACES would like to makemeasurements of atmospheric sources oftrace metals to the ocean in cooperationwith SOLAS. The Scientific SteeringCommittee for GEOTRACES will beformed in the next few months. See www.geotraces.org.
SCOR sponsors working groups ontopics related to SOLAS, includingWG120 on Marine Phytoplankton andGlobal Climate Regulation, WG 123 onReconstruction of Past OceanCirculation (with IMAGES), WG 124 onAnalyzing the Links Between PresentOceanic Processes and Paleo-records(with IMAGES), WG 127 onThermodynamics and the Equation ofState of Seawater, and WG 128 onNatural and Human-Induced Hypoxiaand Consequences for Coastal Areas.
Information about all SCOR activitiescan be found on the SCOR Web site atwww.jhu.edu/scor.
Ed Urban has served as the SCORExecutive Director since October 2000.
only the number but also the variability ofCCN over the remote ocean.
Given that CCN concentrations seem to be modulated by oceanic DMS, it is very probable that cloud formation andtheir properties are affected too, withimportant implications for climate. We arecurrently working to apply this kind ofstatistical approach, based mainly onsatellite measurements and model data, toother oceanic regions and to expand it tothe global scale. Along with continuedfieldwork, this apprach should be veryuseful in future research addressing thevalidity of the CLAW hypothesis and itsimplications in Earth System functioning and Global Change.
Further Reading
Ayers, G. P., J. P. Ivey, and R. W. Gillet(1991), Coherence between seasonal cycles of dimethyl sulphide,methanesulphonate and sulphate in marine air, Nature, 349, 404-406.
Ayers, G. P., and J. L. Gras (1991), Seasonalrelationship between cloud condensationnuclei and aerosol methanesulphonate inmarine air, Nature, 353, 834-835.
Ayers, G. P., and R. W. Gillett (2000), DMS and its oxidation products in theremote marine atmosphere: implications for climate and atmospheric chemistry, J. Sea Res., 43, 275-286.
Prospero, J. M., D. L. Savoie, E. S. Saltzman,and R. Larsen (1991), Impact of oceanicsources of biogenic sulphur on sulphateaerosol concentrations at Mawson,Antarctica, Nature, 350, 221-223.
Vallina, S. M., R. Simo, and S. Gasso (2006),What controls CCN seasonality in theSouthern Ocean? A statistical analysis basedon satellite-derived chlorophyll and CCNand model-estimated OH radical andrainfall, Global Biogeochem. Cycles, 20,doi:10.1029/2005GB002597.
D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D0
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Figure: a) Seasonal evolution (years 2002 to 2004) and the associated Spearman correlation coefficientbetween CHL*OH (a proxy for atmospheric DMS oxidation) and CCN (variables are presented in standardizedform, i.e. subtracted the mean and divided by the standard deviation).b) Seasonal evolution (years 2002 to2004) of the contribution of small mode particles to the Aerosol Optical Depth (ETA parameter = AODsmall /AODtotal) as provided by MODIS, and seasonal evolution (years 2002 to 2004) of the estimated contribution ofbiogenic CCN to the total CCN burden (BETA = CCNbio / CCN).
Spain
The SOLAS-Spain subcommittee, a partof IGBP-Spain, is being re-founded.Ongoing activities include:
1) Assessment of the sources and sinksof CO2 in the Atlantic and Antarctic,and measurement of the drawdownof anthropogenic CO2
2) Study of the role of ecosystemmetabolic balance and hydrography in controlling air-sea CO2 fluxes
3) Study of the effects of aerosoldeposition, planktonic metabolism, UV, and organic matter on the air-seaexchange of CO2 and O2
4) Measurement of the air-seaexchange of organic carbon
5) Study of the biotic and abioticfactors that control oceanic emissionof DMS at multiple scales
6) Study of the contribution of DMSemissions to aerosol formation
7) Study of the role of air-sea interactionin the transport and fate of POPs
8) Study of Trichodesmium and N2fixation in the tropical Atlantic
/ / 18 su r f a ce ocean - l owe r a tmosphe re s tudy
The UK SOLAS funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe)project is built around three fieldexperiments. Two of these will take place in 2007 and aim to investigate the atmospheric multiphase mechanismscontrolling the impacts of halogens in the remote marine boundary layer. The third component is concerned with the characterisation of iodine chemistry and its impacts in coastally-influenced air.
In recent years, it has been found that thecoastal environment may be particularlystrongly influenced by reactive iodinecompounds1,2. Initial interest focussed on theeffects of iodine photochemistry insignificantly influencing the local oxidantbudget. The reactive radicals iodinemonoxide (IO) and iodine dioxide (OIO) areformed when iodine atoms are produced inthe presence of ambient ozone. The iodineatoms are released from the photolysis ofprecursors emitted into the atmosphere frombrown kelps such as Laminaria and Fucusspecies. Such emission of reactive iodineprecursors or “iodovolatilisation” has beenknown since the 1920s, and recently it hasbeen shown that a range of macroalgalspecies emit large amounts of halocarbons.Coastal halocarbon concentrations show atidal signature, and it is likely that infralittoralmacroalgal exposure at daytime low tide isthe key to increased emission flux.
In addition to the tidal signal in halocarbonemissions, the formation of ultrafineparticles at one of the coastal locationscharacterised by intense iodine chemistry3
has been found to be strongly correlatedwith the incidence of daytime low tides3,2
(see the top panel of the figure). The particle formation was linked to iodinephotochemistry in smog chamber studies of the photo-oxidation of diiodomethane(CH2I2), one of the most photolabilehalocarbons emitted by kelps3. However,both the details of the postulated
mechanism of particle formation and thenature of the iodine precursor have beenquestioned4,5 and it is now thought thatmolecular iodine (I2) emissions from themacroalgae are responsible for the particle“bursts”. The bottom panel of the figureshows that the increase in the total numberof particles formed by a unit mass ofLaminaria digitata in laboratory exposure toozone broadly follows the amount of I2emitted. It is important to establish the exact mechanism and source of theparticles, since the contribution to the direct reflection of incoming sunlight, andpotentially indirect increases in the albedothrough cloud formation, may makesignificant contributions to the radiativebudget on local and regional scales. Suchclimate effects and possible feedbackmechanisms are a major focus of SOLAS(indeed, the formation of new particles in the marine environment has beenpostulated as one of the key processes, with the greatest uncertainty, in the widelyinvestigated CLAW hypothesis). A model ofparticle formation from I2 has been used todemonstrate that the particles may be ableto grow to cloud condensation nuclei sizeunder ambient conditions2.
The RHaMBLe coastal experiment is due totake place in late summer 2006. We havebeen exploring possible locations on theNorth Brittany coastline and are hopefulthat collaboration with the CNRS StationBiologique de Roscoff will enable us tomake a large scale deployment ofinstrumentation from the shoreline adjacentto their station. We intend to make in situmeasurements of the concentrations of allpotential reactive iodine compoundsincluding IO, OIO, I2, CH2I2 and otheriodocarbons in addition to long-path opticalmeasurements of IO, OIO and I2, RelaxedEddy Accumulation (REA) measurements ofiodocarbon and I2 fluxes, Eddy Correlation(EC) measurements of particle emission andozone deposition fluxes and measurements
The science behind the coastal studies within the RHaMBLe projectGordon McFiggans1, Stephen Ball2, Bill Bloss3, Lucy Carpenter4, Dwayne Heard3, John Plane3
1 University of Manchester; 2 University of Leicester; 3 University of York; 4 University of Leeds
partner projects Gordon McFiggans is a NERC Research Fellow in the School ofEarth, Atmospheric & Environmental Sciences at the Universityof Manchester. His work focuses on chemistry & physics of theatmospheric aerosol, and he has a keen interest in the interactionsof marine boundary layer halogens with seasalt aerosol and in theformation of new particles from macroalgal emissions of iodine.
The Precursors to Particles (P2P) 2006campaign was conducted from 30 Janto 24 Feb, with scientists from Australiaand New Zealand, and groups from theUniversity of Heidelberg (UH) and theUniversity of Colorado. The campaignbuilt on the many routine observationsmade as part of the science program atthe Cape Grim Baseline Air PollutionStation. The aims of P2P were to identifythe precursors to particles at Cape Grim,with particular emphasis on biogenicprecursors from plankton and kelp. Theresearchers sampled during cleanonshore winds and light easterlies, thelatter bringing air from the beach belowCape Grim to the Station above.
Instrumentation included a ProtonTransfer Reaction Mass Spectrometer(PTRMS) from the AustralianCommonwealth Scientific and Research Organization (CSIRO) Marine & Atmospheric Research (CMAR),monitoring hydrocarbons, includingDMS. A CO2/O2 instrument from theNew Zealand National Institute of Waterand Atmospheric Research (NIWA) wasutilized to assess whether the oceanupwind of Cape Grim is a source or sinkfor CO2. There were a large number ofadditional instruments from CSIRO,NIWA and Queensland University ofTechnology, to augment the routineparticle program. These instruments are used to size particles in the range5nm up to 10 µm, assessing numberconcentrations and particle chemistry.Buckets of kelp were brought to theStation and placed in a flux chamber toassess particle formation and chemistry.
Three Multi-Axis Differential OpticalAbsorption Spectroscopes (MAX-DOAS)were used in the campaign. One (UH)sampling between 560-630 nm, focusedon OIO and I2 and the other two (UHand NIWA) sampled between 330-450nm, focusing on IO. A PhD student fromthe University of Tasmania performed 24hour assessments of methyl halides(surface water and air) and biology(species, nutrients, chl-a) from the beach,using a long tube out into Valley Bay. In addition, the student performed thesame measurements on a 5km transect,along 270°, at four stations, with fourdepths from surface to 20m.
The group at UH will use the data fromthe campaign in a model to assess particleformation at Cape Grim. Twice dailyradiosondes were launched to characterisethe boundary layer to determine thesize of the Cape Grim “box”.
Jill Cainey, Campaign Leader / Officer in Charge, Cape Grim Baseline Air Pollution Station
national reportsof the full aerosol size distribution. Such measurements should provide acomprehensive enough dataset tocharacterise the iodine-mediated particleformation phenomenon and enable adetailed analysis of its mechanism. Thiswork is needed to enable generalisation ofthe process and to give more confidence inthe estimates of the impacts of macroalgaliodine emissions.
Acknowledgements
Thanks to NERC for funding RHaMBLe andto Carl Palmer for providing the data for thebottom panel of the figure
References
1. Peters, T, S. Pechtl, J. Stutz, K. Hebestreit,G. Hönninger, K. G. Heumann, A. Schwarz,J. Winterlik, and U. Platt.: Reactive andorganic halogen species in three differentEuropean coastal environments, Atmos.Chem. Phys. Discuss., 5, 6077–6126, 2005
2. Saiz-Lopez, A., J. M. C. Plane, G.McFiggans, P. I. Williams, S. M. Ball, M.Bitter, R. L. Jones, C. Hongwei and T.Hoffmann.: Modelling molecular iodineemissions in a coastal marine environment:the link to new particle formation, Atmos.Chem. Phys. Discuss., 5, 5405-5439, 2005
3. O’Dowd, C., Jimenez, J. L., Bahreini, R.,Flagan, R. C., Seinfeld, J. H., Hämeri, K., Pirjola,L., Kulmala, M., Jennings, S. G. and Hoffmann,T. Marine aerosol formation from biogeniciodine emissions. Nature 417, 632-636, 2002b
4. McFiggans, G., H. Coe, R. Burgess, J.Allan, M. Cubison, M. R. Alfarra, R.Saunders, A. Saiz-Lopez, J. M. C. Plane, D.Wevill, L. J. Carpenter, A. R. Rickard and P. S. Monks.: Direct evidence for coastaliodine particles from Laminaria macroalgae –linkage to emissions of molecular iodine,Atmos. Chem. Phys., 4, 701-713, 2004
Figure: The top panel of the figure shows that the formation and growth of particles of diameter Dp isdependent on daytime low tides during the NAMBLEX field project at Mace Head on the West Coast of Irelandin 2002. The warmer colours represent higher particle concentrations. The bottom panel, taken from Palmer et al., Environmental Chemistry, 2, 282-290, 2005, shows the relationship between particle formation and iodineemission in laboratory exposure of Laminaria digitata.
United Kingdom
Fieldwork for the UK SOLAS programmemade a dramatic start in February witha combined ship and aircraft campaignoff north west Africa. At sea, EricAchterberg (Southampton) led a one-month research cruise measuring thequantities of atmospherically-deliverednutrients and their effects on the oceanecosystem. The cruise, on the Germanship RV Poseidon, started and ended inthe Canary Islands, with a port call atMindelo, Cape Verde. Meanwhile inthe air, Dr Ellie Highwood (Reading)carried out a series of sorties fromDakar, Senegal, in the NERC/Met OfficeBAe 146 research plane, to track thefate of dust storms from the Sahara and their meteorological (andclimatological) consequences.
Although there wasn’t a directoverflight of RV Poseidon, theinformation from the two studies willbe brought together to improve ourknowledge of air-sea interactions inthis important region. Further researchflights are scheduled for late summer,linked to AMMA (African MonsoonMultidisciplinary Analysis), whilstadditional UK SOLAS research cruises inthe Cape Verde region are planned forearly 2007 and 2008.
Media interest in UK SOLAS hasincluded a report in the Guardian (after their journalist joined theresearch cruise for a few days), and a special exhibit in London’s ScienceMuseum, “Scientists chase Saharansandstorms at sea”. For two days inApril, the exhibit included the scientiststhemselves – when Dr Achterberg andother cruise participants provided aninformal account of their work toseveral hundred visitors.
Next time...Coming up in the next issue of SOLAS News ….. Focus 3: Air-Sea Flux of CO2and Other Long-LivedRadiatively Active Gases.
If you would like to contribute to thenext issue, write to [email protected]
Biogeochemistry of DMS and DMSP in the sea-surface microlayerGui-Peng Yang, Wei-Wen Jing, Cheng-Xuan Li, Zhi-Qiang Kang, Gui-Sheng Song and Hong-Hai Zhang - Key Laboratory of Marine Chemistry Theory andTechnology, Ministry of Education, Ocean University of China, Qingdao 266003, China - contact: [email protected]
Dr. Gui-Peng Yang is currently a professor of marinechemistry at Ocean University of China and works onbiogeochemistry of DMS and DMSP in seawater withparticular emphasis on the sea-surface microlayer. He alsostudies liquid-solid interfacial chemistry and photochemistryof organic pollutants in marine environments.
The sea-surface microlayer, the upper severaltens to several hundreds micrometers of theocean surface, plays an important role in theglobal biogeochemical sulfur cycle. To date,almost all the studies on biogeochemicalprocesses of biogenic sulfur have beenconducted in the bulk surface water. Little is known about the distribution ofdimethylsulfide (DMS) and dimethyl-sulfoniopropionate (DMSP) in the sea-surfacemicrolayer. Therefore, a great research effortstill needs to be expended before we finallyunderstand the processes and factors thatcontrol biogenic sulfur distribution andcycling in the sea-surface microlayer.
For the distribution of DMS(P), we are normallyinterested in the extent to which the microlayeris enriched relative to subsurface water. Theenrichment factor (EF) is defined as the ratio ofconcentration of chemical constituent in themicrolayer to that in the subsurface water. EFvalues greater than or less than one representenrichment or depletion, respectively. Since1993, we have conducted over 10 cruises inthe China Seas, Japan coastal sea, the westernNorth Pacific and the western North Atlanticand studied the distribution of DMS and DMSPin the surface microlayer and subsurface waterand the factors influencing them. The in situinvestigative data showed that chlorophyll-aand DMSPp in the microlayer compared to thesubsurface water were enriched in somecircumstances and depleted in others.
In contrast, DMS was, in most cases, depleted inthe microlayer (Fig.), leading to an average EFvalue of 0.76. Sampling the microlayer fordissolved gases is generally very difficult. Owingto its volatility, a part of DMS in the microlayeris always unavoidably lost during the sampling.This was a probable reason why DMS wasdepleted in the microlayer. However, thisreason is not exclusive. Turner and Liss (1985)designed a cryogenic technique to samplemicrolayer sulfur gases, but no significantdifference was observed in enrichment factorsof DMS between the cryogenically collectedsamples and the screen-collected samples. Incontrast to general depletion of DMS in thesurface microlayer, there are a few reportsindicating surface microlayer enrichment ofDMS (Nguyen et al., 1978; Turner and Liss,1985; Yang, 1999). For instance, Turner andLiss (1985) found significant DMS enrichmentsin the microlayer at times of highphytoplankton production. Yang (1999)reported that DMS appeared to be enriched inthe surface microlayer of the South ChinaSea, where dinoflagellates, one of the mostsignificant DMS producers, accounted for 43% of the total phytoplankton species. These observations indicate that the degreeof enrichment of DMS in the microlayerseems to be highly dependent on bothalgal biomass and DMS production rate.
The most striking feature in the present studymay be the fact that DMSPd concentrations in
the microlayer always far exceeded those in thesubsurface water, resulting in high EFs rangingfrom 1.55 to 17.68 with a mean of 4.52. Thehigh enrichment of dissolved organic materialsuch as DMSPd in the surface microlayer couldbe, in part, attributed to simple Gibbs surfaceadsorption, i.e., a solute is concentrated at theair-sea interface when the surface tension ofthe solution is reduced (Adamson, 1976). Inaddition, our research showed that greatmicrolayer enrichments of DMSPd appearedmostly during the phytoplankton bloom whenchlorophyll-a appeared to have accumulated inthe microlayer. This observation suggested thatthe chlorophyll-a enrichment extent in themicrolayer might be an important factoraffecting the extent of enrichment of DMSPin the microlayer. Further research is required.
Further ReadingYang, G.-P., Levasseur, M., Michaud, S.,Scarratt, M., 2005. Biogeochemistry ofdimethylsulfide (DMS) and dimethyl-sulfoniopropionate (DMSP) in the surfacemicrolayer and subsurface water of thewestern North Atlantic during spring.Marine Chemistry 96: 315-329.
Yang, G.-P., Tsunogai, S., 2005.Biogeochemistry of DMS and DMSP in thesurface microlayer of the western NorthPacific. Deep-Sea Research I. 52: 553-567.
Yang, G.-P., Tsunogai, S., Watanabe, S.,2005. Biogenic sulfur distribution andcycling in the surface microlayer andsubsurface water of Funka Bay and itsadjacent area. Continental Shelf Research25: 557-570.
Yang G.-P., Watanabe, S., Tsunogai, S., 2001.Distribution and cycling of dimethylsulfide insurface microlayer and subsurface seawater.Marine Chemistry 76: 137-153.
AcknowledgementsThis work was supported by the NationalNatural Science Foundation of China undergrant Nos. 40476034, 40525017 and40490265. This is a contribution to theChinese SOLAS research program.Figure: Distribution of DMS and DMSPd in the sea-surface microlayer and subsurface water.
Roland von Glasow studied atmospheric physics in Mainz and received his PhD in 2001for modeling the chemistry of reactive halogens, sea salt aerosols, and cloud feedbacksin the marine boundary layer (MBL). After two years at Scripps, he began work at theUniversity of Heidelberg. His group focuses on tropospheric halogen chemistry,halogen-sulfur links, and the microphysics of aerosols and clouds in the MBL.
The primary objective of the project HitT is todetermine the importance of reactive halogencompounds (RHCs) in tropospheric chemistryand climate forcing. Key themes are theinfluence of RHC on the oxidative capacity ofthe atmosphere, the ozone budget on regionaland global scales, aerosol nucleation andgrowth. As the product of an expertworkshop held in Heidelberg, Germany in May2004 a White Paper is being finalized whichhas also undergone a phase of open discussionin the scientific community. This articlesummarizes the main ideas behind HitT and the envisioned implementation steps.Tropospheric halogen chemistry, its sources andatmospheric impacts is a very interdisciplinaryfield that involves disciplines like chemistry,physics, meteorology, and (micro-) biology.
Reactive halogen compounds (X, XO, X2, XY,OXO, HOX, XONO2, XNO2, where X, Y=Cl, Br, I)– in particular halogen oxides - are present invarious domains throughout the troposphere(see Figure). Characterization, quantification,and understanding their abundance and cycles has already begun in many of thedomains. However, beyond the present,pioneering and explorative efforts acomprehensive approach is needed, which is beyond the national scope and requiresinternational and interdisciplinary cooperation.
A major section of the HitT White Paper isdevoted to listing the current knowledgeregarding halogens in the troposphere andraises the main open questions.
The following topics were suggested toreceive priority in the next years:
1) Sources and distribution of RHCs:
Determine the emission fluxes of and keyrelease processes for RHCs and theirprecursors from the open and coastal oceans,polar regions, land surfaces, volcanoes, andurban-industrial areas. In order to achieve thisgoal existing techniques have to be refinedand new faster and more sensitive methodsfor measuring RHCs have to be developed.
2) Transformation and transport of RHCs:
Develop a detailed understanding of themultiphase chemical processes that determinethe distribution of RHCs and their precursorsat different spatial and temporal scalesthroughout the troposphere and the physicalprocesses including aerosol- and cloud-microphysics and transport. This effort shouldultimately lead to a realistic representation innumerical models.
3) Implications of RHCs:
Integrate different measurement techniques andmodels to determine the regional and global roleof RHCs in a series of physico-chemical processesin the troposphere, including: troposphericoxidation processes (esp. of sulfur species),the ozone budget, HOx and NOx radicalcycles, and aerosol nucleation and evolution.
Key to extending our knowledge are fieldcampaigns and long-term observations, whichwill be accompanied by and closely coordinated
with laboratory and modeling studies. We plan HitT activities over the next 9 years,divided into three 3-year phases. Each phaseshould comprise major field campaigns in areas (i.e. domains) where we know that RHCs are present. The goal of thesecampaigns is to provide all relevant informationto comprehensively address the researchquestions from all perspectives. Suited for thisare, for example, the polar regions (esp. duringthe International Polar Year 2007/2008), salt lakes (esp. Dead Sea with its specialtopography), coastal regions (Mace Head, Bayof Maine, Brittany, or other coastal regions withknown presence of iodine chemistry; the EU-funded MAP project started in October 2005),upwelling regions, and the open ocean.
In each phase, several pilot studies should bemade at promising sites, where no previoushalogen measurements were taken before inorder to identify locations suitable for largefuture campaigns. They should preferrably bedesigned as “add-ons” to other fieldcampaigns so that other measurements areavailable which can be helpful for a betterunderstanding of the underlying processes.Possible locations include coastal regions otherthan the previously studied locations like MaceHead and Appledore Island to investigate howwidespread coastal halogen chemistry is,megacities (both coastal and non-coastal), thetropics, and the free troposphere (airborne).
In addition to the field campaigns, long termobservatories are necessary to study temporaltrends. These are especially valuable for thepolar regions and the free troposphere. Atsome observatories halogen measurementsare already being made, other sites could be supplemented by a suite of RHCmeasurements. These long termobservatories include ground stations butsatellites and measurement packages aboardcommercial aircraft (CARIBIC II, IAGOS, etc)are also highly desirable.
The key research questions of HitT arefundamental topics also addressed in thesponsoring research activities IGAC andSOLAS. Close collaboration is envisioned withexisting international tasks. The next step forHitT is an implementation workshop whichwill be advertised shortly.
The SOLAS session on “Sea Surface Scienceand Marine Boundary Layers” was populatedby papers with a strongly mechanistic insightinto air-sea exchange, including severalpapers emphasizing surface waves, wavebreaking and bubbles.
Important new measurements werepresented of both the spectra of ordinarysurface waves (Hwang) and the characteristicscales and intensities of breaking waves(Gemmrich). The importance of differentwave scales is also an active area ofinvestigation (Zappa, Gemmrich). Previousresearch has mostly emphasized either“microscale” breaking or the dominant longwaves, but a strong case has emerged forconsidering intermediate scales wherebreaking is very intense. Several papersdiscussed the observation and modelling ofbubbles and their role in air-sea interaction(Soloviev, Woolf and Vagle). Measurements ofthe transfer velocity of DMS show a differentbehaviour to carbon dioxide at higher windspeeds, consistent with the importance ofbubbles (Huebert). New measurements athigh wind speeds are a priority, and David Hopresented new dual-tracer measurements inthese conditions. The importance ofwhitecapping and bubbles underlines theimportance of measurements of bubbles andwhitecapping (Soloviev, Woolf, Litchendorf).New measurements of gas saturationanomalies (Baschek, McNeil, Gueguen) andinvestigations of their relationship to forcingare also imperative. Marine surface films areanother important influence on air-seaexchange and appropriately receivedattention in several presentations; rangingfrom modelling of the attenuation of wavesby surface films (Brown) to the chemistry andmicrobiology of surface microlayers(Karuppiah, Wurl, Sintes). Mechanisticinsights into air-sea exchange demand a moresophisticated approach to retrieval of gastransfer velocities from satellite instruments;this was exemplified by the “dual-frequencyaltimeter” approach (Glover and Frew).
Chairs: D. K. Woolf, N. M. Frew and A. Soloviev
Aerosols in the Marine Atmospheric Boundary Layer
The first oral sessions was focussed on “Seaspray production and composition”. Topicsaddressed were satellite detection of whitecaps(Anguelova), laboratory studies on breakingwave energy and production rate (Fairall).Newly developed techniques were applied todetermine droplet production in the field(Norris) and a Phase-Doppler Anemometer wasflown by Asher. Organic material adds tomarine aerosol through the microlayer (Matrai)and through cloud processing (Altieri).
The second oral session was focussed on theatmospheric aerosol contribution to thenutrients cycle over the open ocean. Laboratoryexperiments were presented addressing the ironcycle processes at the air-sea interface (Losno;Paulk). Field experiment results were presentedby Nakamura and by Wagener, providing veryuseful information on atmospheric depositionover remote marine areas.
The poster session was a mix of these twosessions, with two posters on direct eddycorrelation measurements of aerosol fluxes(Griesbaumm; De Leeuw). Three postersaddressed dust input into the ocean: effects ofIron fertilization (Toda), the occurrence of dust(Losno), and measurements of sulphatesduring a dust event (Narita). Two posters dealtwith micro-organisms (Nagai; Shank).
Chairs: G. de Leeuw and R. Losno
Iron Workshop in WellingtonWhen John Martin originally proposed his ironhypothesis, he suggested primary productivityin areas of the ocean remote fromatmospheric dust sources was limited by ironsupply and that changes in this supply couldlead to climatologically significant changes inatmospheric CO2. The realisation of theglobal significance of atmospheric inputs toocean systems that flows from this hypothesiswas central to the development of SOLAS.
To test his hypothesis, Martin initiated severalcruises during which iron was added to watersamples which were then incubated shipboardto investigate the effects of iron addition. Whilethese experiments demonstrated a response toiron, concerns were expressed by somebiological oceanographers over “bottle effects”,arising from confinement of the planktoniccommunity within a small plastic bottle. These concerns over bottle effects led to thedevelopment of SF6 tracer techniques whichallow the addition of iron to unconfined oceanareas of several square kilometres to be tracked,even in the dynamic environments of highlatitude waters. This technique has now beenused in 12 large scale international experimentsto test the iron hypothesis.
During the first international SOLAS conference inHalifax in 2004, a series of discussion workshopswere held, and one of these considered what hadbeen learned from the various deliberate in situiron addition experiments that have taken placeover the previous decade. From this workshop it was clear that iron was now universallyrecognised as a key potential limiting nutrient ofmarine primary productivity, a major paradigmshift, provoked by Martin’s insight. The livelydiscussion at Halifax suggested that there weremany similarities and differences seen in the
/ / 22 su r f a ce ocean - l owe r a tmosphe re s tudy
SOLAS Special Reports
The participants in the 2005 Wellington workshop on iron enrichment pose for a photo near NIWA.
SOLAS sessions held at the AGU/ASLO/TOS Ocean Sciences Meeting, Honolulu February 20-24, 2006.
planktonic community response to iron additionsin the various experiments and that a synthesis of these responses would be very valuable. TheInternational SOLAS Scientific Steering Committeetherefore initiated a process to achieve such asynthesis and also to consider how this can helpdevelop our understanding of the oceanic ironcycle and the role of iron limitation.
To meet these goals we organised a meeting inWellington New Zealand from 30 October to 3November 2005 hosted by NIWA. We invitedleaders of each of the deliberate iron additionexperiments along with a group of experts onvarious aspects of the global oceanic iron cycle.In all, 21 people from 9 countries participated in the meeting including modellers andexperimentalists and with expertise ranging fromocean physics, through chemistry to biology. Theparticipants prepared short presentations aheadof the meeting which were delivered to themeeting and followed by extensive discussion. Asynthesis of some aspects of the results of theseexperiments was also published shortly beforethe Wellington material by Hein de Baar and hiscolleagues. During the meeting, we reviewed allaspects of the results of the iron additionexperiments, including physics, chemistry andbiology, to identify common responses to ironaddition in these experiments. In cases whereapparently rather different responses were seenwe investigated if these differences could berationalised by factors such as physical conditionsor antecedent biogeochemical conditions. Wealso compared the results of these experimentsto studies undertaken in areas of natural ironenrichment within otherwise iron poor areas,such as island systems in the Southern Ocean.This work then led on to sessions to considerwhat are the outstanding key issues that needto be addressed to further our understanding ofocean iron biogeochemistry and what strategies,including further iron addition experiments,should be adopted to address these issues.
Overall the meeting was a great success. Weanticipate that the results will appear as a peer-reviewed paper currently being written andauthored by all the participants. This synthesisesthe results of the iron addition experiments andtheir implications for our understanding of theoceanic iron cycle and its relation to the carboncycle. It also identifies the key future researchneeds. In addition to the science, we enjoyedthe excellent hospitality of our hosts NIWA andthe beautiful spring weather of the lovely city ofWellington, it was hard to leave.
We thank all the participants for theirenthusiastic contributions to the meeting, and we thank the SOLAS International ProjectOffice, NSF, UK Royal Society, NZ Royal Societyand NIWA for their financial support of themeeting, together with many of theparticipant’s home institutions.
Stéphane Blain (France), Ed Boyle (USA), Phil Boyd (NZ), Ken Buesseler (USA),Kenneth Coale (USA), John Cullen (Canada),Hein de Baar (Netherlands), Mick Follows(USA), Mike Harvey (NZ), Tim Jickells (UK),Cliff Law (NZ), Christiane Lancelot (Belgium),Maurice Levasseur (Canada), RaymondPollard (UK), Jorge Sarmiento (USA),Veroniqué Schoemann (Belgium), VictorSmetacek (Germany), Shigenobu Takeda(Japan), Atushi Takeda (Japan), Sue Turner,(UK), Andy Watson (UK).
The First Workshop on Asian Dustand Ocean EcoSystem (ADOES)On October 12-13, 2005, an annual workshopof Chinese SOLAS project granted by NFSC(National Foundation of Natural Sciences ofChina) was held at Weihai, Shandong, China.More than 50 researchers and an officer fromNFSC joined the meeting. Two cruisingobservation campaigns carried out duringMarch to May of 2005 over Yellow Sea andSouth China Sea were reported and primaryresults were exchanged and discussed.
After two days’ report and discussions on theannual progresses in Chinese SOLAS project, the First Workshop on Asian Dust and OceanEcoSystem (ADOES) was held on Oct. 14-15,organized by Ocean University of China andInstitute of Atmospheric Physics, ChineseAcademy of Sciences. Over 50 scientists fromChina, Japan and Korea participated in thisworkshop. An observer, Dr. Miguel D. Fortes,
head of office of the regional secretariat ofUNESCO-IOC/WESTPAC attended the workshop.
During the workshop, the scientists from China,Japan and Korea reported their progresses andthe up-to-date status and activities of the SOLAScommunities in their own countries, especiallythe studies related to Asian dust and its effects.Dr. Guangyu Shi, as the PI of the CNC-IGBP-SOLAS, proposed ADOES within the InternationalSOLAS framework, and the meeting approvedestablishment of a new ad hoc task teamADOES-TT for preparing the proposal. Theobjectives, scientific foci, implement strategy, andother relevant points for ADOES were proposedand discussed. Regional cooperation on SOLASwas discussed during the later session of theworkshop within Asian countries.
After discussion, it was unanimously agreedthat, Asian dust affects significantly marineecosystem of the North Pacific Region, andglobal oceans as well, as one of the criticalissues in global change studies, effect of Asiandust should be more emphasized in SOLASactivities; ADOES-TT would prepare a proposalto SOLAS SSC by the end of 2005; the secondADOES workshop would be scheduled tocomplete the proposal for establishing the taskteam; the regional cooperation should beenhanced, including exchange of personneland information, coordination of fieldobservations, application of joint researchprojects, etc., to make more contribution tothe SOLAS; ADOES is open for the researchersfrom SOLAS countries beyond Asia.
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