Organic Carbon, Nitrogen, and PhosphorusCycles and the composition of marine phytoplankton
1. C, N, P cycles
2. Major biochemicals in marine phytoplankton
3. Introduction to dissolved organic carbon
TOC in the N. Passic
From Peltzw and Hayward. 1996
Particulate organic carbon (POC) and
Dissolved organic carbon (DOC)
PARTICULATE w BACTERIA - DlSSOLVED
MESO. MICRO. NANO. PICO- PtANKTON -
- COLLOlDAL I I I
3
1OOmm IOmm 1mm 100nm IOnm TOA
i 0 . fmm 0.3 nm 0 .O.OOl mm 1 - POC IiDOC -e
-3
-2
-1
0
+1
+2
+3
+4
+5
Norg NH4+
N2
N2O
Fixa
tion
NO
NO3-
N re
duct
ionN
itrification
Denitrification
NO2-Oxi
datio
n st
ate
of N
itrog
en
THE NITROGEN CYCLE
Nitrogen CycleN2
Fixation(lightning)
Denitrification Fertilizer Factory
Bacteria in Nodules
AnimalsPlantsNO3
Decay and waste
DecomposersNH4+Nitrite Bacteria
NO2
Nitrate Bacteria
N Fixing Bacteria
Figure by MIT OCW.
GLOBAL NITROGEN FIXATION (GT N/YR)
Industrial
Fossil Fuel Combustion
Lightning
AgricultureForests, etc.
Ocean
0.05
0.02
0.01
0.090.05
0.04
Figure by MIT OCW.
Crust Ocean
Terrestrial
AtmosphereOutgassing 1
NOx Dep36 N2 Fix
150
Ind Fix40
MicrobNOx
8
NOxDep11
Denit147
NH3Vol 122
N2fix 40
NH3 Dep23
NH3 Dep 89
Weathering 5
Sedimentation 14
Rivers
Denitrification 30
THE NITROGEN CYCLE (Tg N/year)
34
Figure by MIT OCW.
Figure by MIT OCW.
Dissolved Nitrogen (pM) at HOTS
,... . .
0 l o 20 30 40 SO n i I
+ Nitrate
Dissolved organic Nitrogen
Bacteria
MicrobialFood Web
Protozoa Zooplankton Fish
Euphotic Zone
0-150 m
150-6000 m
Phytoplankton
Aggregation and Sinking of Particulate Organic Matter
Upwelling
Riverine Input (TDP):3.15 x 1010 mol p yr-1
Occanic P Reservoir3.2 x1011mol P
Atmospheric Input:1 x 1010 mol p yr-1
Preservoirs and Cycling in the Ocean
P Burial: 11-34.1 x 1010 mol P Yr-1Sedimentary P Reservoir1.3 x1011mol P
SRP
SNP
The pre-anthropogeric marine Pcycle. see text for detaills on fluxes.
Figure by MIT OCW.
Chlorophyceae Protein (green algae) Tetraselrnis rnaculata 72 Dunaliela salina 5 8
Chrysophyceae (golden brown algae) Monochrysis lutheri 53 Syracosphae ra carterae 70
Bacillariophyceae (brown algae, diatoms) Chaetoceros sp. 68 Skeletonerna costaturn 5 8 Coscinodjscz~s sp. 74 Phaeodac tylurn tricornu turn 49
Dynophyceae (dinoflagellates) Arnphidiniurn carteri 3 5 Exuriella sp. 37
Carbohydrate Lipid Ash
Average 57
RUBISCO
RUBISCO fixes CO2 in photsynthesis
fixes in photsynthesis
amino acid
R-C-COOH I
NH2
Proteins
proreins serve as eminyes and structural compomtsof cells
polymers of amino acids UN = 4, 80% of all nitrogen in marine algae
250% clf the carbon
CH
CH2H2C
CH
CC C C
O O
OO
C
C
C
C
OO
CH
CHHCHC CH
OH
CH2
CH2
S
CH2
CH2
CH2
C C C CNN N
HHH HH
HH
HH
NN
Methionine
Tyrosine
PEPTIDE
Figure by MIT OCW.
Figure by MIT OCW.
Figure by MIT OCW.
Amino Add Cmpdtlaa wf A l p hCowynmdCnmkr~l%6)
Picture removed due to copyright restrictions.
Palysacc haride analysis
H+ 1 hydrolysis
OO
O
hydrolysisH+
Polysaccharide Analysis
1
2
3
4
4
56
78
0Minutes
23
2 Fructose, Glucose3 Sucrose
Figure by MIT OCW.
Lipid biosynthesis occurs via two pathways
1) polyketide polymerization of acetate I(CH3000H). products usually have an even number of carbons
2) imprenoid polymerization of isoprene a five carbon HC Products have 10,15,20,rarbns
(head)
Figure removed due to copyright restrictions.Source Unknown.
Terrestrial Plant organic components
Lignin is a complex structural polymer of hydroxycinnamyl alcohols that are linked together in a number of different linkages and patterns Lignin and cellulose make up a large percentage of the carboninwoody and nonwoody tissues of higher plants.
Figure by MIT OCW.
DIN vs DIP,and TDN vs TDP at station ALOHA
00 0.4
Nitrogen versus phosphorus correlations for samples collected in the upper 0-400 m of the water column at Sta. ALOHA during the period October 1988 to December 1997. The bottom line is for nitrate plus nitrite (N+N) versus soluble reactive phosphorus (SRP) concentrations and the top line is for total dissolved nitrogen (TDN) versus total dissolved phosphorus (TDP). Model II linear regression analyses: N+N (µM) = 14.62 [14.58 to 14.66] SRP (µM) -1.08 [-1.10 to -1.06], r = 0.996, n = 3299 and TDN (µM) = 14.57 [14.45 to 14.69] TDP (µM) + 1.50 [1.44 to 1.56], r = 0.981, n = 2060. Values in brackets indicate the 95% confidence intervals of the respective slope and intercept values.
0.8Phosphorus (µM)
1.2 1.6 2
10
Nitr
ogen
(µM
) 20
30
Figure by MIT OCW.
DON and DOP at station ALOHA,HOTS
1100
900
700
500
300
100
00 2 4
DON (µM)
Dep
th (m
)6 8 10
1100
900
700
500
300
100
00 0.1 0.2
DON (µM)
Dep
th (m
)
0.3 0.4
Figure by MIT OCW.
N/P ratios at station ALOHA, HOTS
1000
800
Inorganic Total
600
400
200
00 5
N:P (mol:mol) N:P (mol:mol) N:P (mol:mol)10 15 0 10 20 10 15 20 25 30
Dep
th (m
)
Nitrogen-to-phosphorus (N:P) ratios versus water depth for samples collected at Sta. ALOHA during the period Oct. 1988 to Dec. 1997. (Left) Molar N:P ratios for dissolved inorganic pools calculated as nitrate plus nitrite (N + N): soluble reactive phosphorus (SRP). (Center) Molar N:P ratios for the "corrected" total dissolved matter pools. (Right) Molar N:P ratios for total dissolved matter pools, including both inorganic and organic compounds, calculated as total dissolved nitrogen (TDN) : total dissolved phosphorus (TDP). As a point for reference, the vertical dashed line in each graph is the Redfield-Ketchum-Richards molar ratio 16N:1P.
Figure by MIT OCW.
Global inventory of DOC
DOC measured by hightemperature catalytic oxidation(HTCO) method.
Global inventory was measured byInternational JGOFS program (680 GT C).
Depth pretty much the same everywhere,with high surface water values (40-80 uM C)and low deep water values (40 uM C).Deep sea concentrations are nearly constant.
Solar ility
14C Producfi~n Distribution amonC reservoirs
CaC6, Seds I
14C Production
Distribution amongC reservoirs
Geomagnetic Field Intensity
Cosmic Rays
Atm
Surf
Deep
Bio/Soils
14CO2
∆ 14C Cycle
SolarVariability
CaCO3 Seds
Deep
Surf
Variab
g
Figure by MIT OCW.
Radiocarbon Age of Dissolved Organic Carbon
ACID
DO1'C and 0Ii4C in the Atlantic Ocean
r Sargassa Sea DOC
L SaTgaw Sea DIG
D0I4C m d D 114C in the Atlantic and Pacific Ocean
I Sergarraa Sea WC
r Sam- Sea DIG
8 Paclflc Ocaan aOC
A PactflcOceen MC
Radiocarbon measurements show that the average ageof deep sea DOC is > 5000 yr. If the global inventory is700 GT C, then the annual flux of C to maintain the systemat steady state can be calculated as:
700 GT/ 5000 yr = 0.14 GT C yr-1
The annual input of DOC from rivers is 0.2-0.4 GT C yr-1, While annual marine primary production is 60-75 GT Cyr-1
Either source adds enough C per year to maintain the system.
So what is the source of oceanic DOC?
Origin of DOC from stable carbon isotopes
Wrap up
The elemental composition (C, N, P, S) of marine and terrestrialorganisms is a reflection of their biochemical composition at the molecular level.
Marine organisms (in terms of their carbon) are made of proteins > carbohydrates > lipids > nucleic acids. In terms of N, 70-80% is in proteins. The remaining is distributed betweennucleic acids, carbohydrates, pigments, etc. The proportions ofbiochemicals are variable and reflect both environmental factorsAnd physiological status.
N and P are limiting nutrients in the euphotic zone. Most ofthe N and P in the euphotic zone occur as DON and DOP.It is not known why these reservoirs of organic nutrients exist.Is the ocean N or P limited???
DOC is the largest reservoir of organic carbon in seawater. >98%of organic carbon in the ocean is DOC. It has high concentrationsIn the euphotic zone indicating net production or at least input.Values at depth are low (about half surface water values) and nearlyConstant.
Radiocarbon values of DOC are highly depleted, consistent withAn average residence time of 5000-6000 years. Several oceanMixing cycles!!! No one knows why, but surely this impactsOrganic nutrients.
