Joseph P. Smith, Joseph P. Smith, jpsmith@usna.edujpsmith@usna.eduOceanography Department, US Naval AcademyOceanography Department, US Naval Academy

Marine Biogeochemistry (Code 6114)U. S. Naval Research Laboratory, Washington, DC

Acknowledgements: Richard Coffin, Leila Hamdan, Rebecca Plummer, NRL, DC; Warren Wood, Allen Reed – NRL, Stennis MS; Kelly Rose – Department of Energy, NETL, Morgantown, WV

What are Gas Hydrates?What are Gas Hydrates?• Ice-like solids comprising a lattice of hydrogen-bonded water molecules;

guest molecules (methane, other gases) occupy cavities of the lattice

Hydrate Gas ContentStructure I

+H2OHydrate

164 m3 0.8 m3

Structure II

1 m3

Structure H “The ice that burns…”

Coffin, NRL

The Ice That BurnsThe Ice That Burns

Hydrate Stability ZoneHydrate Stability ZoneL• Low temperature

• High pressure• Methane source• Methane source

Free GasFree Gas

GEOTHERMAL GRADIENT

NETL

Deposits Occur as:• Disseminated Grains• Layers• Nodules• Veins (Fractures)Veins (Fractures)• “Cement”

Global Methane Hydrate Occurrence and NRL Hydrate Research

MITAS 09Beaufort Sea

AC07Alaminos Canyon, GoM

= Recovered Gas Hydrates

= Inferred Gas Hydrates = Planned NRL Research

= Past NRL Research

Why Conduct Methane Hydrate Research?

• Power and EnergyGl b l Cli t Ch• Global Climate Change

• Biodiversity• Global Carbon Cycle• Sediment Water Air Interactions• Sediment-Water-Air Interactions• Underwater Acoustics and Optics• Slope Stability

Organic Carbon in the Earth’s Reservoirs1

Gas hydrates( h & ff h )

Atmosphere, 3.6Waste material, 67

(onshore & offshore),10000

Peat, 500 Land (animal & plant), 830 Dissolved organic matter in water, 980S il 1400

2500-5000

Recoverable & non-

Soil, 1400

recoverable fossil fuels (coal, oil, natural gas),5000

Units = gigatons (1015 tons) carbon

Potentially Vast Energy Source

1After Kvenvolden, 1998; Does not include organic carbon dispersed in rocks/soil

…Potentially Vast Energy Source…

Coffin, NRL

Methane H d tHydrates:Hazards, ConcernsConcerns

• Formation in pipelines, bore-holes, etc.

• Dissociation – Release

• Slope Instability

Heriot Watt Institute of Petroleum EngineeringCentre for Gas Hydrate Research (www.pet.hw.ac.uk)

Slope Instability

MethaneMethane Hydrates:ClimateClimate

• Atm. CO2 ~400 parts per million2

• Atm. CH4 ~1790 parts per billion

• CH4 can trap about 20 - 40 x more h t (IR) th COheat (IR) than CO2.

USGS

Methane Hydrates: Underwater Acoustics and OpticsUnderwater Acoustics and Optics

Echosounder data from Westbrook et al., 2009.

SoundSound propagation in hydrate bearing sediments

Life at Hydrate Mounds and Cold Methane Seeps

Life at Hydrate Mounds and Cold Methane Seeps

www.noaa.govhttp://people.whitman.edu/~yancey/califseeps.html www.nasa.gov

Shallow Sediment Methane CyclingShallow Sediment Methane CyclingPhytoplankton

Shallow SedimentDissolved

SedimentO i

OrganicCarbon

DissolvedI i Shallow Sediment Organic

CarbonInorganicCarbon

SedimentInorganic

Methane

gCarbon

Deep Sediment Methane

Coffin, NRL

How to ConductHow to Conduct Methane Hydrate

Research?Research?BSR =

Bottom Simulating Reflector

• Presence of a BSR does not always indicate

hydrates

• Absence of a BSR does not always indicate lack of

hydratesy

www-odp.tamu.edu

Sediment Porewater Geochemistry

Anaerobic Oxidation of Methane (AOM):CH SO 2 HCO HS H O

Organoclastic Sulfate Reduction (SR): 2(CH2O) + SO4

-2 → 2HCO3- + H2O

CH4 + SO4-2 → HCO3

- + HS- + H2O

Methanogenesis:CO2 + 4H2 CH4 + 2H2O

Thermogenic Methane Production:CH3(CH2)n(CH3) >150C CH4SMI = Sulfate Methane Interface

SMT = Sulfate Methane Transition

• Sulfate (SO4-2)

• Sulfide (HS-)• Dissolved Inorganic Carbon (DIC)

AOM: CH4 + SO4-2 → HCO3

- + HS- + H2O

J α -Ds(dC/dz) ~ Methane Flux?*• Chloride (Cl-)• Methane* (CH4)SO4

-2 diffusion rates can be estimated from the slope of the linear fit to the SO4

-2

concentration gradient (Berner 1964

J α Ds(dC/dz) Methane Flux?

Borowski et al., 1999

concentration gradient (Berner, 1964, 1978, 1980).

CH4 + SO42- HCO3- + HS- + H2O

Vertical Methane Flux

A. Shallow BSR, high heat flow, sulfate depletionB. C.

No BSR, high heat flow, shallow SMIBSR, intermediate heat flow, SMI

SO4-2

A B

D. No BSR, low heat flow, deep SMI, ,

ACMBS

F C

D

Mound

Wipe Out SulfateBSRB

D

pC

Methane Flow

Coffin, NRLBorowski et al., 1999

Vertical Methane Flux Advection or DiffusionVertical Methane Flux Advection or Diffusion

OxidizationWater Column

Permeability trap

Anaerobic Methane Oxidation and Methane Production Shallow Sediment

Strat traps

Deep Sediment

ReservoirDistributed Source

Thermogenic and Biogenic Methane Production

Coffin, NRL

GeophysicsGeophysicsCrosslineCrosslineCrossline

Inline 986

14000 13960 13920 13880 13840 13800 13760 13720 13680 13640

De

2.68

Crossline

Inline 986

14000 13960 13920 13880 13840 13800 13760 13720 13680 13640

De

2.68

c16c21c14c4c8

epth (km)3.28

2.98

c7 c16c21c14c4c8

epth (km)3.28

2.98

c7

c15c5c6 c9c15c5c6 c9

Sediment CoringSediment Coring

Piston Coring

VibracoringVibracoring

Multicoring

Multicore and CTD CastsMulticore and CTD Casts

M lti coring CTD CastsMulti-coring CTD Casts

Core ProcessingCore ProcessingSampling

Thermal Profiles

Porewater sampling

Core SplittingCore logging

On Board GeochemistryOn Board Geochemistry

Coulometer Gas Chromatograph (GC-FID) Ion Chromatograph

Detailed biogeochemical analysis (stable isotopes, DOC, heavy isotopes, elemental analysis, porewater cations, particle size) performed in land-based

laboratorieslaboratories

Other Shipboard ActivitiesOther Shipboard ActivitiesBiology BiochemistryBiology, Biochemistry

Sedimentology & Lithostratigraphy

MicrobiologyMicrobiology

GEOLOGIC CONTROLS ON GEOLOGIC CONTROLS ON POREWATER GEOCHEMISTRY IN GASPOREWATER GEOCHEMISTRY IN GASPOREWATER GEOCHEMISTRY IN GAS POREWATER GEOCHEMISTRY IN GAS HYDRATE BEARING SEDIMENTS IN HYDRATE BEARING SEDIMENTS IN

THE GULF OF MEXICOTHE GULF OF MEXICO

U S Naval Research Laboratory (NRL) Marine BiogeochemistryU S Naval Research Laboratory (NRL) Marine BiogeochemistryU. S. Naval Research Laboratory (NRL), Marine Biogeochemistry U. S. Naval Research Laboratory (NRL), Marine Biogeochemistry (Code 6114), Washington, DC(Code 6114), Washington, DC

U. S. Naval Research Laboratory (NRL), GeologyU. S. Naval Research Laboratory (NRL), Geology--Geophysics Geophysics (Code 7432), (Code 7432), StennisStennis Space Center, MSSpace Center, MS

http://www.photolib.noaa.gov/coastline/line0043.htm

Methane Hydrates –Gulf of MexicoGulf of Mexico

Joint Industry Program in Gulf of Mexico involving: US Dept of Energy, Dept. g p gy pInterior, Chevron-Texaco, Schlumberger, Halliburton, ConocoPhillips, TotalFinaElf, Japan National Oil Corp.

Goals:• Characterize natural gas hydrates g y

in the Gulf of Mexico; and• Understand the hazards of drilling

through the hydrate stability zone

Atwater Valley

Status:• Geochemical, geophysical survey

conducted – NRL & USGSS l i

Alaminos Canyon

• Several sites• Data evaluation ongoing

Coffin, NRL

Crossline

14000 13960 13920 13880 13840 13800 13760 13720 13680 13640

AlaminosAlaminos Canyon 07 Line 986Canyon 07 Line 986

D

Inline 986

14000 13960 13920 13880 13840 13800 13760 13720 13680 13640

2.68SO4-2 CH4

DIC Depth (km

)

2.98

Cl-

c5c6 c15

c16c21c14c4c8

3.28

c7

c9

SO4-2 (mM)0 5 10 15 20 25 30

bsf

0

200

SO4-2 (mM)0 5 10 15 20 25 30

bsf

0

200

400

SO4-2 (mM)0 5 10 15 20 25 30

bsf

0

200

400

SO4-2 (mM)0 5 10 15 20 25 30

bsf

0

200

400

AC07 - Core 21

cmb 400

600

800

CH4 (mM)0 5 10 15 20 25

DIC (mM)0 5 10 15 20 25 30

AC07 - Core 5

cmb 400

600

800

CH4 (mM)0.00 0.02 0.04 0.06 0.08 0.10

DIC (mM)0 5 10 15 20 25 30

AC07 - Core 6

cmb 400

600

800

CH4 (mM)0 5 10 15 20 25

DIC (mM)0 5 10 15 20 25 30

AC07 - Core 9

cmb 400

600

800

CH4 (mM)0.00 0.02 0.04 0.06 0.08 0.10

DIC (mM)0 5 10 15 20 25 30

DIC (mM)

Cl- (mM)400 500 600 700 800 900 1000

DIC (mM)

Cl- (mM)400 500 600 700 800 900 1000

DIC (mM)

Cl- (mM)400 500 600 700 800 900 1000

DIC (mM)

Cl- (mM)400 500 600 700 800 900 1000

AOM: CH4 + SO4-2 → HCO3

- + HS- + H2O

Crossline

Inline 986

14000 13960 13920 13880 13840 13800 13760 13720 13680 13640

2.68 AlaminosAlaminos Canyon 07 Canyon 07

Depth (km

)

2.98

Line 986Line 986

c5c6 c15

c16c21c14c4c8

3.28

c7

c9

SO4-2

mol

/m2 -y

r) -50-40-30-20-10

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0(m

m -100

Dep

th

mbs

f)

00100015002000

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

SM

I (cm

0500

Cl-

M) 800

1000

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Avg

(m

400600

AtwaterAtwaterAtwater Atwater Valley 04Valley 04

SO

4-2

mm

ol/m

2 -yr) -300

-200-100

0

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0(m 0

Dep

th

mbs

f)

200400600

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

SM

I (cm

0200

Cl-

M) 800

1000

Reference Distance (km)-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Avg (m

M

400600

Gulf of Mexico Summary

• At the Atwater Valley 04 and Alaminos Canyon 07 sites, porewater geochemistry is largely influenced by local geology

• At the Atwater Valley 04 site, high methane vertical flux rates are likely due to fluid advection and increasing porewater salinity resulting from

salt intrusion reducing gas hydrate stabilityg g y y

• At the Alaminos Canyon 07 site there are relatively low CH4 fluxes and porewater geochemistry appears to be largely influenced by faults or

fissures evident in seismic data

• The occurrence and scale of geologic features at the two sites has a i ifi t i fl fl id fl d flsignificant influence on fluid flow and gas fluxes

• Targeted, high-resolution geophysical and geochemical characterization is critical to understanding fluid and methane flux in gas hydrate bearingis critical to understanding fluid and methane flux in gas hydrate bearing

marine sediments

Preliminary Data from Preliminary Data from Methane In The Arctic Methane In The Arctic yyShelf/SlopeShelf/Slope (MITAS) Expedition on the (MITAS) Expedition on the

Alaskan Beaufort Shelf/SlopeAlaskan Beaufort Shelf/Slopepp

Code6114

Marine Biogeochemistry

1 Naval Research Laboratory, Washington, DC. 2 Naval Research Laboratory, Stennis, MS.

3 National Energy Technology Laboratory, Morgantown, WV. 4 Universiteit Gent, Gent, Belgium.

5 Royal Netherlands Institute for Sea Research, Texel, Netherlands.

MITAS Research TeamChief Scientists

CS: Richard B. Coffin, NRLrichard.coffin@nrl.navy.milCO-CS: Jens Greinert, NIOZ, NetherlandsJens.Greinert@NIOZ.nl CO-CS: Warren Wood, NRL-Stenniswarren.wood@nrlssc.navy.milCO-CS: Kelly Rose, NETL-Morgantown

Layton Bryant, Milbar HydroTestMatt Cottrell University of Delaware

Kelly.rose@netl.doe.gov

Stefan Krause, IFM-GEOMARRandy Larsen St Mary’s College

Onboard ScientistsOnboard Scientists

Matt Cottrell, University of DelawareMara Dougherty, University of MarylandRoss Downer, Milbar HydroTestChad Greene, UTCraig Joseph, NETL

Randy Larsen, St. Mary s CollegeThomas Lorenson, USGSCurt Millholland, NRLJennifer Presley, NETLKoen de Rycker, RCMGS i R Sh h NRLLeila Hamdan, NRL

Pat Hart, USGSEdna Huetten, NIOZDave Kirchman, University of DelawareChris Kinoshita, University of Hawaii

Sunita R Shah, NRLJoe Smith, NRLTina Treude, IFM-GEOMARBrandon Yoza, HNEIPreston Wilson, UTChris Kinoshita, University of Hawaii ,

Why Study the U.S. B f t?Beaufort?

Studies of shelf and slope regions

Ground ice

p gin the Arctic worldwide have documented

Ground ice

Ice bonded

Permafrost

Sub permafrost

focused flow of methane from subsurface

l tiOil - Gas

Gas Hydratesaccumulations through sediments and into the overlying wateroverlying water column Coastal Permafrost &

Hydrate Stability ConditionsConditions

USGS

Rose , NETL

Potential Role of Gas Hydrates- USGS

Gas Hydrate Stability Zone Thickness

-15 -10 -5 0 5 10 15 20Temperature (°C)

0Gas Hydrate dissociation

Presenttime

13.5 kaBP

8 kaBP

Methane hydrate

from

seab

ed(m

)

-500

Dep

thf

-1000

Permafrost thawing

Gas Hydrate dissociation- USGS

Gas Hydrate dissociation

Rose , NETL

Collaborative Field PlanCollaborative Field Plan

CH4 CH4ShallowFlux to theAtmosphere

CO2 CO2

TDOM

ACDOM

ED

CO2

Acoustics

Water

Tundra Inputand Cycling

TGHS

PermafrostHydrate HCO -

AOMAerobic

DOMTDOM

GasCH4 C

2

HCO3-

ColumnMethaneCycling

PermafrostyCH4

HCO3Oxidation

Hydrates

Gas Hydrate Stability

AOMBBGHS

y

HCO3-

Methane

HydrateCH4

Free Methane Gas

Methane Cycling

Coffin, NRL

Three transects across the shelf & slope

Halkett

Thetis Is

Hammer Head

Rose , NETL

While at sea…• 12 days at sea (9/14 thru 9/26/2009)• 12 days at sea (9/14 thru 9/26/2009)• >4000 km of acoustic transects &

atmospheric measurements

Rose , NETL

While at sea…• 3 vibra-cores• 14 piston cores• 20 multi-cores• 34 CTD casts

Hammerhead – Slope

Hammerhead Offshore –Base of Slope PC04

• Site 4 was taken near the base of the slope in 2077 m waterin 2077 m water depth.

• It contained firm to very firm, silty clay.very firm, silty clay.

• At 34 cm a thick, 20 cm, poorly sorted, subangular tosubangular to subrounded gravel bed was present.

• With a scoured baseWith a scoured base this bed was underlain by a FeS mottled, clayey silt.

Gravel bed in PC04

Rose , NETL

LegendPiston Core

80 km

HammerheadHammerheadSO4-2 (mM)

0 5 10 15 20 25 300

SO4-2 CH4* DICcm

bsf

0

200

400

Halkett

SO4-2 (mM)0 5 10 15 20 25 30

0

200

Cl-

PC-04

600

800

CH4 (μM)0 2 4 6 8 10

0 5 10 15 20 25 30

Th ti I l d

Halkett

PC-02

cmbs

f

400

600

DIC (mM)0 5 10 15 20 25 30

Cl- (mM)400 500 600 700 800 900 1000

Prudhoe Bay

Thetis Island800

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 5 10 15 20 25 30

Cl- (mM)400 500 600 700 800 900 1000

SO4-2 (mM)0 5 10 15 20 25 30

f

0

200

Prudhoe Bay

Prudhoe Bay

Hammerhead

PC-03

cmbs

f

400

600

8000 2 4 6 8 10

Alaska North Slope

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 5 10 15 20 25 30

Cl- (mM)400 500 600 700 800 900 1000

Thetis – Shelf to Slope Transect

Thetis Offshore – Top of Slope PC08

• Site 8 was the upslope piston coring location on this transect. Th t i d fi t• The core contained firm to very firm, clayey silt with rare silt lamina F S ttli d b d• FeS mottling and bands throughout.

• Rare shell fragments and organic t i l t i th lmaterial were present in the lower

half of the core.

Photo of PC08 (with rhizon water samplers) illustrating the FeS

b d th h t thbands common throughout the middle of the cored interval

Rose , NETL

=LegendPiston Core

80 km

Thetis IslandThetis IslandSO4-2 (mM)

0 5 10 15 20 25 30

cmbs

f

0

100

200

300

SO4-2 (mM)0 5 10 15 20 25 30

f

0

100

200

SO4-2 CH4

DICCl-

Halkett

PC-08

400

500

600

CH4 (mM)0 2 4 6 8 10 PC-06

cmbs

f

300

400

500

600HalkettDIC (mM)

0 5 10 15 20 25 30

Cl- (mM)200 300 400 500 600 700 800

SO4-2 (mM)

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 5 10 15 20 25 30

Cl- (mM)400 500 600 700 800 900 1000

Prudhoe Bay

Thetis Island0 5 10 15 20 25 30

mbs

f

0

100

200

300

SO4-2 (mM)0 5 10 15 20 25 30

0

100

200Prudhoe Bay

Prudhoe Bay

Hammerhead

PC-09

cm

400

500

600

CH4 (μM)0 2 4 6 8 10 PC-07

cmbs

f

300

400

500

600

Alaska North Slope

CH4 (μM)

DIC (mM)0 10 20 30 40 50

Cl- (mM)400 500 600 700 800 900 1000

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 5 10 15 20 25 30

Cl- (mM)400 500 600 700 800 900 1000

Halkett – Shelf to Slope Transect

Halkett - Offshore Line

SMT@ 1036cmbsfSMT@ 629@ 629cmbsfSMT@ 373cmbsfSMT@ 147cmbsfSMT@ 106 cmbsfShallow Gas?USGS 77cmbsfShallow Gas?USGS 77 HalkettTransect

Rose , NETL

Halkett – Top of S C &Slope, PC12 & 13

• At Sites 12 & 13 gas-rich coresAt Sites 12 & 13 gas rich cores were recovered.

• Sediments were firm, clayey silts • FeS mottling shell fragments and• FeS mottling, shell fragments, and

terrestrial organic debris (reeds).

Rose , NETL

LegendPiston Core

80 km

HalkettHalkettSO4-2 CH4

SO4-2 (mM)0 5 10 15 20 25 30

0

200

SO4-2 (mM)0 5 10 15 20 25 30

0

200

DICCl-

PC-10

cmbs

f

400

600

800

HalkettPC-11

cmbs

f

400

600

800

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 10 20 30 40 50

Cl- (mM)400 500 600 700 800 900 1000

CH4 (μM)0 2 4 6 8 10

DIC (mM)0 10 20 30 40 50

Cl- (mM)400 500 600 700 800 900 1000

SO4-2 (mM)0 5 10 15 20 25 30

0

200

Thetis IslandSO4-2 (mM)0 5 10 15 20 25 30

0

200

SO4-2 (mM)0 5 10 15 20 25 30

0

200

PC-12

cmbs

f

400

600

Hammerhead

PC-13

cmbs

f

400

600

800

PC-14

cmbs

f

400

600

800

800

CH4 (mM)0 2 4 6 8 10 12 14 16

DIC (mM)0 20 40 60 80

Cl- (mM)200 300 400 500 600 700 800

Alaska North Slope

800

CH4 (mM)0 2 4 6 8 10 12 14 16

DIC (mM)0 20 40 60 80

Cl- (mM)200 300 400 500 600 700 800

CH4 (mM)0 2 4 6 8 10 12 14 16

DIC (mM)0 20 40 60 80

Cl- (mM)200 300 400 500 600 700 800

80 km

Piston Est. Sulfate

Cruise Line

Piston Core

NumberSMT

(cmbsf)φ

(avg)

Est. Sulfate Diffusion Rate (mmol/m2-yr)

Hammerhead PC02 5176* 0.63 -1.3

Halkett

Hammerhead PC02 5176 0.63 1.3Hammerhead PC03 2520* 0.64 -5.6Hammerhead PC04 - 0.51 -Th ti I l d PC06 0 63

Th ti I l d

HalkettThetis Island PC06 - 0.63 -Thetis Island PC07 1053* 0.48 -9.1Thetis Island PC08 176 0.48 -53.4

Thetis IslandThetis Island PC09 - 0.66 -Halkett PC10 1045* 0.72 -17.9Halkett PC11 - 0.71 -

HammerheadHalkett PC11 0.71Halkett PC12 145 0.68 -134.9Halkett PC13 106 0.66 -159.0H lk tt PC14 341 0 71 49 5

Alaska North Slope

Halkett PC14 341 0.71 -49.5

80 km

Halkett

Th ti I l d

Halkett

CH Diffusion Thetis IslandCH4 Diffusion Rate?

Hammerhead

Alaska North Slope

Arctic Ocean Surface Circulation

Arctic Ocean

tion.

htm

l

Arctic Ocean circulation. Image courtesy of Arctic Monitoring and Assessment P (AMAP)

cess

es/c

ircul

at Programme (AMAP), Figure 3.29, AMAP (1998).

rg/s

eaic

e/pr

ocht

tp:/

/nsid

c.or

h

Arctic Ocean Sea Ice Circulation

Plot showing mean (average) Arctic ice motion from 1978 to 2003 Arrowsto 2003. Arrows show the direction and velocity of the ice, with longer arrows representing higher velocities. Image courtesy of the National Snowthe National Snow and Ice Data Center, University of Colorado, Boulder, COCO.

LegendPiston Core

80 km

[CH[CH44] and ] and δδ1313CCCH4 (mM)

0.0001 0.001 0.01 0.1 1 10

0

δ13C-CH4, ‰VPDB

-110 -100 -90 -80 -70 -60 -50 -40

Thetis Island cmbs

f

0

100

200

300

400Thetis Island

Halkett

PC03500

600

700

800

CH4 mMδ13C-CH4

Halkett

CH4 (mM)CH4 (mM)

0.0001 0.001 0.01 0.1 1 10

0

100

δ13C-CH4, ‰VPDB

-110 -100 -90 -80 -70 -60 -50 -40

0.001 0.01 0.1 1 10

0

100

δ13C-CH4, ‰VPDB

-110 -100 -90 -80 -70 -60 -50 -40

Hammerhead

cmbs

f

100

200

300

400

500

cmbs

f

200

300

400

500

Alaska North Slope

PC08600

700

800

PC13600

700

800

SummarySummaryyy

• Spatial variation in estimated sulfate diffusion rates.East WestEast – West

Nearshore - Offshore

• Highest estimated sulfate diffusion rates and• Highest estimated sulfate diffusion rates and methane concentrations* observed in cores collected

on Western-most (Halkett) line.

• Higher sulfate diffusion rates and methane concentrations* observed in slope cores 200-1000m.

• Methane is biogenic source

“The Spring Thaw: Investigating Radiation and Conduction of Heat Energy in Soil Cores”:

Spring Thaw ModelHEAT LAMP =

Energy in Soil Cores :

Figure 1: Model Setup

SUN

A B

C

Figure 2: Participants

(A) Shaita Picard and Jourdan Jackson. (B) Dexter Miller. (C) Alcina Tran. (D) Jonathan Clifford.

SOIL CORE =

Temp. at 1 cmTemp. at

3 cm

Re-radiation

Soil

Radiation D Special Thanks:Kelly Houser

The Richard J. Murphy School

3 cmTemp. at

5 cm

Procedure:

1. Cool soil core in refrigerator (or freezer).

Materials:• Soil Core with holes @ 1cm,

So

Heat Lamp On Heat Lamp Off

g ( )2. When soil core is cold, remove from refrigerator and set up model as

shown in Figure 1.3. When ready, start experiment by turning on heat lamp and starting

stopwatch.4. Record temperature @ 1cm, 3cm, and 5cm each minute for 15 minutes.5. After 15 minutes, shut off heat lamp. 6. Record temperature @ 1cm, 3cm, and 5cm each minute for 5 more

Soil Core with holes @ 1cm, 3cm, 5cm • Heat Lamp• Stopwatch • Temperature Probes (3)• Colored Pencils, Rulers

Figure 3: Temperature vs. time @ 1cm, 3cm, and 5cm deep in the soil core. Student assessment performance1 suggests this lesson plan was successful in teaching the complex concept of heat transfer.

minutes. Also record temperatures @ 25 minutes, and @ 30 minutes.7. Record temperature ~1 hour after starting experiment.8. Create data table of measurements.9. Graph temperature @ each depth vs. time on the same graph (Figure

3).10. Discuss Results.

Target grade level:Grade 6 (groups of 4-6 students)

Duration: 65 min.

References:Lawrence Hall of Science, University of California Berkeley. (2004). “Water and Weather”. Full Option Science System (FOSS). Investigation 4: Heat Transfer. pp. 113-140.

Questions?Questions?Questions?Questions?

410410--293293--65686568jpsmith@usna.edujpsmith@usna.edu