joseph p. smith, [email protected] oceanography department ... · gulf of mexicogulf of mexico joint...
TRANSCRIPT
Joseph P. Smith, Joseph P. Smith, [email protected]@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, [email protected]: Jens Greinert, NIOZ, [email protected] CO-CS: Warren Wood, [email protected]: Kelly Rose, NETL-Morgantown
Layton Bryant, Milbar HydroTestMatt Cottrell University of Delaware
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?
[email protected]@usna.edu