determining a proxy for sediment oxygen demand of coastal estuaries erin anderson 1, karen mcneal 1,...
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Determining a PROXY for Sediment Oxygen Demand of Coastal
Estuaries Erin Anderson1, Karen McNeal1, Mel Parsons2, Sandra Ortega-Achury3, Curry Templeton1, Alon Blakeney4,
Jonathon Geroux1
This material is based upon work supported by the National Science Foundation under Grant No. DGE-0947419 and the USEPA under Grant No. AE83604801at Mississippi State University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation and the USEPA.
1Department of Geosciences, Mississippi State University, PO BOX 5448, Mississippi, 397622 USEPA Region 4 Science & Ecosystems Support Div., 980 College Station Road, Athens, GA 30605-27203Department of Civil and Environmental Engineering, Mississippi State University, PO Box 9546, Mississippi, 397624Department of Biology, Mississippi State University, PO Box 9536, Mississippi, 39762
Sediment Oxygen Demand
SOD = O2 used by biological +
chemical processes
http://apps.startribune.com/blogs/user_images/fdsmith_1332283277_1fishkill0321.jpg
High SOD + Low O2 =
http://www.tampabay.com/multimedia/archive/00188/clwbloom082711_188617c.jpg
High SOD + Low O2 =
Microbial Metabolisms
http://njscuba.net/zzz_biology/low_oxy_evnt_1.gif
• Non-ubiquitous O2
circulation
• Decomposition and
Respiration still occurring
• Low O2 levels cause death,
continuing
decomposition
Biological SOD
Fe (II)Mn (II)
Fe(OH)2
Mn(OH)3
Fe (II)Mn (II)
Chemical Sediment Oxygen Demand
http://www.sciencedirect.com/science/article/pii/S0141113612001043
1. Can we estimate SOD without benthic oxygen chambers?
Research Questions
1. Can we estimate SOD without benthic oxygen chambers?2. Can geochemical
measurements in the water column and porewater give an accurate prediction of SOD?
Research Questions
http://www.envcoglobal.com/files/MO-YSI-600R.jpg
•pH
•Eh
•Temperature
•DO
Water Column
Porewater
• Eh
• pH
• Oxygen
• Sulfide
http://www.unisense.com/files/Images/Sensorbilleder/PH-100_900x430.jpg
•Aluminum
• Iron
•Manganese
•Sulfide
Porewater
Sediment• Short-Term (C-D) Reactive Iron• Long-Term (HCl) Reactive Iron
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
6
8
10
12
Water Column pH and Salinity for Site 9
pH
Salinity
pH units & salinity
De
pth
(ft
)
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
6
8
10
12
Water Column pH and Salinity for Site 3
pH
Salinity
pH units & salinity
De
pth
(ft
)
Water Column Data Weeks BayTampa Bay
0 50 100 150 200 250-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
H2S and O2 sediment profile site 9
Sulfide
Oxygen
Concentration (μmol/L)
De
pth
(c
m)
Porewater DataWeeks BayTampa Bay
0 20 40 60 80 100 120-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
H2S and O2 sediment profile site 3
Sulfide
Oxygen
Concentration (μmol/L)
De
pth
(c
m)
Porewater DataWeeks BayTampa Bay
-300
-200
-100
0 100
200
300
400
500
-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
pH and redox sediment profile site 3
pH
Redox
pH and redox potential units
De
pth
(c
m)
-300
-200
-100
0 100
200
300
400
500
-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
pH and redox sediment profile site 9
pH
Eh
pH and redox potential units
De
pth
(c
m)
0 1 2 3 4 5 6 7-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
Porewater Iron Concentration for Site 3
Iron
mg/L
De
pth
(c
m)
0 1 2 3 4 5 6 7-0.5
0.5
1.5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
Porewater Iron Concentration for Site 9
Iron
mg/L
De
pth
(c
m)
Porewater DataWeeks BayTampa Bay
Weeks BayTampa Bay
Solid-Phase Reactive Iron
6.0 56.0 106.0 156.00.00
2.00
4.00
6.00
8.00
10.00
Total Solid Reactive Fe for site 3
HCl Fe C-D Fe
Fe Concentration mg/L
De
pth
(c
m)
6.0 56.0 106.0 156.00.00
2.00
4.00
6.00
8.00
10.00
Total Solid Reactive Fe for site 9
HCl Fe
C-D Fe
Fe Concentration mg/LD
ep
th (
cm
)
Tampa & Weeks PCA Eigenvalues > 1
Factor Component 1(49.89 %)
Component 2(39.79%)
SOD -.150 -.741
H2S_core .664 .734
pH_core -.926 -.184
O2_core .889 .413
Eh_core .429 .818
Fe_PW .189 .910
CD_Fe .892 .398
HCl_Fe .876 .456
H2S_OW .704 .684
O2_OW .262 .941
Eh_OW -.625 -.704
pH_OW -.899 -.401
Temp -.909 -.090
*
*
TemppH_PW
pH_OW
Eh_OW SOD
Fe_PWO2_OW
Eh_core H2S_coreH2S_OW
HCl FeO2_core
CD_Fe
Component Plot in Rotated SpaceCo
mpo
nent
2
Component 1
KeyWC = Water ColumnPW = PorewaterCore = porewater
Com
pone
nt 2
Component 1
TemppH_PW
pH_OW
Eh_OW SOD
Fe_PWO2_OW
Eh_core H2S_coreH2S_OW
HCl FeO2_core
CD_Fe
Component Plot in Rotated Space
KeyWC = Water ColumnPW = PorewaterCore = porewater
Com
pone
nt 2
Component 1
TemppH_PW
pH_OW
Eh_OWSOD
Fe_PW O2_OW
Eh_core
H2S_coreH2S_OW
HCl FeO2_core
CD_Fe
Conclusion & Future Goals• Preliminary data suggest an easier indirect proxy to
estimate SOD exists
• Which proxies consistently fluctuate with SODs in SEUS estuaries?
• Can we build and validate a diagenesis model, using an empirical model based on the Chesapeake Bay Sediment Flux Model for SOD estimation?
• Why do certain factors fluctuate with SOD?
Acknowledgements• NSF GK 12 Project Grant No. DGE-
0947419 • USEPA under Grant No. AE83604801
• A.D.’s camera skills
Erin Anderson [email protected]