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

pHSalinity

pH units & salinity

Dep

th (f

t)

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

pHSalinity

pH units & salinity

Dep

th (f

t)Water Column Data

Weeks BayTampa Bay

0 50 100 150 200 250-0.50.51.52.53.54.55.56.57.58.59.5

10.5

H2S and O2 sediment profile site 9

Sulfide

Oxygen

Concentration (μmol/L)

Dep

th (c

m)

Porewater DataWeeks BayTampa Bay

0 20 40 60 80 100 120-0.50.51.52.53.54.55.56.57.58.59.5

10.5

H2S and O2 sediment profile site 3

Sulfide

Oxygen

Concentration (μmol/L)

Dep

th (c

m)

Porewater DataWeeks BayTampa Bay

-300

-200

-100

0 100

200

300

400

500

-0.50.51.52.53.54.55.56.57.58.59.5

10.5

pH and redox sediment profile site 3

pH

Redox

pH and redox potential units

Dep

th (c

m)

-300

-200

-100

0 100

200

300

400

500

-0.50.51.52.53.54.55.56.57.58.59.5

10.5

pH and redox sediment profile site 9

pH

Eh

pH and redox potential units

Dep

th (c

m)

0 1 2 3 4 5 6 7-0.50.51.52.53.54.55.56.57.58.59.5

10.5

Porewater Iron Concentration for Site 3

Iron

mg/L

Dep

th (c

m)

0 1 2 3 4 5 6 7-0.50.51.52.53.54.55.56.57.58.59.5

10.5

Porewater Iron Concentration for Site 9

Iron

mg/L

Dep

th (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

Dep

th (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

epth

(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 ela52@msstate.edu