Institute of Food and Agricultural Sciences (IFAS)

Biogeochemistry of Wetlands S i Science and dA Applications li ti

SULFUR Wetland Biogeochemistry Laboratory Soil and Water Science Department University of Florida Instructor : Patrick Inglett [email protected] 6/22/2008 6/22/2008 6/22/2008

WBL P.W. Inglett

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Sulfur ‰ Introduction ‰

‰

S Forms, Distribution, Importance

Basic processes of S Cycles ‰ Examples

of current research ‰ Examples of applications ‰

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Key points learned

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Sulfur Learning Objectives ‰ Identifyy the forms of S in wetlands ‰ Understand the importance of S in wetlands/global processes ‰ Define the major S processes/transformations ‰ Understand the importance of microbial activity in S transformations ‰ Understand the potential regulators of S processes ‰ See the application of S cycle principles to understanding natural and man-made ecosystems

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Sources of Sulfur • Sulfur is a ubiquitous element element. • Various sulfur compounds are present in: – – – – – – –

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The atmosphere Minerals Soils Plant tissue Animal tissue Microbial biomass Sediment

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Reservoirs of Sulfur •Atmosphere •Lithosphere •Hydrosphere – Sea – Freshwater •Pedosphere – Soil S il – Soil Organic matter •Biosphere

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4.8 x 109 kg 24.3 x 1018 kg 1.3 x 1018 kg 3.0 x 1012 kg 2.6 2 6 x 1014 kg k 14 0.1 x 10 kg 8.0 x 1012 kg

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General Forms of Sulfur in the Environment • Organic S in plant, animal, and microbial tissue (as essential i l components off amino i acids id and d proteins) i ) Methionine

Cysteine H3C-S-CH2-CH2-

HS-CH2Thioester O R1-C~S-R2

– Organic sulfur primarily in soil and sediments as humic material (naturally occurring soil and sediment organic matter)

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General Forms of Sulfur in the Environment • Gaseous S compounds (SO2, H2S, DMSO, DMS) • Oxidized Inorganic S (sulfate, SO42-, is the primary compound). Seawater contains about 2,700 mg/L (ppm) of sulfate

• Reduced Inorganic S (elemental sulfur, So, and sulfide, S2-)

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General Forms of Sulfur in the Environment • Minerals Galena (PbS2)

Gypsum (CaSO4)

Jarosite(Fe2S)

Barite (BaSO4)

Pyrite (FeS2)

• Fossil F il Fuels F l – Petroleum (0.1-10%) – Coal (1-20%)

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Oxidation states of selected sulfur compounds • • • • • •

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Organic S (R-SH) Sulfide (S2-) Elemental S (S0) Sulfur dioxide (SO2) Sulfite (SO3-2) Sulfate (SO42-)

-2 -2 0 +4 +4 +6

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Global Sulfur Cycle

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Sulfur Cycling Processes 1. Dissimilatory sulfate reduction 2. Assimilatory sulfate reduction 3. Desulfurylation 4. Sulfide oxidation 5. Sulfur oxidation 6. Dissimilatory So reduction

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Sulfur Cycle So 4 5

SH groups

2

Aerobic

SO4

of protein

2-

Anaerobic

S2-

1 2

Anaerobic

Aerobic

3

3

SH groups 5

of protein

4 6

So 6/22/2008

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Distribution of sulfur in soils Organic sulfur [93%] – Carbon-bonded sulfur (cysteine and methionine) 41% – Non-carbon-bonded sulfur (ester sulfates) 52%

Inorganic sulfur [7%] – Adsorbed + soluble sulfates 6% – Inorganic compounds less oxidized than sulfates and reduced sulfur compounds (e.g. sulfides) 1%

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Organic Sulfur Forms 20 Freshwater

Sulfur, g/kg S

15 10

Brackish Salt

5 0

Ester

C-S

Total

Organic Geochemistry vol. 18, no. 4, pp. 489-500, 1992 6/22/2008

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Inorganic Sulfur Forms 4

400 Freshwater

3

Brackish

2

200 Salt

1

100

Sulfur, g/kg S

Su ulfur, mg/kg

300

0

0 FeS

So

FeS2

HCl

Krairapanond et al. 1992. Organic Geochemistry 18: 489-500. 6/22/2008

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Organic S Hydrolysis

R-S S-H H2 + H2O Thiol

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R-OH R OH + H2S

Sulfohydrolase

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Sulfur – Organism Groups Assimilatory Sulfate Reduction • Bacteria, Bacteria fungi fungi, algae, algae and plants

Dissimilatory Sulfate Reduction • Hetrerotrophs Desulfovibrio, Desulfotomaculum, Desulfobacter, Desulfuromonas

Sulfide Oxidation • Phototrophs: Chlorobium, Chromatium • Chemolithoautotrophs: Thiobacillus, Beggiatoa

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Sulfate Reducing Bacteria: SRB (habitats)

Desulfovibrio - found in water-logged soils. Desulfotomaculum - spoilage of canned foods. Desulfomonas - found in intestines. Archaeglobus - a thermophilic Archea whose optimal growth temperature is 83oC. C

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Sulfate Reduction Deposition

SO42Tidal Exchange

SO42AEROBIC

SO42-

Reduction

S2-

Reduction

SO42-

So Microbial Biomass-S

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Adsorbed 2 SO42-

ANAEROBIC

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Glucose Oxidation kJ/mol Glucose

Oxidation – Reduction Reaction C6H12O6 + 6O2 = 6CO2 + 6H2O

2,880

5C6H12O6 + 24NO3- + 24H+ = 30CO2 + 12N2 +42H2O

2, 712

C6H12O6 + 12MnO2 + 24H+ = 6CO2 + 12Mn2+ + 18H2O

1,920

C6H12O6 + 24Fe(OH)3 + 48H+ = 6CO2 + 24 Fe2+ +66H2O

432

C6H12O6 + 3SO42- = 6CO2 + 3S2- + 6H2O

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381

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Oxygen EquivalentsEnergy Yield from Glucose

% of Ae erobic Energy Yield

120 100 80 60 40 20 0

O2 6/22/2008

NO3MnO2 Fe(OH)3 Electron Acceptors P.W. Inglett

SO4222

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Oxidation-Reduction SO42CO2

Mn4+

S2-

CH4

-200

Fe3+

-100

0

Mn2+ NO3-

Fe2+

+100

+200

O2

H2O

N2

+300 +400

Redox Potential, mV (at pH 7) 6/22/2008

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Sequential Reduction of Electron Acceptors

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Redox Zones With Depth WATER

D Depth

SOIL

Oxygen Reduction Zone Eh = > 300 mV

I

II

Nitrate Reduction Zone Mn4+ Reduction Zone Eh = 100 to 300 mV

III

Fe3+ Reduction Zone Eh = -100 to 100 mV

IV

Sulfate Reduction Zone Eh = -200 to -100 mV

V

Methanogenesis Eh = < -200 mV

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Aerobic Facultative

Anaerobic

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Redox Potential and pH 1000

Eh [mV]

800 600 400 200 0 -200 -400 -600 6/22/2008

0

2

4

pH

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8

10 12 Baas Becking et al. 26

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Microbial Activity [Site: Water Conservation 2A] y = 0.33x + 1.3 r2 = 0.88; 0 88; n = 24

50

[mg kg-1 hour-1]

Sulfate e reducing conditions

60

40 30 20 10 0 10

0

20

30

40

50

60

Aerobic [mg kg-1 hour-1] 6/22/2008

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Sulfate Respiration Detrital Matter Complex Polymers

Enzyme Hydrolysis

Monomers Sugars, Amino Acids F tt Acids Fatty A id

Cellulose, Hemicellulose, Proteins, Lipids, Waxes, Lignin

Uptake

Glucose Glycolysis

Oxidative phosphorylation

Pyruvate

TCA Cycle Products: CO2, H2O, S2-, Nutrients

CO2

Substrate level phosphorylation

Acetate

SO42- + e-

Uptake

Lactate

Substrate level phosphorylation

Organic Acids [acetate, propionate, butyrate, lactate, alcohols, H2, and CO2]

ATP [Sulfate Reducing Bacterial Cell] 6/22/2008

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[Fermenting Bacterial Cell] 28

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Electron donors used during sulfate reduction

• SRB lack enzymes necessary for complex carbon assimilation

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Electron donors used during sulfate reduction

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Decreasing energy yield

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Electron Donors

Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. 6/22/2008

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Sulfate Reduction Rates Activity [[nmol/g g per p day] y]

Low carbon wetland

23

Peaty wetland

130

Oligotrophic lake

707

Eutrophic lake

1,224

Marine and salt-marsh

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744-24,000

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Salt Marshes Respiration [g C/m2 year] Sapelo Island Sippewissett Sapelo Island [GA] [MA] (199 ) (1997)

Aerobic respiration Denitrification Mn and Fe reduction Sulfate reduction Methanogenesis S Respiration

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390 10 ND 850 40 ~65%

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390 3 ND 1,800 1-8 18 ~82%

2,000

~69-87%

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Sulfate Respiration

Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. 6/22/2008

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Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. 6/22/2008

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Seasonal Effects

Jorgensen, 1977. Marine Biology 41:7-17. 6/22/2008

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Seasonal Effects Spartina alterniflora marsh Great Sippewissett Marsh

Moles SO42- m-2 d-1 M

05 0.5 0.4 0.3 0.2 0.1 0.0 J

F

M

A

M

J

J

A

S

O

N

D

Months Howarth and Giblin, 1983. Limnol and Oceanogr, 28:70-82. 6/22/2008

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Seasonal Effects Spartina alterniflora marsh

05 0.5

Moles O2 m-2 d-1 M

Moles SO42- m-2 d-1 M

0.03 0.4 0.3 0.2 0.1

0.02

0.01

0.0 -5

0

5

10

15

20

25

30

Temp (C)

-5

0

5

10

15

20

25 30

Temp (C) Howarth and Teal. 1979. Limnol and Oceanogr, 24: 999-1013.

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Regulators of Sulfate Reduction • P Presence off electron l t acceptor t with ith higher hi h reduction potentials • Oxygen is toxic to sulfate reducers • Sulfate concentration – Freshwater (< 0.1 mM) – Marine (20-30 mM)

• Substrate/Electron Donor • Temperature • Microbial populations 6/22/2008

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Decreasing energy yield

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Anaerobic Sludge Reactor (FISH) Sulfidogenic aggregate

Sulfidogenic/Methanogenic aggregate

Archeal Probe

SRB Probe

Appl Environ Microbiol. 1999 October; 65(10): 4618–4629. 6/22/2008

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Competition With Methanogens

X X X X

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Sulfate Reducers vs Methanogens

Sulfate reducers

Vmax

Vmax Methanogens

V = [Vmax S]/Km + S Km

Km [Substrate]

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Sulfate Reduction Typical Lake Sediments

mM SO42-

20

SO42-

0.4

10

mM CH4

0.6

CH4

0.2

20

0

40

60

80

100

Days from Jorgensen: in Microbial Geochemistry. Krumbein, ed: 1983 Blackwell. 6/22/2008

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Sulfate Reduction Typical Lake Sediments mM SO42-

mM SO420.1

0.2

20

10 0

12 8

2 SO42-

SO42-

0.5

1.0

0

m

cm

4

4

CH4

8 12

2.0 1

2 mM CH4

Freshwater 6/22/2008

CH4

1.5

0.5

1.0 mM CH4

Marine

from Jorgensen: in Microbial Geochemistry. Krumbein, ed: 1983 Blackwell. P.W. Inglett 46

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Sulfate Reduction Cattail Marsh – Sunnyhill Farm Wetland CH4 (mg L-1) 0

5

10

15

10

W t Water

0

Depth (cm)

Soil

CH4

-10

SO42-

-20

-30 0

20

40

60

80

100

SO42- (mg L-1) 6/22/2008

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Sulfate Reduction

Iversen and Jorgensen. 1985. Limnol Oceanogr, 30: 944-955. 6/22/2008

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Sulfur Emissions

H2S DMS

Mineralization

Org-S

H2S DMS

Mineralization

O S Org-S

AEROBIC

Reduction 2 S2-

Reduction

So

2 SO42-

ANAEROBIC

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Gaseous S Emissions

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Gaseous Speciation DeLaune et al. 2001

SALT

BRACKISH

FRESH

CO-S

H 2S

H3C-S-CH3

ug S m-2 hr-1

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Sulfide Formation

H2S DMS

Mineralization

Org-S

H2S DMS

Mineralization

O S Org-S

AEROBIC

Reduction 2 S2-

Reduction

So

2 SO42-

ANAEROBIC

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Sulfide Speciation

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Problems With Hydrogen Sulfide

• Malodorous (rotten egg smell) • Acidic (corrosion/fouling) • Toxic (reactive with metalloenzyme systems)

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Sulfide Toxicity Tall vs. Short Spartina alterniflora

Short Form

Tall Form

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Tall vs. Short Spartina alterniflora Sapelo Island Marsh

Tall

Creek

Short

Kostka et al., 2002. Biogeochemistry 60:49-76. P.W. Inglett 57

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Sulfide Toxicity Tall vs. Short Spartina alterniflora NH4+ Uptake Lower Vmax

Higher Vmax

Higher Km

Lower Km

MHT MLT

Inc. NH4+, S2-, and Salt Concentrations

Inc. Flood Frequency, Pore Water Turnover 6/22/2008

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Sulfide Precipitation

AEROBIC

Reduction 2 S2-

Reduction

So

2 SO42-

Me+-S

FeS2

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ANAEROBIC

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Iron and Sulfide Interactions 2F OOH + H2S = So + 2Fe 2FeOOH 2F 2+ + 4OHFe2+ + H2S = FeS + 2H+ FeS + So = FeS2

Acid Volatile S (AVS) 6/22/2008

Chromium Reducible S (CRS) P.W. Inglett

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Pyrite Framboids

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Pyrite Formation Fe Oxides Monosulfides (AVS)

FeS

ΣH2S

S0 Intermediate Redox S

FeS2 Pyrite (CRS)

Sulfate Reduction 6/22/2008

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Pyrite Formation Sapelo Island Marsh Solid--Fe Solid

AVS

CRS

Creek Tall Short

Kostka et al., 2002. Biogeochemistry 60:49-76. 6/22/2008

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ZnS

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Metal Sulfide Solubility% Uptake of added 35S

Uptake by Rice Plant 5 Na2S 4 3 2 MnS FeS ZnS

1 0 0 10

10-10

10-20

C S CuS

10-30

H S HgS

10-40

10-50

Solubility Product (Ksp) 6/22/2008

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Engler and Patrick, 1981

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Metal Sulfide Solubility

Yu et al. 2001. Wat Res. 35:4086-4094. 6/22/2008

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Sulfur Oxidation

Tidal Exchange

SO42H2S DMS

Oxidation

Oxidation

So

SO42-

AEROBIC

Reduction 2 S2-

So

ANAEROBIC

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Sulfide Oxidation 2H2S + O2 = 2So + 2H2O -204 204 kJ/ kJ/reaction ti

2So + 3O2 + 2H2O = 2SO42- + 4H+ -583 kJ/reaction

H2S + 2O2 = SO42- + 2H+ -786 86 kJ/reaction J/ eact o

H2S 6/22/2008

So

SO32P.W. Inglett

SO4268

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Sulfur Cycling Cyanobacterial Mat Sediments

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Sulfur Cycling Cyanobacterial Mat Sediments

Surface Aphanothece Diatoms 6/22/2008

Green Layer Phormidium, Lyngbya P.W. Inglett

Red Layer Chromatium salexigens Thiocapsa halophila. 70

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Oxidation-Reduction Soil-floodwater Interface O2 Floodwater Aerobic soil

SO42-

H2S + O2

SO42-

H2S

Anaerobic soil

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Sulfur Cycling Salt Marsh Surface Sediments

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Oxidation-Reduction Root- Soil Interface

AEROBIC

ANAEROBIC

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Oxidation-Reduction Infaunal Burrows

Uca spp.

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Oxidation-Reduction Infaunal Burrows

ca. 12” Deep

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Sulfur Cycle

Rates = mmol/m2 day from Jorgensen: in Microbial Geochemistry. Krumbein, ed: 1983 Blackwell. 6/22/2008

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Pyrite Oxidation FeS2 + 3.5O2 + H2O = Fe2+ + 2SO42- + 2H+ Fe2+ + 0.25O2 + H+ = Fe3+ + 0.5H2O (1) FeS2 + 3.75O2 + 0.5H2O = Fe3+ + 2SO42- + H+ (2) FeS2 + 14Fe3++ 8H2O = 15Fe2+ + 2SO42- + 16H+

O2

Fe2+

Slow (at low pH) Biological

[Thiobacillus ferrooxidans]

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Fe3+ P.W. Inglett

SO42- + H+ Fast Chemical/ Biological

FeS2

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Drainage Effects on Acid Sulfate Soils

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Acid Sulfate Soils

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Acid Mine Drainage

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Sulfur Cycling in Wetlands Plant Biomass-S

Deposition

SO42Litterfall

H2S DMS

Tidal Exchange

SO42Mineralization

Org-S

H2S DMS

Mineralization

S2-

SO42-

Org-S

So

Reduction 2 S2-

Me+-S

FeS2 6/22/2008

Oxidation

Oxidation

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.

SO42-

Reduction 2 SO42-

So Microbial Biomass-S

AEROBIC

Adsorbed SO42-

ANAEROBIC

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Hg Methylation

Gilmore et al., 1992. Env Sci Tech. 26:2281-2287. 6/22/2008

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Hg Methylation

Gilmore et al., 1992 6/22/2008

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Hg Methylation Desulfobacteriaceae Acetate

Lactate

Control

King et al., 2000. Applied and Environmental Microbiology, June 2000, p. 2430-2437.

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Hg Methylation

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Periphyton Delta 32S September 1996

87

Methylmercury in Floating Periphyton All Cycles 1995-1996

ug/k g

> 6 4

2

0

Kendall et al., http://sofia.usgs.gov/publications/posters/ 6/22/2008

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Hg Methylation S2S0

Hg

HgS0

?

HgS2 6/22/2008

H3C-Hg

SRB

SO42P.W. Inglett

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Importance of Sulfur in Wetlands

• • • • • • •

Source of nutrient Source of energy Role in decomposition of organic matter Adverse effects of sulfide on plant growth Immobilization of toxic metals Contribution to acid development (oxidation) Role in methylation of Hg

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