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Institute of Food and Agricultural Sciences (IFAS) . Biogeochemistry of Wetlands Science and Applications. SULFUR. Wetland Biogeochemistry Laboratory Soil and Water Science Department University of Florida. Instructor : Patrick Inglett pinglett@ufl.edu. 10/31/2019. 10/31/2019.
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Institute of Food and Agricultural Sciences (IFAS) Biogeochemistry of Wetlands Science and Applications SULFUR Wetland Biogeochemistry Laboratory Soil and Water Science Department University of Florida Instructor : Patrick Inglett pinglett@ufl.edu 10/31/2019 10/31/2019 WBL 1 1 10/31/2019 P.W. Inglett WBL 1
Sulfur • Introduction • S Forms, Distribution, Importance • Basic processes of S Cycles • Examples of current research • Examples of applications • Key points learned P.W. Inglett
Sulfur Learning Objectives • Identify 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 P.W. Inglett
Sources of Sulfur • Sulfur is a ubiquitous element. • Various sulfur compounds are present in: • The atmosphere • Minerals • Soils • Plant tissue • Animal tissue • Microbial biomass • Sediment P.W. Inglett
Reservoirs of Sulfur • Atmosphere 4.8 x 109 kg • Lithosphere 24.3 x 1018 kg • Hydrosphere • Sea 1.3 x 1018 kg • Freshwater 3.0 x 1012 kg • Pedosphere • Soil 2.6 x 1014 kg • Soil Organic matter 0.1 x 1014 kg • Biosphere 8.0 x 1012 kg P.W. Inglett
O Thioester R1-C~S-R2 General Forms of Sulfur in the Environment • Organic S in plant, animal, and microbial tissue (as essential components of amino acids and proteins) • Organic sulfur primarily in soil and sediments as humic material (naturally occurring soil and sediment organic matter) Methionine HS-CH2- Cysteine H3C-S-CH2-CH2- P.W. Inglett
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-) P.W. Inglett
General Forms of Sulfur in the Environment • Minerals Galena (PbS2) Gypsum (CaSO4) Jarosite(Fe2S) Barite (BaSO4) Pyrite (FeS2) • Fossil Fuels • Petroleum (0.1-10%) • Coal (1-20%) P.W. Inglett
Oxidation states of selected sulfur compounds Organic S (R-SH) -2 Sulfide (S2-) -2 Elemental S (S0) 0 Sulfur dioxide (SO2) +4 Sulfite (SO3-2) +4 Sulfate (SO42-) +6 P.W. Inglett
Global Sulfur Cycle P.W. Inglett
Sulfur Cycling Processes 1. Dissimilatory sulfate reduction 2. Assimilatory sulfate reduction 3. Desulfurylation 4. Sulfide oxidation 5. Sulfur oxidation 6. Dissimilatory So reduction P.W. Inglett
Sulfur Cycle So 4 5 Aerobic SH groups of protein 3 2 Anaerobic SO42- 1 S2- Aerobic 2 3 Anaerobic SH groups of protein 5 4 6 So P.W. Inglett
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% P.W. Inglett
Organic Sulfur Forms 20 Freshwater 15 Brackish 10 Salt Sulfur, g/kg 5 0 Ester C-S Total Organic Geochemistry vol. 18, no. 4, pp. 489-500, 1992 P.W. Inglett
Inorganic Sulfur Forms 4 400 Freshwater 3 300 Brackish 2 200 Sulfur, g/kg Salt Sulfur, mg/kg 1 100 0 0 FeS So FeS2 HCl Krairapanond et al. 1992. Organic Geochemistry 18: 489-500. P.W. Inglett
R - S-H2 + H2O R-OH+ H2S Sulfohydrolase Thiol Organic S Hydrolysis P.W. Inglett
Sulfur – Organism Groups • Assimilatory Sulfate Reduction • Bacteria, fungi, algae, and plants • Dissimilatory Sulfate Reduction • Hetrerotrophs • Desulfovibrio, Desulfotomaculum, Desulfobacter, Desulfuromonas • Sulfide Oxidation • Phototrophs: Chlorobium, Chromatium • Chemolithoautotrophs: Thiobacillus, Beggiatoa P.W. Inglett
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. P.W. Inglett
S2- SO42- SO42- So SO42- Sulfate Reduction Deposition Tidal Exchange AEROBIC Adsorbed SO42- Reduction Reduction SO42- Microbial Biomass-S ANAEROBIC P.W. Inglett
Glucose Oxidation P.W. Inglett
Oxygen Equivalents- Energy Yield from Glucose 120 100 80 60 % of Aerobic Energy Yield 40 20 0 O2 NO3- MnO2 Fe(OH)3 SO42- Electron Acceptors P.W. Inglett
Oxidation-Reduction SO42- S2- Mn4+ Mn2+ O2 H2O NO3- N2 CO2 CH4 Fe3+ Fe2+ -200 -100 0 +100 +400 +200 +300 Redox Potential, mV (at pH 7) P.W. Inglett
Sequential Reduction of Electron Acceptors P.W. Inglett
Redox Zones With Depth WATER Aerobic Oxygen Reduction Zone SOIL Eh = > 300 mV I Nitrate Reduction Zone Facultative Mn4+ Reduction Zone II Eh = 100 to 300 mV Fe3+ Reduction Zone III Depth Eh = -100 to 100 mV Sulfate Reduction Zone Anaerobic IV Eh = -200 to -100 mV Methanogenesis V Eh = < -200 mV P.W. Inglett
Redox Potential and pH 1000 800 600 400 Eh [mV] 200 0 -200 -400 -600 0 2 4 6 8 10 12 pH P.W. Inglett Baas Becking et al.
60 y = 0.33x + 1.3 r2 = 0.88; n = 24 50 40 Sulfate reducing conditions [mg kg-1 hour-1] 30 20 10 0 10 20 30 40 50 60 0 Aerobic [mg kg-1 hour-1] Microbial Activity [Site: Water Conservation 2A] P.W. Inglett
Sulfate Respiration Products: CO2, H2O, S2-, Nutrients Detrital Matter Enzyme Hydrolysis Monomers Sugars, Amino Acids Fatty Acids Complex Polymers Cellulose, Hemicellulose, Proteins, Lipids, Waxes, Lignin Uptake Glucose Glycolysis Oxidative phosphorylation Pyruvate TCA Cycle Substrate level phosphorylation CO2 Acetate Organic Acids [acetate, propionate, butyrate, lactate, alcohols, H2, and CO2] Uptake SO42- + e- Lactate Substrate level phosphorylation ATP [Sulfate Reducing Bacterial Cell] [Fermenting Bacterial Cell] P.W. Inglett
Electron donors used during sulfate reduction • SRB lack enzymes necessary for complex carbon assimilation P.W. Inglett
Electron donors used during sulfate reduction P.W. Inglett
Decreasing energy yield P.W. Inglett
Electron Donors • Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. P.W. Inglett
Sulfate Reduction Rates Activity [nmol/g per day] Low carbon wetland 23 Peaty wetland 130 Oligotrophic lake 707 Eutrophic lake 1,224 Marine and salt-marsh 744-24,000 P.W. Inglett
~65% ~82% ~69-87% S Respiration Salt Marshes Respiration [g C/m2 year] • Sapelo Island Sippewissett Sapelo Island [GA] [MA] (1997) Aerobic respiration 390 390 Denitrification 10 3 Mn and Fe reduction ND ND Sulfate reduction 850 1,800 2,000 Methanogenesis 40 1-8 P.W. Inglett
Sulfate Respiration • Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. P.W. Inglett
Capone and Kiene. 1988. Limnol Oceanogr, 33: 725-749. P.W. Inglett
Seasonal Effects Jorgensen, 1977. Marine Biology 41:7-17. P.W. Inglett
J F M A M J J A S O N D Seasonal EffectsSpartina alterniflora marsh Great Sippewissett Marsh 0.5 0.4 0.3 Moles SO42- m-2 d-1 0.2 0.1 0.0 Months Howarth and Giblin, 1983. Limnol and Oceanogr, 28:70-82. P.W. Inglett
0.5 0.4 0.3 0.2 0.1 0.0 Seasonal EffectsSpartina alterniflora marsh 0.03 0.02 Moles O2m-2 d-1 Moles SO42- m-2 d-1 0.01 -5 0 5 10 15 20 25 30 -5 0 5 10 15 20 25 30 Temp (C) Temp (C) • Howarth and Teal. 1979. Limnol and Oceanogr, 24: 999-1013. P.W. Inglett
Regulators of Sulfate Reduction • Presence of electron acceptor with higher reduction potentials • Oxygen is toxic to sulfate reducers • Sulfate concentration • Freshwater (< 0.1 mM) • Marine (20-30 mM) • Substrate/Electron Donor • Temperature • Microbial populations P.W. Inglett
Decreasing energy yield P.W. Inglett
Anaerobic Sludge Reactor (FISH) Sulfidogenic aggregate Sulfidogenic/Methanogenic aggregate Archeal Probe SRB Probe Appl Environ Microbiol. 1999 October; 65(10): 4618–4629. P.W. Inglett
Competition With Methanogens X X X X P.W. Inglett
Sulfate reducers Vmax Vmax Methanogens V = [Vmax S]/Km + S Km Km [Substrate] Sulfate Reducers vs Methanogens P.W. Inglett
0.6 CH4 20 SO42- mM SO42- 0.4 mM CH4 10 0.2 20 40 60 80 0 100 Days Sulfate ReductionTypical Lake Sediments from Jorgensen: in Microbial Geochemistry. Krumbein, ed: 1983 Blackwell. P.W. Inglett
Sulfate ReductionTypical Lake Sediments mM SO42- mM SO42- 20 0.2 10 0.1 0 12 SO42- 8 SO42- 0.5 4 1.0 0 cm m 4 CH4 1.5 CH4 8 12 2.0 0.5 1 2 1.0 mM CH4 mM CH4 Marine Freshwater from Jorgensen: in Microbial Geochemistry. Krumbein, ed: 1983 Blackwell. P.W. Inglett
CH4 (mg L-1) 0 5 10 15 10 Water 0 Soil Depth (cm) CH4 -10 SO42- -20 -30 0 20 40 60 80 100 SO42- (mg L-1) Sulfate ReductionCattail Marsh – Sunnyhill Farm Wetland P.W. Inglett
Sulfate Reduction • Iversen and Jorgensen. 1985. Limnol Oceanogr, 30: 944-955. P.W. Inglett
H2S DMS S2- H2S DMS So Sulfur Emissions Mineralization AEROBIC Org-S Mineralization Reduction Reduction SO42- Org-S ANAEROBIC P.W. Inglett
Gaseous S Emissions P.W. Inglett