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Microbial sulfate reduction and metal attenuation in pH 4 acid mine water.

Church CD, Wilkin RT, Alpers CN, Rye RO, McCleskey RB - Geochem. Trans. (2007)

Bottom Line: Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates.Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria.DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.

View Article: PubMed Central - HTML - PubMed

Affiliation: US Geological Survey, California Water Science Center, 4165 Spruance Road, San Diego, CA 92101, USA. clinton.church@ars.usda.gov

ABSTRACT
Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2-3 per thousand heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.

No MeSH data available.


Eh-pH diagram (S-H2O system) for Penn Mine ground water and microcosm studies (Total S = 0.01 m).
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Figure 5: Eh-pH diagram (S-H2O system) for Penn Mine ground water and microcosm studies (Total S = 0.01 m).

Mentions: At the conclusion of the experiments, the two low-pH and the two near-neutral-pH experiments were sampled and analyzed by DGGE. It is noteworthy that XRD analysis of the precipitate in the experiments revealed the presence of iron sulfide in the neutral-pH experiments and elemental sulfur in the low-pH experiments. The formation of iron sulfide in the near-neutral pH microcosms is not surprising; the development of black precipitates is often used as a visual indicator of sulfate reduction in bacterial cultures [70]. The formation of elemental sulfur in the low-pH microcosms suggests that oxidation of H2S(aq) occurred in the experiments. Inspection of an Eh-pH diagram for the S-H2O system indicates that the low-pH microcosms are in fact near the stability field for elemental sulfur (Figure 5). Therefore, at pH <5 there is a thermodynamic driving force for the precipitation of elemental sulfur from the microcosm solutions, i.e., the sulfur may not be a direct metabolic product. As a point of comparison, recent Eh-pH results from a low-pH sulfidogenic bioreactor study [14] are also shown on Figure 5. Note in all cases, the microcosm and bioreactor results fall in the aqueous sulfate field, but are close to the S(-II)-S(VI) boundary. Redox conditions in the Penn Mine ground water are more oxidizing compared to the microcosms (Figure 5); consequently, as previously noted it is possible that more reducing conditions were present in the mine workings below the sediment-water interface as compared to the overlying water column.


Microbial sulfate reduction and metal attenuation in pH 4 acid mine water.

Church CD, Wilkin RT, Alpers CN, Rye RO, McCleskey RB - Geochem. Trans. (2007)

Eh-pH diagram (S-H2O system) for Penn Mine ground water and microcosm studies (Total S = 0.01 m).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211471&req=5

Figure 5: Eh-pH diagram (S-H2O system) for Penn Mine ground water and microcosm studies (Total S = 0.01 m).
Mentions: At the conclusion of the experiments, the two low-pH and the two near-neutral-pH experiments were sampled and analyzed by DGGE. It is noteworthy that XRD analysis of the precipitate in the experiments revealed the presence of iron sulfide in the neutral-pH experiments and elemental sulfur in the low-pH experiments. The formation of iron sulfide in the near-neutral pH microcosms is not surprising; the development of black precipitates is often used as a visual indicator of sulfate reduction in bacterial cultures [70]. The formation of elemental sulfur in the low-pH microcosms suggests that oxidation of H2S(aq) occurred in the experiments. Inspection of an Eh-pH diagram for the S-H2O system indicates that the low-pH microcosms are in fact near the stability field for elemental sulfur (Figure 5). Therefore, at pH <5 there is a thermodynamic driving force for the precipitation of elemental sulfur from the microcosm solutions, i.e., the sulfur may not be a direct metabolic product. As a point of comparison, recent Eh-pH results from a low-pH sulfidogenic bioreactor study [14] are also shown on Figure 5. Note in all cases, the microcosm and bioreactor results fall in the aqueous sulfate field, but are close to the S(-II)-S(VI) boundary. Redox conditions in the Penn Mine ground water are more oxidizing compared to the microcosms (Figure 5); consequently, as previously noted it is possible that more reducing conditions were present in the mine workings below the sediment-water interface as compared to the overlying water column.

Bottom Line: Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates.Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria.DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.

View Article: PubMed Central - HTML - PubMed

Affiliation: US Geological Survey, California Water Science Center, 4165 Spruance Road, San Diego, CA 92101, USA. clinton.church@ars.usda.gov

ABSTRACT
Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H2S of Cu and Cd, relative to Zn; (2) stable isotope ratios of 34S/32S and 18O/16O in dissolved SO4 that are 2-3 per thousand heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.

No MeSH data available.