Sulfate contamination in groundwater near an abandoned mine: hydrogeochemical modeling, microbiology, and isotope geochemistry
Sulfide oxidation in a carbonate environment produces a groundwater problem similar to acid mine drainage, except the contaminant is sulfate. An example of this little-studied phenomenon occurred around the zinc-lead mines near Shullsburg, Wisconsin. Sulfate concentrations as high as 40 mmol/l (16 times the safe drinking water level) were found after the mines closed in 1979 and 11 wells were abandoned. The 1983 groundwater flow pattern showed groundwater flowing toward the mines to fill the cone of depression created by dewatering of the mines, thus localizing contamination. A three-dimensional groundwater flow model was constructed which predicts groundwater will begin flowing away from the mines between 1989 and 1994. However, sulfate levels should remain low in areas distant from the mines because of dilution of sulfate. Geochemical modeling of chemical reactions and isotope effects using the USGS computer program PHREEQE showed the importance of dolomite, calcite, CO/sub 2/, and iron hydroxides in controlling the water chemistry. Microbiological sampling and sulfur isotopes indicated that Thiobacillus bacteria that thrive under neutral pH conditions may be involved in the oxidation process. Acidophilic bacteria such as T. ferrooxidans were also found. The role of biological factors in oxidation was further investigated by oxidizing a variety of sulfide minerals in the presence of carbonate buffer. The oxygen isotope ratios from both inoculated and sterile experiments indicated a large portion of sulfate oxygen comes from water rather than atmospheric oxygen. The possibility of multiple reaction pathways makes it difficult to use oxygen isotopes to distinguish mechanisms of oxidation.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 6793941
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
GROUND WATER
FLOW MODELS
WATER CHEMISTRY
WATER POLLUTION
MINING
ENVIRONMENTAL EFFECTS
WISCONSIN
ABANDONED SHAFTS
CALCITE
CARBON DIOXIDE
CHEMICAL REACTIONS
DOLOMITE
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
HYDROLOGY
IRON HYDROXIDES
OXIDATION
PH VALUE
SULFATES
SULFIDES
THIOBACILLUS FERROXIDANS
ALKALINE EARTH METAL COMPOUNDS
BACILLUS
BACTERIA
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHEMISTRY
FEDERAL REGION V
HYDROGEN COMPOUNDS
HYDROXIDES
IRON COMPOUNDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MASS TRANSFER
MATHEMATICAL MODELS
MICROORGANISMS
MINE SHAFTS
MINERALS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
POLLUTION
SHAFT EXCAVATIONS
SULFUR COMPOUNDS
SULFUR-OXIDIZING BACTERIA
TRANSITION ELEMENT COMPOUNDS
USA
WATER
520200* - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)
580100 - Geology & Hydrology- (-1989)