Document Detail

Effects of increasing acidity on metal(loid) bioprecipitation in groundwater: column studies.
MedLine Citation:
PMID:  17993159     Owner:  NLM     Status:  MEDLINE    
Large-scale column experiments were carried out over a period of 545 days to assess the effect of increasing acidity on bacterial denitrification, sulfate reduction, and metal(loid) bioprecipitation in groundwater affected by acid mine drainage. At a groundwater pH of 5.5, denitrification and Cu2+ removal, probably via malachite (Cu2(OH)2CO3) precipitation, were observed in the ethanol-amended column. Sulfate reduction, sulfide production, and Zn2+ removal were also observed, with Zn2+ removal observed in the zone of sulfate reduction, indicating likely precipitation as sphalerite (ZnS). Se6+ removal was also observed in the sulfate reducing zone, probably as direct bioreduction to elemental selenium via ethanol/acetate oxidation or sulfide oxidation precipitating elemental sulfur. A step decrease in groundwater pH from 5.5 to 4.25 resulted in increased denitrification and sulfate reduction half-lives, migration of both these redox zones along the ethanol-amended column, and the formation of an elevated Cu2+ plume. Additionally, an elevated Zn2+ plume formed in the previous sulfate reducing zone of the ethanol-amended column, suggesting dissolution of precipitated sphalerite as a result of the reduction in groundwater pH. As Cu2+ passed through the zone of sphalerite dissolution, SEM imaging and EDS detection suggested that Cu2+ removal had occurred via chalcocite (Cu2S) or covellite (CuS) precipitation.
Alexander C Davis; Bradley M Patterson; Michelle E Grassi; Blair S Robertson; Henning Prommer; Allan J McKinley
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-11-12     Completed Date:  2007-12-19     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7131-7     Citation Subset:  IM    
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
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MeSH Terms
Acids / chemistry*
Chemical Precipitation
Hydrogen-Ion Concentration
Metals / chemistry*
Sulfates / chemistry
Water Pollutants, Chemical*
Reg. No./Substance:
0/Acids; 0/Metals; 0/Sulfates; 0/Water Pollutants, Chemical

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