The Fate of Lead and Zinc in Soils Down-river from Mining Occurring in the Coeur d’Alene River Valley
MRIC 2008/09
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"The Fate of Lead and Zinc in Soils Down-river from Mining Occurring in the Coeur d’Alene River Valley"
September 23rd
Daniel G. Strawn - Plant, Soil, and Entomological Sciences
Abstract: The Fate of Lead and Zinc in Soils Down-river from Mining Occurring in the Coeur d’Alene River Valley The lower Coeur d’Alene (CDA) River Basin floodplain lies downstream of Idaho’s historic Silver Valley, one of the richest lead and silver mining regions in the world, and now one of the largest Superfund sites in the U.S. The Basin encompasses 19,200 acres, of which 95% have Pb, As, Cd, and Zn concentrations that exceed the EPA’s cleanup criteria, due to alluvial deposition of mine tailings and mill wastes. Contaminants in the soils have caused waterfowl mortality, decreases in aquatic species populations and diversity, and metal leaching to river and groundwater. The region hosts rural communities, includes tribal lands, several thousand acres of agriculture land, and is a recreational attraction. Thus metal-contaminated soils within the CDA Basin pose significant human exposure risks.
In this presentation an overview of the contaminant cycling in the soils developing in the CDA basin will be presented. Because soils are integral components of the ecosystem, the fate of the contaminants and potential toxicity is dependent on their speciation in the soils. In the soil chemistry laboratory we are currently investigating the speciation of Pb and Zn in these soils, and assessing their relative solubility, which controls transport and bio-uptake. We are discovering that Pb and Zn are intimately associated with iron and manganese oxide solid phases. Our results will allow land and resource managers to do better risk management and more efficiently implement remediation.
Daniel G. Strawn - Plant, Soil, and Entomological Sciences
Abstract: The Fate of Lead and Zinc in Soils Down-river from Mining Occurring in the Coeur d’Alene River Valley The lower Coeur d’Alene (CDA) River Basin floodplain lies downstream of Idaho’s historic Silver Valley, one of the richest lead and silver mining regions in the world, and now one of the largest Superfund sites in the U.S. The Basin encompasses 19,200 acres, of which 95% have Pb, As, Cd, and Zn concentrations that exceed the EPA’s cleanup criteria, due to alluvial deposition of mine tailings and mill wastes. Contaminants in the soils have caused waterfowl mortality, decreases in aquatic species populations and diversity, and metal leaching to river and groundwater. The region hosts rural communities, includes tribal lands, several thousand acres of agriculture land, and is a recreational attraction. Thus metal-contaminated soils within the CDA Basin pose significant human exposure risks.
In this presentation an overview of the contaminant cycling in the soils developing in the CDA basin will be presented. Because soils are integral components of the ecosystem, the fate of the contaminants and potential toxicity is dependent on their speciation in the soils. In the soil chemistry laboratory we are currently investigating the speciation of Pb and Zn in these soils, and assessing their relative solubility, which controls transport and bio-uptake. We are discovering that Pb and Zn are intimately associated with iron and manganese oxide solid phases. Our results will allow land and resource managers to do better risk management and more efficiently implement remediation.
Original url: http://www.uidaho.edu/class/mric/archives/pre-2010/fall2008/strawn