Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California
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Abstract
As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.
Study Area
Publication type | Article |
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Publication Subtype | Journal Article |
Title | Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California |
Series title | Journal of Environmental Monitoring |
DOI | 10.1039/C2EM30135K |
Volume | 14 |
Issue | 7 |
Year Published | 2012 |
Language | English |
Publisher | Royal Society of Chemistry |
Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
Description | 16 p. |
First page | 1798 |
Last page | 1813 |
Country | United States |
State | California |
Other Geospatial | Mojave Desert |
Google Analytic Metrics | Metrics page |