Figure 1. Selenium can be a natural contaminant in soils and water enriched by agricultural irrigation in arid and semi-arid environments. High concentrations of selenium can lead to birth defects and reproductive disorders in fish and waterfowl. One of many possible selenium cycles, "from rock to duck" is well documented at Kesterson National Wildlife Refuge. (for location see Figure 2).

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http://geology.wr.usgs.gov/wreg/env/cycle.html
Contact: Margaret A. Keller (mkeller@usgs.gov)
Western Region Energy Group–Environmental Studies
Modified: July 31, 2002

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