Movement of arsenic from mining wastes and into the environment

3 Movement of arsenic from mining wastes and into the environment 

Humans and wildlife are exposed to arsenic from mining wastes through food, water, and air (Chapter 4). Arsenic in mine drainage and other waters may also enter plants and aquatic animals. Terrestrial 

Streams are another important medium for distributing arsenic-bearing tailings over long distances. Rather than immediately decompose, arsenic-bearing tailings and other solid wastes often wash into nearby streams, where they may be transported over hundreds of kilometers (Hudson-Edwards et al., 

The Rio Pilcomayo is a major river that originates in Bolivia and forms part of the boundary between Paraguay and Argentina. The water and sediments in the river are substantially contaminated with arsenic from the Potosi mines in Bolivia (Hudson-Edwards et al., 2001), 245. The arsenic content of Rio Pilcomayo actually increases from 65 pg L-1 at 10.2km downstream from the mines to 100 pg L-1 at about 151 km downstream (Hudson-Edwards et al., 2001), 240, 244. The arsenic increase may be due to a decrease in pH (from 10.3 to 8.42), increased oxidation of the river sediment, and increased activity of sulfide-oxidizing bacteria (Hudson-Edwards et al., 2001), 244-245. 

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