Environmental significance of elevated natural levels of arsenic

Abstract

Globally, arsenic introduced into the biosphere by human activities has greatly surpassed arsenic from natural sources, the supply of the element from these two sources being approximately 60 and 40%, respectively. However, numerous regions of the world have elevated concentrations of arsenic from natural sources. Arsenopyrite may contain up to 6000 μg∙g⁻¹ of arsenic and the weathering of such geological materials can increase the levels of arsenic in groundwater. Long-term consumption of groundwater containing elevated concentrations of arsenic has caused natural chronic arsenic intoxication in local populations in Taiwan, Mexico, Chile, Argentina, and other countries. An endemic disease commonly called blackfoot disease, which is also caused by arsenic in drinking water, was documented in Taiwan in 1963. For more than 80 years local populations had consumed well water with arsenic concentrations as high as 1829 μg∙L⁻¹. The widespread geographical distribution of minerals with high arsenic content suggests that many new regions with natural arsenic contamination will be identified in the near future.Key words: arsenic, natural, cycling, chronic, contamination.