Arsenic Compounds in Water

Arsenic is the twentieth most abundant element in the earth's crust; it occurs naturally in the environment in both inorganic and organic forms. Arsenic is also released to the environment by anthropogenic activities such as pesticide use, wood preservation, mining, and smelting. Human exposure to arsenic by the general population occurs primarily from drinking water and food. In areas of endemic arsenic poisoning such as Bangladesh, India, Inner Mongolia, and Taiwan, the main exposure is through drinking water where inorganic arsenic levels can reach concentrations in the hundreds or thousands of micrograms per liter. The arsenic is released from natural mineral deposits into the groundwater in endemic areas. Groundwater is the primary drinking water source in these areas. Arsenic is present in a variety of inorganic and organic chemical forms in water. This is a result of chemical and biological transformations in the aquatic environment. The specific arsenic compound present determines its toxicity, biogeochemical behavior, and environmental fate. Keywords: arsenite; arsenate; methylated arsenic compounds; particulate arsenic; arsenic speciation; arsenic metabolites; arsenic analysis; surface water; groundwater; monomethylarsonic acid; monomethylarsonous acid; dimethylarsinic acid; dimethylarsinous acid; trimethylarsine oxide; oxythioarsenic acid