ABSTRACT
This chapter highlights the fact that high concentrations of naturally occurring arsenic in groundwater are reported in countries of Southeast Asia, some countries in Europe, some countries in Latin America, and some parts of the USA. Southeast Asian countries, including Bangladesh, India, China, Vietnam, Taiwan, Thailand, and Nepal, are of particular concern because of widespread arsenic-related diseases. The western part of the USA, including Michigan, Minnesota, South Dakota, Oklahoma, and Wisconsin as well as Maine, is contaminated with groundwater arsenic poisoning. Arsenic contamination is also documented in some European countries, for instance, Greece, Hungary, Romania, Croatia, Serbia, Germany, Turkey, Spain, and the UK. Moreover, many Latin American countries, including Argentina, Chile, Bolivia, Mexico, and El Salvador, are exposed to elevated levels of arsenic concentrations in their groundwater. This worldwide distribution of arsenic in groundwater poses a significant risk to human health, and about 300 million people worldwide are at risk of arsenic poisoning. The primary source of groundwater arsenic is natural and derived predominantly from interactions between groundwater and aquifer sediments of minerals, including pyrite, arsenopyrite, and other sulfide minerals. The geochemistry of arsenic is a function of multiple oxidation states, speciation, and redox transformation. Mobilization of arsenic in groundwater is controlled by adsorption onto metal oxyhydroxides and clay minerals.
