Arsenic in Ground Water Interest in arsenic in ground water has greatly increased in the past decade because of the increased awareness of human health effects and the costs of avoidance or treatment of ground water supplies used for consumption. The goal of this book is to provide a description of the basic processes that affect arsenic occurrence and transport by providing sufficient background information on arsenic geochemistry and descriptions of hi arsenic ground water both affected and unaffected by human activity. An understanding of thermodynamics adsorption and the speciation of arsenic in solid phases which are described in first three chapters is needed to predict the fate of arsenic in ground water systems. Large scale and deep movement of ground water can and has redistributed arsenic in the near surface environment as described in the next two chapters. These large scale systems can affect large volumes of both ground water and surface water such as in the Yellowstone system and can produce mineralised zones that subsequently release arsenic to ground water supplies. Regional identification of high arsenic ground water and its consumption as described in the next three chapters clearly demonstrates a need for increased wat quality monitoring particularly in south and southeast Asia. Chapters 9 11 provide examples of high arsenic ground water associated with sulfide mineral oxidation and alkaline conditions. Finally smaller scale studies of the effects of human activities that have produced high arsenic ground water and methods for attenuation of ground water are presented. Arsenic thermodynamic data and environmental geochemistry Spectroscopic Investigations of Arsenic Species in Solid Phases Geochemical Processes Controlling Transport of Arsenic in Groundwater: A Review of Adsorption Geothermal Arsenic Role of Large Scale Fluid Flow in Subsurface Arsenic Enrichment Arsenic in ground water used for drinking water in the United States Arsenic in groundwater — south and east Asia The scale and causes of the groundwater arsenic problem in Bangladesh Mechanisms of Arsenic Release to Ground Water from Naturally Occurring Sources Eastern Wisconsin Arsenic in southeastern Michigan Occurrence of arsenic in ground water of the Middle Rio Grande Basin central New Mexico Arsenic Contamination in the Water Supply of Milltown Montana Natural Remediation Potential of Arsenic Contaminated Ground Water Modeling in situ iron removal from groundwater with trace elements such as As In situ Arsenic Remediation in a fractured alkaline aquifer.