Arsenic in Groundwater

Synonyms

Arsenate; Arsenite; As

Definition

Inorganic arsenic (abbreviation: As) is a trace element found in the earth’s crust. Arsenic is present in groundwater as inorganic arsenate (As(V)) and arsenite (As(III)).

Origins of arsenic in groundwater

Arsenic enters groundwater from the surrounding substrate (soil and bedrock). It is generally believed that weathering reactions, microbial and human activities result in mobilization of inorganic arsenic from the substrate to groundwater (Appelo and Heederik, 2006).

In the substrate, As is commonly concentrated in sulfide bearing minerals, has strong affinity for pyrites, and is concentrated in hydrous iron oxides. Sulfide minerals usually contain high concentrations of As; consequently, oxidation of sulfide minerals releases inorganic As in groundwater. For instance, in the aquifers of alluvial river basins of the Ganges delta (parts of West Bengal, an Indian state, and Bangladesh), presence of organic matter in soil leads to complex redox...