Well characteristics influencing arsenic concentrations in ground water

• Published in: Water research (Oxford) Vol. 39; no. 16; pp. 4029 - 4039
• Main Authors: Erickson, Melinda L., Barnes, Randal J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2005; Elsevier Science
• Subjects: Adsorption; Applied sciences; Arsenic; Arsenic - analysis; Arsenic - chemistry; Biological and medical sciences; Biotechnology; Environment and pollution; equipment design; Exact sciences and technology; Facility Design and Construction; Fundamental and applied biological sciences. Psychology; Geochemistry; Geological Phenomena; Geology; Ground water; groundwater contamination; Industrial applications and implications. Economical aspects; Other industrial wastes. Sewage sludge; physical properties; Pollution; Solubility; statistics; Wastes; Water Movements; water quality; Water Supply; Water treatment and pollution; Well characteristics; wells; South Dakota; Iowa; Minnesota; North Dakota; USA, Midwest; Geochemistry; Arsenic; Well characteristics; Ground water; Mobilization; Pollution; Water well; Surveillance; Desorption; Dissolution; Aquifers
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.07.026

Naturally occurring arsenic contamination is common in ground water in the upper Midwest. Arsenic is most likely to be present in glacial drift and shallow bedrock wells that lie within the footprint of northwest provenance Late Wisconsinan glacial drift. Elevated arsenic is more common in domestic wells and in monitoring wells than it is in public water system wells. Arsenic contamination is also more prevalent in domestic wells with short screens set in proximity to an upper confining unit, such as glacial till. Public water system wells have distinctly different well-construction practices and well characteristics when compared to domestic and monitoring wells. Construction practices such as exploiting a thick, coarse aquifer and installing a long well screen yield good water quantity for public water system wells. Coincidentally, these construction practices also often yield low arsenic water. Coarse aquifer materials have less surface area for adsorbing arsenic, and thus less arsenic available for potential mobilization. Wells with long screens set at a distance from an upper confining unit are at lower risk of exposure to geochemical conditions conducive to arsenic mobilization via reductive mechanisms such as reductive dissolution of metal hydroxides and reductive desorption of arsenic.