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Effects of Water Use on Arsenic Release to Well Water in a Confined Aquifer
Author(s) -
Gotkowitz Madeline B.,
Schreiber Madeline E.,
Simo J.A.
Publication year - 2004
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.2004.tb02625.x
Subject(s) - aquifer , arsenic , groundwater , sulfide minerals , borehole , environmental chemistry , biogeochemical cycle , arsenic contamination of groundwater , hydrogeology , water quality , water well , geology , environmental science , hydrology (agriculture) , chemistry , mineralogy , pyrite , ecology , geotechnical engineering , organic chemistry , biology
Field‐based experiments were designed to investigate the release of naturally occurring, low to moderate (< 50 ug/L) arsenic concentrations to well water in a confined sandstone aquifer in northeastern Wisconsin. Geologic, geochemical, and hydrogeologic data collected from a 115 m 2 site demonstrate that arsenic concentrations in ground water are heterogeneous at the scale of the field site, and that the distribution of arsenic in ground water correlates to solid‐phase arsenic in aquifer materials. Arsenic concentrations in a test well varied from 1.8 to 22 ug/L during experiments conducted under no, low, and high pumping rates. The quality of ground water consumed from wells under typical domestic water use patterns differs from that of ground water in the aquifer because of reactions that occur within the well. Redox conditions in the well can change rapidly in response to ground water withdrawals. The well borehole is an environment conducive to microbiological growth, and biogeochemical reactions also affect borehole chemistry. While oxidation of sulfide minerals appears to release arsenic to ground water in zones within the aquifer, reduction of arsenic‐bearing iron (hydr)oxides is a likely mechanism of arsenic release to water having a long residence time in the well borehole.