Microbiological Processes Affecting the Hydrogeochemistry of Arsenic-Contaminated Groundwater in the Datong Basin, Northern China

Abstract

Arsenic contamination in drinking groundwater in the Datong Basin, northern China has been threatening millions of people's health for decades. To delineate the hydrogeochemical characteristics of arsenic contaminated water is the key to understanding arsenic mobilization. Groundwater in the Datong Basin was characterized as soda water, with a high concentration of HCO3− and Na+. The elevated concentration of HCO3− in groundwater was considered to result largely from the decomposition of organic matter in the sediment. Indirect evidence implied that the second dominant cation in groundwater, Mg2+, was linked to bacterial sulfate reduction (BSR), which could favor dolomite precipitation at earth surface temperatures. Additionally, Ca2+ in groundwater may go through this modification, in addition to Mg2+. In this investigation, As concentrations in groundwater negatively correlated with Mg2+. Although there was a lack of strong evidence from this study, as well as in the documented literature, Mg is perhaps directly involved in arsenic mobilization during microbiological processes. The role of Mg in arsenic biogeochemical cycling needs to be further investigated to better understand environmental constraints on arsenic geochemical behavior.