Validity of the Latest Research Findings on Causes of Groundwater Arsenic Contamination in Bangladesh

Abstract

The groundwater arsenic contamination problem in Bangladesh is the worst in the world. Two hypotheses are prevailing as the cause (mobilization) of groundwater arsenic contamination in Bangladesh. One is called “pyrite oxidation” and the other is “oxy-hydroxide reduction.” According to the first hypothesis, groundwater arsenic contamination is human-made, which has a relationship with excessive groundwater withdrawal. On the other hand, according to the second one, the contamination is natural. The British Geological Survey (BGS) conducted an investigation to identify the cause of groundwater arsenic contamination in Bangladesh. Based on their findings, they rejected the pyrite oxidation hypothesis and accepted the oxy-hydroxide reduction hypothesis. However, several experts are opposing their research findings. Therefore, a case study is undertaken to examine the validity of the BGS findings. Although we obtained results which are similar to the BGS, the errors in the estimates of percent of wells contaminated, the key parameter of these analyse show that the present as well as BGS results are not dependable to make any conclusion about the cause of contamination. Moreover, the validity test shows that space-dependent relationships among different hydro-geological parameters for the heterogeneous aquifer system are not valid to represent time-dependent phenomena. Therefore, the conclusion made by the BGS is not valid. Still, there is a possibility that the pyrite oxidation hypothesis could be accepted. For a final conclusion we must observe these relationships in a time domain by generating reliable time-dependent field data.