Temporal and seasonal variability of arsenic in drinking water wells in Matlab, southeastern Bangladesh: A preliminary evaluation on the basis of a 4 year study

Abstract

Temporal and seasonal variability of As concentrations in groundwater were evaluated in As-affected areas of Matlab, southeastern Bangladesh. Groundwater samples from 61 randomly selected tubewells were analyzed for As concentrations over a period of three years and four months (from July 2002 to November 2005) and monitored seasonally (three times a year). The mean As concentrations in the sampled tubewells decreased from 153 to 123 μg/L during July 2002 to November 2005. Such changes were pronounced in tubewells with As concentration >50 μg/L than those with As concentrations <50 μg/L. Similarly, individual wells revealed temporal variability, for example some wells indicated a decreasing trend, while some other wells indicated stable As concentration during the monitoring period. The mean As concentrations were significantly higher in Matlab North compared with Matlab South. The spatial variations in the mean As concentrations may be due to the differences in local geological conditions and groundwater flow patterns. The variations in mean As concentrations were also observed in shallow (<40 m) and deep (>40 m) wells. However, to adequately evaluate temporal and seasonal variability of As concentration, it is imperative to monitor As concentrations in tubewells over a longer period of time. Such long-term monitoring will provide important information for the assessment of human health risk and the sustainability of safe drinking water supplies.

Maternal arsenic exposure and birth outcomes: A comprehensive review of the epidemiologic literature focused on drinking water

“…Exposure was assigned by the iAs concentration previously reported for source wells, although consumption volume and duration was not accommodated (with the exception of the dichotomized time analysis). Whereas iAs concentrations in Bangladeshi wells are likely constant over short time intervals, additional evidence suggests mild to marked variability in association with climatic events in particular for more shallow aquifers (Bhattacharya et al, 2011; Cheng et al, 2005); thus exposure measurement misclassification error was possible. Birth outcomes were collected by standardized personal interview, without clinical confirmation, again raising the possibility for self-reporting biases.…”

A prospective cohort study of stroke mortality and arsenic in drinking water in Bangladeshi adults

“…In western Nevada in the United States, and northern Argentina the water arsenic concentrations remained about the same over periods of 10–20 years [43,44]. Moreover, in our study area, when following 61 randomly selected tube wells three times per year over a 3-year period, no systematic time trends could be shown [45]. Therefore, findings are to be interpreted under the assumption of constant source of As measured in 2003 and that the impact of possible changes is unknown.…”

Evidence of decoupling between arsenic and phosphate in shallow groundwater of Bangladesh and potential implications

“…However, long-term trends in As concentrations, both increases and decreases, have been documented over a period of 8 years for a number of wells within a relatively small region of West Bengal, India (McArthur et al, 2010). Some shorter time series have shown significant seasonal variability in groundwater composition, particularly in shallow aquifers, but by and large variations in groundwater As have been much more limited (BGS/DPHE, 2001; Cheng et al, 2005; Dhar et al, 2008; Bhattacharya et al, 2011; Planar-Friedrich et al, 2012; Neidhardt et al, 2013; Radloff et al, this volume). Only for large perturbations induced by local pumping in the vicinity of a spatial gradient have larger variations in groundwater As concentrations been reported (McArthur et al, 2010; Jessen et al, 2012; Neidhardt et al, 2013).…”