Evaluation of the fate of arsenic-contaminated groundwater at different aquifers of Thar coalfield Pakistan

Abstract

In present study, the ground water at different aquifers was evaluated for physicochemical parameters, iron, total arsenic, total inorganic arsenic and arsenic species (arsenite and arsenate). The samples of groundwater were collected at different depths, first aquifer (AQ1) 50-60 m, second aquifer (AQ2) 100-120 m, and third aquifer (AQ3) 200-250 m of Thar coalfield, Pakistan. Total inorganic arsenic was determined by solid phase extraction using titanium dioxide as an adsorbent. The arsenite was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate as a chelating reagent, and resulted complex was extracted by Triton X-114. The resulted data of groundwater were reported in terms of basic statistical parameters, principal component, and cluster analysis. The resulted data indicated that physicochemical parameters of groundwater of different aquifers were exceeded the World Health Organization provisional guideline for drinking water except pH and SO4(2-). The positive correlation was observed between arsenic species and physicochemical parameters of groundwater except F(-) and K(+), which might be caused by geochemical minerals. Results of cluster analysis indicated that groundwater samples of AQ1 was highly contaminated with arsenic species as compared to AQ2 and AQ3 (p > 0.05).

Evaluates the chemical fractions of arsenic bounded to solid matrixes of thar coalfield of pakistan by sequential extraction method

“…The correlation of depths with As concentration in all studied samples of block 3 were higher as compared to block 5. One of the major sources of As contamination in ground water is due to release of Ascontaining solid matrices in mining area [37]. The results obtained in this study are consistent with those reported by other researchers [38].…”

“…The resulted data indicates high content of acid-soluble fraction of As in sand than those values obtained in clay and soil samples of both blocks. The reducible fraction (F 2 ) of As, bound with iron or manganese oxides are commonly extracted with HONH 2 ÁHCl in acidic medium [37]. It was observed that acid-soluble fraction of arsenic in soil, sand, and clay was corresponding to 6.93-9.19%, 8.46-10.5%, and 9.74-13.4%, respectively, of total As content in all three solid matrices [42].…”

“…The acid-extractable As might contaminate the groundwater of Thar coalfield due to change of the pH, under certain conditions [43]. The reducible fraction (F 2 ) of As, bound with iron or manganese oxides are commonly extracted with HONH 2 ÁHCl in acidic medium [37]. The concentration of As in the F 2 fraction of soil, sand, and clay samples were found 25-31%, 18-20%, and 43-47%, respectively, of total As content in these matrices (Table 4a,b).…”

“…Arsenic leachability depended on the pH values, so its external influence enhance the mobility under natural conditions, and it is easily leached into the environment to take part in biogeochemical cycling [36]. One of the major sources of As contamination in ground water is due to release of Ascontaining solid matrices in mining area [37]. The use of waterextractable test enables one to evaluate possible environmental risks.…”

Willingness to Pay for Improved Water Services in Mining Regions of Developing Economies: Case Study of a Coal Mining Project in Thar Coalfield, Pakistan

“…The other sources include private boreholes, handpumps, public and private tube wells, and Tarais (underground storage tanks to store rainwater). Groundwater is already classified as saline and brackish, and is highly contaminated with arsenic [15]. In addition, a physiochemical analysis of the groundwater found high concentrations of heavy metal and total dissolved solids, exceeding the quality standards of the World Health Organization (WHO) [16].…”