Rotoevaporated Arsenicrich Water Residues From Contaminated Handtubewells

After studying arsenic along with other heavy metals in borehole sediment samples from arsenic-affected districts of West Bengal, it was felt necessary to study the heavy metals in the arsenic-rich underground water from hand tubewells of the affected districts. In this work, the water samples (each 10 l) were roto-evaporated and finally the solid mass obtained was dried on silica gel in a vacuum desiccator. Twenty-two well water samples having an arsenic concentration in the range of 200-2480 ^g/l from eighteen affected

Fig. 8. Polished section study under ore microscope of some arsenicrich particles from sludge samples showing huge amounts of pyrite grains.

Fig. 8. Polished section study under ore microscope of some arsenicrich particles from sludge samples showing huge amounts of pyrite grains.

blocks, were roto-evaporated to dryness. While studying the borehole sediment samples we observed good correlations in linear regression between As and Fe, Pb, Mn and Zn. Regression analyses were further carried out between the arsenic and other heavy metals for all the 22 water samples which were evaporated to dryness. The linear regression shows good correlations also between As and Fe, Pb, Mn and Zn (Table 9). The similar correlations between arsenic and heavy metals in borehole sediment and water residues (Table 9) indicates the possibility that arsenic and heavy metals in water are of sedimentary origin.

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