Pollution Status of Trace Metals in Groundwater Due to Industrail Activities in and Around Dhaka Export Processing Zone, Bangladesh

Abstract

Effluents from multiindustrail activities influence inland water system directly, which subsiquently affect groundwater quality and human health. Some previous reports indicated that inadequate treatment process of discharged effluent of Dhaka Export Processing Zone (DEPZ) increased the concentrations of pollutants in surface water system and deteriorated total fishing and agricultural system around DEPZ and its connected area. Therefore, the present study was conducted to investigate wether the concentration of selective metals viz. Li, V, Cr, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Pb and U in two types of groundwater sources were either with in the permissible guidlines or influenced by DEPZ multi industrail on their levels of contamination. The concentrations of metals were determined using inductively Couples Plasma Mass Spectrometry (ICP-MS). The mean concentrations of the elements in both types of groundwater were in the levels of their permissible guidlines, except for Ni (12.91 µg/L), Ga (0.48µg/L), Sr (90.26 µg/L) and Cs (0.07µg//L)in groundwater inside DEPZ, which were 1.30, 5.00, 1.50 and 1.40 times higher than the maximum permissible limit (MPL) of 10 µg/L, 0.09 µg/L, 60 µg/L, and 0.05µg/L, respectively. The mean concentrations of Li (6.85 µg/L), Zn(268 µg/L), Ga (0.12 µg/L), Sr (131 µg/L) and Cs (0.07 µg/L) were 3.43, 1.34, 1.33, 2.18, 1.40 times higher then the MPL of 2 µg/L, 200 µg/L, 0.09 µg/L, 60 µg/L and 0.05 µg/L, respectively, in groundwater around DEPZ. Comparatively Zn and Sr possessed higher concentrations, and Cs and U possessed lower concentration in both types of groundwater sources. The elements were distributed in homogeneous and hetrogeneous manner among the source points for deep-tubewell (DTWS) and shallow tubewell (STWs), respectively. The significant positive correlations were found between the elements viz., Co-V (0.85), Ni-Sr ((0.70), Co-Cd (0.86), As-Se (0.99), Cs-Zn (0.95), Li-U (0.,71), Zn-U (0.69), Ga-U (0.77), Sr-Pb (0.85) and Ba-Ag (0.99) in the grounwater samples inside DEPZ, and for Cu-Cs (0.78), Cu-Ba (0.73), Pb-Cu (0.69), Cu-U (0.70), Cr-Cd (0.71), Ni-Cu (0.83), Ni-Se (0.70), Li-Se (0.72), Li-Cd (0.84), Cu-V (0.78), V-Ga (0.82), Sr-V (0.68), Ba-V (0.67), Zn-Ga (0.75), Zn-Ag (0.69), Se-Ga (0.67), As-Rb (0.84), Se-Ba (0.67), Sr-Ba (0.79), Sr-Pb (0.71), Cs-U (0.83) and Pb-Ba (0.98) in the groundwater around DEPZ at 0.05 to 0.01 level. Considering the elemental load, it was assumed that the groundwater of DTWs inside DEPZ are still isolated from potential contaminated sources, whereas groundwater of STWs around DEPZ seemed to be gradually affected by the sources of these toxic trace metal.