Investigation of soil quality and heavy metal concentrations from a waste dumping site of Konabari industrial area at Gazipur in Bangladesh

Abstract

The study was conducted to determine the soil pollution from the downstream area of the waste dumping site in relation to changes in soil quality as well as chemical characteristics and heavy metals concentrations in Konabari industrial area of Bangladesh, during the period from July to December 2011. Soil samples were collected from five different points at a distance of 10 m from each other. Samples were collected from two layers i.e. from surface and subsurface at a depth of 0-15 and 15-30 cm, respectively. The study concluded that the waste material produced tangible impacts on the soil quality, while the samples contained higher available sulphur (S), but lower total nitrogen (N), available phosphorus (P) and organic matter (OM) contents. The dumping of waste resulted in a marked increase in the concentration of heavy metals in soils, and the measured metals varied in the order of iron (Fe) > zinc (Zn) > lead (Pb) > copper (Cu) > cadmium (Cd). The mean concentrations of the selected heavy metals in the surface soil of the dumped site were 0.40, 1.42, 0.46, 350.38 and 0.03 ppm for Cu, Zn, Pb, Fe and Cd, respectively, while the mean concentrations of the heavy metals in the subsurface soil were 0.39, 1.36, 0.47, 313.3 and 0.03 ppm for Cu, Zn, Pb, Fe and Cd, respectively. This could be attributed to the leachates percolated from the wastes. The metal species were found comparatively lower on the solid waste accumulation site and higher on the industrial effluents accumulation site. Such a condition could be regarded as unsafe as these heavy metals are eventually picked up by growing plants and thereby entering the food chain. So, careless disposal of the waste should be discouraged, and a waste management and treatment policy should be put in place for the waste dumping and/or disposal.