Heavy Metal Contamination in Agricultural Soil at DEPZA, Bangladesh

Higher accumulation of toxic heavy metals in rice grown in agricultural soil may lead to health disorder. The present study was carried out to assess the levels of different heavy metals like potassium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc in agricultural soil. The soil samples were collected by soil auger from the arable fields of Nolam near Dhaka Export Processing Zone Area (DEPZA), Savar, Dhaka of Bangladesh. The samples were irradiated using 3MV Van de Graaff Accelerator at the Atomic Energy Centre, Dhaka and Proton Induced X-ray Emission (PIXE) technique was employed for the analysis. The results indicated a substantial build-up of heavy metals in surface soil andsub-surface soil. Average metal concentrations were calculated and compared with reference values. The persistence of heavy metals in surface soil was higher than the sub-surface soil and it exceeded the standard safe limit. Uptake and translocation factor of heavy metal from surface soil to sub-surface soil were quite distinguished for almost all elements examined. In terms of health risk, the observed highest concentrations of these elements in soil could have an effect on human health which may pose public health hazards and for this pretreatment process of waste water is necessary for reducing the amount of heavy metals before using it to the agricultural soil. Wastewater from industries or other sources carries an appreciable amount of toxic heavy metals therefore their discharge into the environment must be minimized and carefully controlled.