Soil Contamination Due to Heavy Metals at Electronic Waste Dumpsites in Karachi, Pakistan

Abstract

The Shershah market is the oldest and largest scrap market in the Karachi city. The recycling, dismantling and burning of electronic waste (e-waste) in and around the market are causing the significant environmental and human health risk. Furthermore, it is estimated that around 1-2 million people daily pass through the market, since it is situated at the linked road, connecting three towns i.e. Baldia, S.I.T.E and Lyari. The present study was designed to explore the level of heavy metals (Cd, Cr, Cu, Fe, Ni, Pd and Zn) contamination from the e-waste produced in the market. Therefore, the two dumping sites were selected and the sampling was carried out from the surface and depth of the soil biannually from 2015 to 2018. The assay was carried out by Atomic Absorption Spectroscopy (AAS). A control sample had also been taken from the non-e-waste site. Heavy metal concentration (mg.kg^-1) in the soil surface samples were found as Cd (0.63-0.26), Cr
(2.91-0.78), Cu (332.42-46.51), Fe (6.63-2.97), Ni (5.74-3.42), Pb (111.93-66.45) and Zn (125.41-74.69), and for the depth samples, the heavy metals were as Cd (0.41-0.12), Cr (1.39-0.18), Cu (86.24-6.98), Fe (4.65-1.11), Ni (2.38-0.88), Pd (71.59-19.24) and Zn (44.19-9.63), respectively. The insignificant concentration of the metals was analyzed at the control site. The data was compared with the international standards i.e. USEPA standards, FAO/WHO guidelines, EU guidelines etc. The level of Pb and Cu was higher than the allowable limits, indicating the risk associated with the soil and to the local public. Therefore, the e-waste dumpsites should be shift away from the city.