Assessment of heavy metals in soils at Bayan Lepas industrial zone, Penang, Malaysia

Abstract

Soil is the most important environmental component to ecosystem. It plays a significant role as a geochemical sink for contaminants. It also acts as a natural buffer to control transport of chemical elements and substances. Heavy metals are one of the significant contaminants in soils due its persistence and toxicity. Concentrations of 12 heavy metals (Al, As, Cd, Cr, Co, Cu, Fe, Mg, Mn, Ni, Pb, and Zn) at 14 sampling sites in Bayan Lepas Industrial Area, Penang were analyzed using Inductively Coupled Plasma (ICP) and Optical Electro Spectrometer (OES) standard methods. The assessment of heavy metals at the study area were based on single element pollution index, combined pollution index, enrichment factor and geo-accumulation index. Geo-accumulation indices and contamination factors indicated moderate to strong contamination for 8 boreholes, BL-1, BL-2, BL-6, BL-8, BL-9, BL-10, BL-12 and BL-13, while the other five (except for BL-14) were extremely contaminated. BL-3 and BL-11 appeared as the most polluted sites with high levels of Cd and Pb. These boreholes were located within the small and medium industries zone; food processing, paint and printing industry, automation industry, electrical and electronics manufacturing. The results also showed that Cd and Pb concentrations at BL-3 were an order of magnitude and three times higher than global limits, respectively. Serious attention should be given to SME's in order to manage their effluent disposal effectively, thus, protecting public safety.