Heavy metal concentrations in soil and wild plants growing around Pb-Zn sulfide terrain in the Kohistan region, northern Pakistan

This study investigates the soil and wild plants of the Pb-Zn sulfide bearing mineralized zone of Indian plate (IP) in the Pazang and Lahor sites, Kohistan region, northern Pakistan. Soil and plants were analyzed for major cations (Na, K, Ca, Mg, Fe, Mn) and heavy metals (Pb, Zn, Cd, Cu, Cr, Ni, Co) concentrations by using atomic absorption spectrometer. Metal concentrations were used to quantify pollution contamination factors such as pollution load index (PLI) and plant bioaccumulation in soil and plants developed in mineralized zones in the Lahor and Pazang sites and an unmineralized zone (reference sites) of the Besham area. Soil and plants of the mineralized zone and surrounding areas have higher heavy metal (HM) contamination (P<0.01) as compared to the reference site, which can be attributed to the dispersion of metals due to mining. Furthermore, in mineralized zones, the Lahor site was more contaminated than the Pazang site. This high HM contamination may pose potential threats to local communities of Kohistan region. The results also showed that plant species (Plectranthus rugosus, Rumex hastatus, Fimbristylis dichotoma, Heteropogon conturtus and Myrsine Africana) were the best HM accumulators. (C) 2011 Elsevier B.V. All rights reserved.