Heavy metal contamination in soil and some medicinal plant species in Ahangaran lead-zinc mine

Ahangaran lead-zinc mining area located in the west part of Iran is a mountainous region. In this study, medical plants and soils from 3 different sites in this area were collected in spring 2012. Soil and medical plants were analyzed for heavy metals [lead (Pb), zinc (Zn), cadmium (Cd) and copper (Cu)] concentrations using inductively coupled plasma (ICP) optical emission spectrometer (Varian 710-Es) and the physical properties of soils [(pH) and electrical conductivity (EC)] were measured. Soil and medical plants of the mineralized zone and surrounding areas have higher heavy metal contamination (P < 0.05) as compared to the reference site, which can be attributed to the dispersion of metals due to mining. This high heavy metal contamination may pose potential threats to local medical plants and soil of Ahangaran region. Furthermore, the concentrations of Pb and Cd in soil surrounding the mine were higher than the US environmental protection agency (USEPA) standard, and the concentration of Pb in medical plant species surrounding the mine was higher than the world health organization (WHO) standard for edible plants (P < 0.05).