Quantification of Potentially Toxic Elements in Degraded Mining Soils and Medicinal Plants: A Case Study of Indus Kohistan Region Northern Pakistan

In recent years, a series of environmental and ecological problems have occurred due to enhanced anthropogenic disturbances for precious minerals mining. Traditional medicines have become an important pillar in national homeopathic treatment system especially in mountainous environment of developing countries. The current study investigates the level of potentially toxic elements ( PTEs ) contamination in degraded mining soil and medicinal plants along the mafic-ultramafic rocks in the Kohistan region. Soil samples and medicinal plant species were collected from the degraded mining area and were screened for PTEs (Pb, Cr, Ni, Mn, Zn, and Cd) using atomic absorption spectrometry. Various pollution indices were used for PTEs such as contamination factor (CF), pollution load index (PLI) and translocation factor (TF) in degraded mining soil and medicinal plants. The mean concentration of PTEs found in soil were in order of Mn>Ni>Cr >Pb>Zn>Cd, while in medicinal plants were Pb>Cr>Mn>Ni>Zn>Cd. Highest bioaccumulation was observed in Ajuga bracteosa (Cr=349 mg kg –1 ), Phlomis bracteosa (Pb=335 mg kg –1 ), Chenopodium ambrosioides (Mn = 304.3 mg kg –1 ), Isatis costata (Ni=169 mg kg –1 ), Ajuga parviflora (Zn = 38.4 mg kg –1 ) and Salvia moorcoftiana (Cd=11 mg kg –1 ). Furthermore, the concentrations of PTEs were significantly higher ( p <0.001) in degraded mining soil and medicinal plants than the reference site, which may be attributed to the mining and open dumping of mining wastes. The present study revealed that chromite mining and open dumping of mining wastes can cause serious environmental problem in the study area. Furthermore, medicinal plants grown in degraded mining soil may pose risk to the local inhabitants as most of the people consume these plants for various health problems.