Heavy Metal Contamination Status of Water, Agricultural Soil, and Plant in the Semiarid Region of Kandahar, Afghanistan

Agricultural irrigation using wastewater containing heavymetals(HM) might impose risks in bioaccumulation in foods. The current studywas performed to assess the status of HM in terms of water-soil-plantsystems in Kandahar, Afghanistan, where industrial and domestic wastewaterwas partially reused for irrigation. Water, soil, and plant sampleswere collected from wastewater sites in Haji-Arab (HA), Bala-Karz(BKZ), and Mahal-e-Nejat (MN) in comparison with those from a freshwater-irrigatedsite in Char-Bagh (CB). The HM levels in unfiltered water samplesremained lower than the World Health Organization (WHO) and Food andAgriculture Organization (FAO) permissible values, but the HM concentrationsin soil and crops were higher at the HA, BKZ, and MN (wastewater-irrigatedsites) than those at the CB site (freshwater-irrigated site). Lead(Pb) levels were high in soils (43-83 mg/kg) and crops (18-36mg/kg) and extremely exceeded the safe limits even for those cropsamples cultivated in the freshwater-irrigated site. Continuous wastewaterirrigation increased the HM concentration in water, soil, and plants,but the Pb pollution was found to be ascribed to the minerals in thatarea since the underground water was showing high Pb levels. The bioaccumulationof HM in the studied sites was related to the cultivated crops andcorrelated with the land use in the watershed area. This study isimportant in understanding the risks associated with HM and exercisingprudence when applying various irrigation resources in Afghanistan.

Automated summary

The study analyzed the risks of bioaccumulation of heavy metals in food through agricultural irrigation using wastewater. Samples of water, soil, and plants were collected from wastewater-irrigated sites in Kandahar, Afghanistan and compared with a freshwater-irrigated site. The results showed higher concentrations of heavy metals, especially lead, in soil and crops from the wastewater-irrigated sites, with the Pb pollution attributed to minerals in the area and high levels in underground water. This study highlights the importance of understanding and managing heavy metal risks in irrigation practices in Afghanistan.