Heavy metal contamination through wastewater irrigation on the soil and vegetables: Impact on the nutrient content and health risks ​

The use of wastewater irrigation may contribute to the metal accumulation, and reduction of nutrient level of vegetables, which would then have an adverse effect on human health. Therefore, in the present study we investigated heavy metals contamination and its impact on nutrient quality of vegetables and health risk. The study was conducted from the agricultural fields of Varanasi distinct during the period from March 2022 to June 2023 and all the laboratory work was carried in the department of Botany, Banaras Hindu University. Heavy metal concentrations in water, soil, and vegetable samples were measured using an atomic absorption spectrophotometer. The physiochemical property (pH), daily intake of metal, metal pollution index and health quotient were also calculated according to the published protocols. All heavy metal were found in higher concentrations in the wastewater irrigated soil that control site. The Lohta site had the highest concentration of heavy metals in the vegetables, followed by Dinapur, and least at control site (BHU). The highest concentration of metals (Cu, Zn, and Pb) were found in the leafy vegetables (S. oleracea and A. esculentus) whereas lowest in fruity vegetables (P. vulgaris). The rise in the Metal Pollution Index (MPI) also provided evidence for the greater metal content of these vegetables. The S. oleracea was found to have the highest DIM (0.061 g/g) while P. vulgaris had the lowest (0.007 g/g). HQ values of these metals were found greater than one ( greater than 1) for both children and adults on the ingestion of the vegetables of wastewater irrigated sites. Further, nutrient contents (Na, Mg, Ca) were also declined in the vegetables of wastewater irrigated site when compared to control site. These findings suggest that the consumption of such vegetables leads to compromised health and might be associated with severe health risk in the human.