Appraisal of heavy metal pollution in groundwater of Malwa region, Punjab (India) using stress biomarkers in Brassica juncea

Heavy metals are known for their toxicity which poses risk to human health even at very low levels. In the present work, groundwater from 24 different sites of Malwa region were analyzed for heavy metal contents (Cadmium, Chromium, Copper, Mercury, Manganese, Lead, and Zinc) and possible health risks along with ecotoxicological impact of contaminated groundwater using stress biomarkers in Brassica juncea seedlings. Mean concentrations of Cd, Cr, Cu, Hg, Mn, Pb, and Zn (µg/l) in groundwater samples was found to be 1.00, 6.16, 70.40, 0.27, 709.23, 59.38, and 368.15, respectively, during summer and 0.69, 4.03, 53.75, 1.21, 98.21, 69.58, and 254.92, respectively, during winter season. The concentrations of detected metals were above the acceptable groundwater standard limits for Mn, Hg and Pb. The average daily dose (ADD) and hazard quotient (HQ) values for Cu and Pb were above the threshold values at Bathinda during both the seasons. The results of phytotoxicity indicated that the groundwater affected the antioxidant enzymes and the biochemical parameters such as malondialdehyde (MDA), protein and chlorophyll content in Brassica juncea. Our findings suggested that the groundwater is significantly contaminated with heavy metals and its long-term use for drinking purpose without any pre-treatment may cause severe health risks in humans and irrigation of agricultural fields also results in their bioaccumulations in food crops.