MANJIL SANGEETA DUNGDUNG, ASHISH KUMAR SAHU, SAWAN KUMAR SAHOO, SUBHASHREE SUBHADARSINI MISHRA, NARAD RAJESH AND ISWAR BAITHARU
Abstract
The River Mahanadi is a critical source of drinking water, irrigation, and agricultural production in Odisha. However, rapid urbanization, industrial expansion, and intensive agricultural practices have raised concerns regarding seasonal deterioration of water quality and the accumulation of toxic metals in edible crops. This study evaluated seasonal variations in physico-chemical characteristics, heavy metal contamination, water quality status, and associated human health risks. Surface water samples were collected from 20 locations during the pre-monsoon, monsoon, and post-monsoon seasons. Physicochemical parameters were analysed using standard APHA methods, while arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) were quantified by inductively coupled plasma mass spectrometry (ICP-MS). Heavy metal concentrations in six commonly consumed leafy and non-leafy vegetables cultivated along the riverbanks were also determined. Water Quality Index (WQI) was computed using the weighted arithmetic method, and human health risks associated with vegetable consumption were assessed following USEPA guidelines. Significant seasonal variations were observed in water quality and metal concentrations. Although most physicochemical parameters and dissolved heavy metals remained within BIS and WHO permissible limits, elevated fluoride concentrations were detected at several locations during the pre- and post-monsoon seasons, while chromium concentrations increased during the post-monsoon period. WQI classified most sampling sites as unfit for drinking, particularly during the monsoon season, indicating the cumulative impacts of domestic sewage, agricultural runoff, and industrial discharges. Leafy vegetables accumulated substantially higher metal concentrations than non-leafy vegetables, with cadmium and lead exceeding FAO/WHO permissible limits in most samples. These findings highlight the need for continuous environmental monitoring, improved wastewater management, and stricter regulation of agricultural and industrial discharges to protect water quality, food safety, and public health in the downstream Mahanadi River basin.