Seasonal analysis of heavy metal contamination in the indus river: impacts on aquatic life and human health risks

In this study, we investigated the seasonal variations in heavy metal pollution specifically, Cd, Cr, Pb, and Cu in water, sediment, and the tissues of rohu (Labeo rohita) across three different sites along the Indus River in Mianwali, Pakistan. Heavy metal levels were higher during the pre-monsoon season, with decreasing order of Pb > Cr > Cu > Cd in water and Cr > Pb > Cu > Cd in sediment. Metal concentrations were highest in gills, followed by liver, and lowest in muscle tissues. Principal component analysis (PCA) and cluster analysis showed that gills and liver clustered together, while muscles and water formed another group, with sediment closer to gills and liver. Pb shared the same source across seasons, unlike other metals. Human health risk analysis showed a higher Hazard Index (HI) in pre-monsoon, though values remained below 1, indicating safe consumption. On the other hand, elevated pre-monsoon HI values highlight potential risks, necessitating continuous monitoring and pollution control measures. These findings emphasize the urgent need to address rising pollution levels in the Indus River to safeguard freshwater resources and ensure sustainable fish consumption in the region.