Ecological risk and source identifications of heavy metals contamination in the water and surface sediments from anthropogenic impacts of urban river, Indonesia

Heavy metal pollution in urban rivers corresponds to anthropogenic impacts. Considering the environmental importance of the Winongo River for domestic use, agriculture, and fisheries, a comprehensive study of heavy metal contamination in this river needs to be conducted. This research focused on the assessment of heavy metal in the water and sediment using the enrichment factor (EF), geo-accumulation index (I(geo)), Ecological Risk Index (E(r)), and Potential ecological risk index (RI). Results showed that the concentrations of the heavy metals Pb, Cu, Cd, Al, and Fe in the water samples exceeded thresholds. Based on EF, I(geo), and E(r) assessment, the level of contamination by the heavy metals Pb, Cu, Cr, and Cd was found to be low, and that by Fe and Al was found to be moderate to high. The mean values of heavy metals in sediment in the descending order are as follows Fe > Al > Pb > Cu > Cr > Cd (1,445, 2692.42, 0.17, 0.048, 0.016, 0 mg/kg) respectively. Meanwhile, the mean values of heavy metals in the water in descending were Al (1.208), Fe (0.857), Pb (0.155), Cu (0.018), Cr (0.009), and Cd (0 mg/L) respectively. The sources pollution of Cu, Cd, and Pb were identified as anthropogenic sources such as city effluent, road, fisheries, and mechanic workshops. Fe and Al from sediment exhibit strong correlation (r = 0.688). This suggests that Fe and Al possibly comes from same sources originating from earth materials. In general, the potential risk assessment showed that in the Winongo River, the midstream area had higher pollution levels than the downstream and upstream areas (pollution in midstream > downstream > upstream). The sources of pollution in the midstream were identified as city effluent, roads, fisheries, and mechanic workshops. For this reason, the findings of this research are expected to provide a scientific basis for pollution control.