Receptor model-based source apportionment and ecological risk assessment of metals in sediment of river Ganga, India.

Ganga river surface sediment was sampled from 11 locations, which revealed average concentrations (mg/kg) of metals in the order Mn (296.93) > Zn (61.94) > Cr (54.82) > Cu (30.19) > Pb (24.42) > Cd (0.36). Sediment quality guidelines showed metals rarely to occasionally exhibit adverse biological effects. Indices like potential ecological risk, contamination security index, hazard quotients, multiple probable effect concentrations quality, mean probable effects level quotients, mean effects range median quotient suggest nil to a very low level of pollution with low ecological risk. Contamination factor, geo accumulation index, enrichment factor, quantification of contamination revealed that Pb and Cd originated from anthropogenic activities. APCS-MLR model revealed that metals contributed from natural sources (Zn, Mn, Cr; 20.18 %), industrial-agricultural (Cd; 21.35 %); and discharge of paints, Pb batteries, fossil fuel (Pb; 8.49 %). Present findings will serve as an effective guideline for managing and ameliorating pollution in the river system.

Ameliorative effect of natural floating island as fish aggregating devices on heavy metals distribution in a freshwater wetland.

Growing human population and climate change are leading reasons for water quality deterioration globally; and ecologically important waterbodies including freshwater wetlands are in a vulnerable state due to increasing concentrations of pollutants like heavy metals. Given the declining health of these valuable resources, the present study was conducted to evaluate the effect of natural floating island in the form of fish aggregating devices (FADs) made of native weed mass on the distribution of heavy metals in the abiotic and bio compartments of a freshwater wetland. Lower concentrations of surface water heavy metals were observed inside the FADs with a reduction of 73.91%, 65.22% and 40.57-49.16% for Cd, Pb and other metals (viz. Co, Cr, Cu, Ni and Zn), respectively as compared to outside FAD. These led to 14.72-55.39% reduction in the heavy metal pollution indices inside the FAD surface water. The fish species inside the FADs were also found less contaminated (24.07-25.07% reduction) with lower health risk indices. The study signifies the valuable contribution of natural floating island as FADs in ameliorating the effect of heavy metals pollution emphasizing the tremendous role of the natural floating islands in sustainable maintenance of freshwater wetlands for better human health and livelihood.