Dynamics of metal ions in suspended sediments in Hugli estuary, India and its importance towards sustainable monitoring program

SummaryMetal contamination in a river has often been assessed based on total metal ion concentrations without relating them with the amount of suspended solids. This approach masks lot of important dynamics of metal ions in water. This is first time in India, a study has been undertaken to present how the level of metal ions in river water is influenced by suspended solids in response to spatial and seasonal conditions in Hugli estuary, India and to focus necessity of harmonizing science and policy. This study presented extent of metal pollution and distribution pattern over the stations, seasons, tides and depth. Major fraction of metal ions is associated with suspended sediments and discharges into the largest alluvial fan, Bengal fan, in the world. Enrichment factors indicated that major source of metal contamination is large influx of sediment due to strong natural activities and moderate anthropogenic activities over the years strong seasonal change, variable tidal energy level and irregular estuarine geometry play crucial role in maintaining metal concentrations in water column. Findings of this study would help to refine existing monitoring practice and to understand its importance in water quality management.