Contamination of potentially toxic metals (PTMs) can be detrimental to ecological processes, diversity and physiology of biological components of the surrounding habitat of estuarine and coastal environment. In our study, an inclusive approach to measure ecotoxicological parameters was followed considering spatial concentration of PTMs in the sediment system, sediment quality status, ecological risk level, bioconcentration in mangrove tissue and resulting biochemical and antioxidative response in mangroves Avicennia alba and Excoecaria agallocha in eight locations in and around Indian Sundarban. Sediments in location L4 and L8 showed highest concentration of PTMs having maximum enrichment factors, geo-accumulation indices, contamination factors and pollution load indices signifying progressively deteriorated sediment quality of the estuary and considerable ecological risk for cadmium. Significant statistical correlation observed between chlorophyll content, free radical scavenging activity, reducing ability and stress enzyme activity (peroxidase, catalase and super oxide dismutase) of mangroves with PTM concentration in respective study areas. This work will help to frame effective prediction, assessment and management policies in this extremely eco-sensitive region by envisioning the status of augmented human activities leading to considerable metal stress in the estuarine sediment and consequent ecotoxicological response as the coping up mechanisms.

Present study revolves around the assessment of basic physicochemical parameters, dissolved PTEs, and microplastics (MPs) in riverine water to illuminate the policies for better sustainable management practices in river Hooghly. The samples were analysed in ICP-OES and fluorescence microscope to enumerate PTEs and MPs. The distribution of PTEs indicates that highest concentration of Al, Co, and Cu was in estuarine zone; Cd, Cr, Fe, Mn, Ni, and Pb in mixo-haline zone and Zn in freshwater zone. The maximum concentration of MPs was observed near Bali Khal, which acts as a sewage canal of the urban conglomerate of Howrah. Overall, the size of MPs was observed between 150 and 4560 lm with an abundance frequency of 1000 pieces/m$^3$ near the mouth of the sewers. Dissolved PTEs concentration was found to be lower than previous works, which can be attributed towards GoI approved Cagship program ‘Namami Gange Mission’. The study emphasizes the necessity of a uniform national water policy for better management of Indian rivers and estuaries.