Industrial Effluents and Biodiversity Collapse: A Review of Subarnarekha River Pollution in Jamshedpur and Indian Urban Rivers

The ecological consequences of industrial effluents are mediated by river hydrology and sediment dynamics. Indian cities have expanded around rivers that historically sustained drinking water supply, fisheries, floodplain agriculture, cultural practices, and high freshwater biodiversity. Yet, many urban rivers now function as conduits for industrial effluents, municipal sewage, and contaminated stormwater, producing chronic chemical stress, habitat degradation, and biological impoverishment. This review synthesizes published evidence on the Subarnarekha River with emphasis on the Jamshedpur industrial corridor, and situates this case within the wider crisis of Indian urban rivers. The Subarnarekha exemplifies a coupled “industrial–urban river syndrome” in which metal-rich and oxygen-demanding wastes interact with altered flow regimes and sediment processes to create persistent exposure pathways for aquatic biota. The literature consistently indicates (i) elevated potentially toxic elements in water and bed sediments, (ii) strong seasonality linked to monsoonal dilution and dry-season concentration, (iii) sediment acting as both sink and secondary source of contaminants, and (iv) bioaccumulation in lower trophic levels and fish, with implications for ecological integrity and human dietary risk. Evidence from other Indian urban rivers demonstrates similar patterns, including contaminant mixtures (metals, antimicrobials, plastics), microbial community shifts, and degradation of sensitive macroinvertebrate and fish assemblages. The review highlights mechanistic pathways from effluent discharge to biodiversity collapse: toxicity, food-web disruption, eutrophication–hypoxia cycles, and selection for pollution-tolerant taxa. It also evaluates monitoring approaches and management options—source control, improved treatment, sediment risk management, environmental flows, and biomonitoring—relevant to Subarnarekha and comparable rivers. The paper concludes with a synthesis of actionable research priorities and governance needs to reverse biodiversity loss in industrial–urban river systems. Comparative evidence from other Indian urban rivers shows that Subarnarekha is not an isolated case but part of a broader pattern in which contaminant mixtures, oxygen stress, and habitat degradation restructure biological communities.