Assessment of River Water Quality Using Macroinvertebrate Organisms as Pollution Indicators of Tamirabarani River Basin, Tamil Nadu, India

摘要

River monitoring study was conducted to assess the current water quality status employing macrobenthic organisms as pollution indicators at 12 sampling stations of the perennial river Tamirabarani during March to December 2008. The river is the main source for potable water supply, irrigation, domestic uses, industrial processes etc., to the two districts namely Tirunelveli and Thotthukudi with the population of more than 42,96,261 people. Based on the physicochemical study, the river water quality deteriorates mainly due to organic contaminants which was measured through high BOD, COD and TKN content of the water samples and due to high discharge of domestic discharges, sewage wastes, open defecation, livestock discharges all along the river course. A sum of 3372 macrobenthic individuals comprising of 58 families were collected during the study. The macrobenthic abundance (97 numbers) was perceived at Pabanasam (T1) during March and June; less (36 numbers) assemblage was observed at Thiruppudaimaruthur (T4). The Family Biotic Index level indicates excellent quality at 10.42% of the sampling stations, very good quality at 6.25% stations, good quality at 25% stations, fair quality at 20.83% stations, fairly poor quality at 16.67% stations and poor quality of water at 20.83% of the stations; EPT and EPT/C Index shows uneven distribution of pollution sensitive and pollution tolerant organisms throughout the river system. ASPT and BMWP score of the study showed the water quality from excellent to poor. At present the perennial river is under threat of anthropogenic disturbances during festival periods especially at upstream areas, Tirunelveli city and suburban reaches due to higher pilgrimage and various religious and rituals practices.