Abstrato

The Pollutant Content in the Padma River Water Draining from Rajshahi City and impact on fisheries

Golam Mortuza

The study was carried out to assess surface water quality of Rajshahi City of Bangladesh. Based on surveys and chemical analyses, we performed a case study of the surface water collected from three different areas, in order to understand the sources of water pollution and the evolution of water quality in Rajshahi City, Bangladesh. Concentrations of major chemical elements in the surface water were related to the source of the agricultural, industrial and municipal sewerage. Low dissolved oxygen, pH, Secchi depth and high electrical conductivity, total phosphorous total nitrogen and heavy metals were strongly associated with the effluent impacted sites and greatly influenced the fish community structure. The Padma river bank close to the city side was more polluted by the domestic and sewerage system than that of opposite side. This study recommends the use of fish as valuable biological indicators in aquatic environmental pollution assessment. River water is very much important for domestic, agriculture and industrial use in Bangladesh which is in critical condition from long time based on research data. During last 40 years, extreme pollution events occurred in peripheral rivers surrounding Dhaka city and Karnaphuli River in Chittagong city. Present data showed that other urban rivers are also in critical condition especially Korotoa, Teesta, Rupsha, Pashur and Padma. The pollutants flowing with water made a severe pollution in downstream areas of rivers. Metals concentrations in river water was found to be higher in dry season. Dissolve oxygen (DO) was nearly zero in Buriganga River and several points in Turag, Balu, Sitalakhya and Karnaphuli River. NO3-, NO2- and PO43- pollution occurred in different rivers. Zn, Cu, Fe, Pb, Cd, Ni, Mn, As and Cr concentration was above drinking water standard in most of the river and some metals was even above irrigation standard in water from several rivers. Sediment data showed very much higher metal concentrations in most of the rivers especially peripheral rivers in Dhaka and Karnaphuli, Korotoa, Teesta, Rupsha and Meghna River. Metal concentrations in sediment was above US EPA threshold value in most of the rivers. Metal concentrations in fish and agricultural crops showed that bioaccumulations of metals had occurred. The concentration of metals showed the trend like: water