effects of season and altitude on copper and zinc concentrations in benthos (chironomids and gammarids) and sediment

concentration of heavy metals in aquatic ecosystems is considered as an important environmantal issue. in this study, the namrood river located in firoozkooh (tehran province, iran) was assessed for the existence of heavy metals. the namrood river is situated by the main road being by pollutants from tourism and recreational centers, gas stations, sewage of villages, agricultural wastewater and fish culture effluent. the water is extremely contaminated in some parts and possibly contains heavy metals. in the present study, two stations up- and downstream were determined to sample the sediments and chironomidae and gammarus pluex in both cold and warm seasons of the year (middle of march and middle of august). the copper and zinc were measured in sediment and benthos. the results showed that copper and zinc concentrations ranged 0.170-0.966 and 0.187-3.846 ppm, respectively. sediments of the upstream station had the highest copper concentration among the samples in both cold and warm seasons of the year.