Sediment toxicity and ecological risk of trace metals from streams surrounding a municipal solid waste landfill.

The present study is an attempt to assess the pollution intensity and corresponding ecological risk of heavy metals such as Cd, Ni, Pb, Cu, Zn and Cr using various indices like geo-accumulation index, concentration factor, pollution loading and ecological risk index. In all 21 surface sediments samples were collected from the stream flowing around the solid waste disposal landfill of Qayen city in southeastern Iran. Although Igeo values for Cd varied greatly, sites 18-21 with class 5 show heavy loads of Cd (values between 4.13 and 4.45). PLI values (3.37-12.89) clearly suggest strong contamination with respect to the measured metals. This study clearly indicates that the contamination risk in the downstream reservoir is much higher than upstream sites due to transfer and accumulation of leached metals from upstream to downstream.