Role of suspended particulates on heavy elements transport in the middle part of Dez River

This study was performed in order to monitor and recognize the condition of transported suspended particulates and absorbed heavy metals in Dez river between Shahid Abbaspour Dam and Shotate river Junction and the effect of inflow from two tributaries in Kouzestan province, Iran. We took 38 samples in three steps including a base flow period and two flood events from four gauging sites including Dokouheh on Balaroud, Zourabad on Kohnak, Dezful on Dez upstream and Harmalah on Dez downstream. After sediment filtration, some samples were analyzed by Inductively Coupled Plasma to determine 12 heavy metals. The results showed that the river suspended sediment classified as not polluted by heavy metals for agriculture purpose at least for studies samples. However, the amount of three heavy metals including Cobalt (20-22 ppm), Chrome (88-96 ppm) and Nickel (76-91 ppm) are more than environmental safe thresholds. In addition, the concentration of those heavy metals in downstream station is more than tributaries which is probably due to deposition of coarser sediment particles. Therefore, it can be concluded that the suspended sediments between Dokouheh to Haramalah reach and Zourabad to Haramalah reaches are polluted by three mentioned heavy metals.