Aida Biati - Department of Environmental Science, Graduate Faculty of the Environment and Energy, Science and
Abdulreza Karbassi - Graduate Faculty of the Environment, Department of Environmental Engineering, University of Tehran,

Flocculation process as an effective mechanism in metals removal during estuarine mixing is of special importance. In the present investigation, flocculation of metals during mixing of Siyahrud river water with Caspian Sea water is studied. The maximum flocculation of elements occurs in the salinities 1.67 to 3.67‰ (except for Zn). The flocculation trend of Zn (80.9)> Mn (58.3) > Cu (30.5) > Ni (25.9) > Pb (19.5) indicates that flocculation of metals have nonlinear behavior towards salinity changes during estuarine mixing. Electrical conductivity shows a linear behavior in different proportions of salinity which is in contrast with the behavior of other studied parameters. Cluster analysis indicates that pH and NO3 are governing factors in flocculation of Cu, Mn and Pb. The results of this research show that 80.9, 19.5, 25.9, 30.5, 58.3% of dissolved Zn, Pb, Ni, Cu and Mn flocculate during estuarine mixing. Total amount of studied dissolved element flowing in to the Caspian Sea would decrease from 5.62 to 2.76 Ton/Yr.

Metals, Flocculation, Estuarine mixing, Caspian Sea