Flocculation of dissolved Mn, Zn, Ni and Cu During the mixing of tadjan river water with caspian sea water

Abstract

This is the first study of flocculation of dissolved Zn, Cu, Ni and Mn during the mixing of Tadjan River water with the largest lake in the world (the Caspian Sea). Flocculation of Dissolved metals was investigated on a series of mixtures with salinities ranging from 0.16 to 9.5 ppt. The flocculation rates (Zn (96%) > Mn(58%) > Cu(42%) > Ni(7%)) are indicative of the non-conservative behavior of Zn, Mn and Cu and the conservative behavior of Ni during estuarine mixing. Statistical analysis indicates that the flocculation of Cu, Ni, Zn, and to an extent Mn, is governed by pH. The flocculation rates reveal that the overall dissolved metal pollution loads may be reduced to about 50% during estuarine mixing of the Tadjan River with Caspian Sea water.

Comparison of controlling mechanisms of flocculation processes in estuaries

“…The concentration of studied metals in Minab River water during estuarine mixing has been compared with the concentration of elements in flocculants of five rivers flowing into the Caspian Sea in North of Iran (Table 2). As can be seen in Table 2, except for Zn and Pb other studied elements in Minab River water flocculate at higher rates in comparison with the river flowing into the Caspian Sea (Karbassi and Nadjafpour, 1996;Saeedi et al, 2003;Karbassi et al, 2007;Karbassi et al, 2008a,b) and this might be due to higher initial metal contents in Minab River water than the northern river of Iran (Biati et al, 2010 b). The lowest flocculation rate in Minab river is associated with Pb (38 %) and in Tadjan, Talar, Babolrud and Haraz (Rivers flowing into the Caspian Sea) Ni flocculates in the lowest rate (7.1 %, 18.8 %, 12.2 % and 11.3 %, respectively).…”

“…Statistical analysis reveals that the flocculation of dissolved metals in Tadjan river which is governed by pH has an inverse relationship with TOC, EC and salinity. This suggests that increasing salinity, TOC and EC leads to a decrease of pH and elemental flocculation (Saeedi et al, 2003). Karbassi and Nadjafpour (1996) concluded that in Shirud Estuary, the main governing factor of metal flocculation (Pb and Zn) is salinity.…”

“…Cu) in Babolrud estuarine mixing. It should be pointed out that the processes responsible for removal of dissolved PO 4 at high concentrations encountered in the Babolrud estuary include precipitation of apatite (calcium phosphate), viviane (ferrous phosphate) and magnesium-ammonium phosphate but these have not been indentified in situ or in laboratory experiments simulating estuarine conditions (Deck, 1981;Saeedi et al, 2003). Considering the mean discharge of the rivers (Table 3) concentrations of dissolved metals in river water and also percentage of elemental removal via estuarine mixing (Table 2), amount of elemental load entering to the Sea and removal of dissolved metals due to flocculation process are estimated.…”

“…(Hunter, 1983;Zhiqing et al, 1987;Shankar and Karbassi 1992;Featherstone and O'Grady, 1997;Matagi et al, 1998). Due to growing concern over the divers effects of heavy metals and their compounds on aquatic ecosystems, many investigations have been carried out on dissolved elemental concentrations and then controlling mechanisms in some rivers flowing in to the Caspian Sea in North of Iran and the Persian Gulf in the South of Iran (Karbassi and Nadjafpour, 1996;Saeedi et al, 2003;Karbassi et al, 2007, Karbassi et al, 2008Biati et al, 2010 b). In the present study, controlling mechanisms of elemental flocculation during estuarine mixing in northern and southern estuaries of Iran in relation to the various physical-chemical parameters of water are compared.…”

Competitive heavy metals adsorption on natural bed sediments of Jajrood River, Iran

“…According to their findings, exobiological factors such as temperature, ion number, sediment type, and size of sediment particles, pH, and the simultaneous existence of several heavy metals affect the amount of heavy metals adsorption on the sediments. Some studies on the heavy metals pollution and their behavior in Iranian rivers have been conducted recently (Saeedi et al 2003(Saeedi et al , 2004Saeedi and Karbassi 2008;Karbassi and Nadjafpour 1996;Karbassi et al 2007Karbassi et al , 2008, but the adsorption process of metals onto the sediments is rarely studied.…”