Effect of physicochemical conditions on heavy metal biosorption in natural environments

Küçükçekmece Lake is one of the natural lagoon lakes in the world that contains various endemic species inside of it. In Küçükçekmece Lake, heavy metal observations are done in water and sediment structure and high amounts iron, copper and zinc metals are found (Ustun et al., 2005). Biosorption/bioaccumulation characteristics of cyanobacteria that are isolated from Küçükçekmece Lake in the period of eutrophication is researched.In this study, firstly; resistance of five cyanobacteria species that isolated from Küçükçekmece Lake are investigated against Fe+2, Cu+2 ve Zn+2 metals. As a result of resistance study, E35 (Synechocystis sp.) coded isolate is observed as the most resistant isolate. Growth curve of E35 coded isolate is drawn by chlorophyll measurement in metal containing medium.Generally in receiving body, a lot of metals have been found together. Fort this purpose, biosorption/bioaccumulation kinetics of cyanobacteria is investigated in single, double and ternary metal mixtures of Fe+2, Cu+2 ve Zn+2 at optimum growth conditions (23 °C, pH 7).When single biosorption/bioaccumulation experiment set is examinated, metal transfer speed from water to cell surface is Cu+2 > Zn+2 > Fe+2, and metals transfer speed from cell surface to cell inside is Fe+2>Cu+2 > Zn+2.In double metal solutions, metal transfer speed from water to cell surface is Zn+2 >Cu+2 > Fe+2 respectively, and metals transfer speed from cell surface to cell inside is Fe+2 > Cu+2 > Zn+2 respectively.In ternary metal mixtures, it is observed that metal transfer speed from water to cell surface is Zn+2 ? Fe+2 >Cu+2 respectively, and metals transfer speed from cell surface to cell inside is Fe+2 >Zn+2>Cu+2 respectively.In order to make approaches to behaviors of resistant isolate in its natural habitat, biosorption/bioaccumulation studies have done with the natural water examples that are taken from Küçükçekmece Lake. In this period of resistant isolate, it has been found that mostly Fe+2 then Cu+2 and Zn+2 ions are taken in to the cell.As a result of Fe+2, Zn+2 ve Cu+2 experiments that have done with Synechocystis sp. (E35) isolate, it has been found that biosorption is both suitable for Freundlich and Langmuir isotherm models.Differences that have done E35 isolate morphological structures and Synechocystis sp. (E35)?s defense system that is formed against Fe+2, Zn+2 and Cu+2 metals have shown by electron microscopy images. In the electron microscopy images of E35 exposed to 10 ppm Fe+2, exopolysaccharide structures (EPS) are observed. 10 ppm Zn+2 and 5 ppm Cu+2 ions caused EPS forming but not much as iron.