Geographical information systems based ecological risk analysis of metal accumulation in sediments of İkizcetepeler Dam Lake (Turkey)

Abstract

This study analyzed the spatial distribution, potential ecological risks and possible sources of metal concentrations, organic carbon, chlorophyll degradation products and CaCO3 content from surface sediment samples in İkizcetepeler Dam Lake using ecological-toxicological indices, multivariate statistical analysis, and geographical information systems (GIS) software. One core sample and 32 surface sediments were taken from the Dam Lake, while seven lithologic samples were taken from various points in the basin. To identify anthropogenic influences in the Dam Lake from the before dam was constructed period to the present day, the enrichment factor (EF), contamination factor (CF), geoaccumulation index (Igeo), toxic risk index (TRI) and pollution load index (PLI) indices were calculated based on lithologic background values. Modified ecological risk (mER) and modified potential ecological risk (mPER) were calculated separately according to core sample and lithologic background values. Therefore, ecological risk during Anthropocene was determined using core sample values. Results pointed to significant enrichment of Ni (6.93), moderate enrichment of As (3.88), Cr (2.86), Mn (2.54), Hg (2.34), and Cd (2.04) and low level enrichment of Pb (1.20), Cu (1.15), Zn (1.08), and Fe (0.80). Ecological risk was listed as Hg (94) > Cd (61) > As (38) > Ni (35) > Cu (5.98) > Cr (5.72) > Pb (5.68) > Zn (1.07) according to lithologic background values and as Hg (59) > Cd (29) > As (9) > Ni (8) > Cu (7) > Pb (5) > Cr (2.97) > Zn (1.42) according to core background values. A significant level of ecological risk was determined for Hg (94), medium level ecological risk for Cd (61), and close to moderate level ecological risk for As (38) and Ni (35). The risk was low for all the other metals. According to the core sample background values, ecological risk was at the lowest limit of the most significant level for Hg (81), moderate for Cd (50) and low for other metals. Overall, this indicates a low (123) and moderate (201) potential ecological risk in İkizcetepeler Dam Lake based on core and lithologic background values, respectively.