Temporal evolution of lead isotope ratios and metal concentrations in sediments of the north Aegean Sea, in Turkish coast

Abstract

In present research, fifteen surficial and two profile sediment samples were studied in terms of sediment chronology and pollution degree on the ground of pollution indexes such as enrichment factor (EF), contamination factor (CF), Pollution Load Index (PLI) and lead isotope ratios (206Pb/207Pb, 208Pb/206Pb). Lead-210 (polonium-210) activity concentrations were measured by utilizing alpha spectrometry. Sediment chronology was determined via modified CRS mathematical model. Average mass accumulation rates are 0.301 and 0.227 g cm−2 year−1 in Bakircay River mouth and Ayvalik offshore stations respectively. Mass accumulation rates do not display the systematic increases along the cores from bottom layers to top layers. In Bakircay River mouth station 210Pb flux is higher than the range of global atmospheric 210Pb flux value. Due to the high CF and EF values of Sr both of stations have hydrothermal features. Ayvalik offshore station has displayed Na, Cd pollution since 1945, but Na, Cd, As, Mo, Ag pollutions have existed in Bakircay River mouth station since 1983 in terms of CF and EF values. According to PLI index, Bakircay River mouth station has “starting level pollution” degree and it displayed an “acute corruption” in 1981. 206Pb/207Pb ratios range from 1.17 to 1.25, 208Pb/206Pb ratios range from 1.99 to 2.16 in study area. When 206Pb/207Pb and 208Pb/206Pb ratios are evaluated with together, it is seen that both of the stations have had the natural (geologic) sediments since 2011.