Share of Natural and Anthropogenic Sources in Distribution of Heavy Metals in a Sediment Core from Zarivar Lake

Sediment core samples can provide useful information about aquatic environment. Sedimentation rate, climate changes and heavy metal concentration are among the most important studies that are carried out on sediment cores. In this study, a sediment core of 70cm with aim of metal concentration investigation is collected from central part of the Zarivar lake in the vicinity of the Marivan city in Kurdistan province. After sub sectioning the bulk concentration of metals was obtained using HF- HCl- HNO3. The share of lithogenous and anthropogenic concentration of metals was brought out by chemical partitioning technique. The results of chemical partitioning studies revealed that a considerable part of metals are present in anthropogenic fraction as follows
Pb (76.2%)>Mn(53.3%)>Co(50.6%)>Cu(47.4%)>Zn(27.5%)>Ni(18%)>Fe(7.9%)
Results of the present investigation showed that statistical studies such as cluster analysis are not sufficient to identify existence of pollution. The results of chemical partitioning studies indicate that Zarivar lake is polluted but cluster analysis illustrates an unpolluted environment. Except for Cu, a significant portion of other metals are present as loosely bonded ions that can be easily released into the overlying waters due to slight changes in physico-chemical characteristics of water column. Presence of small amount of Fe and Mn as sulfides is indicative of prevailing redox conditions over the anoxic ones. Based on the obtained data, the existing condition of Zarivar lake in terms of contamination is not suitable and with increasing of red ox condition, the possibility of increase in contamination is probable