HEAVY METAL POLLUTION IN KOYCEGIZ-DALYAN COASTAL LAGOON WATERSHED (MUGLA) SW TURKEY: AN INDEXING APPROACH

This study was carried out to assess the water pollution in Köyceğiz-Dalyan Coastal Lagoon Watershed (KDCLW), including Köyceğiz, Alagöl and Sülüngür Lakes and Dalyan Channel, located near the Mediterranean Sea in Muğla province, SW Turkey by using an indexing approach. A total of 30 samples were collected from the lakes, streams, groundwaters, the subaqueous hot and cold springs and on-land hot springs and pH, electrical conductivity and the concentrations of five heavy metals (Cr, Fe, As, Sb and Pb) were determined. Accordingly, pH values vary between 6.70 and 8.91 implying that the samples are near neutral to basic in character. Electrical conductivity values of all the samples exhibit a wide range: from 0.31 to 53.29 mS/cm. The samples with the highest EC values resembling the EC values of typical seawater are the ones collected from Alagol lake. Relatively higher heavy metal concentrations were detected in the on-land and subaqueous hot springs when compared to the cold waters. Alagöl lake samples exhibited high concentrations of dissolved heavy metals, likewise the EC values, because it is located downstream of the area where most surface waters gather. Cr, As, Sb and Pb are present in all of the samples in concentrations varying between 2.8 and 291.4; between 1 and 404.8; between ~0 and 5.6; between 1.3 and 180.1, respectively. High concentrations of Fe, As and Pb were attributed to either the natural or anthropogenic discharge of the geothermal springs. So as to assess the extent of pollution, Heavy Metal Pollution Index (HPI) values were calculated for all of the samples and the average and maximum HPI values for the cold waters came out to be 297.1 and 1162.9, respectively. The highest HPI values were observed in samples taken from the Dalyan Channel and Alagöl Lake. In general, pollution levels increase from north to south, reaching the maximum value at the outlet point, due to the increased contribution from thermal water discharge.

Acknowledgments

This study was carried out as a part of a project supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK, Project Number 112Y137).