Assessment of heavy metal pollution in Koycegiz-Dalyan coastal lagoon watershed (Mugla) SW Turkey

Abstract

This study is carried out to assess the water pollution in Koycegiz-Dalyan Coastal Lagoon Watershed located near the Mediterranean Sea in Mugla province, SW Turkey, by using heavy metal pollution index (HPI). A total of 30 samples were collected from the lakes, streams, groundwaters, the subaqueous hot and cold springs, and on-land hot springs, and Cr, Fe, As, Sb, and Pb concentrations were determined. Elevated concentrations of Fe, As, and Pb were detected in most of the samples; the sources of which are either the natural or anthropogenic discharge of the geothermal springs and seawater mixing. As and Pb concentrations in some locations are found to exceed both acute and chronic exposure criteria for aquatic life, posing a threat to the species hosted by these environments. To determine the magnitude of pollution, HPI calculations were carried out. The average and maximum HPI values for the cold waters are 297.1 and 1162.9, respectively, both of which are higher than the critical pollution index value. The highest HPI values are observed in samples taken from the Dalyan Channel and Alagol 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 and mixing with seawater.