A RESEARCH ON PHOSPHORUS FRACTIONS IN SEDIMENT OF KOYCEGIZ LAKE  (MUGLA-TURKEY), AND ITS POTENTIAL RELEASE INTO THE LAKE

Ahmet Demirak, Yalçın Şahin, Feyyaz Keskin
Mugla University, Science Faculty, Department of Chemistry, Turkey

Abstract

The most sensitive regions of Turkey for environmental problems are those known as having important touristic potentials. Touristic investments done in a lot of cities, districts and towns on the shorelines of Mediterranean and Aegean Regions lose their traditional qualities increasingly due to population growth and structuring and these regions are left to the hands of tourism called as an “uncertain” area by the influence of economical motives without having any cultural and social preparation. Thus, Mugla shoreline is the region which is the most effected and mostly changed by them.  In this way, the region is the first sample in Turkey as a planned tourism progress directed by the State which is examined due to damages to natural environment and ecological values. In this context, the region is included into the “Private Environment Protection Area (PEPA) set by a decree law dated as 13th November 1989 and numbered as 383.
This study was conducted to find out the seasonal and spatial patterns of the phosphorus in the littoral sediment and its potential release into the Köyceğiz Lake between November 2011 and March 2012. Total phosphorus and phosphorus fractions in the sediment and overlying water samples mainly taken from three determined stations from the lake and additionally some chemical and physical measurements were done. The amount of the released phosphorus was estimated by using total filterable orthophosphate concentrations related to sediment pore water and overlying water with the water content of the sediment and the diffusion coefficient depending on the temperature. In the period of the research, the total phosphorus (TP) concentrations of the sediment samples were changed between 980.390 μg/gDW (dry weight) - 1990.810 μg/gDW and the trophic level of the lake was found to be eutrophic. The more proportion of phosphorus fractions in hindering phosphorus release into the lake was estimated as organic bound phosphorus fraction (Org≈P) (90,20 %), this fraction was followed by calcium bound phosphorus fraction (Ca≈P) (9,06 %), iron+aluminium bound phosphorus fraction (Fe+Al≈P) (0,47 %) and carbonate bound phosphorus fraction (CO3≈P) (0,27 %) respectively.

Keywords: Phosphorus Fractions, Sediment, Köyceğiz Lake (Turkey), Private Environment Protection Area (PEPA)