Spatial Assessment of the Effect of Sediment Quality on the Nutrient Levels in Shallow Waters: Cernek Lake Case

Abstract

This study was conducted to determine the water-sediment quality and trophic status changes of Cernek Lake located in the Kızılırmak Delta (one of the most important wetlands in Turkey) and protected as a Ramsar site. The main objective, was evaluated and examined the effects on trophic level of surface water that the layers of lake sediments can create. In the study, the periodic exchange on trophic level have been evaluated with Geographic Information Systems (GIS) by identifying existing water of lake and sediment quality of lake. Spatial analysis was realized for water and sediment quality parameters (pH, salinity, Secchi disc depth and chlorophyll-a, total phosphate and total organic carbon (TOC) concentrations). The results of field studies conducted at Cernek Lake for three seasons (2010-2011) showed that the sediments contain high phosphate (annual average 541 mg / kg PO4-P, dry weight) and high organic carbon content (annual average 22.4 G / kg TOC, Dry weight). During the summer, Carlson Index values relatively declined during this period compared to autumn (81 to 79), but the eutrophic structure of the lake is still found to be high character. Findings, showed that the contaminated lake sediment layer would be highly effective in trophic level of the lake therefore it has revealed the necessity of taking measures for eutrophication. According to the results of study, taking the medium and long term measures to eutrophication and implementation of the strategic action plan is required.