Spatial distribution and source apportionment of metals in sediments of Meriç-Ergene Basin, Turkey

The present study is aimed to detect and evaluate metal accumulation in the sediments of Meriç-Ergene Basin, which is an industry-intensive area in Turkey. Ten metals and Total Organic Carbon (TOC) concentrations were determined in sediment samples collected from forty-one different sampling points selected considering the pollutant source types and the flow direction from the upstream towards the downstream in July and December 2020 representing the dry and wet periods. Concentrations measured were evaluated in terms of pollution levels, relationship with each other and source distribution using risk indexes and various statistical techniques. According to the findings, TOC and metal concentrations in sediments taken from regions where industrial activities are concentrated were significantly higher. The values measured in these areas especially for chromium, copper and zinc were 8–11 times more of the reference regions. The index calculations showed that the pollution level at industry-intensive areas were enriched by cadmium, chromium, copper, lead, zinc and these particular regions had higher ecological risk than the agricultural areas and the reference site. Hierarchical Cluster Analysis (HCA) was performed to statistically categorize the sampling points and three common spatial distributions were obtained. Principal Component Analysis (PCA) was used to identify common sources of metals, and correspondingly, two common source groups were identified. Accordingly, there appeared a similar pattern and dense pollution in the sediments of the industrialized areas, and more than half of the metal load was found to be due to industrial activities and to the still active unsanitary landfills.