Dependence between the content of copper and the content of major elements in sediments of Polish lakes

In 416 sediment samples taken from the deepest waters of 260 lakes located within the following Lake Districts: Greater Poland, Pomeranian and Masurian, the content of Cu, Ca, Mg, Fe, Mn, K, Na, P and S was determined by the ICP-OES method and the content of the Total Organic Carbon (TOC) was determined by the coulometric titration method. The analyses revealed that in the majority of tested samples, the Cu content did not exceed 50 mg/kg and that the geometric mean of the copper content is 13 mg/kg, and thus it is much higher than the geochemical background for aquatic sediments in Poland. The high dependence determined between the Cu content in sediments and the concentration of Al, K, Mg, S and TOC and a weaker correlation between the Cu concentration and the content of P and Fe indicate that copper in sediments is primarily related to the organic matter and clay minerals and, to a lesser extent, to phosphates and iron compounds. The variation in the copper content in sediments of different Lake Districts and also the variation in the present correlations were observed.