Biogenic components and trace elements in the sediments of river mouths and accumulation areas of the curonian lagoon (South-eastern Baltic sea)

Abstract

Contribution of the Neman (Nemunas) River including the arms Atmata, Skirvytė and Razliv, as well as Matrosovka and Deima rivers to the general enrichment of the Curonian Lagoon with biogenic components and chemical elements is reflected in the composition of surface sediments accumulating in the river mouths. Other part of chemical substances are absorbed by the finest particles and reaches accumulation areas of the lagoon in the south-western and central parts. Results from the study have shown the prevalence of terrigenous and biogenic-terrigenous sediments in the mouths of small rivers. Highest average values of biogenic components (31.46–38.87% of CaCO3; 0.63–1.03% of N; 0.07–0.1% of P) are observed in the accumulation areas of the coarse silt and fine silty mud. Same areas are characterized by the increased amounts of potentially hazardous metals (Cd, Cr, Cu, Ni, Pb, Zn). Results from this study have shown considerable enrichment of sediments with arsenic. In most places average contents of this metalloid are well above the geochemical background values, determined for the south-eastern part of the Baltic Sea. Absolutely highest values of arsenic (91–93 mg/kg) suggesting presence of serious contamination sources were determined in the south-eastern part of the lagoon, adjoining the mouth of small Matrosovka River.