Heavy metal contamination of the Curonian Lagoon bottom sediments (Lithuanian waters area)

Samples of surface (0-3 cm) bottom sediments of the Lithuanian aquatic area of the Curonian Lagoon and Nemunas River delta were taken from 41 sites in 2013 and 2014. Sediment parameters, such as the percentage of particles, concentration of organic carbon and heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, and Hg), were determined. The heavy metal contamination of the surface layer of bottom sediments was determined using the Nemerov's pollution index applied to soil. The spatial distribution of contamination indices and the dependence of contamination dynamics on sedimentation factors were analysed. It was determined that heavy metal concentrations had a tendency to increase as sediment particles became finer and as C-org concentration increased. A greater amount of pollutants got into the aquatic area of the Curonian Lagoon that was closer to the Klaipeda harbour than into other lagoon zones. The heavy metals for the integral pollution index for the Curonian Lagoon and Nemunas River delta surface bottom sediments could be arranged in the following order: Cd>Pb>Cu>Ni>Hg>Cr>Zn.