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Distribution of metals and extent of contamination in sediments from the south-eastern Baltic Sea (Lithuanian zone)

Remeikaitė-Nikienė N., Garnaga-Budrė G., Lujanienė G., Jokšas K., Stankevičius A., Malejevas V., Barisevičiūtė R.

Oceanologia

2018

No. 60 (2)

193--206

The distribution of metals (Pb, Cu, Cd, Ni, Cr, Zn) in surface sediments and the potential pollution sources in the south-eastern part (SE) of the Baltic Sea (Lithuanian zone) were investigated in relation to the environmental characteristics (amount of fine-grained particles, TOC content in sediments, origin of sedimentary organic matter, salinity, water depth) in 2011-2014. The higher metal concentrations were measured in sediments of the Curonian Lagoon and in the open waters. An approach using various environmental indices (enrichment factor EF, geoaccumulation index Igeo and contamination factor CF) was used to quantitatively assess a contamination degree. The principal component analysis (PCA) was applied in order to further scrutinize pollution from metal sources. The values of the contamination indices showed no/very low sediment contamination with Ni and Cr, minor-moderate contamination with Cu, Zn and Pb and moderate-considerable pollution with Cd. The strong relationships among metals suggested their similar distribution pattern and a combination of natural and anthropogenic sources. The higher metal concentrations coincided with an increasing amount of fine-grained fraction and organic carbon. In the territorial waters, the distribution of elements was related to the water depth. In addition, the binding of metals with insoluble iron sulphides might explain their high concentrations at the most remote and deepest stations.

Accumulation of 137Cs in bottom sediments of the Curonian Lagoon

Lujaniene G., Vilimaite-Šilobritiene B., Jokšas K.

Nukleonika

2005

Vol. 50, nr 1

23-29

Measurements of activity concentrations and speciation of 137Cs in bottom sediments of the Curonian Lagoon were carried out in samples collected in 1999-2003. In addition, the sorption-desorption processes of caesium in disturbed bottom sediments of fresh and sea water systems were investigated in long-term experiments (up to 375 days) in order to better understand the caesium behaviour during the Baltic Sea water flooding events to the Curonian Lagoon. The modified Tessier method was used to study caesium associations with geochemical phases of bottom sediments. The effect of carbonate coatings of bottom sediments on the Cs sorption-desorption process was observed. The comparative analyses of 137Cs solid phase speciation in bottom sediments after 241 and 375 days of the sorption experiment with that of the 137Cs speciation, determined in the same sediment sample before the sorption experiment, indicated that after 375 days of sorption the equilibrium was not reached, however, the Cs distribution in geochemical phases was found to be close to equilibrium. The desorption experiments evidenced the release of caesium into solution from regular exchange complex and transfer from other phases to the frayed edge sites on the layered clay minerals with its further fixation in the crystal lattice. The remobilization of "fixed" caesium was not observed, on the contrary, the redistribution of caesium with its subsequent fixation in clay minerals was observed, and on a time scale its fixation kinetics was comparable with the sorption experiment. This study showed that flooding events of sea water contaminated with caesium can cause a significant accumulation of caesium in the bottom sediments of the Curonian Lagoon and result in the redistribution of 137Cs activity concentration in the bottom sediments from one area to another.