The aim of this work was to establish the level of pollution by highly persistent polychlorinated contaminants in sediments from the Vistula Lagoon. Concentrations of PCBs, DDT and its metabolites, isomers of HCH and HCB were determined in the surface sediments (0 - 3 cm depth) from 6 stations. All the substances investigated were present in sediment samples from the Vistula Lagoon in concentrations above the detection limit of the method used (0.01 ng?g-1 d.w.). Concentrations of isomers of HCH and HCB ranged between 0.04 and 0.33 ng?g-1 d.w.. PCB values varied from 0.10 ng?g-1 d.w. to 0.99 ng?g-1 d.w. Of all the substances analysed, DDT and its metabolites were present in the highest concentrations - up to 1.97 ng?g-1 d.w.
Certain ice-related processes and phenomena associated with formation and disintegration of grounded ice hummocks in sheltered areas are discussed. The descriptions and discussion are based on the author?s research carried out over many years in the southern Baltic coastal lagoons. The first part of the paper focuses on the hummocking process which may be invoked to explain the formation of high (up to 10 m above the water level) hummocks. Conditions necessary for hummocking are described and the areas and seasons during which hummocks occur are indicated. In the second part of the paper, the rate at which the hummock height is being reduced during: 1. windless weather with below-zero air temperature, and 2. windy weather (strong wave action) and above-zero air temperature, is discussed. The formation of the so-called ice depression around a hummock is described as well. In the concluding part, attention is being paid to destructive effects of ice in the area affected by hummocking
The Vistula Lagoon is a shallow coastal ecosystem located on the Polish-Russian border in the coastal area of the southern Baltic. It is strongly influenced by inflows of seawater from the Baltic as well as by river inflow from the catchment area. High concentrations of nutrients in the Lagoon cause high primary production rates (ca 190 gC/m2/year) and other processes related to eutrophi-cation. Mathematical modelling of the physical and biogeochemical processes in the Vistula Lagoon has been applied as a tool for environmental assessment. The integrated MIKE 21 two-dimensional modelling system (by the Danish Hydraulic Institute / Water Quality Institute) was applied in the study. The eutrophication model of the Vistula Lagoon describes the nutrient cycle including eutro-phication-related processes. This paper describes the setup and calibration of the eutrophication model and presents the results of the basic calculation reflecting the situation in 1994. The role of the model in the evaluation of the ecological situation and in water management and planning is discussed. The model has been calibrated against monitoring measurements carried out in the Polish and Russian parts of the Vistula Lagoon.
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.