The oxygen and chlorophyll a contents. pH, temperature and transparency were studied in Lake Rzuno in the period from June 1998 - September I 999. This lake has a very strong thermal stratification and weaker oxygenic stratification. The degree of surface water saturation with oxygen was rather small (max. 136%) but the oxygen conditions in the whole Lake Rzuno were good because the total lack of oxygen is noted only in summer and only below 20 m depth. Whereas during autumn and spring circulation the oxygen concentration reaches 5 mg O, drn' al the bottom. The correlation between visibility of Secchi disc and chlorophyll a concentration featured high correlation indicator (r = -0.87). The awerage water transparency, low oxygen deficit and small changes in water reaction show that this lake has moderate eutrophic character.

In the present paper we show results of our research on the contents of selected heavy metals in the surface and subsurface water layers of the estuarine lake Gardno. Obtained results show that there are substantial differences between concentrations of lead, copper and zinc in surface microlayer and subsurface waters. We observed that the surface microlayer is capable of accumulating much higher amounts of these metals than the subsurface waters. Analysis of seasonal changes in heavy metal concentrations in surface microlayers and subsurface waters shows some periodicity of these changes.

The oxygen and thermal conditions in Lake Ińsko were examined in years 1999-2000. Lake Ińsko is one of a dynamictic type and its waters are mixed twice a year. This lake has a strong thermal and oxygen stratification. The oxygen conditions in the lake are very good because the total deficiency of oxygen appears only in summer, on the depth below 30 m, and only in the areas where the influence of town of Ińsko is the strongest. During autumn and winter circulation the concentration of oxygen near the bottom reaches 5 mg O2 dm-3. The concentration of oxygen in the water reflects favorable conditions of biomass production, including primary production of phytoplankton in epilimnion of Lake Ińsko. The intensive development of algas has considerably influenced the transparency of water. On the background of vertical thermal and oxygen differences during the summer there were also differences in the reactions of water.

Physical analysis of the 15-cm top layer of the Rzuno lake bottom sediments showed that their properties changed adequate by depth. They changed from granular structure, in the lakes shallow parts, to amorphic structure, in the lakes deeper parts, from light color to almost black and from loose to gelatinous consistence. Chemical investigation of this lake bottoms sediments showed that their main components is silica (more than 50% of dry matter of sediments), therefore these bottom sediments were classified as silicate sediments. Organic matter was another essential component of these sediments. The content of organic matter increased adequate by depth from 7% to 36%. The investigated sediments exhibited small contents of nitrogen (about 0.6%), with predominance of organic nitrogen. They make up are characterized by small phosphorus contents (about 0.06%), with similar amount of inorganic and organic phosphorus. The content of metals (Ca, Mg, Fe, Al, Mn) was also small in the investigated sediments. Correlation analysis showed that iron ions precipitate phosphate phosphorus from water and accumulate it in sediments. The material deposited in bottom sediments of Rzuno lake in mainly of an autochthonous origin. The chemical composition of bottom sediments of Rzuno lake, as well as its comparison with other lakes, show that this lake is moderately eutrophic.

This paper presents the results of study on heavy metals in soil and in herbaceous plants in selected pine forests in Słowiński National Park. The heavy metals, such as Zn, Cu, Mn and Fe were studied. Concentrations of zinc in tested soil are strongly and very strongly related to manganese and copper content (r = 0.57 do r = 0.98, p < 0.05). Moreover, the soil moistening has vital impact on copper content in the plants of the ground cover. It was also found that moss in comparison to other forest plants captures higher volume of zinc and copper. The content of the above mentioned metals in the plants of dry coniferous forests (Bs), fresh coniferous forests (Bśw) and humid coniferous forests (Bw) of the ground cover constitute the following decreasing series: Mn(438.1) > Fe(98.6) > Zn(35.2) > Cu(3.5).