Peat soils (FAO — Gelic Histosols) in the southern Bellsund coast area occur on slopes and terraces. They are formed in places favourable for plant growth, i.e. adequately moistened and fertilized largely with bird excrements. These formations belong to moss peats which are generally decomposed weakly and moderately to about 0.5 m depth. Their content of organic matter is equal to about 30-90%, but it is higher in terrace peats. The latter are more acidified than slope peats. The reaction both of slope and terrace peat soils is as a rule, slightly acid or neutral, and CaC03 content does not exceed 10%. As regards the content of macroelements, that of Al is the highest followed by Ca, Fe, Mg and P. Little K and Ti, and only traces of Na are found. Microelements occur in the following sequence: Mn, Zn, Cu, Cr, Ni, Pb, Co, Cd. Particularly Mn, Zn as well as Cu and Cd were found in a higher concentration. Slope peat soils are richer in macro- and microelements than terrace ones, e.g. 4 times in the case of Mg. Peat soils poor in ash parts (up to 25% ash), contain the fewest elements. Some regularities concern also a vertical distribution of the particular profiles but only with regard to terrace peat soils.

The aim of the study was to assess the P-PO4 and N-NH4 pollution of water in grasslands located on peat soils and to identify the impact of groundwater level on this pollution formation. The research was conducted in 2000– 2010 on grounds of ITP-PIB in Biebrza village (Poland). Within lowland fen a total of 18 monitoring points of groundwater and watercourses were established in 6 separate test stands. The subject of the research was water collected from drainage ditches/channels and groundwater, which was taken from wells installed in organic-soil layer and wells whose bottom was 15–20 cm below this layer. Water samples were collected several times a year, and in the case of groundwater, its level was also measured. It was found that: 1) due to concentration level of P-PO4 and N-NH4, about 46 and 39% of water samples from organic-soil layer and more than 40 and 37% of water samples from mineral- organic-soil layer respectively, were characterized by poor chemical status; 2) due to the exceeding of the limit values of P-PO4 and N-NH4 concentration, water samples from watercourses in over 30 and 27% respectively were not within 1st and 2nd class of surface water quality; 3) P-PO4 and N-NH4 concentrations in each water type were statistically significant and positively correlated with each other; 4) in organic-soil layer the groundwater level changing every 10 cm was a statistically significant factor differentiating the average P-PO4 concentration in groundwater associated with mineral-organic layer of peat soil and average N-NH4 concentration in each type of water.