The paper presents the results of the studies on a degree of pollution and sanitary-bacteriological stale of bottom sediments of Wigry Lake in I 998 and 1999. Total Viable Count at 20°C (TYC 20°C) and Total Viable Count at 37°C (TYC 37°C) were used as indicators of pollution, while Total Coli (TC), Faecal Coli (FC), Faecal Streptococcus - Enterococcus (FS) and Clostridium perfringens - as indicators of the sanitary stale. Bottom sediment samples wen: collected from 3 sites situated in the centre of the lake and from 6 sites in the vicinity of the lake shore. Sanely and gravel offshore bottom sediments showed less degree or pollution than muddy bottom sediments collected from the centre or the lake. Higher numbers of anaerobic spore-forming and sulphite reducing bacteria (Clostridium pcrfringens) found at sites 1 and 2 in the vicinity of the mouth of Czarna Hańcza River lo Lake Wigry. At those places a higher bacteriological pol lution of bottom sediments samples was found.

The paper presents the results of studies of sanitary microorganisms' vertical distribution in pelagial and profundal waters of Lake Wigry against the background of thermal-oxygen relations and the presence of a chosen chemical compound in the annual cycle. Total Viable Count at 20°C (TYC 20°C) and Total Viable Count at 37°C (TYC 37°C) were used as indicators of pollution, while Total Coli (TC), Faecal Coli (FC) and Faecal Streptococcus-Enterococcus (FS) - as indicators of the sanitary state. Water samples were collected from 3 sites situated in the centre of the lake. Pelagial and profundal waters showed a little degree of pollution. Higher bacteriological pollution was found in some of waters samples from Lake Wigry at site I in the vicinity of the mouth of the Czarna Hańcza River. The most numerous sanitary microorganisms were detected at the deep from I to 5 meters and above the bottom sediments. Number of FC bacteria was only higher at the depth of 5 meters and deeper. An important positive correlation was noted between temperature and TYC 20°C as well as TYC 37°C, while negative between TC also FC during the whole study period. The oxygen content was correlated negative with TYC 20°C, TYC 37°C and FS. The depth was correlated negatively with TYC 20°C only.

This paper presents the results of a sanitary and bacteriological study of Lake Hańcza and its influents and an outflow. The study was conducted from April to October in the years 1998-2000, at 9 sites situated on the lake (pelagic zone, near-shore waters, ecotonal zone), 4 sites situated on the influents (the Czarna Hańcza and Stara Hańcza Rivers, the Spod Przełomki stream and the stream flowing from Lake Boczniel) and one situated on the Czarna Hańcza River, which flows out of Lake Hańcza. Total Viable Count at 20°C (TYC 20°C) and Total Viable Count at 37°C (TYC 37°C) were used as indicators of pollution, while Total Coli (TC), Faecal (therrnotolerant) Coli (FC) and Faecal Streptococcus - Enterococcus (FS) - as indicators of the sanitary state. The indicator bacteria number in the waters of Lake Hańcza and in the outflowing waters were usually typical of clean surface waters (purity class I). The bacteria number in the water inflowing to Lake Hańcza was much higher than that measured in the water of the lake and was usually similar to the values typical of slightly polluted (purity class II) and heavily polluted waters (purity class III). Throughout the study period, higher indicator bacteria numbers were measured in summer months; in other periods a higher number was found only sporadically. Its increase in subsequent years of study in the water at the established sites may be an indication of the increasing effect of allochtonie factors on the waters of Lake Hańcza.

Microbiological studies were carried out of atmospheric air sampled on the area and in the surroundings of a mechanical and biological wastewater treatment plant (WTP) treating municipal sewage. The capacity of the wastewater treatment plant, which also received some wastewater from the dairy industry, was ca 3· 103 m3d-1. Counts ofheterotrophic psychrophilic, psychrotrophic and mesophilic bacteria as well as some physiological groups of microorganisms which belong to Enterobacteriaceae family, Staphylococcus and Enterococcus genera, Pseudomonas fluorescens and P. aeruginosa species, hemolysing bacteria and actinomycetes were analyzed. Air samples were collected in summer, autumn, winter and spring seasons simultaneously by the sedimentation and impact methods at 6 sites located on the area of the WTP and at 5 sites situated in its surroundings. The background was established depending on the direction of wind, always on the windward side in relation to the location of the WTP. In addition, temperature and air humidity as well as wind speed and direction at each sampling sites were observed. Statistically significant differences were found in studied groups of microorganisms counts between air samples collected in different seasons of the year (with the exception of psychrophilic bacteria and by the two different methods (with the exception of psychrophilic bacteria) and microorganisms which belong to Enterobacteriaceae family). The highest mean counts of the microorganisms were usually determined in air samples collected by the sedimentation method, especially during the autumn (with the exception of actinomycetes, which are the most numerous in spring), the lowest ones in winter and/or in summer. No statistically significant differences were observed in counts of the analyzed groups of microorganisms in air sampled at particular sites (with the exception of Enterobacteriaceae bacteria isolated on Chromocult medium). However, higher counts of these microorganisms were typically found in the air sampled in the area of the WTP, particularly near the grit chamber, phosphorus removal tank, nitrification and denitrification chambers and secondary settling tank. According to the Polish Standards used for evaluation of atmospheric air pollution, the air sampled in the area of wastewater treatment plant and in its surroundings was classified as only slightly and sporadically strongly polluted. It was mainly in the spring and autumn seasons that the air was strongly polluted with psychrophilic and mesophilic bacteria. No increased emission of the analyzed groups of microorganisms, including faecal bacteria was determined in the air samples collected outside the WT