Studies were carried out in the summer seasons of l 995-1999 (from June to September) on the quantitative and qualitative composition of Enterobacteriaceae bacteria (including Escherichia coli and Salmonella sp.), and potentially pathogenic bacteria Aeromonas hydrophila, Pseudomonas aeruginosa and Staphylococcus sp. in the water of 8 bathing sites of the Lake Wigry. Aeromonas hydrophila occurred in the all samples of studied water and was the most numerous in water sampled from sites of increased trophic levels. Irrespective of the site and time of sampling Pseudomonas aeruginosa was rarely isolated. In the total of 160 samples of water analysed Salmonella sp.. Escherichia coli and Staphyloccocus aureus were determined in 32 (22.6%), 68 (42.4%) and 90 (55%) samples, respectively. Pathogenic bacteria of the genus Salmonella sp. and potentially pathogenic Staphylococcus aureus and Aeromonas hydrophila identified in the analysed offshore waters (also when Escherichia coli were absent) suggest that the use of the Lake Wigry waters for swimming, falling into account faecal bacterial counts, may not be sufficient to fully reflect safety conditions for bathers. The results of the research suggest that the evaluation of the Lake Wigry surface waters for recreational use should include the frequency of the occurrence of Salmonella sp., Staphylococcus aureus, Aeromonas hydrophila and Pseudomonas aeruginosa. These three species, which arc not directly linked to faecal contamination, can cause various diseases of the skin, nasal and oral cavities, eyes, internal car and other problems in people swimming in contaminated water.

The paper presents the results of studies on detection, occurrence and differentiation of the waterborne bacterial potential pathogens from Staphylococcus genus in the water of Wigry Lake watering places in north-eastern Poland. The samples of water were collected from June 1995 to September 1999 at one-month intervals, during bathing season. Eight sampling stations were selected in the most attended watering places of the lake, situated near landing stages, camping sites and holiday resorts were investigated. The watering places in the northern part of Lake Wigry (called Ploso Northern) showed the highest number of waterborne bacterial pathogens from Staphylococcus genus. The most numerous were species: Staphylocorcus capitis, Staphylococcus cohnii, Staphylococcus len/us and Staphylococcus xylosus. Pathogens from Staphylococcus aureus species identified in I 0% of water samples in the absence of faecal bacteria from Escherichia coli species (in 100 crn' of water). The Czarna Hańcza River, which brought a lot of purified sewage from Wastewater Treatment Plant in Suwałki to northern part of Wigry Lake has immense influence on the pollution of this part Wigry Lake.

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.

Seasonal changes in the numbers of sulphate-reducing bacteria in water, soil, the surface of sedge (Carex acutiformis Ehrb.) immersed in waler and roots (dead and live) were studied. The study on one of larger wetland near Olsztyn (Masurian Lake District) was carried out in two annual cycles. Sulphate-reducing bacteria in the studied ecosystems occurred sporadically and generally in inappreciable count. Their count did not exceed 20 cells in I cm3 ofwaler; in the soil and in di ffercnt parts of sedge the number of bacteria ranged from several lo over dozen thousands cells in I g of dry weight. In the first year of studies these bacteria were the most numerous in June, July and during first days of December, bul in the second - in April (in soil and sedge immersed in water), in August (in soil and dead and live roots), in November (in waler, soil, sedge immersed in water and dead roots) and exceptionally in other months.

Praca obejmuje wyniki trzyletnich badań liczebności bakterii wskaźnikowych stopnia zanieczyszczenia (ogólna liczba bakterii oznaczana na agarze bulionowym w temperaturze 22 i 37°C) i stanu sanitarnego (liczba bakterii grupy coli - TC, bakterii grupy coli typu kałowego - FC, paciorkowców kałowych- FS i beztlenowych bakterii przetrwalnikujących redukujących siarczyny - Clostridium pcrfringensi w wodzie Jeziora Długiego Wigierskiego w warunkach bytowania kormorana czarnego tPhaiocrocorax carbo). Badania przeprowadzono w latach I 998-200 I w 530 próbach wody pobieranych na I 4 stanowiskach wyznaczonych w charakterystycznych miejscach jeziora, ze szczególnym uwzględnieniem miejsc lokalizacji siedlisk kormoranów. Większość (powyżej 60%) przebadanych prób wody Jeziora Długiego Wigierskiego mieściła się w l klasie wód o bardzo dobrej jakości. Okolo 20-30% prób wody mieściła się w Il klasie wód dobrej jakości, tylko niewielki procent prób wody wykazywało nieznacznie większy stopień zanieczyszczenia i zaklasyfikowano je do Ill klasy czystości, tzn. wód o zadowalającej jakości. Wyższym stopniem zanieczyszczenia charakteryzowały się próby wody pobierane zazwyczaj w pobliżu dopływu i odpływu rzeki Dłużankijak też w sąsiedztwie bytowania kormoranów-w pobliżu wyspy Ostrówek i w strefie przybrzeżnej. Próby wód bardziej zanieczyszczonych bakteriologicznie pobierano częściej w okresie wiosenno-letnim, kiedy aktywność ptactwa wodnego i innych zwierząt w rejonie jeziora była większa. Wskazuje na to niski stosunek FC : FS w większości pobieranych w tym czasie prób wody z jeziora. Niski stosunek liczbowy kałowych bakterii grupy coli do paciorkowców kałowych w większości badanych prób wody sugeruje przeważający udział ptactwa wodnego w zanieczyszczaniu tego zbiornika.

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