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