L. Růžek

Air-conditioning and microbiological environment in the lecture room

The influence of indoor climate on human health has been emphasized in numerous scientific and professional papers (F i s k et al., 2007; M u d a r r i , F i s k , 2007). Some studies dealing with the importance of a suitable microclimate in offices (Seppanen et al., 2006) and at schools (K a r w o w s k a , 2003; G r i s o l i et al., 2012) pointed to the impact of the diseases incidence on the regularity of school or office attendance. Inappropriate microclimate may contribute to a higher sickness rate, and thereby may increase the number of days spent out of office or school (M u d a r r i , F i s k , 2007). In the study on indoor air microbiological contamination in various rooms of university buildings, multiple growth of bacteria and significant increase of mould spores was observed in the afternoons (S t r y j a k o w s k a S e k u l s k a et al., 2007). A w a t et al. (2013) mentioned that the outdoor fungal concentration depends on the locality and season. According to their results fungal concentrations were significantly higher in the rural than in the urban environment. The average indoor and outdoor total fungal concentrations were 608 and 675 CFU.m-3 in the urban environment and 1932 and 1872 CFU.m-3 in the rural environment, respectively. The greatest concentrations were found in the autumn and spring season. Indoor and outdoor concentrations were significantly correlated (P < 0.001). Recent years results (not yet published) of microbial air quality measurements in the University campus and its surroundings have shown that the outdoor air concentration of bacteria was in the range of 110–1010 CFU.m-3 and of yeast and filamentous fungi 170–3890 CFU.m-3, positively depending on air temperature, wind gusts, and amount of necrotic aboveground parts of plants at the place of the measurement, and negatively depending on relative humidity of air. The objective of the present paper was to show the true microbiological situation in the lecture room equipped with the air-conditioning (AC) system. Microbiological contamination was monitored at different operating conditions inside the room. As the inlet of the described AC system is situated in a quiet place, without traffic and any special source of pollution, no special attention was paid to the problems of outdoor air pollution. AIR-CONDITIONING AND MICROBIOLOGICAL ENVIRONMENT IN THE LECTURE ROOM

Effects of Conventional and Stabilized Urea Fertilizers on Soil Biological Status

Effects of stabilized urea fertilizers [Alzon 46 (A) and UREAstabil (US)] on soil microbiological and chemical parameters and also on grain yield, 1000-grain weight, and oil content were tested in a precise field study on Luvisol in 2010–2012. Winter rapeseed (Brassica napus L. cv. Californium) was fertilized both in autumn [45 kg nitrogen (N) ha−1] and in spring (155 kg N ha−1) with A [urea with DCD (dicyandiamide) plus pyrrodiazole (1,2,4-1H-triazole)], US {urea with NBPT [N-(n-butyl)-thiophosphoric acid triamide]}, and conventional N fertilizers (pure urea, calcium ammonium nitrate). Eleven parameters were used to evaluate the soil status: microbial biomass carbon (C; microwave method [MW]), dehydrogenase activity, arylsulfatase activity, available organic carbon, electroconductivity, Corg (MW method), and pH (in water, H2O). None of the 11 parameters demonstrated significant difference between control, conventional N fertilizers, and stabilized urea fertilizers. The greatest yield significantly different from the control (zero kg N ha−1; 2598 ± 881 kg ha−1) was found for both stabilized urea fertilizers: A (200 kg N ha−1; 3772 ± 759 kg ha−1) and US (200 kg N ha−1; 3764 ± 625 kg ha−1). The control achieved the greatest oil content (46.0 ± 1.2%), which was significantly different from all N-fertilized variants, and also the greatest 1000-grain weight (5.62 ± 0.62 g).