[Sources and pollution characteristics of antibiotic resistance genes and conditional pathogenic bacteria in concentrated swine feeding operation.] / å »çŒªåœºç©ºæ°”ä¸­æŠ—æ€§åŸºå› å’Œæ¡ä»¶è‡´ç— èŒæ±¡æŸ“ç‰¹å¾.

Air in concentrated animal feeding operations contains antibiotic resistance genes and airborne pathogens, with potential threat to human and animal health. In this study, air was sampled in the living area, outside, and inside of a fattening pig house in a pig farm for 24 and 48 hours. Feedstuffs, drinking water additives, and feces in the pig house were collected. Three kinds of antibiotic resistance genes (macrolide, ß-lactam, and tetracycline) and seven pathogenic microorganisms (Campylobacter, Clostridium perfringens, Enterococcus, Escherichia coli, Yersinia enterocolitica, Staphylococcus spp., and Streptococcus suis) were detected by polymerase chain reaction (PCR). Six genes with high detection rates were selected, with their concentrations being determined by real-time quantitative PCR (qPCR). Results showed that three macrolide and two tetracycline resistance genes were detected in all air samples. Enterococcus, Escherichia coli, Yersinia enterocolitica, and Staphylococcus spp. were detected in air samples and drinking water additive. The concentrations of most target genes were above 104 copies·m-3. The gene concentrations near the pig house were much higher than those in the living area. Main sources of antibiotic resistance genes and pathogens in the air were pig manure and drinking water additive. Sampling time of 24 h in the pig farm met the requirements for PCR detection. Sampling time of 48 h had a higher sampling efficiency than that of 24 h in the living area of the pig farm, whereas sampling time of 24 h was more appropriate than that of 48 h in high bioaerosol concentration area such as the pig house.

[Emission Characteristics and Ozone Formation Potential of VOCs from a Municipal Solid Waste Composting Plant].

In Beijing, the chemical composition and component concentrations of volatile organic compounds (VOCs) were investigated during the municipal solid waste composting process using a portable gas chromatograph coupled with a mass spectrometer. The contributions of VOCs to the ozone formation potential were computed using the maximum incremental reactivity (MIR) scale and the propylene-equivalent concentration scale. The results showed that the concentrations of waste discharge in the sorting room, the first fermentation workshop, the second fermentation workshop, the compost product workshop, and the plant boundary were 10302.1, 15484.1, 929.9, 4693.6 and 370.4 µg·m-3, respectively. The main VOCs of the municipal solid waste composting plant were ethanol, limonene, and acetone. The propylene-equivalent concentrations of waste discharge in the sorting room, the first fermentation workshop, the second fermentation workshop, the compost product workshop, and the plant boundary were 25875.7, 4087.9, 378.0, 747.7 and 296.8 µg·m-3, whereas the O3 formation potentials computed using the MIR scale were 26979.3, 21168.3, 1469.3, 6439.6 and 455.8 µg·m-3. Reducing pollution by controlling the VOCs emission of waste discharge in the sorting room and the first fermentation workshop is important and can decrease the ozone formation potential. Given the accuracy and accessibility of the method, the MIR scale is more suitable for calculating the ozone formation potential of VOCs emitted from the municipal solid waste composting plant.