It is well known that atmospheric electrical conductivity is mainly due to the presence of small ions. Near the surface of the earth, radon and its daughter products predominantly produce small ions. In the presence of aerosol particles, the small ion concentration is reduced due to attachment of small ions to aerosol particles which decreases mobility and conductivity in the atmosphere. The ion pair production rate is estimated from the measured radon and its progeny concentrations and correlated with electrical conductivity of the atmosphere. Measurement of concentrations of suspended particulate matter (SPM), SO2, and NO2 of air was also carried out. Data showed that reduced electrical conductivity was related to concentration of airborne SPM. 相似文献
During two campaigns in winter 2004, size segregated impactor samples (0.1-10 microm) and filter samples were taken in two Central European cities (Vienna, Austria and Ljubljana, Slovenia). The impactor samples were analyzed for major inorganic ions and short-chain organic acids, total carbon (TC) and black carbon (BC). Maximum concentrations of total mass were 71.6 microg m(-3) in Vienna and 73.1 microg m(-3) in Ljubljana. Minimum concentrations in Vienna were only half those in Ljubljana. The BC content of the aerosol was similar (ca. 8%), but the BC/TC ratio was higher in Vienna than in Ljubljana (0.39 vs. 0.29), reflecting the different contribution of diesel traffic emissions. The mass median diameters of the submicron size distributions of all major fractions (total mass, TC, BC and SO(4)(2-)) were smaller in Vienna (0.43 microm, 0.41 microm, 0.38 microm and 0.48 microm, respectively) than in Ljubljana (0.55 microm, 0.44 microm, 0.42 microm and 0.60 microm, respectively). Impactor/filter ratios for total mass were 0.79 in Vienna and 0.82 in Ljubljana, while the ratios for BC were 0.56 in Vienna and 0.49 in Ljubljana. An estimation of the mixing state of accumulation mode BC indicated that 33% and 37% of BC, respectively, are mixed externally to the aerosol in the accumulation size range in Vienna and Ljubljana. 相似文献
Petroleum hydrocarbons, mainly consisting of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), are considered as priority pollutants and biohazards in the environment, eventually affecting the ecosystem and human health. Though many previous studies have investigated the change of bacterial community and alkane degraders during the degradation of petroleum hydrocarbons, there is still lack of understanding on the impacts of soil alkane contamination level. In the present study, microcosms with different n-alkane contamination (1%, 3% and 5%) were set up and our results indicated a complete alkane degradation after 30 and 50 days in 1%- and 3%-alkane treatments, respectively. In all the treatments, alkanes with medium-chain length (C11-C14) were preferentially degraded by soil microbes, followed by C27-alkane in 3% and 5% treatments. Alkane contamination level slightly altered soil bacterial community, and the main change was the presence and abundance of dominant alkane degraders. Thermogemmatisporaceae, Gemmataceae and Thermodesulfovibrionaceae were highly related to the degradation of C14- and C27-alkanes in 5% treatment, but linked to alkanes with medium-chain (C11-C18) in 1% treatment and C21-alkane in 3% treatment, respectively. Additionally, we compared the abundance of three alkane-monooxygenase genes, e.g., alk_A, alk_P and alk_R. The abundance of alk_R gene was highest in soils, and alk_P gene was more correlated with alkane degradation efficiency, especially in 5% treatment. Our results suggested that alkane contamination level showed non-negligible effects on soil bacterial communities to some extents, and particularly shaped alkane degraders and degrading genes significantly. This study provides a better understanding on the response of alkane degraders and bacterial communities to soil alkane concentrations, which affects their biodegradation process.
A continuous two-year atmospheric datasetcomprising gas and aerosol loadings from amountain site in northern England (Holme Moss,W1°5130 N53°320) is presented. The data are analysed with respect to three-dayback-trajectories that are grouped according to aclustering technique that allows speed, directionand curvature of the airmass track to beconsidered. The technique is successful inseparating the data into chemically distinctsubsets. Up to 29% of the variance in the datais explained by back-trajectory clusters. Slow trajectories are associated with highloadings especially for the oxides of nitrogen,which may imply a local source for much of thesuspended pollutant. The data suggest thatproduction of nitrate and sulphate is limited byoxidant availability at least in the winter. Itmay be possible to optimise the analytical powerof the technique by increasing the importance ofrecent airmass track in determining clusterallocation. This applies especially to the totalsulphur loading. 相似文献
The microbiological impact of a detergent and soap industries effluent on Clarias gariepinus was assessed under laboratory conditions. The heterotrophic bacterial count obtained from fish surfaces ranged from 1.2 × 102−2.0 × 102cfu/ml amongst the control, while values of 4.8× 106−8.6 × 106 cfu/ml were obtained for the experimental fish exposed to the industrial effluent (0.025 ppm). The fungal count for the controls ranged from 1.2× 102−1.2 × 103 cfu/ml; while a range of 1.0 × 106−2.0 × 106 was obtained for the fish exposed to the industrial effluent. While twelve bacterial species were isolated from the fish exposed to the industrial effluent, only two were isolated from the parts of the control fish used in the study. The bacterial species are those in the genera Staphylococcus, Proteus, Streptococcus, Micrococcus, Bacillus, Pseudomonas, Serratia, Enterobacter, and Escherichia. The fungal isolates include Saccharomyces, Aspergillus, Rhodosporium, Candida, Alternaria, and Fusarium. The resistance of the bacterial isolates to the commonly used antibiotics showed that 100% were resistant to Augmentin, Amoxycillin and Cloxacillin, 85.71% to Tetracycline, 80.95% to Cotrimoxazole, 71.43% to Erythromycin, 33.33% to Chloramphenicol, and 28.57% to Gentamicin. Among the eight antibiotics tested, five patterns of multiple drug resistance were obtained, with the number of the antibiotics ranging from 4–8. The public health implications of these observations are discussed. 相似文献