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Antibiotic resistance of Shewanella putrefaciens isolated from shellfish collected from the West Sea in Korea 全文
2013
Kang, Chang-Ho | Shin, Yujin | Jeon, HanEul | Choi, Jae-Ho | Jeong, SuYeon | So, Jae-Seong
In this study, we isolated and characterized Shewanella putrefaciens from shellfish harvested from the West Sea in Korea. For the initial isolation of S. putrefaciens, LB agar plates supplemented with ferrous sulfate and sodium thiosulfate were inoculated with shellfish homogenates, incubated for 24h, and then black colonies were selected. Gram-negative and catalase-positive colonies were subsequently confirmed by PCR assays and API 20E kit test system. The Shewanella-specific 16S rRNA and gyrB genes were used to design S. putrefaciens-specific PCR primers. From 6 species of shellfish tested, 24 S. putrefaciens strains were isolated. These 24 isolates had the following profiles of resistance against 16 antibiotics: all the isolates were resistant to cephalothin and vancomycin and 95.8% were resistant to ampicillin. Here, we report the isolation of S. putrefaciens from shellfish and our results point to a new possible route for exposing healthy individuals to S. putrefaciens.
显示更多 [+] 显示较少 [-]Reciprocal experimental transplantations to assess effects of organic enrichment on the recolonization of benthic macrofauna in a subtropical estuary 全文
2013
Gern, Fabiana Regina | Lana, Paulo da Cunha
Coastal benthic habitats are usually in a state of continuous recolonization as a consequence of natural disturbances or human activities. Recolonization patterns can be strongly affected by the quality of the sediment. We evaluated herein the macrobenthic recolonization of organically enriched sediments through a manipulative experiment involving reciprocal transplants between contaminated and non-contaminated intertidal areas. Regardless of the experimental treatments, the density of the polychaete Capitella sp. was extremely high in the contaminated area as well as the density of the gastropod Cylichna sp. in the non-contaminated area. We rejected the hypothesis that differences in sediment quality would determine macrofaunal recolonization at least in the considered scales of space in meters and time in weeks. The recolonization process in a subtropical estuarine environment was strongly dependent on the migration of adults present in the sediments adjacent to the experimental units.
显示更多 [+] 显示较少 [-]Human impact on a small barrier reef meadow of Posidonia oceanica (L.) Delile on the north Tyrrhenian coast (Italy) 全文
2013
Mauro, Lenzi | Paola, Gennaro | Margherita, Volterrani | Rugiada, Roffilli | Francesca, Birardi | Primo, Micarelli | Duccio, Solari | Enrica, Franchi
The health status of an emerging Posidonia oceanica meadow, subject to high human impact, was studied. Biometric variables, heavy metals, PAHs and C, N, P contents were determined in sediment and seagrass samples. The meadow was found to grow under oligotrophic conditions and an increase in nutrient content was only recorded in autumn. In sediment, Hg exceeded its ERL (effects range low) and sometimes also its ERM (effects range medium), and Cu was close to its ERL. In leaves, Hg and Cu were relatively high but below their respective ERLs. Sediments close to the meadow were heavily contaminated with pyrolytic PAHs, some of which exceeded their ERLs. P. oceanica did not show major accumulation of PAHs, lighter molecules predominating. Despite 40years of intense human activity, meadow growth dynamics and contaminant accumulation did not suggest that the meadow was regressing.
显示更多 [+] 显示较少 [-]Entanglement of Antarctic fur seals at Bird Island, South Georgia 全文
2013
Waluda, Claire M. | Staniland, Iain J.
Between November 1989 and March 2013, 1033 Antarctic fur seals Arctocephalus gazella were observed entangled in marine debris at Bird Island, South Georgia. The majority of entanglements involved plastic packaging bands (43%), synthetic line (25%) or fishing net (17%). Juvenile male seals were the most commonly entangled (44%). A piecewise regression analysis showed that a single breakpoint at 1994 gave the best description of inter-annual variability in the data, with higher levels of entanglements prior to 1994 (mean=110±28) followed by persistent lower levels (mean=28±4). Records of entanglements from other sites monitored in the Scotia Sea are also presented. Legislation imposed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has, to a certain extent, been effective, but persistent low levels of seal entanglements are still a cause for concern at South Georgia.
显示更多 [+] 显示较少 [-]Air pollution by fine particulate matter in Bangladesh 全文
2013
Begum, Bilkis A. | Hopke, Philip K. | Markwitz, A. (Andreas)
In Dhaka, Bangladesh, particular matter (PM) is the air pollutant that is most harmful to public health and the environment when compared to other measured criteria pollutants. During recent years, the Government of Bangladesh has tried to control PM emissions coming from anthropogenic sources. About 30–50% of the PM10 mass in Dhaka (depending on location) is in fine particles with aerodynamic diameter less than 2.2 µm. These particles are mainly of anthropogenic origin and predominately from transport–related sources. However, the combination of meteorological conditions, long–range transport during the winter and local sources results in PM concentrations remaining much higher than the Bangladesh National Ambient Air Quality Standard (BNAAQS). It has been found that black carbon accounted for about 50% of the total fine PM mass before the adoption of control policies. As a result, the PM emission as well as BC has not increased in proportion to the increase in the number of combustion sources like motor vehicles, diesel power generator or brick kiln. Positive Matrix Factorization (PMF) was applied to fine particle composition data from January 2007 to February 2009. It was found that motor vehicles contribute less BC with respect to brick kiln industry. This result demonstrates the effectiveness of the government’s policy interventions since previously vehicles represented the major contributors of BC. BC is also transported over long distances, mixing with other particles along the way as demonstrated by a potential source contribution function analysis. Transboundary transport of air pollution in the South Asian region has become an issue of increasing importance over the past several decades. The relative amounts of local and long–range transported pollutants are currently unknown.
显示更多 [+] 显示较少 [-]Characteristics of gas–phase nitric acid and ammonium–nitrate– sulfate aerosol, and their gas–phase precursors in a suburban area in Cairo, Egypt 全文
2013
Hassan, Salwa K. | El–Abssawy, Ahmed A. | Khoder, Mamdouh I.
Simultaneous measurements of gaseous SO2, NO2, HNO3, NH3 and particulate SO42–, NO3– and NH4+ were carried out in a suburban area in Cairo during summer 2009 and winter 2009–2010. PTFE membrane filters were used to collect particulate SO42–, NH4+ and NO3–, followed by the impregnated filter to collect HNO3. Colorimetric methods were used for determination of NO2, SO2, NH3, SO42–, NH4+ NO3–, and HNO3 levels. The mean concentrations of NO2, SO2 and NH3 were 75.0, 40.1 and 29.1 µg/m3 in winter and 54.1, 25.1 and 44.9 µg/m3 in summer, respectively. The daytime/nighttime concentration ratios were 1.3 and 1.2 for NO2, 1.3 and 1.2 for SO2 and 0.6, and 0.8 for NH3 during the winter and summer, respectively. The mean values of NH4+, SO42–, NO3–, HNO3 and total NO3– were 4.4, 19.0, 3.4, 1.1 and 4.5 µg/m3 in winter and 7.5, 28.0, 4.2, 3.1 and 7.3 µg/m3 in summer, respectively. The levels of NH4+, SO42–, NO3– and HNO3 were relatively higher in daytime than in nighttime. Sulfur conversion (Fs) and nitrogen conversion ratios (Fn) in summer were about 1.78 and 2.15 times higher than in winter, respectively. Fs and Fn were higher in daytime than in nighttime. Significant positive correlation was found between Fs and relative humidity. The positive correlation between Fn and relative humidity was insignificant. The correlation between the concentration of NH4+ and NO3– indicates that NO3– may be found in fine mode (NH4NO3) in winter and it may be present predominantly as a coarse mode, such as Ca(NO3)2, Mg(NO3)2 and NaNO3 in summer. The concentration of SO42– was significantly correlated with NH4+ concentration, suggesting neutralization by NH3 and indicating that the forms of (NH4)2SO4 and/or NH4HSO4 exist in the aerosol. The NH4+/SO42– molar ratio indicates that SO42– in aerosol may be present as (NH4)2SO4, (NH4)2SO4.CaSO4.2H2O and CaSO4.
显示更多 [+] 显示较少 [-]A modelling approach for estimating background pollutant concentrations in urban areas 全文
2013
Torras Ortíz, Sandra | Friedrich, Rainer
Air pollution control strategies have helped to improve the air quality over Europe over the last twenty years. Despite this success, the improvements have been insufficient to protect health of those who spend most of their time within urban areas and particularly near major roads. Given the inherent complexity of urban environments and the incomplete understanding of the physical and chemical processes involved in pollutant dispersion, it is a challenging task to estimate urban air quality. In order to address this issue, a new regression model for estimating the urban increment for all cities of a region up to Europe as a whole is developed. The model is able to capture the higher pollutant concentrations commonly found within urban areas for assessing the localized effects associated to urban emissions. This approach is used for estimating annual concentrations of PM10 and NO2 for all urban areas with more than 50 000 inhabitants in Germany for the reference year 2005. The results showed that there are differences on air quality levels across urban areas in Germany. This information is relevant when evaluating the impact of emission reduction policies on air quality, which should take into account the cost–benefit of each measure. Furthermore, as the modelling approach allows for flexibility changing initial conditions and building scenarios, the added values of this approach are the large spatial domain covered, the high spatial resolution, and its inherent flexibility to address other environmental issues, such as analysis of emission reduction scenarios, the human exposure to certain pollutants and their associated human health impacts.
显示更多 [+] 显示较少 [-]Effects of fish farming on phytoplankton community under the thermal stress caused by a power plant in a eutrophic, semi-enclosed bay: Induce toxic dinoflagellate (Prorocentrum minimum) blooms in cold seasons 全文
2013
Jiang, Zhibing | Liao, Yibo | Liu, Jingjing | Shou, Lu | Chen, Quanzhen | Yan, Xiaojun | Zhu, Genhai | Zeng, Jiangning
Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4+, DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter–spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention.
显示更多 [+] 显示较少 [-]Sources and preservation of organic matter in soils of the wetlands in the Liaohe (Liao River) Delta, North China 全文
2013
Lin, Tian | Ye, Siyuan | Ma, Chuanliang | Ding, Xigui | Brix, Hans | Yuan, Hongming | Chen, Yingjun | Guo, Zhigang
Total organic carbon, total nitrogen, δ13Corg, δ15N, and aliphatic and polyaromatic hydrocarbons of fifty-five soil samples collected from the coastal wetlands of the Liaohe Delta were measured, in order to determine the sources and possible preservation of organic matter (OM). The δ15N and δ13Corg values in the samples ranged from 3.0‰ to 9.4‰ and from −30.4‰ to −20.3‰, respectively, implying that the OM in the soils is predominantly derived from C3 plant. The long-chain n-alkanes had a strong odd-over-even carbon number predominance, suggesting a significant contribution from waxes of higher plants. The ubiquitous presence of unresolved complex mixture, alkylated polycylic aromatic hydrocarbons and typical biomarkers of petroleum hydrocarbons (pristane, phytane, hopanes and steranes) indicates that there is a contribution of petroleum hydrocarbons to the organic carbon pool in the wetland soils. P. australis-vegetated wetlands have strong potentials for the preservation of organic carbon in the wetlands.
显示更多 [+] 显示较少 [-]Estimating the near-surface daily fine aerosol load using hourly Radon-222 observations 全文
2013
Crawford, Jagoda | Zahorowski, Wlodek | Cohen, David D. | Chambers, Scott | Stelcer, Eduard | Werczynski, Sylvester
We investigate the extent to which hourly radon observations can be used to estimate daily PM2.5 loading near the ground. We formulate, test and apply a model that expresses the mean daily PM2.5 load as a linear combination of observed radon concentrations and differences on a given day. The model was developed using two consecutive years of observations (2007–2008) at four sites near Sydney, Australia, instrumented with aerosol samplers and radon detectors. Model performance was subsequently evaluated against observations in 2009. After successfully reproducing mean daily radon concentrations (r2≥0.98), we used the model to estimate daily PM2.5 mass, as well as that of selected elements (Si, K, Fe, Zn, H, S and Black Carbon). When parameterizing the model for elemental mass estimates the highest r2 values were generally obtained for H, BC, K and Si. Separating results by season, the r2 values for K and BC were higher in winter for all sites, a period of time where higher concentrations of these elements are seen and a rapid estimation tool would be of particular benefit. The best overall results were obtained in winter for H and BC [r2 = 0.50, 0.68, 0.70, 0.63 (H) and 0.57, 0.57, 0.78, 0.44 (BC)], respectively for Warrawong, Lucas Heights, Richmond and Muswellbrook. Evaluation of model PM2.5 estimates was most successful for days with typical aerosol loads; loads were usually underestimated for, the less frequent, high–to–extreme pollution days. The best elemental results were obtained for BC at Richmond in winter (r2 = 0.68). However, for Warrawong and Lucas Heights r2 values increased from 0.26 to 0.60, and from 0.33 to 0.73, respectively, when several particularly high concentration events were excluded from the analysis. The model performed best at Richmond, an inland site with relatively flat terrain. However, model parameters need to be evaluated for each site.
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