Уточнить поиск
Результаты 481-490 из 2,513
Analysis of daily average PM10 predictions by generalized linear models in Brno, Czech Republic Полный текст
2014
Huebnerova, Zuzana | Michalek, Jaroslav
Ambient air quality assessment and management plays an important role in the current European Union policy. Among others, air pollution by PM10 is being monitored. A previous analysis of PM10 aimed at identifying factors affecting air pollution in stations in the City of Brno using available observed meteorological variables. However, the studied model cannot be used for predicting the level of PM10 pollution because the included meteorological variables are not available exactly at the time when the prediction is requested. In that case, we should base the predictions on available predicted variables, namely on temperature, wind direction, wind speed, and cloud cover. A comparison of obtained predictions with the observed values of PM10 during a testing period allows us to evaluate a loss of prediction quality when the predicted covariates are used instead of the observed ones. The presented analysis based on test of symmetry and test of homogeneity of the marginal distribution of two–way contingency tables shows that the loss of prediction quality by employing the predicted meteorological variables is non–significant in the studied case. This observation suggests that the model with predicted meteorological variables can be employed in environmental management processes.
Показать больше [+] Меньше [-]Downscaling of monthly PM10 indices at different sites in Bavaria (Germany) based on circulation type classifications Полный текст
2014
Beck, Christoph | Weitnauer, Claudia | Jacobeit, Jucundus
Atmospheric circulation affects local concentrations of particulate matter with an aerodynamic diameter of 10μm or less (PM10) in different ways: Via the determination of local meteorological conditions favoring or suppressing the formation and the accumulation of PM10, and through its control on short–and long–range transport of particles and precursors. The quantitative assessment of the connections between the large–scale atmospheric circulation and local PM10 is relevant not only for the understanding of observed variations in PM10 concentrations. It is even more important for estimating the potential effects of projected future changes in large–scale atmospheric circulation on PM10. In this contribution, daily atmospheric circulation types (CTs), resulting from variants of three different classification methods, and their monthly occurrence frequencies have been utilized in three different downscaling approaches for estimating monthly indices of PM10 for the period 1980–2010 at 16 locations in Bavaria (Germany). All variants of approaches have been evaluated via a leave–one–out cross validation procedure in order to attain reliable performance ratings to detect the most suitable downscaling approaches. Results indicate that the highest performance of downscaling approaches is achieved in winter when the best performing models explain on average roughly 50% of the observed PM10 variance. From this it can be concluded that classification–based approaches are generally suitable for the downscaling of PM10, particularly during winter when PM10 concentrations in Bavaria reach maximum values. As preferable settings of the downscaling approaches, the usage of rather small spatial domains and a relatively high number of classes for circulation type classification and furthermore the utilization of multiple linear regression analyses or random forest analyses for relating CTs to PM10 have been ascertained. These findings provide the basis for further enhancements of the classification–based downscaling of monthly PM10 that will be realized in successive investigations.
Показать больше [+] Меньше [-]Analysis of the spatial representativeness of rural background monitoring stations in Spain Полный текст
2014
Martín, Fernando | Fileni, Lorenzo | Palomino, Inmaculada | Vivanco, Marta G. | Garrido, Juan L.
The spatial representativeness of rural background air quality stations was estimated using the spatial distribution of air pollutants computed by the combinations of the results of annual WRF–CHIMERE model simulations and data measured at stations of the Iberian Peninsula in 2008, 2009 and 2010 for NO2, SO2, O3 and PM10. The advantage of using validated models combined with measurements is that effects of the emission sources distribution and atmospheric pollutant processes are both taken into account and that the model bias and errors are corrected. This methodology provides a considerably realistic spatial view of air pollutant concentration distribution around the rural background stations. The criteria for delimiting the representativeness area are based on the assumptions that: (1) concentration does not differ by more than a certain percentage from the concentration at the station; and (2) the air quality in the station and in the representativeness area should have the same status regarding the legal standard. The results showed that there is a large variability in the size and shape of the representativeness area of rural background stations in Spain, also depending on the pollutant and the limit or target value. In addition, the interannual variability of the representativeness areas, station redundancy and network coverage have been analyzed. A high interannual variability of spatial representativeness areas was found, except for daily and hourly SO2, hourly O3 and annual NO2. Roughly 50% of rural background stations measured O3 overlap with other stations in at least 80% of their spatial representativeness area, denoting a high percentage of station redundancy. Concerning network coverage, there are zones that are not covered by stations, the worst coverage being for PM10. The proposed methodology seems to be useful for determining the spatial representativeness of air quality stations.
Показать больше [+] Меньше [-]Effect of coastal urbanization on sandy beach coleoptera Phaleria maculata (Kulzer, 1959) in northern Chile Полный текст
2014
González, Sergio A. | Yáñez-Navea, Katherine | Munoz, Mauricio
The beetle Phaleria maculata is a common inhabitant of the upper intertidal fringe of Chilean beaches. Anthropogenic intervention in coastal areas has increased intensely, leading to changes in the flora and fauna of sandy beaches. To examine the impact of human activities on P. maculata, we studied several beaches along the northern Chilean coast. Beaches were characterized based on morphodynamics and the level of intervention, leading to the estimation of an “Urbanization Index” based on various indicators. The analysis showed a significant inverse correlation between the rate of urbanization and night sky quality. Larval and adult beetles were almost absent on beaches with high levels of urbanization. The results of simple and multiple correlations based on nMDS ordination showed an inverse relationship between increases in urbanization and the abundance of beetles. Because darkling beetles are very sensitive to human interventions on sandy beaches, we suggest that they are ideal indicator organisms for the health of these environments.
Показать больше [+] Меньше [-]Variation in organochlorine accumulation in relation to the life history of the Japanese eel Anguilla japonica Полный текст
2014
Arai, Takaomi
Members of the catadromous eel live in various fresh, brackish and marine habitats. Therefore, these eels can accumulate organic pollutants and are a suitable bioindicator species for determining the levels of organic contaminants within different water bodies. The ecological risk for organochlorine compounds (OCs) in Anguilla japonica with various migration patterns, such as freshwater, estuarine and marine residences, was examined to understand the specific accumulation patterns. The concentrations of HCB, ∑HCHs, ∑CHLs and ∑DDTs in the silver stage (maturing) eel were significantly higher than those in the yellow stage (immature) eel, in accordance with the higher lipid contents in the former versus the latter. The OC accumulations were clearly different among migratory types in the eel. The ecological risk of OCs increased as the freshwater residence period in the eel lengthened. The migratory histories and the lipid contents directly affected the OC accumulation in the catadromous eel species.
Показать больше [+] Меньше [-]The past and future of fish consumption: Can supplies meet healthy eating recommendations? Полный текст
2014
Thurstan, Ruth H. | Roberts, Callum M.
In many developed countries fish and shellfish are increasingly promoted as healthy alternatives to other animal protein. We analysed how much fish was available to UK and global populations after accounting for processing losses, and compared this to recommended levels of fish consumption. In 2012, UK domestic fish landings per capita fell 81% below the recommended intake, although declines were masked by increased imports and aquaculture from the 1970s onwards. Global wild fish supply per capita declined by 32% from its peak in 1970. However, overall fish supplies per capita increased by 10% over the same period due to rapidly expanding aquaculture production. Whilst aquaculture has so far prevented a downturn in global fish supplies, many developed nations continue to aspire to consume more fish than they produce. Until demand is balanced with sustainable methods of production governments should consider carefully the social and environmental implications of greater fish consumption.
Показать больше [+] Меньше [-]Interactions between finfish aquaculture and lobster catches in a sheltered bay Полный текст
2014
Loucks, Ronald H. | Smith, Ruth E. | Fisher, E Brian
Interactions between open-net pen finfish aquaculture and lobster catches in a sheltered bay in Nova Scotia, Canada, were investigated using fishermen’s participatory research in annual lobster trap surveys over seven years.Fishermen recorded lobster catches during the last two weeks of May from 2007 to 2013. Catches for each trap haul were recorded separately for ovigerous and market-sized lobsters. Catch trends within the bay were compared to regional trends. Results of correlation analyses indicated that ovigerous catch trends were strongly affected by the fish farm’s feeding/fallow periods. There was no significant correlation between trends for bay and LFA lobster landings.Patterns of lobster catch per unit effort extending over considerable distance in Port Mouton Bay appear to be influenced by proximity to the fish farm regardless of year-to-year variation in water temperatures and weather conditions. Odours and habitat changes surrounding open-net pen finfish operations are potential factors affecting lobster displacement.
Показать больше [+] Меньше [-]Photochemical transformation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in surface coastal waters: Effects of chloride and ferric ions Полный текст
2014
Zhao, Qian | Zhao, Huimin | Quan, Xie | Chen, Shuo | Zhang, Yaobin
The effects of several aquatic environmental factors on the photochemical transformation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) have been investigated. Ferric ion (Fe(III)) has been found to promote the phototransformation of BDE-47, and this process is further enhanced with the added chloride ion (Cl−), while it is suppressed with increasing pH. Electron spin resonance results show that the formation of hydroxyl radical, and the added Cl− could influence the generation of hydroxyl radical in Fe(III) solution. Hence, Cl− enhances the phototransformation of BDE-47 most probably because of the reaction with Fe(III) species under irradiation, yielding hydroxyl and chloride radicals. These radicals can not only decompose PBDEs, but also lead to their photodebromination and photochlorination. These results indicate that the aquatic environmental factors and Cl− in particular played an important role in the photochemical transformation process of PBDEs, providing insight into the likely fate of PBDEs in the marine environment.
Показать больше [+] Меньше [-]Interactive effects of cadmium and pyrene on contaminant removal from co-contaminated sediment planted with mangrove Kandelia obovata (S., L.) Yong seedlings Полный текст
2014
Wang, Wenyun | Zhang, Xuefeng | Huang, Jing | Yan, Chongling | Zhang, Qiong | Lu, Haoliang | Liu, Jingchun
The interactive effects of cadmium (Cd) and pyrene (Pyr) on contaminant removal from co-contaminated sediment planted with Kandelia obovata were investigated by a pot experiment. We found that dry weight of plant was significantly decreased under high level of Cd–Pyr combined stress. High Pyr caused the increase of Cd toxicity to K. obovata under high Cd stress because more Cd translocated to the plant tissues. Cd toxicity inhibited Pyr degradation in co-contaminated sediments and higher Pyr degradation was found in the rhizosphere than that in the non-rhizosphere sediment under high Cd treatment. The total number of microorganisms in sediments tended to decrease with increasing Cd under Cd–Pyr combined stress and more amount existed in the rhizosphere sediment. In conclusion, Cd and Pyr removal by K. obovata can influence interactions between these two pollutants in co-contaminated sediment. This suggests that this mangrove can effectively remedy sites co-contaminated with these two types of contamination.
Показать больше [+] Меньше [-]Respiration, growth and grazing rates of three ciliate species in hypoxic conditions Полный текст
2014
Rocke, Emma | Liu, Hongbin
Marine hypoxic episodes are affecting both marine and freshwater bodies all over the world. Yet, limited data exists with regard to the effects of decreasing oxygen on protist metabolism. Three ciliate species were therefore isolated from Hong Kong coastal waters. Controlled hypoxic conditions were simulated in the lab environment, during which time growth, respiration and grazing rates were measured. Euplotes sp. and a Oxytrichidae-like ciliate showed decreased growth and respiration below 2.5mgO2L−1, however Uronema marinum kept steady growth and respiration until below 1.5mgO2L−1. Euplotes sp. and the Oxytrichidae-like ciliate had the highest ingestion rate, which dropped significantly below 3.0mgO2L−1. U.marinum grazing rates were affected at and below 1.5mg O2L−1, correlating with their drop in growth and respiration at this lower concentration. This study illustrates the slowing metabolism of key grazing protists, as well as species-specific tolerance in response to hypoxia.
Показать больше [+] Меньше [-]