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81.
82.
The exhaust emissions from two heavy duty diesel vehicles running on eight different fuel compositions were investigated regarding their content of high molecular weight (≥ C12) aliphatic/ olefinic hydrocarbons. It was concluded that the emitted amount of semi‐volatile associated aliphatic hydrocarbons (range C12‐C22) depend on the fuel used in the engines and that these emissions mainly consisted of uncombusted fuel components. It was also found that uncombusted engine lubrication oil was the main constituent of the emitted particulate associated aliphatic hydrocarbons (C17‐C40). These constituted between 58% and 95% of the total emissions of the high molecular weight aliphatic compounds. Emission factors for the total of high molecular aliphatic hydrocarbons (C12‐C40) were demonstrated to be in the range of 15–100 mg/km. Some individual aliphatic hydrocarbons with cocarcinogenic effects were identified and quantified in both particulate and semi‐volatile phases of the exhaust. Multivariate data analysis was used to investigate the relationship between fuel parameters and emission of semi‐volatile aliphatic emission. 相似文献
83.
Juliana M. Harding Michael A. Unger Roger Mann E. Alex Jestel Catherine Kilduff 《Marine Biology》2013,160(12):3027-3042
Imposex and decline in reproductive output in marine gastropods have been linked to tributyltin (TBT) exposure. This study describes Chesapeake Bay, USA, veined rapa whelk Rapana venosa imposex incidence and sex ratios from 1998 to 2009. Tissue TBT concentrations (ng g?1) were examined with respect to whelk sex, size, and water temperature at the time of collection, and also to egg case size, hatching success, and veliger diameter. Imposex incidence declined and population sex ratios moved closer to parity from 1998 to 2009. Observed TBT concentrations (ng g?1) were higher in James River than in Ocean View whelks with higher TBT concentrations observed in males than in females. Exponential declines in TBT concentrations from female-specific first to last clutches within a reproductive season were observed, indicating that whelks depurate TBT through egg case deposition. Egg capsule hatching success and veliger size were similar for female and imposex whelks. The R. venosa imposex levels observed in Chesapeake Bay apparently do not affect the production, release, or viability of larvae. 相似文献
84.
Vicki?L.?StokesEmail author Peter?B.?Banks Roger?P.?Pech 《Behavioral ecology and sociobiology》2012,66(2):329-338
Residency status of individuals in populations may be an important determinant of the outcomes of interspecific competition
between native and introduced species. We examined direct behavioral interactions between two similarly sized rodents, the
alien Rattus rattus and native Rattus fuscipes when they were respective residents and intruders in a small enclosure. Resident individuals were dominant in their behaviors
toward intruders irrespective of the species that was resident. In contrast, interactive behaviors between conspecifics were
often neutral or amicable, supporting suggestions that R. rattus and R. fuscipes are social animals. We then tested whether rodent species use heterospecific odors to avoid aggressive competitive interactions
and partition space in the field. Neither R. fuscipes nor R. rattus responded to traps scented with the odors of male or female heterospecifics. If R. fuscipes does not recognize the odor of introduced R. rattus, then odors will not be cues to the presence or territorial space of competing heterospecifics. Rather, findings from both
enclosure and field trials suggest that direct aggressive interactions between individual R. rattus and R. fuscipes probably facilitate segregation of space between these two species in wild populations, where resident animals may typically
be the winners and exclude heterospecific intruders. These findings have implications for the invasion success of introduced
rodents such as R. rattus into intact forests, where native populations may have competitive advantage because of their residency status. 相似文献
85.
Zhaoqing Yang Kathryn L. Sobocinski Tarang Khangaonkar Roger Fuller 《Ecological modelling》2010,221(7):1043-319
Along the Pacific Northwest coast, much of the estuarine habitat has been lost over the last century to agricultural land use, residential and commercial development, and transportation corridors. As a result, many of the ecological processes and functions have been disrupted. To protect and improve these coastal habitats that are vital to aquatic species, many projects are currently underway to restore estuarine and coastal ecosystems through dike breaches, setbacks, and removals. Understanding site-specific information on physical processes is critical for improving the success of such restoration actions. In this study, a three-dimensional hydrodynamic model was developed to simulate estuarine processes in the Stillaguamish River estuary, where restoration of a 160-acre parcel through dike setback has been proposed. The model was calibrated to observed tide, current, and salinity data for existing conditions and applied to simulate the hydrodynamic responses to two restoration alternatives. Model results were then combined with biophysical data to predict habitat responses within the restoration footprint. Results showed that the proposed dike removal would result in desired tidal flushing and conditions that would support four habitat types on the restoration footprint. At the estuary scale, restoration would substantially increase the proportion of area flushed with freshwater (<5 ppt) at flood tide. Potential implications of predicted changes in salinity and flow dynamics are discussed relative to the distribution of tidal marsh habitat. 相似文献
86.
Toxizität und Risk Assessment fluvialer Sedimente und Schwebstoffe: Eine kurze Übersicht bisheriger und neuerer Entwicklungen 总被引:1,自引:0,他引:1
M. Brinkmann S. Hudjetz S. Keiter T.-B. Seiler J. Wölz A. V. Hallare H. Hollert C. Cofalla S. Roger H. Schüttrumpf S. U. Gerbersdorf 《Environmental Sciences Europe》2010,22(6):651-655
Background In recent years, sediments have become a central topic of scientific and public discussion as an important factor for determining water quality. While the quality of surface waters in Germany has significantly improved during the past years, highly contaminated sediments still create a considerable threat to the quality of several European catchment areas. Main features Here, we summarize different concepts and methods for the assessment of sediment quality and report on some novel integrative test methods for assessing sediment toxicity including contaminant re-mobilization during simulated re-suspension events. Results and discussion Currently, different approaches for assessment of sediment pollution exist. While instrumental chemical analyses are not suitable to accurately describe sediment toxicity, combinations of biological and chemical test procedures and integrated approaches, for example weight-of-evidence studies and effect-directed analysis (EDA), have the potential to identify key contaminants. Inter-disciplinary studies combining hydrodynamic and toxicological aspects coupled to real exposure of aquatic organisms to contaminants are currently being developed. Conclusions Monitoring and assessment of sediment quality are of increasing importance, not only for national legislation but also for the implementation of the European Water Framework Directive (WFD). Integrated approaches for the determination of sediment stability play a key role in the appropriate sediment-monitoring strategies. 相似文献
87.
In the first part of the article, the column and the bag experiments concerning removal of polycyclic aromatic hydrocarbons (PAHs) and nonpolar oil (NPO) from tunnel wash waters using organic sorbent materials have been described. This part presents the results of removal of toxic metals. The metals of concern (Al, As, Cd, Cr, Cu, Fe, Pb, Mo, Ni, and Zn) were selected based on the priority toxicant pollutants defined in surface water quality criteria. Concentrations of these metals in the collected effluent... 相似文献
88.
Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed.These waters represent a wide spectrum of organic and inorganic pollutants,such as polycyclic aromatic hydrocarbons(PAHs)and toxic metals.Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway(Hanekleiv and Bragernes).Due to diverse character of both,treatment media and treated wash waters, the... 相似文献
89.
Lin C Solera Garcia MA Timmis R Jones KC 《Journal of environmental monitoring : JEM》2011,13(3):753-761
A new type of directional passive air sampler (DPAS) is described for collecting particulate matter (PM) in ambient air. The prototype sampler has a non-rotating circular sampling tray that is divided into covered angular channels, whose ends are open to winds from sectors covering the surrounding 360°. Wind-blown PM from different directions enters relevant wind-facing channels, and is retained there in collecting pools containing various sampling media. Information on source direction and type can be obtained by examining the distribution of PM between channels. Wind tunnel tests show that external wind velocities are at least halved over an extended area of the collecting pools, encouraging PM to settle from the air stream. Internal and external wind velocities are well-correlated over an external velocity range of 2.0-10.0 m s?1, which suggests it may be possible to relate collected amounts of PM simply to ambient concentrations and wind velocities. Measurements of internal wind velocities in different channels show that velocities decrease from the upwind channel round to the downwind channel, so that the sampler effectively resolves wind directions. Computational fluid dynamics (CFD) analyses were performed on a computer-generated model of the sampler for a range of external wind velocities; the results of these analyses were consistent with those from the wind tunnel. Further wind tunnel tests were undertaken using different artificial particulates in order to assess the collection performance of the sampler in practice. These tests confirmed that the sampler can resolve the directions of sources, by collecting particulates preferentially in source-facing channels. 相似文献
90.
A common explanation for hunting in groups is that doing so yields a greater per capita caloric benefit than hunting solitarily.
This is logical for social carnivores, which rely exclusively on meat for energy, but arguably not for omnivores, which obtain
calories from either plant or animal matter. The common chimpanzee, Pan troglodytes, is one of the few true omnivores that regularly hunts in groups. Studies to date have yielded conflicting data regarding
the payoffs of group hunting in chimpanzees. Here, we interpret chimpanzee hunting patterns using a new approach. In contrast
to the classical assumption that hunting with others maximizes per capita caloric intake, we propose that group hunting is
favored because it maximizes an individual’s likelihood of obtaining important micronutrients that may be found in small quantities
of meat. We describe a mathematical model demonstrating that group hunting may evolve when individuals can obtain micronutrients
more frequently by hunting in groups than by hunting solitarily, provided that group size is below a certain threshold. Twenty
five years of data from Gombe National Park, Tanzania are consistent with this prediction. We propose that our ‘meat-scrap’
hypothesis is a unifying approach that may explain group hunting by chimpanzees and other social omnivores. 相似文献