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741.
Ronald L. Williams Frank Lipari Robert A. Potter 《Journal of the Air & Waste Management Association (1995)》2013,63(5):747-756
Exhaust and evaporative emissions tests were conducted on several methanol- and gasoline-fueled vehicles. Separate samples for chromatographlc analysis of formaldehyde, methanol, and Individual hydrocarbons were collected in each of the three phases of the driving cycle and in each of the two portions of the evaporative emissions test. One vehicle, equipped with an experimental variable-fuel engine, was tested using methanol/gasoline fuel mixtures of 100, 85, 50,15, and 0 percent methanol. Combustion-generated hydrocarbons were lowest using methanol fuel, and increased several-fold as the gasoline fraction was increased. Gasoline components In the exhaust Increased from zero as the gasoline fraction of the fuel was Increased. On the other hand, formaldehyde emissions were several times higher using methanol fuel than they were using gasoline. A dedicated methanol car and the variable-fuel car gave similar emissions patterns when they both were tested using methanol fuel. The organic-carbon composition of the exhaust was 85-90 percent methanol, 5-7 percent formaldehyde, and 3-9 percent hydrocarbons. Several cars that were tested using gasoline emitted similar distributions of hydrocarbons, even through the vehicles represented a broad range of current and developmental engine families and emissions control systems. These vehicles continue the trend of the past twenty years toward less photochemically reactive exhaust, with higher percentages of methane and total alkanes, and correspondingly lower percentages of oleflns and aromatlcs. 相似文献
742.
While adaptation has received a fair amount of attention in the climate change debate, barriers to adaptation are the focus of a more specific, recent discussion. In this discussion, such barriers are generally treated as having a uniform, negative impact on all actors. However, we argue that the precise nature and impact of such barriers on different actors has so far been largely overlooked. Our study of two drought-prone communities in rural Ethiopia sets out to examine how female- and male-headed households adapt to climate change, particularly focusing on how a variety of barriers influence the choice of adaptation measures to varying extents. To this purpose, we built a conceptual framework based on the Sustainable Livelihood Approach. Data were collected using semi-structured interviews and focus group discussions with male- and female-headed households, community leaders and local extension workers. Our findings suggest that gender-based differences in the choice of adaptation measures at the household level are driven by cultural, social, financial and institutional barriers. Barriers to adaptation—particularly when interacting—have a differentiated impact upon different actors. This outcome hints at the need for donors and policymakers to develop intervention strategies that are sensitive to this fact. 相似文献
743.
Steve Kelling Daniel Fink Frank A. La Sorte Alison Johnston Nicholas E. Bruns Wesley M. Hochachka 《Ambio》2015,44(4):601-611
Data from well-designed experiments provide the strongest evidence of causation in biodiversity studies. However, for many species the collection of these data is not scalable to the spatial and temporal extents required to understand patterns at the population level. Only data collected from citizen science projects can gather sufficient quantities of data, but data collected from volunteers are inherently noisy and heterogeneous. Here we describe a ‘Big Data’ approach to improve the data quality in eBird, a global citizen science project that gathers bird observations. First, eBird’s data submission design ensures that all data meet high standards of completeness and accuracy. Second, we take a ‘sensor calibration’ approach to measure individual variation in eBird participant’s ability to detect and identify birds. Third, we use species distribution models to fill in data gaps. Finally, we provide examples of novel analyses exploring population-level patterns in bird distributions. 相似文献
744.
Julian Adolphs Frank Kleinjung Jorge Numata Hans Mielke Klaus Abraham Helmut Schafft Christine Müller-Graf Matthias Greiner 《Chemosphere》2013
When food producing animals are contaminated with PCDD/F congeners, information on the contaminant’s concentration in the bodies of the animals at time of slaughter is needed for risk management purposes. We have developed a mathematical model for the kinetics of PCDD/Fs in growing pigs in case of contaminated feed fed for a limited duration of time. This model allows the prediction of concentrations in body fat. It considers absorption fractions of PCDD/Fs, clearance by metabolism, dilution by growth and excretion through fecal fat. The model parameters were calibrated by fitting the model to experimental data. On the basis of this toxicokinetic model a probabilistic model has been constructed. The probabilistic model handles the parameters with appropriate probability distributions and Monte-Carlo simulation technique, providing for realistic situations with many animals and a range of contaminations and feeding intervals. We applied the new model to describe the German dioxin incident of winter 2010/2011 and discuss its viability as decision tool. The approach demonstrated here is a showcase how a risk assessment in the case of contaminated feeding can be performed. 相似文献
745.
Frank J. Schenck Vinetta Howard‐King 《Journal of environmental science and health. Part. B》2013,48(1):1-12
Abstract A multiresidue solid‐phase extraction (SPE) method for the isolation and subsequent gas Chromatographie determination of organochlorine and organophosphorus pesticide residues in low‐moisture, nonfatty products is described. Residues are extracted from samples with an acetonitrile/water mixture. Cleanup of the extract is performed using graphitized carbon black and anion exchange SPE columns, and analysis is performed by gas chromatography with Hall electrolytic conductivity and flame photometric detection. Recovery data was obtained by fortifying corn, oats and wheat with pesticides. The average recoveries were 79–123% for eight organochlorine and 51–122% for 28 organophosphorus pesticide residues. The limit of quantitation for chlorpyriphos was 0.05 ppm using the Hall electrolytic conductivity detector and <0.005 ppm using the flame photometric detector. 相似文献
746.
Frank F. Scherr Ajit K. Sarmah 《Journal of environmental science and health. Part. B》2013,48(8):763-772
A simple and robust analytical method was developed to simultaneously detect and quantify 17β-estradiol (E2), estrone (E1), 17β-estradiol-3-sulphate (E2-3S), and estrone-3-sulphate (E1-3S) in aqueous solutions (calcium chloride and artificial urine solutions) and agricultural soils using high performance liquid chromatography and UV detection. The standards for all four compounds were linear in the range of 0.01 to 1.0 μg mL?1 (n = 6) and 1.0 to 20 μg mL?1 (n = 6), respectively, with correlation coefficients > 0.999. The on-column limits of detection at an injection volume of 50 μL and S/N (signal: noise) ratio of 3 were: 9.0 ng mL?1, 10 ng mL?1, 5.0 ng mL?1, and 7.0 ng mL?1 for E2-3S, E1-3S, E2 and E1, respectively. The limit of detection and quantification in artificial urine solution and CaCl2 solution was 1.0 ng mL?1 for all four compounds. Method detection limits for the compounds in the 3 soils ranged from 2 to 2.4 ng g?1 (E2-3S and E1-3S), and 1.0 to 2.9 ng g?1 (E2 and E1), respectively. 相似文献
747.
The Concept of Farm Animal Welfare: Citizen Perceptions and Stakeholder Opinion in Flanders, Belgium
Filiep Vanhonacker Wim Verbeke Els Van Poucke Zuzanna Pieniak Griet Nijs Frank Tuyttens 《Journal of Agricultural and Environmental Ethics》2012,25(1):79-101
Several attempts to conceptualize farm animal welfare have been criticized for diverging reasons, among them often the failure
to incorporate the public concern and opinion. This paper’s objective is to develop a conception of farm animal welfare that
starts from the public’s perception and integrates the opinion of different stakeholder representatives, thus following a
fork-to-farm approach. Four qualitative citizen focus group discussions were used to develop a quantitative questionnaire,
which has been completed by a representative sample of Flemish citizens (n = 459). Exploratory and confirmatory factor analyses were applied to develop a conception of farm animal welfare starting
from an extended list of aspects that relate to animal production and associate with farm animal welfare in the public’s perception.
In depth interviews with stakeholder representatives were used to match and adapt the structure of the animal welfare conception
model. The resulting conception revealed seven dimensions grouped in two different levels. Three dimensions were animal-based:
“Suffering and Stress,” “Ability to Engage in Natural Behavior,” and “Animal Health.” Four dimensions were resource-based:
“Housing and Barn climate,” “Transport and Slaughter,” “Feed and Water,” and “Human-Animal Relationship.” This conception
is distinct from earlier attempts since it is based on public perceptions; it addresses the opinion of different stakeholders,
and it distinguishes empirically between animal-based and resource-based dimensions in the conceptualization of farm animal
welfare. The relevancy of a popular definition is supported by the present demand oriented economy, in which animal welfare
is a non-trade concern, and mainly left to the market where consumers still mainly act as individuals who calculate and weigh
pros and cons. 相似文献
748.
Paul E. Ouboter Gwendolyn A. Landburg Jan H. M. Quik Jan H. A. Mol Frank van der Lugt 《Ambio》2012,41(8):873-882
Mercury levels in sediment and predatory fish were measured for 53 localities in Suriname. The average mercury level in bottom sediment surpassed the Canadian standard for sediment in most localities, except the coastal plains. Of the predatory fish, 41 % had a mercury level above the European Union standard for human consumption of 0.5 μg g−1. Highest mercury levels were found in fish from the Brokopondo Reservoir and from the Upper Coppename River. High levels of mercury in fish in pristine areas are explained by atmospheric transportation of mercury with the northeastern trade winds followed by wet deposition. Contrary to gold mining areas, where mercury is bound to drifting sediments, in “pristine” areas the mercury is freely available for bio-accumulation and uptake. Impacts on piscivorous reptiles, birds, and mammals are unknown, but likely to be negative. 相似文献
749.
Release of methane from aerobic soil: an indication of a novel chemical natural process? 总被引:2,自引:0,他引:2
Methane (CH4) formation under aerobic conditions has been intensely debated, especially since the discovery of CH4 generation by both dried plant material and living plants. In this study we test the hypothesis that non-microbial CH4 formation also occurs in soils. All lyophilised soil samples investigated under aerobic conditions released CH4 at temperatures ranging from 30 to 70 °C exceeding that allowing normal enzymatic activity to proceed. No emissions were observed for single mineral soil components such as quartz sand, clay mineral and iron oxide. Methane release rates from the soils investigated were found to increase both with increasing temperature and higher organic carbon content. Addition of water to dried soils increased CH4 release rates up to 8-fold those observed with the dried material. Our results suggest the existence of a chemical process in soils that produces CH4 under aerobic conditions, a finding which has not been hitherto reported. 相似文献
750.
Methyl chloride emissions from halophyte leaf litter: dependence on temperature and chloride content
Derendorp L Wishkerman A Keppler F McRoberts C Holzinger R Röckmann T 《Chemosphere》2012,87(5):483-489
Methyl chloride (CH3Cl) is the most abundant natural chlorine containing compound in the atmosphere, and responsible for a significant fraction of stratospheric ozone destruction. Understanding the global CH3Cl budget is therefore of great importance. However, the strength of the individual sources and sinks is still uncertain. Leaf litter is a potentially important source of methyl chloride, but factors controlling the emissions are unclear. This study investigated CH3Cl emissions from leaf litter of twelve halophyte species. The emissions were not due to biological activity, and emission rates varied between halophyte species up to two orders of magnitude. For all species, the CH3Cl emission rates increased with temperature following the Arrhenius relation. Activation energies were similar for all investigated plant species, indicating that even though emissions vary largely between plant species, their response to changing temperatures is similar. The chloride and methoxyl group contents of the leaf litter samples were determined, but those parameters were not significantly correlated to the CH3Cl emission rate. 相似文献