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1.
In this paper we examine the trends of nitrous oxide (N2O) emissions of the Spanish agricultural sector related to national production and consumption in the 1961–2009 period. The comparison between production- and consumption-based emissions at the national level provides a complete overview of the actual impact resulting from the dietary choices of a given country and allows the evaluation of potential emission leakages. On average, 1.5 % of the new reactive nitrogen that enters Spain every year is emitted as N2O. Production- and consumption-based emissions have both significantly increased in the period studied and nowadays consumption-based emissions are 45 % higher than production-based emissions. A large proportion of the net N2O emissions associated with imported agricultural goods comes from countries that are not committers for the United Nations Framework Convention on Climate Change Kyoto Protocol Annex I. An increase in feed consumption is the main driver of the changes observed, leading to a remarkable emission leakage in the Spanish agricultural sector. The complementary approach used here is essential to achieve an effective mitigation of Spanish greenhouse gas emissions.  相似文献   

2.
This paper derives expressions for the maximum cross-wind integrated and ceterline concentrations at ground level for an elevated source in the convective boundary layer. These expressions account for the observation that the probability density function (pdf) of vertical velocities in the convective boundary is positively skewed with a negative mode. The estimates obtained with these formulae compare favorably with observations reported by Briggs (1993; Boundary-layer Met.62, 315–328).The paper also examines the error associated with using a symmetric Gaussian pdf instead of the skewed pdf to estimate the ground-level concentration. We show that the error is equivalent to an underestimation of a factor of almost 1.5 for the cross-wind integrated concentration and a factor of 1.3 for the ground-level centerline concentration.  相似文献   

3.
The North Frisian Wadden Sea represents one of the best researched natural regions in the world. Since the end of the 1980s, scientific research has been carried out to scientifically study, analyse and assess this intertidal coastal zone under the conceptual umbrella of ecosystem research. The outcome of this assessment materialised in the establishment of the Nationalpark Schleswig-Holsteinisches Wattenmeer. Its implementation caused considerable conflicts between coastal inhabitants, national park authorities and government officials. Arguments in these disputes revolved around the validity and relevance of scientific knowledge generated to assess and legitimately protect the tidelands and areas of the Waddensea. In summary, the whole implementation process was locally perceived as a politically endorsed top-down enforcement strategy only allowing scientific knowledge for decision-making purposes while local concerns and ‘knowledges’ were not included. To learn from these developments and past mistakes, we compare concepts of co-management, boundary work and boundary objects (BO) to theoretically and methodologically explore their potentials to generate shared meanings and instigate communication in the context of future managing purposes. Against this theoretical background, we propose the empirical show-case example of the German concept of ‘Heimat’ as a BO to assess its applicability to study place-based meanings and to illustrate it as a practice-oriented point of entry to initiate productive science-stakeholder interaction (SSI) in managing the North Frisian Wadden Sea.  相似文献   

4.
ThecharactersfortheboundarylayerandmechanismofacidrainformationintheQingdaoarea,ChinaLiuBaozhang,LiJinlongenterofEnvironmenta...  相似文献   

5.
European regulations exist to phase-out production of the ozone-depleting man-made CFCs. High frequency measurements of the principal CFCs and other radiatively active gases have been collected at Mace Head, Ireland from 1987–1990 as part of the Global Atmospheric Gases Experiment (GAGE). These measurements provide the first clear evidence that this phase-out is effective. Allocation of the time series beginning at the end of 1988, to a particular wind sector combined with simple modelling techniques indicates a significant reduction in European source strengths for CFC-11 and CFC-12 which is consistent with reliable emission estimates for CFC-11, but which seem to indicate a slightly smaller reduction for CFC-12, when likewise compared to emission figures. The study provides evidence that European CH4, CCl2F2 and CCl3F emission have already declined to about one-third of 1987 levels by the end of 1990. Over the same period, no evidence of any phase-out in the European usage of methyl chloroform and CFC-113 was detected.  相似文献   

6.
Since the announcement by Fleischmann and Pons that the excess enthalpy generated in the negatively polarized Pd–D-D2O system was attributable to nuclear reactions occurring inside the Pd lattice, there have been reports of other manifestations of nuclear activities in this system. In particular, there have been reports of tritium and helium-4 production; emission of energetic particles, gamma or X-rays, and neutrons; as well as the transmutation of elements. In this communication, the results of Pd–D co-deposition experiments conducted with the cathode in close contact with CR-39, a solid-state nuclear etch detector, are reported. Among the solitary tracks due to individual energetic particles, triple tracks are observed. Microscopic examination of the bottom of the triple track pit shows that the three lobes of the track are splitting apart from a center point. The presence of three α-particle tracks outgoing from a single point is diagnostic of the 12C(n,n′)3α carbon breakup reaction and suggests that DT reactions that produce ≥9.6 MeV neutrons are occurring inside the Pd lattice. To our knowledge, this is the first report of the production of energetic (≥9.6 MeV) neutrons in the Pd–D system. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

7.
Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with different sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem differential mobility analyzer (TDMA) in terms of hygroscopic growth factor (Gf), with a relative humidity of 85%. With sulfate seed aerosols present, Gf of the aerosols decreased very fast before notable secondary organic aerosols (SOA) formation was observed, indicating a heterogeneous process between inorganic seeds and organic products might take place as soon as oxidation begins, rather than only happening after gas-aerosol partition of organic products starts. The final SOA-coated sulfate particles had similar or lower Gf than seed-free SOA. The hygroscopicity of the final particles was not dependent on the thickness but on the hygroscopicity properties of the SOA, which were influenced by the initial sulfate seed particles. In the two designed aging processes, Gf of the particles increased more significantly with introduction of OH radical than with ozone. However, the hygroscopicity of SOA was very low even after a long time of aging, implying that either SOA aging in the chamber was very slow or the Gf of SOA did not change significantly in aging. Using an aerosol composition speciation monitor (ACSM) and matrix factorization (PMF) method, two factors for the components of SOA were identified, but the correlation between SOA hygroscopicity and the proportion of the more highly oxidized factor could be either positive or negative depending on the speciation of seed aerosols present.  相似文献   

8.
Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with diferent sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem diferential mobility analyzer(TDMA) in terms of hygroscopic growth factor(Gf), with a relative humidity of 85%. With sulfate seed aerosols present, Gf of the aerosols decreased very fast before notable secondary organic aerosols(SOA) formation was observed, indicating a heterogeneous process between inorganic seeds and organic products might take place as soon as oxidation begins, rather than only happening after gas-aerosol partition of organic products starts. The final SOA-coated sulfate particles had similar or lower Gf than seed-free SOA. The hygroscopicity of the final particles was not dependent on the thickness but on the hygroscopicity properties of the SOA, which were influenced by the initial sulfate seed particles. In the two designed aging processes, Gf of the particles increased more significantly with introduction of OH radical than with ozone. However, the hygroscopicity of SOA was very low even after a long time of aging, implying that either SOA aging in the chamber was very slow or the Gf of SOA did not change significantly in aging. Using an aerosol composition speciation monitor(ACSM) and matrix factorization(PMF) method, two factors for the components of SOA were identified, but the correlation between SOA hygroscopicity and the proportion of the more highly oxidized factor could be either positive or negative depending on the speciation of seed aerosols present.  相似文献   

9.
The queens of many eusocial insect species are polyandrous. The evolution of polyandry from ancestral monoandry is intriguing because polyandry undermines the kin-selected benefits of high intracolonial relatedness that are understood to have been central to the evolution of eusociality. An accumulating body of evidence suggests that polyandry evolved from monoandry in part because genetically diverse colonies better resist infection by pathogens. However, a core assumption of the “parasite–pathogen hypothesis”, that there is variation in virulence among strains of pathogens, remains largely untested in vivo. Here, we demonstrate variation in virulence among isolates of Ascosphaera apis, the causative organism of chalkbrood disease in its honey bee (Apis mellifera) host. More importantly, we show a pathogen–host genotypic interaction for resistance and pathogenicity. Our findings therefore support the parasite-parasite hypothesis as a factor in the evolution of polyandry among eusocial insects.  相似文献   

10.
11.
The use of science to inform and underpin decision-making on natural resources is not self-evident as stakeholders often use science in a selective and strategic way. Scientific analyses of science utilisation often focus on how the science–policy interface is organised and from this perspective provide recommendations to scientists about how they can increase their contribution to decision-making. Yet in this paper we argue that a wider perspective on the science–policy interface, in particular by analysing the roles and interactions of actors other than those directly involved, provides both additional explanations and new points of application for strategies aimed at enhancing science utilisation. We illustrate our claim by means of an analysis of decision-making on cockle fisheries and gas mining in the Dutch Wadden Sea between the 1990s and 2004. For many years, scientific studies addressing the ecological effects of these activities were not used to meaningfully contribute to decision-making. In 2004 this situation changed radically. Explanations include the role of intermediaries between scientists, stakeholders and decision-makers and new legislation. Scientists could enhance the chances of knowledge utilisation both by creating a more open science–policy interface and by reframing the policy problems at issue.  相似文献   

12.
Actinobacterial community is a conspicuous part of aquatic ecosystems and displays an important role in the case of biogeochemical cycle, but little is known about the seasonal variation of actinobacterial community in reservoir ecological environment. In this study,the high-throughput techniques were used to investigate the structure of the aquatic actinobacterial community and its inducing water quality parameters in different seasons. The results showed that the highest diversity and abundanc...  相似文献   

13.
A catalyst based on mixed V-Ni oxides supported on TiO_2(Ni-V/TiO_2)was obtained using the sol-gel method.Its catalytic performance relative to dichloromethane(DCM)degradation was investigated.Characterization and analysis were conducted using transmission electron microscopy,H2 temperature-programmed reduction,pyridine-Fourier transform infrared spectroscopy(FTIR)characterization,and X-ray diffraction.Results showed that the original hollow anatase structure of pure Ti02 was well-maintained after Ni-V loading.The loading of NiO-VOx not only significantly improved the stability of pure Ti02 but also inhibited the formation of the by-product monochloromethane(MCM).Among the series of Ni-V/TiO_2 catalysts,4%Ni-V/TiO_2 possessed the highest catalytic activity,with 90%DCM conversion at only 203℃.No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability test.Furthermore,thermogravimetric analysis(O_2-TG)and energy dispersive spectrometer(EDS)characterization of the used 4%Ni-V/TiO_2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.  相似文献   

14.
IntroductionLandscapeboundaries,ortransitionalzones ecotonesamongdifferentlandscapes,haveoftenbeenignoredorreducedtolinesonamapwhenecologistsstudied .Howeverlandscapeboundariesareinherentfeaturesoflandscapesandplayimportantrolesinecosystemsdynamics.Fora…  相似文献   

15.
Boundaries between different forest types in Changbai Mountain Eatern China are results from complex interactions between forest ecosystems,topogrphy,and geomorphology.Detecting and quantifying the transitional zones are highly important since high environmental beterogeneity and biodiversity are ofter found within these zpmes.In this study,we used GIS and multivariate statistics techniques(PCA and MSWA) to analyze data from Landsat TM satellite imageries and quantitatively determined the positions and widths of the landscape boundary betweeen mountain birch and evergreen coniferous forests in the northern slope of Changbai Mountain.The results showed that the widths of the landscape boundary ranges from 30-50 m while using the MWW A or/and PC method.Such detected widths are consistent with field transect data that suggest a 50m tranistional zone width.The results further suggest that TM data can be used in combination with GIS and statistical techniques in determining forest landscape boundaries.MSWA is more reliable than PCA,while PCA can also be used to determine the landscape boundary when transects are properly located.  相似文献   

16.
Hexabromocyclododecanes(HBCDs),a new type of persistent organic pollutants widely used as brominated flame retardants,have attracted wide attention due to their increasing level and toxicity. A method based on high-performance liquid chromatography mass spectrometry(HPLC–MS–MS)in electrospray ionization mode has been developed by optimization of various parameters,which effectively improved the separation degree and responsive intensity of α-,β-and γ-HBCD isomers. The concentrations and distribution profiles of three HBCD isomers were investigated in sediments from the Haihe River in China.It was observed that the concentrations of HBCDs varied in the range of 0.4–58.82 ng/g,showing a decreasing trend along the flow direction,possibly due to attenuation and biodegradation along the flow direction of the Haihe River. The distribution profile of α-,β-,γ-HBCD was 7.91%–88.6%,0–91.47%,and 0.62%–42.83%,respectively. Interestingly,α-HBCD dominated in most sample sites. This was different from the distribution profile in commercial industrial products,which might be attributed to the inter-transformation and different degradation rates of the three HBCD isomers. The potential ecological risk of HBCDs in sediment was characterized under the two-tiered procedure of the European Medicines Evaluation Agency for environmental risk assessment. Although the HBCDs in the selected section of the Haihe River presented "no risk" in the sediment compartment,its risk in sediment cannot be neglected since sediment is one of the important sinks and reservoirs of pollutants.  相似文献   

17.
Hexabromocyclododecane(HBCD) is an effective brominated flame-retardant additive, which is mainly produced in the coastal area of China. This study collected soil samples from a HBCD production plant and its surrounding area in Weifang, Shandong Province, China, and analyzed the temporal–spatial distribution of HBCD and its diastereoisomers in soil. The analysis results showed that the concentration of HBCD in soil near the plant was much higher than normal values, with an annual average concentration reaching 5405 ng/g. Soils 1,2 and 4 km away from the plant were also analyzed, showing that the concentration of HBCD in soil decreased accordingly with the distance from the pollution sources. In order to investigate the effect of the season on HBCD content, the soil samples were collected in all four seasons of the year 2017–2018. According to variations in the wind direction, the concentration of HBCD in soil was also changed. The distribution trend showed that the concentration of HBCD in soil in the downwind direction of the prevailing wind was higher than that in the upwind direction. In addition, this work analyzed the distribution of HBCD in vertical soil sections. It was found that the concentration of HBCD decreased with depth in the soil vertical profile. Finally, the various diastereoisomer patterns in the soil compartments were examined, finding that α-HBCD and γ-HBCD were the predominant diastereoisomers in the soil of the study area.  相似文献   

18.
The reproductive roles of dopamine and dopamine regulation systems are known in social hymenopterans, but the knowledge on the regulation systems in solitary species is still needed. To test the possibility that juvenile hormone (JH) and brain dopamine interact to trigger territorial flight behavior in males of a solitary bee species, the effects on biogenic amines of JH analog treatments and behavioral assays with dopamine injections in males of the large carpenter bee Xylocopa appendiculata were quantified. Brain dopamine levels were significantly higher in methoprene-treated males than in control males 4 days after treatment, but were not significantly different after 7 days. Brain octopamine and serotonin levels did not differ between methoprene-treated and control males at 4 and 7 days after treatment. Injection of dopamine caused significantly higher locomotor activities and a shorter duration for flight initiation in experimental versus control males. These results suggest that brain dopamine can be regulated by JH and enhances flight activities in males. The JH–dopamine system in males of this solitary bee species is similar to that of males of the highly eusocial honeybee Apis mellifera.  相似文献   

19.
This paper aims to practically contribute to the literature on the use of cost–benefit analysis (CBA) and economic evaluation in environmental decision-making through a practical case study: the implementation of the Water Framework Directive (WFD) in France, for the first cycle (2010–2015). The WFD requires that Member States achieve “good status” for all water bodies in 2015. However, exemptions can apply, if justified, on natural, technical or economic reasons. For the latter, EU guidance documents recommend to use CBA. In France, the water agencies carried out 710 CBAs on proposed restoration projects for water bodies. This article reports on this experience. Issues concerning these analyses are discussed, especially the assessment of non-market benefits. Finally, this article questions the use of economic analysis in the implementation of environmental policy.  相似文献   

20.
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