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排序方式: 共有710条查询结果,搜索用时 31 毫秒
701.
Brown LE Mitchell G Holden J Folkard A Wright N Beharry-Borg N Berry G Brierley B Chapman P Clarke SJ Cotton L Dobson M Dollar E Fletcher M Foster J Hanlon A Hildon S Hiley P Hillis P Hoseason J Johnston K Kay P McDonald A Parrott A Powell A Slack RJ Sleigh A Spray C Tapley K Underhill R Woulds C 《The Science of the total environment》2010,409(2):256-369
Several recent studies have emphasised the need for a more integrated process in which researchers, policy makers and practitioners interact to identify research priorities. This paper discusses such a process with respect to the UK water sector, detailing how questions were developed through inter-disciplinary collaboration using online questionnaires and a stakeholder workshop. The paper details the 94 key questions arising, and provides commentary on their scale and scope. Prioritisation voting divided the nine research themes into three categories: (1) extreme events (primarily flooding), valuing freshwater services, and water supply, treatment and distribution [each > 150/1109 votes]; (2) freshwater pollution and integrated catchment management [100-150 votes] and; (3) freshwater biodiversity, water industry governance, understanding and managing demand and communicating water research [50-100 votes]. The biggest demand was for research to improve understanding of intervention impacts in the water environment, while a need for improved understanding of basic processes was also clearly expressed, particularly with respect to impacts of pollution and aquatic ecosystems. Questions that addressed aspects of appraisal, particularly incorporation of ecological service values into decision making, were also strongly represented. The findings revealed that sustainability has entered the lexicon of the UK water sector, but much remains to be done to embed the concept operationally, with key sustainability issues such as resilience and interaction with related key sectors, such as energy and agriculture, relatively poorly addressed. However, the exercise also revealed that a necessary condition for sustainable development, effective communication between scientists, practitioners and policy makers, already appears to be relatively well established in the UK water sector. 相似文献
702.
Oropesa AL Pérez-López M Hernández D García JP Fidalgo LE López-Beceiro A Soler F 《The Science of the total environment》2007,372(2-3):532-538
In November 2002, the tanker Prestige broke in two and sank at the bottom of the ocean spilling about 70,000 t of fuel oil, which reached the coast of Galicia. It was considered the largest spill in maritime history, greatly affecting marine and related avian species. The spilled fuel oil contained high concentrations of polycyclic aromatic hydrocarbons (PAHs). Many species were affected and were found dead, although ongoing research is still being carried out on the sublethal effects. In this sense, little is known about the action of PAHs on Cholinesterase activity in seabirds. Consequently, the purpose of this study was to provide more information on the neurotoxicity of fuel oil on the seabirds most affected by the Prestige accident: common guillemot, Atlantic puffin and razorbill. On the other hand, data on normal values of acetylcholinesterase (AChE) activity were obtained to supply non-exposed values in seabirds. The oil spill produced a clear inhibitory effect on brain AChE activity in common guillemot (16%, p< or =0.01) and razorbill (22%, p< or =0.01), but not in Atlantic puffin (4%). Physiological levels of brain AChE, expressed in nmol acetylcholine hydrolysed min(-1) mg(-1) protein were similar in non-exposed common guillemot (388.6+/-95.0) and Atlantic puffin (474.0+/-60.7), however, razorbill values were higher (644.6+/-66.9). 相似文献
703.
Tracking nonpoint source nitrogen pollution in human-impacted watersheds 总被引:10,自引:0,他引:10
Kaushal SS Groffman PM Band LE Elliott EM Shields CA Kendall C 《Environmental science & technology》2011,45(19):8225-8232
Nonpoint source nitrogen (N) pollution is a leading contributor to U.S. water quality impairments. We combined watershed N mass balances and stable isotopes to investigate fate and transport of nonpoint N in forest, agricultural, and urbanized watersheds at the Baltimore Long-Term Ecological Research site. Annual N retention was 55%, 68%, and 82% for agricultural, suburban, and forest watersheds, respectively. Analysis of δ(15)N-NO(3)(-), and δ(18)O-NO(3)(-) indicated wastewater was an important nitrate source in urbanized streams during baseflow. Negative correlations between δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) in urban watersheds indicated mixing between atmospheric deposition and wastewater, and N source contributions changed with storm magnitude (atmospheric sources contributed ~50% at peak storm N loads). Positive correlations between δ(15)N-NO(3)(-) and δ(18)O-NO(3)(-) in watersheds suggested denitrification was removing septic system and agriculturally derived N, but N from belowground leaking sewers was less susceptible to denitrification. N transformations were also observed in a storm drain (no natural drainage network) potentially due to organic carbon inputs. Overall, nonpoint sources such as atmospheric deposition, wastewater, and fertilizer showed different susceptibility to watershed N export. There were large changes in nitrate sources as a function of runoff, and anticipating source changes in response to climate and storms will be critical for managing nonpoint N pollution. 相似文献
704.
As part of the Southeastern Aerosol and Visibility Study (SEAVS), water-soluble organic species (WSOS) in fine aerosols collected from July 15 to August 25, 1995, at the Great Smoky Mountain National Park, Tennessee (USA), were chemically classified into seven groups, with concentrations ranging from around 1 to >200 ng/m3. Dicarboxylic acids represented the dominant identified compound class, and succinic acid was the most abundant dicarboxylic acid. The trends in data suggest that most WSOS collected in the SEAVS samples were mainly generated from secondary photochemical reactions, especially during the first (cleaner) half of the sampling campaign. High relative humidity at the sampling site resulted in substantial water uptake by the aerosols, which may have enhanced the levels of succinic acid by reducing its rate of photooxidation. Concurrent trends in malic and malonic acid concentrations suggest these were generated from the oxidation of succinic acid. Consistent with the conversion of 3-hydroxypropanoic acid to malonic acid, it appears that 4-hydroxybutanoic acid served as a major precursor contributing to high levels of succinic acid in the daytime. Nocturnal WSOS generally followed the trend of diurnal WSOS, but they exhibited different chemical compositions and lower concentrations, unlike what has been reported for an urban site. A nocturnal-to-diurnal ratio of succinic acid larger than 0.25 may indicate an atmosphere dominated by photochemical reactions, rather than by primary emissions. 相似文献
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708.
Padin S Staniszewski Z Keisler R Joy M Stark AA Ade PA Aird KA Benson BA Bleem LE Carlstrom JE Chang CL Crawford TM Crites AT Dobbs MA Halverson NW Heimsath S Hills RE Holzapfel WL Lawrie C Lee AT Leitch EM Leong J Lu W Lueker M McMahon JJ Meyer SS Mohr JJ Montroy TE Plagge T Pryke C Ruhl JE Schaffer KK Shirokoff E Spieler HG Vieira JD 《Applied optics》2008,47(24):4418-4428
The South Pole Telescope is a 10 m diameter, wide-field, offset Gregorian telescope with a 966-pixel, millimeter-wave, bolometer array receiver. The telescope has an unusual optical system with a cold stop around the secondary. The design emphasizes low scattering and low background loading. All the optical components except the primary are cold, and the entire beam from prime focus to the detectors is surrounded by cold absorber. 相似文献
709.
Broadband CARS spectra of N2 and CO have been obtained from the postflame gases of rich CH4/N2O flames using the nonplanar BOXCARS technique. The temperature and concentration of both N2 and CO in these flames were estimated from CARS spectra with the aid of model calculations and agreed with standard thermochemical predictions. In addition, several pure rotational H2 CARS transitions, certain of which had been previously unobserved, were seen in several spectral regions, most notably in both the CO and NO CARS regions. These observations are important in future modeling of CARS data. 相似文献
710.
更易于从新的地理数据中提取信息的专家分类系统 总被引:3,自引:0,他引:3
1 引言十年能产生什么差别 ?正如 1 0年前 ,羽毛渐丰的地理技术 ( geotechnology)工业正蹒跚地寻找新的地理数据源以满足地理信息系统增长的需要 ,同样地 ,我们遥感界也花费了 2 0世纪 90年代的大部分时间去设计先进的影像卫星 ,优化数字化技术和创建新的数字数据集。作为以上努力的结果 ,遥感界现在所面临的是几乎对立的挑战。空间数据用户能够登录到互联网上去获取令人惊愕的各种卫星影像、数字高程模型( DEM)、预打包 ( pre- packaged)的矢量文件以及其它地理数据 ,这些数据都是以数字格式的而不是模拟的。随着空间数据种类的增加 ,这… 相似文献