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111.
McClenny WA Oliver KD Jacumin HH Daughtrey EH Whitaker DA 《Journal of environmental monitoring : JEM》2005,7(3):248-256
Diffusive sampling of a mixture of 42 volatile organic compounds (VOCs) in humidified, purified air onto the solid adsorbent Carbopack X was evaluated under controlled laboratory conditions. The evaluation included variations in sample air temperature, relative humidity and ozone concentration. Linearity of samples with loading was examined both for a constant concentration with time varied up to 24 h and for different concentrations over 24 h. Reverse diffusion and its increase with accumulation of sample were determined for all compounds. Tubes were examined for blank levels, change of blanks with storage time, and variability of blanks. Method detection limits were determined based on seven replicate samples. Based on this evaluation, 27 VOCs were selected for quantitative monitoring in the concentration range from approximately 0.1 to 4 ppbv. Comparison results of active and diffusive samples taken over 24 h and under the same simulated ambient conditions at a constant 2 ppbv were interpreted to estimate the effective diffusive sampling rates (ml min(-1)) and their uncertainties and to calculate the corresponding diffusive uptake rates (ng ppmv(-1) min(-1)). 相似文献
112.
Material within the terrestrial environment is rarely homogeneously distributed, either spatially or temporally. One consequence of heterogeneity is that uncertainty is usually generated in measurements that are taken with the aim of characterising the environment. For example, a measurement of analyte concentration within soil taken from one sampling location on contaminated land can vary substantially when compared against another sample taken at effectively the same nominal location. The measurement uncertainty arising from the heterogeneity can substantially limit the reliability of the interpretations made upon environmental investigations. The sampling uncertainty usually outweighs the analytical uncertainty from the laboratory, often by a factor of 20 or more. One approach to reducing the uncertainty is to design a more suitable sampling strategy. This might be achieved by predicting the degree of heterogeneity prior to the investigation, but this is often difficult to achieve accurately. Another approach, which was investigated here, is to actually characterise the heterogeneity prior to the main investigation using rapid and inexpensive technology, such as in situ measurement techniques. In situ portable X-ray fluorescence (PXRF) and X-ray microprobe (XMP) techniques were employed to test the feasibility of this approach. Two contrasting contaminated land sites were chosen to characterise the two-dimensional spatial heterogeneity of heavy metal contamination in topsoil at a range of scales (50 m to 0.001 m). The spatial heterogeneity of contaminants, expressed as relative standard deviations, was found to differ between the two sites by a factor of two, largely due to the mode of deposition of pollution. The study also indicated that the heterogeneity did not change systematically with the scale of measurement between sampling locations at either site. 相似文献
113.
In order to investigate the characteristic of optical properties of Asian dust particles, the atmospheric aerosol vertical profile was measured with the multi-wavelength LIDAR system, at the Gosan super site (33 degrees 17'N, 126 degrees 10'E) in Jeju Island, Korea, during the ACE-Asia intensive observation period, 11 March-4 May 2001. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol plume, with high mass loading, from the Chinese desert regions during the period of Asian dust storm events. Vertical atmospheric aerosol profiles on three major Asian dust storm event days, 22 March and 13 and 26 April 2001, have been analyzed. The LIDAR-derived aerosol optical depth values were compared with those measured by a collocated sunphotometer. 相似文献
114.
Iwasaka Y Shi GY Kim YS Matsuki A Trochkine D Zhang D Yamada M Nagatani T Nagatani M Shen Z Shibata T Nakata H 《Environmental monitoring and assessment》2004,92(1-3):5-24
Measurements of aerosols were made in 2001 and 2002 at Dunhuang (40 degrees 00'N, 94 degrees 30'E), China to understand the nature of atmospheric particles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had noticeable peaks in super micron size range not only in the boundary mixing layer but also in the free troposphere. Super-micron particle concentration largely decreased in the mid tropopause (from 5 to 10 km; above sea level, a.s.l.). Lidar measurements made during August 2002 at Dunhuang suggested the possibility that mixing of dust particles occurred from near the ground to about 6 km even under calm weather conditions, and a large depolarization ratio of particulate matter was found in the aerosol layer. The top of the aerosol layer was found at heights of nearly 6 km (a.s.l.). It is strongly suggested that nonspherical dust particles (Kosa particles) frequently diffused in the free atmosphere over the Taklamakan desert through small-scale turbulences and are possible sources of dust particles of weak Kosa events that have been identified in the free troposphere not only in spring but also in summer over Japanese archipelago. Electron microscopic experiments of the particles collected in the free troposphere confirmed that coarse and nonspherical particles observed by the mineral particle were major components of coarse mode (diameter larger than 1 microm) below about 5 km over Dunhuang, China. 相似文献
115.
A. Haurie J.J.E. Kübler A. Clappier H. van den Bergh 《Environmental Modeling and Assessment》2004,9(1):1-12
A method is proposed to build integrated models (also called Metamodels) aimed at quantifying the economic efficiency of air quality policies. This Metamodeling approach is based on the coupling of two complementary models, that operate at different scales in space and time, and which represent the economic and the physical and chemical processes, respectively. The joint consideration of the physico-chemical and techno-economic structure of the pollution control problems permits a comprehensive evaluation of air pollution abatement strategies. The motivating pollution control problems include urban-regional air quality management through efficient energy and traffic control policies. A pilot study, exploiting data collected in the Geneva canton (Switzerland), is used to demonstrate the potential of the approach. 相似文献
116.
Brundtland GH 《环境》1994,36(10):16-20
Norway's Prime Minister Gro Harlem Brundtland holds a medical degree from the University of Oslo and a Master's degree in Public Health from Harvard University. She served as Norway's Minister of the Environment during 1974-79, and was elected to the Norwegian parliament in 1977. Brundtland is currently chairperson of the World Commission on Environment and Development with ten years of experience as a physician and twenty years as a politician. An edited version of her keynote address to the 1994 International Conference on Population and Development is presented. The Minister's experience has taught her that improved life conditions, a greater range of choices, access to unbiased information, and true international solidarity are the signs of human progress. She stresses the need to empower people, educate them, care for their health, and provide them with equal opportunity to achieve economically. Available combined resources need to be used more efficiently through a reformed and better coordinated UN system, policies must be changed, the role and status of women strengthened, safe, comprehensive reproductive health services provided, and measures taken to achieve a balance between population size and sustainable development in keeping with available global resources. 相似文献
117.
P. M. Lutz Selena Bauer N. L. Gale J. Hewett P. E. Phillips F. M. Looney H. Bengsch 《Environmental geochemistry and health》1994,16(3-4):179-189
Lead has been found to depress the immune system in animal studies at levels far below those responsible for overt toxicity. Literature studies in animal systems most clearly showed an effect of lead on response to a specific immunogenic stimulus. Data are sparse concerning the effects of lead on the immune system in the human population at greatest risk for exposure-children up to six years of age. This portion of the Phase I study reports concentrations of IgG, IgM, IgA, and IgE, as well as antibody titers to the specific antigenic stimuli provided by the vaccines against diphtheria, tetanus, and Rubella. The study population consisted of a group of 193 children, ages 9 months to 6 years, who participate in the WIC (Women, Infants and Children) and Lead Poisoning Prevention Programs in the urban area of Springfield-Greene County Missouri. Blood lead levels ranged from 1 to 50 g dL–1. Total Ig levels were determined and the data were analysed. No consistent significant differences were observed among the risk categories in the five age groups examined. A single Ig class in each of three age groups showed apparent significant differences among the various risk categories, but these differences were not correlated with blood lead. An analysis of specific antibody titers to diphtheria, tetanus, and Rubella was performed. Regression analyses of current data in Phase I of this study suggest a detrimental effect of lead on the antibody titres to diphtheria and Rubella. 相似文献
118.
Gary H. Heinz David S. Miller Brian J. Ebert Kenneth L. Stromborg 《Environmental monitoring and assessment》1994,33(3):175-182
From 1977–1978 to 1990, concentrations of polychlorinated biphenyls (PCBs) and most organochlorine pesticides declined in eggs of red-breasted mergansers (Mergus serrator) nesting on islands in northwestern Lake Michigan. Total PCBs decreased 60% (from 21 ppm in 1977–1978 to 8.5 ppm in 1990) and p,p-DDE decreased 66% (from 6.5 to 2.2 ppm). Dieldrin decreased only 16% (from 0.82 to 0.69 ppm). In 1990, 79.1% of incubated eggs hatched, which was not significantly different from the 83.5% that hatched in 1977–1978.The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. 相似文献
119.
Pelgrom SM Lamers LP Lock RA Balm PH Bonga SE 《Environmental pollution (Barking, Essex : 1987)》1995,90(3):415-423
Sexually mature female tilapia were exposed to sublethal concentrations of waterborne Cu and/or Cd over 6 days, and subsequent body concentrations of these metals were determined in several organs. The results show that the distribution of Cu and Cd was metal and organ specific. This is demonstrated, for example, by the observation that in tilapia, Cu exposure did not result in Cu accumulation in the liver, whereas in the intestinal wall, notably high concentrations of Cu and Cd were measured in metal exposed fish. In addition to single metal exposed fish, we also determined Cu and Cd body distribution in Cu?Cd co-exposed fish. The observed interactions in metal accumulation were most pronounced in the organs of fish exposed to low, environmentally realistic, metal concentrations. 相似文献
120.
本文总结中国东南沿海高钾钙碱性—双峰式火山岩带中已勘查大中型矿床成矿环境的共性:矿床所处区域构造的部位、成岩与成矿时代、矿床与岩浆成因类型、火山构造及其基底构造控矿性、矿床与爆发角砾岩、矿床与矿化类型叠加与共生、矿化与蚀变的分带往、矿床定位深度与剥蚀深度。作者认为这八点可作为找寻与评价大(中)型矿床的地质准则。通过火山地质与矿床地质统一的研究提出本区晚中生代以火山为中心地热体系的成矿模式。并就三个方面作类比:①与现代火山地热体系成矿作用类比;②以紫金山高硫型浅成低温热液矿床与世界同类型矿床作比较;③与环太平洋其他火山岩带同类型矿床模式作类比.通过建立本区的模式与类比获得进一步找矿中值得重视的一些思路. 相似文献