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441.
Space shuttle launches produce localized hydrochloric acid deposition. The interaction of solid rocket motor exhaust and deluge
water released on the pad at the time of launch results in the formation of an exhaust cloud. The spatial pattern and extent
of deposition from the launch cloud are predicted by the rocket exhaust effluent diffusion (REED) model. The actual pattern
of deposition has been mapped by field surveys for each shuttle launch since 1981. In this paper we use a geographical information
system (GIS) to compare model predictions with ground patterns for 49 shuttle launches. We also compile cumulative maps of
deposition patterns needed to consider long-term impacts. The direction of launch cloud movement did not differ significantly
from model predictions. The REED model overpredicted both the area that received deposition and the maximum distance from
the launch pad that deposition occurred. Severe vegetation damage was restricted to near-field deposition areas within 1980
m north of each launch pad. Total area impacted from launches has been 87.0 ha around pad 39A and 52.9 ha around pad 39B.
Far-field deposition has caused leaf spotting from acid droplets or aluminum oxide over a wider and more variable area than
near-field. A total of 19,397 ha has received deposition, but 63.6% of this area has received deposition only one time and
92.2% not more than three times. GIS techniques provide means to test spatial models and compile information useful for assessing
cumulative impacts. 相似文献
442.
长江中游致洪暴雨天气气候特征 总被引:7,自引:1,他引:7
本文从建国以来长江中游地区发生的所有暴雨事件中选出四个典型年,并从这些典型年的暴雨个例中得出暴雨和大暴雨和大暴雨的分布范围和暴雨特征,由此而造成的特大洪水情况,以及洪涝灾害对国民经济的影响。最后应用天气归纳方法分析了暴雨的大尺度环流背景。 相似文献
443.
444.
The sulphur dioxide and nitrogen oxides emissions from all sources in Alberta, Canada, during 1982 amounted to 488,297 and 353,511 tonnes, respectively. During this year deposition of wet sulphate from all stations in the province, 8 kg ha–1 yr–1, compares well with the five-year average (1978–1982) value of 10 kg ha–1 yr–1. These measurements are about one-half of the wet sulphate deposition criteria of 20 kg ha–1 yr–1 established for protecting the moderately sensitive aquatic ecosystem in eastern Canada. Due to dry, cold, continental climate conditions of Alberta, dry sulphate or sulphur deposition is equally or more important than wet deposition. No effects of the long-range transport of atmospheric pollutants (LRTAP) on the ecosystems in Alberta have been observed to date. Atmospheric deposition target loadings of SO4
–2, NO3
–, and H+ for Alberta and western Canadian environmental conditions should be developed to protect the highly sensitive ecosystems. Some future research and monitoring priorities for Alberta and western Canada are outlined. 相似文献
445.
Air pollution has become a serious problem in China as a result of that country's efforts in the last 30 years to become a great industrial power. The burning of coal, which currently provides over 70% of all China's energy needs, is a major source of air pollution. Because Chinese coal is high in sulfur and ash content and because most combustion devices in China have low efficiencies, SO2 and particulate emissions are a serious problem and are comparable to or exceed those found in many countries that are much more industrialized. Although most coal is burned in North China, acid precipitation is most severe in South China because of the lack of buffering loess dust found in the former region.The Chinese government has already taken major steps to mitigate air pollution, such as relocating polluting industries, supplying coal with lower sulfur content, using gas instead of coal for residential heating, and levying fines on industries that exceed pollution standards. Atmospheric environmental impact assessment (AEIA) is also required for all major new projects. This article describes three types of mathematical diffusion models and field and wind-tunnel experiments that are used in such assessments.The Chinese authorities believe that a range of technological, managerial, locational, and behavioral changes must be effected before the air of Chinese cities can be significantly improved. 相似文献
446.
The governments of British Columbia, Alberta, Saskatchewan, Manitoba, Northwest Territories, and Canada held joint consultations in 1980 to review the available information on acid rain from Western and Northern Canada. It was concluded that acid rain might become a problem in the future and, hence, a research, monitoring, and management strategy for acidic deposition was needed. An overview of the joint governments' management strategy, organization of research and monitoring programs, and accomplishments to date are discussed in this article.The authors are members of the Technical Committee for the Long Range Transport of Atmospheric Pollutants (LRTAP)/Acid Deposition in Western and Northern Canada, and represent Alberta and British Columbia, respectively. 相似文献
447.
深圳地狭人多,特区人口密度高达7310人/平方公里,是中国人口密度最大的城市之一。随着社会经济的高速发展,汽车拥有量的急剧增加,汽车排气污染已成为深圳市最主要的大气污染问题。文章分析了深圳市汽车排气污染的状况及其对城市空气质量的影响,简要介绍了近年来深圳市在控制汽车排气污染方面所做的工作。 相似文献
448.
449.
Monitoring the results of Canada/U.S.A acid rain control programs: some lake responses 总被引:1,自引:0,他引:1
Jeffries DS Brydges TG Dillon PJ Keller W 《Environmental monitoring and assessment》2003,88(1-3):3-19
Aquatic acidification by deposition of airborne pollutants emerged as an environmental issue in southeastern Canada during the 1970s. Drawing information from the extensive research and monitoring programs, a sequence of issue assessments demonstrated the necessity of reducing the anthropogenic emissions of acidifying pollutants, particularly sulphur dioxide (SO2). The 1991 Canada-U.S. Air Quality Agreement (AQA) was negotiated to reduce North American SO2 emissions by 40% relative to 1980 levels by 2010, and at present, both countries have reduced emissions beyond their AQA commitment. In response to reduced SO2 emissions, atmospheric deposition of sulphate (SO4
2–) and SO4
2– concentrations in many lakes have declined, particularly in south-central Ontario and southern Québec. Sulphate deposition still exceeds aquatic critical loads throughout southeastern Canada however. Increasing pH or alkalinity (commonly deemed recovery) has been observed in only some lakes. Several biogeochemical factors have intervened to modify the lake chemistry response to reduced SO4
2– input, notably release of stored SO4
2– from wetlands following periods of drought and reduction in the export of base cations from terrestrial soils. Three examples from Ontario are presented to illustrate these responses. Significant increases in pH and alkalinity have been observed in many lakes in the Sudbury area of Ontario due to the large reductions in local SO2 emissions; early-stage biological recovery is evident in these lakes. An integrated assessment model predicts that AQA emission reductions will not be sufficient to promote widespread chemical or biological recovery of Canadian lakes. Monitoring and modeling are mutually supporting assessment activities and both must continue. 相似文献
450.