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991.
从桥梁建筑、桥梁壅水与洪水侵桥等3方面,定性、定量、全面系统地研究了发生50年一遇或100年一遇洪水灾害时,大型桥梁防洪影响的评估分析方法,并结合实例,验证了所提方法的适用性与可靠性,在此基础上,提出了减轻和避免不利影响的对策及改善措施.  相似文献   
992.
北京市工业污染源大气污染物排放比较严重,其TSP,PM10,PM2.5,SO2,NOx和CO的排放量均占北京市固定污染源排放量的54%以上,煤烟型污染是工业污染的主要部分,占源污染物排放量比面源大,污染物排放主要集中在电力行业和冶金行业,污染源主要分布在城八区中的外四区,特别是工业比较集中的石景山地区和朝阳区,工业污染源排放的颗粒物中细颗粒物比例较高。  相似文献   
993.
排污权交易是利用市场机制控制环境污染的有效途径。明确排污权的产权性质无论是对生产者还是对管理者都具有十分重要的意义。本论文将对排污权的产权性质和内涵进行分析。  相似文献   
994.
ABSTRACT: An analysis of storm runoff is presented, giving primary attention to deterministic-systemic relationships. So that system aspects can be emphasized, other aspects are kept simple; analysis is made for uniform rainfall on a strip of uniform width, limiting direct applicability to small areas. Two relationships between excess rain and time of concentration, one based on hydraulic parameters, the other on hydrologic characteristics, are combined in a solution for peak discharge. The hydraulic expression gives the interrelationship of time of concentration, excess rain, friction, length, and slope. The hydrologic relationship is achieved by converting ordinary intensity-duration curves to corresponding excess rain intensity-duration curves, thereby interrelating excess rain, time of concentration, and loss characteristics. The resulting solution for peak discharge allows for systemic feedback among both hydraulic and hydrologic parameters.  相似文献   
995.
为了使SO2排污费的征收有个比较准确的确定方法,对物料衡算法和实测法进行了比较试验。系统分析了物料衡算法的误差产生原因,对实测法中的瞬时值法和连续采样法进行了比较,得出结论:物料衡算法测算SO2有较大的误差;应尽可能采用连续采样法测定SO2;对于有大量废气排放的单位,应尽量保持煤源的一致性,减少不必要的纠纷。  相似文献   
996.
/ Freshwater inflow is one of the most influential landscape processes affecting community structure and function in lagoons, estuaries, and deltas of the world; nevertheless there are few reviews of coastal impacts associated with altered freshwater inputs. A conceptual model of the possible influences of freshwater inflows on biogeochemical and trophic interactions was used to structure this review, evaluate dominant effects, and discuss tools for coastal management. Studies in the Gulf of Mexico were used to exemplify problems commonly encountered by coastal zone managers and scientists around the world. Landscape alteration, impacting the timing and volume of freshwater inflow, was found to be the most common stress on estuarine systems. Poorly planned upstream landscape alterations can impact wetland and open-water salinity patterns, nutrients, sediment fertility, bottom topography, dissolved oxygen, and concentrations of xenobiotics. These, in turn, influence productivity, structure, and behavior of coastal plant and animal populations. Common biogeochemical impacts include excessive stratification, eutrophication, sediment deprivation, hypoxia, and contamination. Common biological impacts include reduction in livable habitats, promotion of "exotic" species, and decreased diversity. New multiobjective statistical models and dynamic landscape simulations, used to conduct policy-relevant experiments and integrate a wide variety of coastal data for freshwater inflow management, assume that optimum estuarine productivity and diversity is found somewhere between the stress associated with altered freshwater flow and the subsidy associated with natural flow. These models attempt to maximize the area of spatial overlap where favorable dynamic substrates, such as salinity, coincide with favorable fixed substrates, such as bottom topography. Based upon this principle of spatial overlap, a statistical performance model demonstrates how population vitality measurements (growth, survival, and reproduction) can be used to define sediment, freshwater, and nutrient loading limits. Similarly, a spatially articulate landscape simulation model demonstrates how cumulative impacts and ecosystem processes can be predicted as a function of changes in freshwater, sediment, and nutrient inflows.KEY WORDS: Resource management; Landscape impacts; Freshwater discharge; Coastal, ecosystem models; Coastal wetlands  相似文献   
997.
The catalytic effect of alumina on the destruction of toluene, benzene, acetone and methanol, in DC pulsed corona discharge reactor was studied. In the presence of alumina the inlet concentration of the VOCs was varied from ~5×10-6mol/L to ~80×10-6mol/L, and their decomposition efficiency (conversion %) was found to be 99%—80% for toluene, 99%—97% for benzene, 95%—92% for acetone, and 72%—85% for methanol. Corresponding decomposition in the absence of alumina was 90%—38% for toluene, 89%—57% for benzene, 42%—30% for acetone, and 47%—19% for methanol. Feed gas flow rate was 400 cm3/min and power reading from DC source was 7.4 W in all of the experiments. Alumina also shifted the CO/CO2 ratio in the by products in favor of CO2. Ozone concentration at the reactor outlet was higher in the presence of alumina. Enhancement in VOCs decomposition by alumina was explained on the basis of higher concentration of ozone and its precursor atomic oxygen [O] . Decomposition efficiency (conversion %) for individual compounds was found to be inversely proportional to the ionization potential of the compound, under identical conditions. Double DC high voltage sources pulse generator was tested and found to improve VOCs decomposition compared with the conventional single DC high voltage source.   相似文献   
998.
火电厂废水零排放技术的研究   总被引:1,自引:0,他引:1  
肖萍  朱法华  徐志清  徐忠  李兴德 《环境科技》2003,16(1):12-13,23
讨论了火电厂各种废水的处理技术,结合我国的实际情况,探讨适用的火电厂零排放技术。  相似文献   
999.
通过对环境激素双酚A的概念、危害、应用、释放、降解与去除的介绍,指出在今后的科研工作中,加强双酚A降解菌的筛选,并研究其生理、生化、遗传特性,对从分子水平了解其降解机制以及构建高效工程菌具有重要意义。  相似文献   
1000.
水环境容量研究在环境管理中的实施过程初探   总被引:1,自引:0,他引:1  
本文在地表水环境容量测算分析的基础上,分析测算中需要重视的关键问题,提出几个对测算结论影响较大的关键参数,并分析了环境容量在管理中应用的技术方法与手段,提出了水环境容量资源分配与管理中的解决方案。  相似文献   
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