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排序方式: 共有1302条查询结果,搜索用时 774 毫秒
381.
随着城市化进程的加快和城市中心人口密度的激增,微生物污染问题成为人们关注的热点.本文利用病毒群体动力学演化模型研究非稳态微生物污染的产生过程,并将模型结果作为非稳态污染源的源强引入污染物对流扩散方程.假设没有继发性感染,研究致病性微生物污染源对建筑群环境的影响,得到了建筑群表面及周围污染物浓度随时间的变化规律.假定致病感染浓度,得到了微生物污染源的影响范围,这为控制污染物扩散和建立致病微生物污染预警系统提供了理论指导. 相似文献
382.
383.
西安市是我国西北政治、经济和文化中心,工业发达,但空气污染事件对社会经济的高质量发展带来极大挑战,探究该地区大气污染特征并厘清其对人体健康产生的影响至关重要.对西安市2015~2021年大气污染物的时空趋势变化特征进行分析;其次,利用空气质量指数(AQI)、综合空气质量指数(AAQI)和空气质量健康指数(HAQI)结合AirQ2.2.3 模型量化各污染物对人体的健康效应.结果发现,研究区整体空气质量呈良好状态,各大气污染物呈现下降态势.污染物主要以PM10 、PM2.5 和O3 为主,地形特征和人为排放的混合式污染是研究区的主要污染特征.AAQI和HAQI相较于AQI对污染水平表现出较好的分类效果,HAQI揭示研究区全年约有80 %左右的人口暴露于不健康的空气中,其中冬季暴露于不健康空气中的人群最多,其次为秋季、春季,夏季最少.AirQ2.2.3 模型量化出归因于PM2.5 、PM10 、SO2 、CO、NO2 和O3 的总死亡率比例分别为0.99 %、2.04 %、0.41 %、1.72 %、8.76 %和3.67 %,且呼吸系统和心脑血管疾病死亡率的可归因比例与总死亡率变化规律较为一致. 相似文献
384.
R. Peter Richards 《Journal of the American Water Resources Association》1989,25(4):891-904
ABSTRACT: Evaluation of the non-point source pollutant load entering a lake from multiple tributaries requires either that all tributaries be monitored or that some extrapolation method be used to estimate loads originating in areas not monitored. Unmonitored areas include not only watersheds of tributaries that are not monitored, but also portions of a monitored tributary's drainage basin downstream from the monitoring site and areas of direct drainage. Significant portions of large lake drainage basins are often not monitored, and loads for these areas are often estimated by extrapolation. Six simple extrapolation procedures were evaluated by using them to estimate loads for areas that had been monitored and comparing the estimated loads with the monitored loads. Three approaches were based on inter-basin ratios of area, C-factor, and discharge. The other approaches used regression relationships between concentration and flow to estimate concentrations for the unmonitored basin. The ratio approaches generally were more reliable than the regression approaches. However, extrapolation by any method tested was not very precise. Some methods also were biased when applied to watersheds of a size different than the monitored one. Extrapolation by any of these methods would compromise the precision of the lake-wide load estimate, if the unmonitored area were a significant part of the entire basin. 相似文献
385.
酒店主要产品服务经济-能源-环境系统分析 总被引:4,自引:0,他引:4
利用投入产出分析方法和能耗寿命周期分析方法相结台。建立了主要产品中间生产和最终服务经济-能源-环境系统投入产出综合计算模型;对国内有代表性的八家酒店主要产品服务系统进行了计算与综合分析:结果显示酒店之间投入产出指标值量大相差2倍以上。具有巨大的改进潜力;酒店内部餐饮服务系统是传统的线性开放式经济发展模式的突出代表。应进行蕾业规模调整、合理配置能源种类和消耗比例、重点实施清洁生产。 相似文献
386.
Abstract: Dry weather runoff in arid, urban watersheds may consist entirely of treated wastewater effluent and/or urban nonpoint source runoff, which can be a source of bacteria, nutrients, and metals to receiving waters. Most studies of urban runoff focus on stormwater, and few have evaluated the relative contribution and sources of dry weather pollutant loading for a range of constituents across multiple watersheds. This study assessed dry weather loading of nutrients, metals, and bacteria in six urban watersheds in the Los Angeles region of southern California to estimate relative sources of each constituent class and the proportion of total annual load that can be attributed to dry weather discharge. In each watershed, flow and water quality were sampled from storm drain and treated wastewater inputs, as well as from in‐stream locations during at least two time periods. Data were used to calculate mean concentrations and loads for various sources. Dry weather loads were compared with modeled wet weather loads under a range of annual rainfall volumes to estimate the relative contribution of dry weather load. Mean storm drain flows were comparable between all watersheds, and in all cases, approximately 20% of the flowing storm drains accounted for 80% of the daily volume. Wastewater reclamation plants (WRP) were the main source of nutrients, storm drains accounted for almost all the bacteria, and metals sources varied by constituent. In‐stream concentrations reflected major sources, for example nutrient concentrations were highest downstream of WRP discharges, while in‐stream metals concentrations were highest downstream of the storm drains with high metals loads. Comparison of wet vs. dry weather loading indicates that dry weather loading can be a significant source of metals, ranging from less than 20% during wet years to greater than 50% during dry years. 相似文献
387.
在分析建立和完善排污权市场机制必要性的基础上,提出了排污权一级市场和二级市场的概念,阐述了参与主体不同、实施手段不同、风险大小不同和作用效果不同是一级市场与二级市场的主要区别;指出排污权一级市场需要解决的核心是公平问题,二级市场需要解决的核心是效率问题,并提出了保证排污权一级市场的公平性和提高二级市场效率的若干重要措施.这对于当前我国实施排污权有偿取得与排污交易,建立排污权市场机制具有重要借鉴意义. 相似文献
388.
我国部分地方规定了水污染物排放许可证制度,由于此类法律文件法律效力的低层级性,制约着水污染防治的司法与执法实践。提高设定该制度法律文件效力位阶,不仅可以解决调整该制度法制不统一状况,而且为其进行法律规制提供了直接、具体的法律依据。对促使排污主体科学、合理排污将起到积极作用。 相似文献
389.
G. Vachon P. Louka J-M. Rosant P.G. Mestayer J-F. Sini 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):127-140
A full scale experiment has been performed in a streetcanyon, the Rue de Strasbourg in Nantes (France). Thiscampaign, the Nantes'99 experiment, provided a detaileddata base documenting, amongst others, the production ofturbulent kinetic energy (TKE) by vehicles within thestreet. Airflow and CO concentration measurements have beenanalysed during days with low wind perpendicular to thestreet axis, i.e. for conditions expected to greatly favourthe enhancement of the turbulence produced by traffic onflow and dispersion within the street canyon. It is shownthat traffic is associated with an increase in turbulentkinetic energy at the lowest levels of the street,especially at the leeward side of the street. It issuggested that turbulent kinetic energy increases with thenumber of vehicles up to a threshold value and thendecreases when vehicles form a `block' shape that limitsthe additional production of turbulence. Moreover, it issuggested that traffic-produced turbulence affectspollutant dispersion reducing CO concentration at the lowerlevels of the leeward side of the street from a thresholdvalue of TKE equal to about 0.15 m2 s-2. On the other hand, high traffic density generates less turbulencewhich in turn leads to a lower pollutant dispersion. 相似文献
390.
王彬辉 《中国环境管理干部学院学报》2000,(2)
长期以来,我国对排污或超标排污实行征收排污费制度。九届人大常委会第13次会议修订通过的《海洋环境保护法》对此进行了改革。本文对此进行了深入分析。 相似文献