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491.
对兰州市春季不同功能区大气降尘有机质中PAHs种类的分析,检出了大气降尘中有机质USEPA优控PAHs有11种以上,含量较高的萘、荧蒽、菲、芘、,占各采样点PAHs总量的70%以上。源解析表明,兰州市各功能区大气降尘中PAHs来源不仅有较高的燃煤源、交通源(汽车尾气),同时PAHs的组成与分布也在很大程度上受到采样点周围居民居住环境的影响。  相似文献   
492.
In the buoyancy and turbulence-driven atmospheric circulations (BTDAC) that occur over urban areas where the approach means wind speeds are very low (less than turbulent fluctuations and typically < 3 m/sec), the surface temperatures are significantly higher than those in the external rural areas, and the atmosphere above the mixing layer is stably stratified. In this paper, the mechanisms of BTDAC formation are studied through laboratory experiments and modelling, with additional low-level inflow from external rural areas and a divergent outflow in the opposite direction in the upper part of the mixed layer. Strong turbulent plumes in the central region mix the flow between lower and higher levels up to the inversion height. There are shear-driven turbulent eddies and weaker buoyant plumes around the periphery of the urban area. As the approach flow is very weak, the recirculating streamlines within the dome restrict the ventilation, and the dispersion of pollution emitted from sources below the inversion height leading to a rise in the mean concentration. Low-level air entrained from rural areas can, however, improve ventilation and lower this concentration. This trend can also be improved if the recirculating structure of the BTDAC flow pattern over urban areas breaks down as a result of the surface temperature distribution not being symmetrical, or as the approach wind speed increases to a level comparable with the mean velocity of circulation, or (except near the equator) the urban area is large enough that the Coriolis acceleration is significant.  相似文献   
493.
国家标准GB/T13201-91推荐基于单箱模型推导出来的A值法制定地方大气污染物排放总量标准,该文在放弃了控制区呈圆形的假设之后推导出可利用风向大气稳定度联合频率的更为详细的单箱模型,并用于计算杭州、宁波、温州、衢州的SO2排放年总控制量,在温州和衢州得到不同于A值法的结果。   相似文献   
494.
Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha−1 yr−1) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range.  相似文献   
495.
It is known that fugitive dust can cause human health and environmental problems, alone or in combination with other air pollutants. These problems are referred to as ‘external costs’ that have been traditionally ignored. However, there is a growing interest towards quantifying externalities to assist policy and decision-making. With this in mind, the present study aimed at discussing the environmental regulations that deal with fugitive dust, the impact of fugitive dust on human health and global climate system, and the available methods for calculating fugitive dust externalities. The damage cost associated with human health and global environmental problems was predicted based on the environmental strategy priority model. The damage cost estimated by the model ranged from 40 to 374 EUR/kg of emitted fugitive dust with a mean value of 120 EUR/kg of emitted fugitive dust. It was also found that PM2.5 and PM10 have contributed to about 60% and 36% of the estimated damage cost, respectively. The remaining 4% was attributed to both nitrate and sulfate aerosols.  相似文献   
496.
A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM10 and PM2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October-December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.  相似文献   
497.
通过在2012年5月-2013年4月1个周期年内,对修复基地和对照点每月大气降尘中铅、镉、砷沉降量的监测,结果表明:修复基地大气降尘中铅、镉、砷含量明显较对照点高,年总沉降量分别是对照点的17.6倍、16.3倍和14.1倍,表明铅冶炼企业对基地大气降尘中铅、镉、砷含量影响显著;大气降尘中铅、镉、砷沉降量受位置和时间影响较大,在相距不到100 m的测点间,沉降量相差1倍以上,冬季主导风明显、地面植被少、二次扬尘大,使处于铅冶炼企业下风向的基地降尘中铅、镉、砷沉降量较大。沉降量时空不均匀与土壤污染不均匀现状一致,也验证了铅冶炼企业是基地大气和土壤重金属污染的主要来源。以降尘缸模拟土壤进行测算,结果表明大气降尘中镉对土壤污染速度最快,风险最大。  相似文献   
498.
基于环境库兹涅茨曲线特征的桂林市大气环境状况研究   总被引:1,自引:0,他引:1  
根据2006年-2012年桂林市经济发展主要指标和大气环境污染指标的统计资料,分析了该市人均 GDP 与SO2、NO x、烟(粉)尘排放量及 PM10质量浓度和 API优良率等大气环境指标的相关关系,建立了经济发展与大气环境指标之间的模拟曲线。模拟结果表明,桂林市处于工业时期,随着人均GDP增加,SO2和烟(粉)尘排放得到了一定程度的缓解,而NO x 和 PM10排放从长期看还处于上升趋势。建议改善能源结构,调整产业结构和工业布局,制定财税激励政策,开展环境综合整治,加大机动车排污防治力度,进一步控制大气污染。  相似文献   
499.
石家庄市大气颗粒物中水溶性无机离子污染特征研究   总被引:3,自引:0,他引:3  
用超声萃取-离子色谱法分析了石家庄市大气颗粒物中8种水溶性无机离子。结果表明,NO3-、SO2-4、NH4+及 Ca2+为主要组分;各个离子的质量浓度均有季节及空间变化差异;不同粒径颗粒物中 SO2-4和 NO3-相关性均很好,NH4+与 SO2-4、NO3-在细颗粒物中具有良好的相关性,Ca2+在粗粒子中与 NO3-和 SO2-4的相关性也较好。SO2-4/NO3-质量比季节变化表明,春、夏季固定源与流动源对大气颗粒物贡献相当,秋季流动源贡献较大,冬季固定源贡献较大。PM2.5中SO2与SO2-4、NO2与 NO3-转化率表明,SO2-4、NO3-主要是由二次转化而来。  相似文献   
500.
上海地区大气二氧化硫污染的控制对策   总被引:2,自引:1,他引:2  
上海地区的能源结构以燃煤为主。针对上海的实际和未来的发展态势,为实现2000年全市二氧化硫排放总量不超过1995年水平的目标,就如何削减二氧化硫排放量提出了5个方面的对策建议,阐述了削减二氧化硫的基本技术政策要点和总体方案思路。  相似文献   
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