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121.
Eugene Yee 《Environmental Fluid Mechanics》2009,9(4):389-407
The relationships between various normalized higher-order concentration moments in plumes dispersing in a built-up (urban)
environment have been investigated using a large concentration data set obtained in a boundary-layer water channel. This data
set consists of measurements of plume dispersion in a number of idealized obstacle arrays (e.g., cubical and non-cubical obstacles
in aligned and staggered arrangements with uniform, random and alternating heights). A remarkably robust feature of all the
concentration data was the observed collapse of the third- and fourth-order normalized concentration moments on the second-order
normalized concentration moment. The data are shown to collapse to a series of universal curves (independent of the geometry
of the obstacle array) and these curves were found to be identical to those observed previously for open-terrain plumes. The
results imply that the probability law of concentration in a plume dispersing in either a built-up environment or open terrain
has a universal form that can be specified by at most two independent parameters. The universal functions representing the
relationships between the normalized concentration moments were found to be well modeled (approximated) using a two-parameter
clipped-gamma probability law for the concentration. Finally, the clipped-gamma distribution was found to be in very good
conformance with the measured probability distribution of concentration for plumes dispersing in a built-up environment. 相似文献
122.
怠速条件下汽车排气污染物在排气尾流中扩散特性的实验研究 总被引:4,自引:0,他引:4
通过实验的方法对怠速条件下汽车排气污染物在排气尾流中的扩散特性进行了研究.测定了怠速条件下汽车排气尾流中的污染物体积分数及其分布,并比较分析了3种不同类型汽车的污染物排放体积分数及其变化.实验结果表明,怠速时汽车排气尾流中的污染物体积分数按照近似指数函数的趋势迅速降低到接近大气背景值;不同类型汽车排气尾流中的污染物体积分数的差别非常明显;排气方向对汽车排放污染物的扩散及其分布具有重要的影响.研究工作可以为怠速工况下汽车排气污染物对周围环境的影响评价提供更多的有用信息. 相似文献
123.
124.
南京市机动车排气监测与评价 总被引:2,自引:2,他引:0
刘继明 《环境监测管理与技术》2004,16(1):23-25
通过对南京市机动车排气污染物的年检监测,表明南京市的汽油车、柴油车、摩托车排气合格率总体呈上升趋势,2002年全市机动车排气监测总合格率为99.9%,比1993年上升了8.6个百分点;汽车尾气达标率也呈上升趋势,2002年达83.8%,比1993年上升了2.6个百分点。对机动车排气路检结果表明,CO超标的车辆占84.4%,CO、HC两项指标都超标的车辆占31.1%。对各类汽油助力车排气监测结果表明,二冲程汽油助力车尾气中CO、HC排放量要高于四冲程汽油助力车的排放量。对各类正三轮摩托车排气抽检结果表明,大部分四冲程正三轮摩托车尾气排放污染物能达标,且排气管无碳烟;二冲程正三轮摩托车尾气中HC值偏高,排气管碳烟明显。 相似文献
125.
阐述了化学合成类制药工业污染排放自行监测方案的编制依据,分析了化学合成制药的生产工艺与污染排放特征,在此基础上提出了自行监测方案的主要内容,以及监测点位、监测指标、监测频次设定的注意事项,并明确了特殊情况监测方案的设计原则及自行监测信息记录的相关内容。 相似文献
126.
Dawei Yu Jianxing Wang Libin Zheng Qianwen Sui Hui Zhong Meixue Cheng Yuansong Wei 《Frontiers of Environmental Science & Engineering》2020,14(6):101
127.
Composite samples of Australian farmed Yellowtail Kingfish (Seriola lalandi) (YTKF) (n = 27), Mulloway (Argyrosomus hololepidotus) (n = 6) and manufactured feed (n = 5) were analysed to benchmark levels of a broad range of residues and contaminants of potential public health and trade significance. A subset of these samples [YTKF (n = 5), Mulloway (n = 2) and feed (n = 5)] was analysed for dioxins and polychlorinated biphenyls (PCBs). The mean concentration of dioxins in YTKF was 0.6 pg TEQ g−1 (range 0.22-0.8) and in Mulloway was 0.16 pg TEQ g−1 (range 0.16-0.16). The mean concentration of dioxins and dioxin-like PCBs in YTKF was 2.6 pg TEQ g−1 (range 1.4-3.5), while Mulloway had a mean concentration of 0.67 pg TEQ g−1 (range 0.57-0.76). The mean concentration of PCBs in YTKF was 21 μg kg−1 (range 8.6-29) and in Mulloway was 5.4 μg kg−1 (mean 4.7-6). The mean concentration of dioxin-like PCBs in YTKF was 2.1 pg TEQ g−1 (range 1.2-2.8) and in Mulloway was 0.51 pg TEQ g−1 (range 0.41-0.61). The mean mercury concentration in YTKF was 0.03 mg kg−1 (range 0.02-0.05) and in Mulloway it was 0.02 mg kg−1 (range 0.02-0.04). There were no detectable levels of any pesticide or antimicrobial compounds in any sample of YTKF or Mulloway. Attention is drawn to technical differences in port of entry testing programs such as sampling strategies, portion tested, laboratory methodology, residue definitions and reporting conventions that exporters’ products may be subject to. All residues and contaminants were either undetectable or present at very low levels when judged against Australian, Japanese and European Union regulatory standards (where set). 相似文献
128.
湖泊水流运动和污染物的迁移路径对湖泊水质起着关键作用。采用水动力和粒子示踪耦合模型,并结合野外粒子示踪实验来调查鄱阳湖洪水季节空间水流运动和污染物迁移路径。模拟结果显示,流域五河点源入湖污染物和湖区空间面源分布污染物均会沿着不同方向迅速进入湖泊主河道,在快速水流推动下逐渐向北部湖区迁移,但部分污染物因东北部湖湾区存在顺时针方向环流而发生长时间滞留和富集。野外粒子示踪实验同样表明,东北部湖湾区污染物迁移路径随着该湖区水流运动表现得复杂多变,除了可以明显观察到顺时针方向的污染物运动,还可以发现污染物向湖岸边界和湖汊迁移,最终滞留在东北部湖湾区,而康山湖区污染物在快速水流推动下主要沿主河道向西北主湖区迁移,未发现污染物进入东北部湖湾区的迹象。鄱阳湖洪水季节水流运动和污染物迁移路径具有枯水期水流-污染物传输特性。模拟得出鄱阳湖洪水期的平均换水周期约89 d,表明其可能需要近3个月时间才能彻底完成一次换水。研究成果可为大型通江湖泊"江湖关系变化"研究提供参考,对保护"一湖清水"、保障长江中下游水环境安全具有重要现实意义。 相似文献
129.
Construction and demolition wastes (CDW) have increasingly serious problems in environmental, social, and economic realms. There is no coherent framework for utilization of these wastes which are disposed both legally and illegally. This harms the environment, contributes to the increase of energy consumption, and depletes finite landfills resources. The aim of this paper is to evaluate the impacts of two alternatives for the management of CDW, recycling and disposing. The evaluation is carried out through developing a dynamic model with aid STELLA software by conducting the following steps: (1) quantifying the total cost incurred to mitigate the impacts of CDW landfills and uncollected waste on the environment and human health; (2) quantifying the total avoided emissions and saved energy by recycling waste; (3) estimating total external cost saved by recycling waste and; (4) providing a decision support tool that helps in re-thinking about waste disposal. The proposed evaluation methodology allows activating the stringent regulations that restrict waste disposal and developing incentives to encourage constructors to recycle their wastes. The research findings show that recycling CDW leads to significant reductions in emissions, energy use, global warming potential (GWP), and conserves landfills space when compared to disposal of wastes in landfills. Furthermore, the cost of mitigating the impact of disposal is extremely high. Therefore, it is necessary to recycle construction and demolition wastes. 相似文献
130.
城市大气污染物总量控制最大排放量模型法及其应用 总被引:6,自引:0,他引:6
本文建立了城市大气污染物总量控制最大排放量模型.把该模型应用于广东省某市SO_2总量控制计算,结果表明。该模型的应用效果是较理想的.为城市大气污染物总量控制提供了一种有效的方法. 相似文献