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101.
将运筹学中“部分排序”的概念引入对污染物的环境影响比较评价中,以环境中常见的10种残留农药为应用实例,用Hasse图表示出比较评价的结果。和普遍排序技术相比,部分排序的评价结果简明直观、合理、可靠。Hasse图技术充分考虑了所要评价的各方面因素,避免了在普遍排序过程中由于确定评价模型中的权值而带来的主观因素的影响。 相似文献
102.
上海城市街道峡谷道路绿化模式研究 总被引:2,自引:0,他引:2
街道峡谷在上海城市中普遍存在,街道峡谷中污染气体的扩散受到屋顶风向、风速、高宽比、峡谷两侧建筑物的对称性、高度分布和街区形状等因素的影响。文章对适合于不同街道峡谷形式的、较为典型的道路绿化模式进行了研究。结果表明,上海城市街道峡谷中的道路绿化模式可归纳为:梯级递进式、斑块复合式、疏朗开敞式、模纹花镜式和独立行道树式5种。当街道峡谷与主导风垂直:(1)街道峡谷的W/H>5且为平行型峡谷时,绿化模式应采用梯级递进式或疏朗开敞式;(2)街道峡谷的W/H为0.6~5且为平行型峡谷时,绿化模式在迎风侧采用流朗开敞式、背风侧采用模纹花镜式,或者两侧都采用模纹花镜式;(3)街道峡谷的W/H<0.6且为平行型峡谷时,绿化模式应采用模纹花镜式或独立行道树式;(4)街道峡谷的W/H<0.6且为递升型峡谷时,绿化模式在迎风侧采用斑块复合式或模纹花镜式,背风侧采用模纹花镜式或独立行道树式;(5)街道峡谷的W/H<0.6且为递降型峡谷时,绿化模式可采用模纹花镜式或独立行道树式;当街道峡谷与主风向平行:宽、高比大的街道绿化模式应采用梯级递进式或斑块复合式,当街道峡谷的高度是宽度的倍数时,道路绿化宜采用疏朗开敞式或独立行道树式。 相似文献
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大气微生物粒子与飘尘粒子的关系 总被引:1,自引:0,他引:1
用ANDERSEN生物粒子采样器和光散射气溶胶粒子计数器,在北京西单对大气细菌、真菌和飘尘粒子的浓度、粒度分布及它们之间的关系进行了观测和研究。结果表明,大气细菌的粒度是负偏态分布,大气真菌是对数正态分布,飘尘是正偏态分布。大气细菌浓度与飘尘浓度的比值冬季大,为119538;夏季小,为24217;年平均比值为67517,>2.0μm的菌尘比值为1525387,2.0μm~8.2μm的菌尘比值为3318,>8.2μm的菌尘比值为394。大气真菌浓度与飘尘浓度的比值冬季大,为212770;夏季小,为65585;年平均比值为135344,<2.0μm的菌尘比值为952698,2.0μm~8.2μm的菌尘比值为5343,>8.2μm的菌尘比值为2632。 相似文献
105.
A study of the noise generated by hand-held pneumatic rock drills at 15 road works locations in Hong Kong was conducted in 1989. The locations of road construction works were identified over one week period. Sound pressure levels (SPL) and band frequency analysis were measured with the integrated sound level meter at the level of the operator's ears. The sound levels for all 15 operators exceeded the local statutory limit of 90 dBA. The average sound level was 107.4 dBA and the corresponding continuous equivalent level adjusted to 8 hours or L
eq (8h) was 104.8 dBA. The sound levels for the octave frequencies from 125 Hertz to 8000 Hertz were all in excess of 90 dBA. Estimates of the risk of developing hearing impairment for conversation speech among the operators were 18% and 42% after 5 and 10 years of exposure, respectively. Although there is adequate statutory control to restrict and reduce the hazards caused by noise at road construction works to the workers and to the public at large, no noise control measures were noted at the work sites and none of the operators used hearing protection. This situation was compounded by the short-term nature of road works and the high mobility of the operators. 相似文献
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108.
Yang Wang Wenjie Du Lianliang Chen Haoran Wang Ziyang Shan Zhengyang Zhou Wenwei Li 《环境科学学报(英文版)》2023,35(2):745-757
Air pollution is a major obstacle to future sustainability, and traffic pollution has become a large drag on the sustainable developments of future metropolises. Here, combined with the large volume of real-time monitoring data, we propose a deep learning model, iDeepAir, to predict surface-level PM2.5 concentration in Shanghai megacity and link with MEIC emission inventory creatively to decipher urban traffic impacts on air quality. Our model exhibits high-fidelity in reproducing pollutant concentrations and reduces the MAE from 25.355 µg/m3 to 12.283 µg/m3 compared with other models. And identifies the ranking of major factors, local meteorological conditions have become a nonnegligible factor. Layer-wise relevance propagation (LRP) is used here to enhance the interpretability of the model and we visualize and analyze the reasons for the different correlation between traffic density and PM2.5 concentration in various regions of Shanghai. Meanwhile, As the strict and effective industrial emission reduction measurements implementing in China, the contribution of urban traffic to PM2.5 formation calculated by combining MEIC emission inventory and LRP is gradually increasing from 18.03% in 2011 to 24.37% in 2017 in Shanghai, and the impact of traffic emissions would be ever-prominent in 2030 according to our prediction. We also infer that the promotion of vehicular electrification would achieve further alleviation of PM2.5 about 8.45% by 2030 gradually. These insights are of great significance to provide the decision-making basis for accurate and high-efficient traffic management and urban pollution control, and eventually benefit people's lives and high-quality sustainable developments of cities. 相似文献
109.
Surface air concentrations of 7Be at a number of stations in Oceania show a distinct annual cycle. We apply a sinusoidal model to describe this cycle. The results show that peak 7Be concentrations in surface air occur during early spring at tropical latitudes and during mid-to-late summer at middle latitudes. Comparison with available 90Sr surface air data for the southern hemisphere indicates that stratosphere-to-troposphere exchange is an active atmospheric process controlling the 7Be annual cycle throughout the Oceania region. Vertical transport of air within the troposphere also seems to influence the observed annual cycle. Seasonality in rainfall is not thought to control the annual cyclic behaviour of 7Be in surface air. 相似文献
110.
氢化物发生-原子荧光法同时测定污水中的砷和硒 总被引:7,自引:0,他引:7
用HNO3-HClO4消解液消解水样,断续流动进样,在KBH4-酸体系中,采用氢化物发生-原子荧光法同时测定污水中的砷和硒。在含浓盐酸2.0mL的介质中加入硫脲-抗坏血酸溶液5mL,在温度高于15℃时放置30min后,以15g/L KBH4溶液为还原剂,5%(体积分数)HCl为载流测定砷、硒荧光强度。在最佳实验条件下,砷、硒的相对标准偏差分别小于4%和2%,检出限分别为0.89μg/L和0.51μg/L,加标回收率分别为91.5%~101.2%和94.0%~100.5%。该方法精密度高、测定结果稳定,达到环境监测要求。 相似文献