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531.
Determining the equilibrium partitioning coefficients of volatile organic compounds at an air-water interface 总被引:1,自引:0,他引:1
The single equilibration technique (SET) was adopted to determine the partitioning coefficients (pc) at an air-water interface for volatile organic compounds (VOCs), including ethanol, iso-propanol (IPA), iso-butanol (IBA), methyl ethyl ketone (MEK) and toluene, all extensively used in industrial processes. Standard SET procedures were established. The liquid concentrations (CL) of tested VOCs ranged from 10 to 125 mg l(-1) for alcohols and MEK, and from 0.5 to 20 mg l(-1) for toluene. The temperatures (Tw) of aqueous VOC solutions were maintained at 27, 32, 38 and 42 degrees C to determine the gaseous concentrations at equilibrium (Cg*) and pc of VOCs, using the formula pc=(Cg*/CL). Results reveal that the pc values of all tested components increase slowly with Tw given a constant CL, and that the pc of alcohols and MEK fall as CL increases at a constant Tw. In contrast, the pc of toluene is not significantly impacted by a variation in CL at a constant Tw. However, the effect of CL concentration has seldom been discussed. The heats of liquid and gaseous phase transfer (DeltaHtr) of VOC, and the highly linear regression (with squared correlation coefficients, R2, from 0.901 to 0.999) between lnCg* and Tw(-1) are also evaluated. The experimental results and the VOC mass transfer characteristics are helpful for evaluating the emission of VOC from the water surface of wastewater treatment facilities. 相似文献
532.
Sensitivity analysis of ground-level ozone concentration to emission changes in two urban regions of southeast Texas 总被引:1,自引:0,他引:1
Lin CJ Ho TC Chu HW Yang H Chandru S Krishnarajanagar N Chiou P Hopper JR 《Journal of environmental management》2005,75(4):315-323
Air pollutant emission is one of the predominant factors affecting urban air quality such as ground-level ozone formation. This paper assesses the impact of changing emission inventory scenarios, based on combinations of point, mobile, area/non-road and biogenic sources, on the tropospheric ozone concentration in two southeast Texas urban areas, i.e. Houston-Galveston and Beaumont-Port Arthur, during the rapid ozone formation event (ROFE) on August 25, 2000. The EPA's Community Multiscale Air Quality (CMAQ) modeling system with 1999 national emission inventory (NEI99) estimates and updated SAPRC99 chemical mechanism are used in the sensitivity analysis for twelve different emission scenarios. Based on model results, it is found that the point source emission of NOx and VOC contributes the greatest ozone peak in the ROFE. Removing Texas point sources of VOC and NOx emission from the inventory results in a reduction in peak O3 concentration by 128 and 70 ppbv in Houston urban area, respectively. Similar but less drastic impact from point source is also observed in the Beaumont-Port Arthur area. The effect on peak ozone concentration due to mobile, area and non-road sources emissions are less significant compared to that of point source emission. Reducing VOC emission appears to be more effective than reducing NOx emission in lowering peak O3 concentration in the studied region. Although biogenic emission can contribute up to 37 ppbv of peak ozone level over a large area, the affected area is away from the urban region of concern, and should not be the main cause for O3 non-attainment in the two urban areas. Removing CO emission from mobile sources does not lead to significant reduction (< 1 ppbv) in ozone concentrations. The modeled data also show that the transport of O3 precursors from adjacent states can cause a significant ozone plume near Beaumont due to its proximity to the state border based on the conditions during the August 25, 2000 O3 episode. 相似文献
533.
Jan‐Tai Kuo Wen‐Cheng Liu Ruey‐Tyng Lin Wu‐Seng Lung Ming‐Der Yang Chou‐Ping Yang Show‐Chyuan Chu 《Journal of the American Water Resources Association》2003,39(3):671-687
ABSTRACT: Field data collected from the Feitsui Reservoir in Taiwan indicate that the water is at a stage between mesotrophic and eutrophic. Recent measurements such as total phosphorus, chlorophyll a and Secchi depth levels suggest that the water quality has been declining. A two‐dimensional, laterally averaged, finite difference hydrodynamic and water quality model was used to simulate the water quality in the Feitsui Reservoir in an effort to determine sound water quality management strategies. The model was calibrated and verified using data collected in 1996 and 1997. The calibrated model was used to simulate algal biomass (in terms of chlorophyll a) levels under various wasteload reduction scenarios. Model results show that 50 percent reduction of the total phosphorus load will improve the existing water quality, shifting the trophic status from eutrophic/mesotrophic to oligotrophic. The modeling effort has yielded valuable information that can be used by decision makers for the evaluation of different management strategies of reducing watershed nutrient loads. 相似文献
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535.
环境执法是将环境法规中抽象的权利义务变成环境法中具体的权利义务的过程.环境执法是中国环境法制建设的一个重要组成部分.相关国家环保行政职能部门在行使行政权力时,享有很大的自由裁量权,他们能否合法有效地行使好行政权力,直接关系到国家的环保事业和发展.针对当前中国环境执法的现状及环境依法行政的重要意义,以期为政府制定相关环境执法政策、措施提供科学的决策依据和建议,提出了几点环境依法执法的构思:建立系统的、严谨的环境执法理论,树立崭新的执法理念,运用崭新的执法方式,严格依据法定程序办事,健全依法行政责任制和监督机制,推行政务公开,创建公正有效的执法环境. 相似文献
536.
根据上海市新一轮“环境保护和建设三年行动计划”(2006-2008年)提出的未来3年全市将有11家电厂的35台共约650.8万kW燃煤发电机组实施烟气脱硫的目标,结合上海市实际,建立相关假定条件,并考虑SO2减排的作用及脱硫产物的利用等方面因素,从经济、环境等角度对上海市650.8万kw燃煤发电机组实施湿法烟气脱硫的成本、效益进行了综合分析。结果显示,燃煤电厂烟气脱硫的固定资产投资和运行费用均较大,而脱硫产生的直接经济效益相对较小,其效益更多地体现在无法直接以货币形式衡量的环境效益、社会效益上。 相似文献
537.
基于区域大气环境模拟系统RegAEMS开发了大气污染物来源解析模块APSA,以京津冀及周边"2+26"城市为研究对象,模拟2017年12月26日~2018年1月2日该地区一次PM2.5重污染过程,对PM2.5进行区域和行业来源解析.结果表明:本次污染持续时间长、影响范围广、污染程度重,"2+26"城市PM2.5小时最大值为201~507μg/m3,RegAEMS可较好模拟出PM2.5时空分布;区域来源解析表现为外围区域对"2+26"边界城市影响较大,贡献为15.3%~57.5%,"2+26"中部城市受外围区域影响较小,贡献为0.3%~8.4%,区域传输特征明显,受近地面风场影响较大;行业来源表现为区域内生活源、工业源贡献较大,分别为26.6%~45.8%、16.4%~37.8%,交通源占比13.0%~35.9%.本文研究表明RegAEMS可以实现重污染过程PM2.5的数值模拟和来源解析,在大气污染精准管控方面具有较好应用前景. 相似文献
538.
浅谈水面溢油污染防治技术及其应用 总被引:4,自引:0,他引:4
楚海明 《石油化工环境保护》2004,27(1):16-17
指出水面溢油污染的产生及危害,并提出溢油污染的防治技术和应用。 相似文献
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540.