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991.
Vertical distribution of polycyclic aromatic hydrocarbons in atmospheric boundary layer of Beijing in winter 总被引:1,自引:0,他引:1
Shu Tao Yi Wang Shiming Wu Shuzheng Liu Han Dou Yanan Liu Chang Lang Fei Hu Baoshan Xing 《Atmospheric environment (Oxford, England : 1994)》2007,41(40):9594-9602
Air samples were collected using active samplers at various heights of 8, 15, 32, 47, 65, 80, 102, 120, 140, 160, 180, 200, 240, 280 and 320 m on a meteorological tower in an urban area of Beijing in two campaigns in winter 2006. Altitudinal distributions of polycyclic aromatic hydrocarbons (PAHs) in atmospheric boundary layer of Beijing in winter season were investigated. Meteorological conditions during the studied period were characterized by online measurements of four meteorological parameters as well as trajectory calculation. The mean total concentrations of 15 PAHs except naphthalene of gaseous and particulate phase were 667±450 and 331±144 ng m−3 in January and 61±19 and 29±6 ng m−3 in March, respectively. Domestic coal combustion and vehicle emission were the dominant PAH sources in winter. Although the composition profiles derived from the two campaigns were similar, the concentrations were different by one order of magnitude. The higher concentrations in January were partly caused by higher emission due to colder weather than March. Moreover, weak wind, passing through the city center before the sampling site, picked up more contaminants on the way and provided unfavorable dispersion condition in January. For both campaigns, PAH concentrations decreased with heights because of ground-level emission and unfavorable dispersion conditions in winter. The concentration ratio of PAHs in gas versus solid phases was temperature dependent and negatively correlated to their octanol–air partition coefficients. 相似文献
992.
993.
Chang TJ Kao HM Hsieh YF 《Journal of the Air & Waste Management Association (1995)》2007,57(2):179-189
An indoor size-dependent particulate matter (PM) transport approach is developed to investigate coarse PM (PM10), fine PM (PM2.5), and very fine PM (PM1) removal behaviors in a ventilated partitioned indoor environment. The approach adopts the Eulerian large eddy simulation of turbulent flow and the Lagrangian particle trajectory tracking to solve the continuous airflow phase and the discrete particle phase, respectively. Model verification, including sensitivity tests of grid resolution and particle numbers, is conducted by comparison with the full-size experiments conducted previously. Good agreement with the measured mass concentrations is found. Numerical scenario simulations of the effect of ventilation patterns on PM removal are performed by using three common ventilation patterns (piston displacement, mixing, and cross-flow displacement ventilation) with a measured indoor PM10 profile in the Taipei metropolis as the initial condition. The temporal variations of suspended PM10, PM2.5, and PM1 mass concentrations and particle removal mechanisms are discussed. The simulated results show that for all the of the three ventilation patterns, PM2.5 and PM1 are much more difficult to remove than PM10. From the purpose of health protection for indoor occupants, it is not enough to only use the PM10 level as the indoor PM index. Indoor PM2.5 and PM1 levels should be also considered. Cross-flow displacement ventilation is more effective to remove all PM10, PM2.5, and PM1 than the other ventilation patterns. Displacement ventilation would result in more escaped particles and less deposited particles than mixing ventilation. 相似文献
994.
Baek KH Kim HH Bae B Chang YY Lee IS 《Journal of environmental biology / Academy of Environmental Biology, India》2005,26(1):151-154
The herbaceous plant Echinochloa crusgalli var. frumentacea is highly resistant to a wide range of heavy metal concentrations. In this study we tested the phytoextraction capacity of E. crusgalli var. frumentacea. Specifically, we compared the effect of EDTA on lead (Pb) accumulation in two groups of plants: those sown in lead contaminated soil and those transplanted to the contaminated soil as seedlings. The result of the time development of the Pb concentrations in the plants in the seedling and seed groups shows that for the seedling group, the effect of adding EDTA to the Pb-contaminated soil was even more pronounced in the shoots than the roots, which showed Pb concentrations 32-fold higher. Compared to the seedling group, the Pb concentrations in the roots of plants in the seed group were approximately 5 times higher in controls and 2 to 10 times higher in the presence of EDTA. Collectively, these results might be considered that EDTA elevates the bioavailability of Pb in soil and this native species is particularly suited to use in Pb phytoextraction. 相似文献
995.
介绍了隆回县金银花资源培育和加工利用现状,综合分析了金银花的综合价值和发展前景,针对当前金银花产业发展中存在的经营方式落后、加工粗放、销售不畅等问题,提出了金银花产业发展的对策. 相似文献
996.
997.
简述了可接受风险水平的内涵及其发展历程,介绍了国外污染场地环境风险评价中可接受风险水平的选取。提出我国污染场地风险评价和修复治理应合理选取风险可接受水平数值,梳理现有修复治理工程修复目标值的制定过程,建立差异化的可接受风险水平标准体系。 相似文献
998.
Zhengyan Li Mark Gibson Chang Liu Hong Hu 《Environmental monitoring and assessment》2013,185(6):5221-5230
Nonylphenol is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This study aims to investigate the distribution and ecological risks of nonylphenol in the Daliao River Estuary, China. Nonylphenol, together with other phenolic endocrine disruptors (bisphenol A, 4-t-butylphenol, 4-t-octylphenol, and 2,4-dichlorophenol), was detected in surface water and sediment on three cruises in May 2009, June 2010, and August 2010, respectively. A large flooding occurred during our sampling campaign in August and its effect on nonylphenol concentrations and fluxes in the estuary was therefore evaluated. The results showed that nonylphenol with a concentration range between 83.6–777 ng l?1 and 1.5–456 ng?g?1 dw in surface water and sediment was the most abundant among the phenolic compounds, accounting for 59.1–81.0 and 79.9–92.1 % of the total phenolic concentration in surface water and sediment, respectively. The concentrations recorded in May and June were comparable, whereas those in August were considerably higher, mainly due to the flush of flooding. The flooding also caused a 50 times increase in nonylphenol flux from the estuary into the adjacent Bohai Sea. Nonylphenol concentrations in the estuary have exceeded the threshold level of undesirable effects with a potential risk of harm to local species, especially benthic organisms. 相似文献
999.
It is significant to design best management practices (BMPs) and determine the proper BMPs placement for the purpose that
can not only satisfy the water quantity and water quality standard, but also lower the total cost of BMPs. The spatial rainfall
variability can have much effect on its relative runoff and non-point source pollution (NPSP). Meantime, the optimal design
and placement of BMPs would be different as well. The objective of this study was to discuss the relationship between the
spatial variability of rainfall and the optimal BMPs placements. Three synthetic rainfall storms with varied spatial distributions,
including uniform rainfall, downstream rainfall and upstream rainfall, were designed. WinVAST model was applied to predict
runoff and NPSP. Additionally, detention pond and swale were selected for being structural BMPs. Scatter search was applied
to find the optimal BMPs placement. The results show that mostly the total cost of BMPs is higher in downstream rainfall than
in upstream rainfall or uniform rainfall. Moreover, the cost of detention pond is much higher than swale. Thus, even though
detention pond has larger efficiency for lowering peak flow and pollutant exports, it is not always the determined set in
each subbasin. 相似文献
1000.
Role of Geographic Information System (GIS) in Watershed Simulation By Winvast Model 总被引:2,自引:0,他引:2
The uncertainty of modeling input will increase the simulation error, and this situation always happens in a model without user-friendly interface. WinVAST model, developed by the University of Virginia in 2003, treats an entire multi-catchment by a tree-view structure. Its extra computer programs can connect geographic information system (GIS). Model users can prepare all the necessary information in ArcGIS. Extracting information from GIS interface can not only decrease the inconvenience of data input, but also lower the uncertainty due to data preparation. The Daiyuku Creek and Qupoliao Creek in the Fei-tsui reservoir watershed in Northern Taiwan provided the setting for the case study reported herein. The required information, including slope, stream length, subbasin area, soil type and land-use condition, for WinVAST model should be prepared in a Microsoft Access database, which is the project file of WinVAST with extension mdb. In ArcGIS interface, when the soil layer, land-use layer, and Digital Elevation Model (DEM) map are prepared, all the watershed information can be created as well. This study compared the simulation results from automatically generated input and manual input. The results show that the relative simulation error resulting from the rough process of data input can be around 30% in runoff simulation, and even reach 70% in non-point source pollution (NPSP) simulation. It could conclude that GIS technology is significant for predicting watershed responses by WinVAST model, because it can efficiently reduce the uncertainty induced by input errors. 相似文献