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631.
Trapping and decomposing of color compounds from recycled water by TiO2 coated activated carbon 总被引:1,自引:0,他引:1
Five types of commercially available activated carbons (ACs) were coated with TiO2 nanoparticles prepared using a sol–gel method. Color and trace organics remaining in the actual treated effluent were adsorbed by TiO2 coated ACs. The absorbed organic compounds were then decomposed using a photocatalytic process, and the ACs were regenerated for reuse. The efficiency of the process was assessed by the characterization of true color and A254 (the organics absorption at the wavelength of 254 nm) at the beginning and the end of the experiment. The effects of UV light source, UV irradiation time, hydrogen peroxide and ultrasound on the efficiency of photocatalytic regeneration were also investigated. Significant differences in the efficiency were observed between uncoated ACs and TiO2 coated samples. Among the 5 types of ACs tested, AC-3, AC-4 and their coated ones achieved better efficiency in color and A254 removal, with around 90% or more color and A254 being removed within 1 h of treatment. The data obtained in this study also demonstrated that the photocatalytic process was effective for decomposing the adsorbed compounds and regenerating the spent TiO2/AC-3. Finally, it was found that this regeneration process could be greatly enhanced with the assistance of H2O2 and ultrasound by reducing the required regeneration time. 相似文献
632.
冬季沈阳市典型源排放PM_(10)浓度分布模拟分析 总被引:2,自引:0,他引:2
选取沈阳市7个典型的大气污染源2006年12月~2007年2月的PM10排放浓度资料,利用CALPUFF对PM10浓度月平均分布做模拟分析。模拟结果分析表明:冬季月平均PM10浓度分布的范围与风场、地形有直接的关系。地势平坦、风速大时,污染物扩散范围大,污染物浓度小;地势不平、风速小时,污染物扩散范围小,污染物浓度大。1月份是沈阳市冬季月平均大气污染最严重的月份,污染物分布主要集中在市区的北部、东部和南部地区,东部地区大气污染最为严重。 相似文献
633.
In light of the practical need for research to inform policy in Beijing,this study evaluates the economic cost of the impact of PM10 pollution in Beijing from 2001 to 2006,taking health as the main impact,and mortality as the main outcome.Based on the literature review,this study adopts relatively conservative parameters as the basis for calculating the health impacts.It concludes that nearly 30% of mortality among registered residents above age 30 in Beijing can be attributed to PM10 pollution,and that the economic cost equals 0.8%-1.2% of the city's GDP over the same period.This is lower than the results of previous studies,but still high enough to warrant a commitment to solve the city's air pollution problem. 相似文献
634.
635.
以20台沸腾炉(功率小于等于60 MW)的燃料特性分析数据和大气污染物的排放实测数据为基础,利用统计分析方法,研究了燃烧过程中排放的颗粒物(PM)、SO_2和NO_x初始排放浓度的影响因素,分析了沸腾炉PM、SO_2和NO_x排放现状,探讨了我国中小型沸腾炉PM、SO_2和NO_x排放管理控制的潜力和可行性.实验结果表明:在锅炉运行负荷大于等于80%的条件下,中小型沸腾炉PM的初始排放浓度基本上不受锅炉出力、过量空气系数和燃煤灰分含量的影响;燃煤的硫含量越高,SO_2初始排放浓度越高;过量空气系数越大,燃煤挥发分越低,NO_x初始排放浓度越高. 相似文献
636.
West Nile virus (Flaviviridae: Flavivirus) is a serious infectious disease that recently spread across the North America continent. A spatial analysis tool was developed
on the ArcMap 9.x platform to estimate potential West Nile virus activity using a spatially explicit degree-day model. The
model identifies when the virus Extrinsic Incubation Period (EIP) is completed within the vector longevity during mid-summer
months. The EIP is treated as a threshold indicator of the potential for virus emergence and activity. Comparing the number
of West Nile virus cases in Wyoming reported from 2003 to 2005 with model results, actual cases and predicted events of West
Nile virus activity match relatively well. The model represents a useful method for estimating potential West Nile virus activity
in a large spatial scale. 相似文献
637.
Yi Zhang Lin Wu Chao Zou Boyu Jing Xiaoyu Li Tim Barlow Turpin Kevin Michel André Yao Liu Peipei Ren Gongdong Wang Hongjun Mao 《Environmental Modeling and Assessment》2017,22(5):445-458
This paper reports on the development and application of an urban high temporal-spatial resolution vehicle emission inventory model and decision support system based on the current situation in China and actual vehicle emission control requirements. The system incorporates a user-friendly modular architecture that integrates a vehicle emission model and a decision support platform and includes scenario analysis and visualisation capabilities. A bottom-up approach based on localised emission factors and actual on-road driving condition has been adopted to develop the system. As a case study of application and evaluation, an emission reduction effect analysis of the supposed low-emission zone (LEZ) policy in Beijing (2012) was conducted. According to the simulated results in the forms of tables, histograms and grid maps, the establishment of this LEZ had a definite effect on the emission reduction of various types of air pollutants, especially carbon monoxide and hydrocarbon. In the system, the simulation methodology for identifying environmental benefits brought by the LEZ policy could be used to assess other similar environmental policies. Through flexible modification of configuration values or input data variables, the efficacy of separate or joint policies could be quantifiably evaluated and graphically displayed. 相似文献
638.
Geostatistical models play an important role in spatial data analysis, in which model selection is inevitable. Model selection methods, such as AIC and BIC, are popular for selecting appropriate models. In recent years, some model averaging methods, such as smoothed AIC and smoothed BIC, are also applied to spatial data models. However, the corresponding averaging estimators are outperformed by optimal model averaging estimators (Hansen in Econometrica 75:1175–1189, 2007) for the ordinary linear models. Therefore, this paper focuses on the optimal model averaging method for geostatistical models. We propose a weight choice criterion for the model averaging estimator on the basis of the generalized degrees of freedom and data perturbation technique. We further theoretically prove the resultant estimator is asymptotically optimal in terms of the mean squared error, and numerically demonstrate its satisfactory performance. Finally, the proposed method is applied to a mercury data set. 相似文献
639.
Organisms are typically exposed to mixtures of chemicals over long periods of time; thus, chronic mixture toxicity analysis is the best way to perform risk assessment in regards to organisms. However, most studies focus on the acute mixture toxicity. To investigate the difference between chronic mixture toxicity and acute mixture toxicity, Photobacterium phosphoreum were exposed to chronic (24 h exposure) and acute (15 min exposure) toxicity of single sulfonamide (SA) and their potentiator (trimethoprim, TMP), both individually and mixtures (SA with TMP). A comparison of chronic vs. acute mixture toxicity revealed the presence of an interesting phenomenon, that is, that the joint effects vary with the duration of exposure; the acute mixture toxicity was antagonistic, whereas the chronic mixture toxicity was synergistic. Based on the approach of Quantitative Structure Activity Relationships (QSARs) and molecular docking, this phenomenon was proved to be caused by the presence of two points of dissimilarity between the acute and chronic mixture toxicity mechanism: (1) the receptor protein of SAs in acute toxicity was Luc, while in chronic toxicity it was Dhps, and (2) there is a difference between actual concentration of binding-Luc in acute toxicity and individual binding-Dhps in chronic toxicity. This deep insight into the difference between chronic and acute mixture toxicity will benefit environmental science, medical science, and other disciplines. The existence of these differences poses a challenge for the assessment of routine combinations in medicine, risk assessment, and mixture pollutant control, in which, previously, only a synergistic effect has been observed between SA and their potentiator. 相似文献
640.