排序方式: 共有123条查询结果,搜索用时 812 毫秒
91.
Lin ZENG Xin DONG Siyu ZENG Tianzhu ZHANG Jing LI Jining CHEN 《Frontiers of Environmental Science & Engineering》2015,9(4):712
China has developed more than 20 water pollution control plans for river basins (RBWPs) since 1996. However, the implementation has generally lagged. This paper proposes a three-step, post-evaluation methodology to analyze the implementation result of a RBWP and its influential factors. First, a multi-attribute evaluation method based on an index system is established to score the enforcement results of a RBWP. Indicators measure how well a RBWP has achieved its objectives, which include water quality compliance, pollution load control, project construction, financial inputs, and related management requirements. Second, an interpretive structural model is used to detect the significant factors that affect RBWP implementation. This model can effectively analyze the cause-effect chain and hierarchical relationship among variables. Five groups of factors were identified, namely, plan preparation, water resource endowment, policy, institution, and management. Both qualitative and quantitative methods are employed in the third step to evaluate the extent to which these factors have influenced the execution result of a RBWP, including pre-post contrast, scenario analysis, and correlation analysis. This research then post-evaluated the implementation of the Huai River Basin water pollution control plans (H-RBWPs) over a period of 10 years as a case study. Results showed that the implementation of the H-RBWPs was unsatisfactory during 2001–2005, although it improved during 2006–2010. The poor execution of these plans was partially caused by the underestimation of regional economic development in combination with ineffective industrial structure adjustment policies. Therefore, this case study demonstrates the feasibility and flexibility of the proposed post-evaluation methodology. 相似文献
92.
Shuai MA Siyu ZENG Xin DONG Jining CHEN Gustaf OLSSON 《Frontiers of Environmental Science & Engineering》2015,9(4):694
Full-scale experiments have been carried out to adapt the activated sludge model ASM2d to include the influence of metal dosage (Fe3+ and Al3+) for phosphorus removal. Phosphorus removal rates, nitrification rates, as well as pH and sludge settling performance, were evaluated as functions of the metal dosages. Furthermore, models relating certain parameters to the dosage of chemicals have been derived. Corresponding parameters in the ASM2d and the secondary settler models, included in the Benchmark Simulation Model No 1 (BSM1), have been modified to take the metal influence into consideration. Based on the effluent limits and penalty policy of China, an equivalent evaluation method was derived for the total cost assessment. A large number of 300-day steady-state and 14-day open-loop dynamic simulations were performed to demonstrate the difference in behavior between the original and the modified BSM1. The results show that 1) both in low and high mole concentrations, Fe3+ addition results in a higher phosphorus removal rate than Al3+; 2) the sludge settling velocity will increase due to the metal addition; 3) the respiration rate of the activated sludge is decreased more by the dosage of Al3+ than Fe3+; 4) the inhibition of Al3+ on the nitrification rate is stronger than that of Fe3+; 5) the total operating cost will reach the minimum point for smaller dosages of Fe3+, but always increase with Al3+ addition. 相似文献
93.
多环芳烃(PAHs)在环境中的光降解动力学受环境介质吸光组分的影响.为揭示介质吸光组分对PAHs光降解影响的内在机制,以吸光很弱的甲醇和吸光较强的丙酮和二甲基亚砜(DMSO)为模拟环境介质,考察不同吸光性溶剂介质对3种PAHs(菲、芘和苯并[a]芘)光解的影响;并采用密度泛函理论(DFT)计算,分析了溶剂分子光敏化能量/电子转移反应对PAHs光解的影响机制.结果表明,激发态的丙酮分子抑制了菲和芘的光解,而加快了苯并[a]芘的光解;激发态的DMSO分子抑制了菲的光解,促进了芘和苯并[a]芘的光解.过滤掉DMSO所吸收的部分光谱频段后,PAHs在DMSO中的光解速率与甲醇中的接近.DFT计算表明,激发态的丙酮或DMSO主要作为电子受体与PAHs发生光敏化电子转移反应,是影响PAHs光解的内在原因. 相似文献
94.
Shuai MA Siyu ZENG Xin DONG Jining CHEN Gustaf OLSSON 《Frontiers of Environmental Science & Engineering》2014,8(1):128-136
The prediction of the influent load is of great importance for the improvement of the control system to a large wastewater treatment plant. A systematic data analysis method is presented in this paper in order to estimate and predict the periodicity of the influent flow rate and ammonia (NH3) concentrations: 1) data filtering using wavelet decomposition and reconstruction; 2) typical cycle identification using power spectrum density analysis; 3) fitting and prediction model establishment based on an autoregressive model. To give meaningful information for feedforward control systems, predictions in different time scales are tested to compare the corresponding predicting accuracy. Considering the influence of the rainfalls, a linear fitting model is derived to estimate the relationship between flow rate trend and rain events. Measurements used to support coefficient fitting and model testing are acquired from two municipal wastewater treatment plants in China. The results show that 1) for both of the two plants, the periodicity affects the flow rate and NH3 concentrations in different cycles (especially cycles longer than 1 day); 2) when the flow rate and NH3 concentrations present an obvious periodicity, the decreasing of prediction accuracy is not distinct with increasing of the prediction time scales; 3) the periodicity influence is larger than rainfalls; 4) the rainfalls will make the periodicity of flow rate less obvious in intensive rainy periods. 相似文献
95.
为从根本上解决隧道内空气污染问题,达到运营节能的目的 ,利用Fluent软件建立数值模拟模型,通过分析直线隧道内污染物分布规律,确定吊顶式净化通风系统设置位置及净化范围,同时建立吊顶式净化通风系统隧道模型,对其纵向布置方案进行优化研究.结果 表明:隧道内CO浓度基本呈线性分布,在距隧道入口1300 in位置,需布置吊顶... 相似文献
96.
罗丹明6G共振散射光谱法测定水中痕量六价铬 总被引:2,自引:0,他引:2
在 0 .0 4mol/L H2 SO4 和 8.0× 10 - 4mol/L KI介质中 ,罗丹明 6G ( Rh G)在 5 80 nm处有 1个同步荧光峰。当有 Cr( )存在时 ,Cr( )与过量的 I-反应生成 I- 3,I- 3与 Rh G形成缔合微粒 ,在 32 0、40 0、5 95 nm处产生 3个共振散射 ( RS)峰 ;而在 5 80nm处荧光峰猝灭。六价铬浓度在 1.0× 10 - 7~ 2 0× 10 - 7mol/L范围内与 40 0 nm波长处的共振散射光强度成线性关系。据此建立了测定水中六价铬的共振散射光谱分析法。光谱研究结果表明 ,( Rh G-I3) n缔合微粒和界面的形成是导致体系 RS增强的根本原因。 相似文献
97.
脆弱生态区类型划分及其脆弱特征分析 总被引:7,自引:0,他引:7
本文应用聚类分析方法,根据全国各县市耕地面积等26项指标的有关数据,对我国生态区进行了类型划分,还分别以环境资源因子、经济发展水平因子、经济技术替代能力因子、域外支持能力因子以及社会发展水平因子等5类因子为聚类变量,对我国脆弱生态区进行了类型划分,并对脆弱特征进行了分析。 相似文献
98.
Tongyao Ju Siyu Han Fanzhi Meng Li Lin Jinglin Li Kailun Chen Jianguo Jiang 《Frontiers of Environmental Science & Engineering》2023,17(9):112
99.
AbstractCooking of foods and the burning of biomass and fossil fuels in stoves are the main sources of cooking fumes, with carbon black and polycyclic aromatic hydrocarbons as main components. The toxicity of carbon black and polycyclic aromatic hydrocarbons has been well studied individually, but the combined toxicity is much less understood. Carbon black can adsorb benzo(a)pyrene to form a complex which displays an altered physical form which in this study has been constructed to simulate particles in the cooking fumes and explore the combined toxic effect on rat alveolar macrophages. The complex-induced cell apoptosis and blocked cell autophagy flux compared with both individually. The mechanism of toxicity may be by intracellular reactive oxygen species generation, impairing the mitochondrial membrane potential and activating apoptosis signaling pathways. 相似文献
100.
Epigenetic change is a key factor for esophageal cancer progression. This study shows that upon exposure of primary cultures of human esophageal epithelial cells obtained from people of the Kazakh nationality in China to N-methyl-N′-nitro-N-nitrosoguanidine at concentrations of 0.75, 1.50, and 3.00 mg/L, (1) cell proliferation was inhibited, the percentages of cells in the G0 and G1 phases declined, and those in the S and G2 + M phases increased at all concentrations, while apoptosis rates increased at medium and high concentrations; (2) the content of DNA-methyltransferases 3a and 3b and the activities of DNA-methyltransferase 1 and DNA-methyltransferase 3a increased at all concentrations while the content of DNA-methyltransferase 1 and the activity of DNA-methyltransferase 3b were increased only at the high concentration; (3) messenger RNA and protein levels of DNA-methyltransferases 1, 3a, and 3b were increased at all concentrations. Obviously, N-methyl-N′-nitro-N-nitrosoguanidine in the low mg/L range can inhibit the proliferation of normal Kazakh esophageal epithelial cells, can cause cell cycle arrest in the S and G2 + M phases, promote apoptosis, and increase the activities of DNA-methyltransferases 1, 3a, and 3b. 相似文献