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391.
As part of a comprehensive environmental management system, many countries establish emission control targets for mass emissions of a pollutant. Such targets are often the key objective of an environmental policy, such as an emission trading program. In China, however, it is more than just an objective of one particular policy; it has become a concept that has influenced many national environmental policies and activities. The objective of this article is to review the implementation of the total emission c... 相似文献
392.
As an important traditional labor-intensive industry of both India and China, the cocoon silk industry has long made great contributions to the ecological environment protection, rural economic development and the increase in export income of both countries. India is not only a very important cocoon silk trading partner, but an important production competitor of China. In recent years, there has been a large increase in the production and trade of the cocoon silk between China and India; however, China relies heavily on Indian market, which leads to a tendency of further deterioration in the silk trade environment between both countries. The present article makes an empirical study of the cocoon silk resources of the two countries and the scale, product mix and market structure of China-Indian silk trade from 2001 to 2007. Overall silk trading volumes from China to India and market concentration rate are on the increase because of the superiority of Chinese cocoon silk production over that of India. Owing to scattered market share and export that mainly focused on raw materials product, there has been a phenomenon of price reduction and quantity increase. India carries out fierce competition with China in the international market and even imposes antidumping sanction on Chinese silk, which are key factors restricting further increase between China-India trade. Based on the abovementioned facts, the authors aim to put forward suggestions for steadily developing the production and trade of China's silk. 相似文献
393.
394.
Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport 总被引:1,自引:0,他引:1
Feng Pan Ming Ye Jianting Zhu Yu-Shu Wu Bill X. Hu Zhongbo Yu 《Journal of contaminant hydrology》2009,103(3-4):194-205
This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport. 相似文献
395.
北京市春季大气颗粒物污染特性研究 总被引:3,自引:0,他引:3
为研究北京市春季大气颗粒物污染特性,2008年3月至2008年5月,对北京市西三环大气颗粒物进行采样分析.测定了总悬浮颗粒物(TSP)与可吸入颗粒物(PM10)的日平均质量浓度,使用扫描电子显微镜(SEM)观察大气颗粒物的微观形貌,并通过X射线能谱仪(EDX)对样品中的元素组成进行分析.结果表明,TSP和PM10日平均质量浓度以初春最高,春天次之,春夏交际最低;PM10/TSP以春夏交际最高,初春次之,春天最低;大气颗粒物形态有规则和不规则2类,以不规则形态居多,同时发现花粉颗粒存在.EDX分析表明,大气颗粒物所附着的重金属中Pb所占的质量分散最高,并且集中吸附在细粒子颗粒物上. 相似文献
396.
为了解决大庆油田现有核桃壳、石英砂过滤器反冲洗憋压、跑料和滤料再生困难等问题,在对原有过滤装置分析的基础上,根据反冲洗特性,对过滤器进行了改造,开发出低压稳流核桃壳过滤器和低压稳流石英砂过滤器。经现场测试,核桃壳过滤器反冲洗压力由原来的0.15~0.5 MPa降低到0.03~0.08 MPa,石英砂过滤器反冲洗压力由原来的0.27~0.46 MPa降低到0.17~0.20 MPa,且均能实现罐群水反冲洗。改造后核桃壳过滤器出水油平均含量13.4 mg/L,平均去除率为78.1%;出水悬浮物平均含量20.5 mg/L,平均去除率为55%。改造后石英砂过滤器出水油平均含量5 mg/L以下,平均去除率达到75%以上;出水悬浮物平均含量为9.8 mg/L,去除率达到80%以上。为了进一步提高过滤效果,在二级滤前投加絮凝剂形成微絮凝过滤工艺,出水悬浮物可达到3 mg/L,通过两级过滤达到特低渗透地层回注水标准。 相似文献
397.
398.
生活垃圾加载介质层填埋法对初期渗滤液污染抑制效果研究 总被引:1,自引:0,他引:1
以传统卫生填埋柱R2为对照,通过往生物反应器填埋柱R1内加载可渗透反应介质层1和2进行模拟试验,主要探讨了填埋柱R1垃圾渗滤液COD、总氮、氨氮及总磷的变化趋势,探索一种新型的加载介质层垃圾填埋处理方法。试验结果表明,填埋20周后, R1柱COD浓度基本维持在40 000~45 000 mg/L间,约为R2柱的20%~30%;第24周,R1柱总氮和氨氮分别为206.5 mg/L和167.3 mg/L,在16~24周内,R1总氮和氨氮分别约为R2的14.5%~17.5%和36.2%~43.6%;18周时,R1柱总磷达最大值1.704 mg/L,至第24周降为0.673 mg/L, 整个实验过程R1柱总磷约为R2的0.15%~0.56%。 相似文献
399.
400.
石油化工废水处理技术新进展 总被引:2,自引:1,他引:1
针对石油化工废水处理领域目前尚存在的问题,介绍了有关石油化工废水处理的各种方法,阐述了物理化学处理技术、生物处理技术、生物法与物理化学法组合技术等方面的研究进展,指出难生物降解废水的处理是继续研发的重点. 相似文献