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221.
中国不同地区发展水平存在较大的差异.面临的环境问题和可持续发展的优先领域也不同。因此.可持续发展评价与政策制定需要与区域发晨实际相结合。选取上海、德州和固原三个地区作为中国发达、发展中和欠发达地区的代表.选择可操作和可比性强的指标.基子压力-状态-响应模型.构建了环境可持续性趋势系数.对比不同发展水平地区环境发展的状态、趋势和存在的主要问题。得出以下结论:近20年来.虽然中国总体环境保护能力有了一定的提高.但污染物排放压力持续增长.环境质量普遍恶化的趋势没有得到根本改变;上海、德州和固原环境可持续性趋势系数分别为0.82、0.55和0.45.发达地区环境可持续性最强.发展中地区一般.欠发达地区量差;目前我国环境政策领域往往注重经济发展的“两极”:高度发达地区和欠发达地区,本文的研究结果表明。面积占全国67%、人口占全国40%的发展中地区环境问题最为突出。  相似文献   
222.
The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factors to elucidate the toxicity of As.The results showed low concentrations of As(O-1 mg/kg)stimulated seed germination and the growth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contents Of O2-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at high concentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE).As induced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.  相似文献   
223.
输变电工程建设的环保要求及其变化趋势分析   总被引:3,自引:3,他引:0  
从环境敏感区的保护、公众参与、土地占用、施工期环境影响、景观协调性等方面对输变电工程规划、设计和建设过程中的环保要求以及变化趋势进行了较为全面的分析,对输变电工程规划、选址、选线、施工阶段等环节提出环境保护方面的意见和建议.  相似文献   
224.
说明了污水处理厂自动控制系统的类型、特点与应用研究现状,介绍了自控系统在国内外污水处理厂的应用研究现状,分析了污水处理厂自控系统广泛应用的限制因素,并指出了今后污水处理厂自控系统的发展趋势。  相似文献   
225.
In the light of the historical substantial data (covering a 70-year period) collected in the Lower Jingjiang segment and aided by topological grey method, here we attempt to characterize the occurrence and future trend of flood calamities in the study area. Our findings indicate that overall the high-frequent flood disasters with middle to lower damage prevail at present. A series of dramatic flood waves will appear in the years of 2016, 2022, 2030and 2042, particularly a destructive flood will occur between 2041 and 2045 in the Lower Jingjiang reaches. Typical of sensitive response to flood hazards in close association with its special geographical location, the lower Jingjiang segment hereby can reflect the development trend of floods in the middle Yangtze reaches. According to the results, a good fitness was revealed between the prediction and practical values. This actually hints that the topological grey method is an effective mathematical means of resolving problems containing uncertainty and indetermination, thus providing valuable information for the flood prediction in the middle Yangtze catchment.  相似文献   
226.
ABSTRACT: Many studies of ground water pollution in general and nitrate contamination in particular have often relied on a one-time investigation, tracking of individual wells, or aggregate summaries. Studies of changes in spatial distribution of contaminants over time are lacking. This paper presents a method to compare spatial distributions for possible changes over time. The large-scale spatial distribution at a given time can be considered as a surface over the area (a trend surface). The changes in spatial distribution from period to period can be revealed by the differences in the shape and/or height of surfaces. If such a surface is described by a polynomial function, changes in surfaces can be detected by testing statistically for differences in their corresponding polynomial functions. This method was applied to nitrate concentration in a population of wells in an agricultural drainage basin in Iowa, sampled in three different years. For the period of 1981–1992, the large-scale spatial distribution of nitrate concentration did not show significant change in the shape of spatial surfaces; while the magnitude of nitrate concentration in the basin, or height of the computed surfaces showed significant fluctuations. The change in magnitude of nitrate concentration is closely related to climatic variations, especially in precipitation. The lack of change in the shape of spatial surfaces means that either the influence of land use/nitrogen management was overshadowed by climatic influence, or the changes in land use/management occurred in a random fashion.  相似文献   
227.
Mann-Kendall检验及其在河流悬沙浓度时间序列分析中的运用   总被引:1,自引:0,他引:1  
探讨了Mann-Kendall非参数秩次相关检验在时间序列分析方面的应用,并以云南省文山州盘龙河为例,把它运用到河流悬沙浓度时间序列的趋势分析和突变分析研究中。结果表明:①M-K检验同样适用于河流悬沙浓度的趋势与突变分析;②盘龙河自20世纪60年代初至90年代末河流悬沙浓度一直表现为波动上升趋势,1999年后有下降的迹象;③盘龙河的河流悬沙浓度自20世纪60年代以来存在着两个明显的突变点,其一在1973年,其二在1999年。  相似文献   
228.
Abstract: Coalbed methane (CBM) development raises serious environmental concerns. In response, concerted efforts have been made to collect chemistry, salinity, and sodicity data on CBM produced water. However, little information on changes of stream water quality resulting from directly and/or indirectly received CBM produced water is available in the literature. The objective of this study was to examine changes instream water quality, particularly sodicity and salinity, due to CBM development in the Powder River watershed, which is located in the Rocky Mountain Region and traverses the states of Wyoming and Montana. To this end, a retrospective analysis of water quality trends and patterns was conducted using data collected from as early as 1946 up to and including 2002 at four U.S. Geological Survey gauging stations along the Powder River. Trend analysis was conducted using linear regression and Seasonal Kendall tests, whereas, Tukey’s test for multiple comparisons was used to detect changes in the spatial pattern. The results indicated that the CBM development adversely affected the water quality in the Powder River. First, the development elevated the stream sodicity, as indicated by a significant increase trend of the sodium adsorption ratio. Second, the development tended to shrink the water quality differences among the three downstream stations but to widen the differences between these stations and the farthest upstream station. In contrast, the development had only a minor influence on stream salinity, as indicated by that the stream electrical conductivity exhibited either no trend or a marginally significant positive trend. Hence, the CBM development is likely an important factor that can be managed to lower the stream sodicity. The management may need to take into account that the effects of the CBM development were different from one location to another along the Powder River.  相似文献   
229.
This article makes an attempt to answer the three questions of why China is devoting its full effort to promoting a circular economy, what a circular economy is, and how to implement a circular economy in China. The evolutionary process of a circular economy in China, from introduction of the concept and the relevant actions of national decision making to demonstration of the system nationwide, has taken only around 6 years, with strong encouragement from politicians and the urgent need to cope with environmental pollution and a severe shortage of natural resources. The circular economy in China is now being actively implemented at three levels: enterprises, eco-industrial parks, and regions. The consolidated theoretical bases of ecology and economics have helped the circular economy to define its position as a new economic model to effectively resolve the problems of resources and the environment. In this regard, material flow management is naturally a unique planning and management method for implementation of a circular economy, and eco-efficiency is a good indicator to measure circular economic activities. Of particular significance has been initiation of the legislative process for the Circular Economy Law, which is among a number of initiatives developing core policies for a circular economy in China. Stringent enforcement of a set of policies for energy saving and pollution abatement nowadays in China will certainly create an enabling environment for the development of a circular economy.  相似文献   
230.
通过对云南省1981—2003年的交通事故统计数据的分析研究,给出了交通事故死亡人数的预测模型。通过与发达国家类似的交通事故历史数据的对比分析,给出以时间和机动车拥有量为自变量、交通事故死亡人数为因变量的简单预测模型,该模型对2004年的交通事故死亡人数的预测是准确的;同时采用该模型预测了云南省交通事故死亡人数的峰值及其年份。结论指出:基于目前的人、车、路和管理水平及发展趋势,云南省的交通事故死亡人数在2013—2018年之间将达到高峰,高峰时的交通事故死亡人数在5528~7369人之间。  相似文献   
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