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171.
富营养化水体底泥释磷的影响因素及其机理   总被引:4,自引:2,他引:4  
磷是湖泊富营养化的主要限制因子,在此综述了沉积物中磷的赋存形态,释放机理及其影响因素。内源磷的赋存形态主要分为铝磷、铁磷、钙磷及有机磷,磷释放受pH值、溶解氧、生物、温度、扰动等5种因素影响,对富营养水体内源磷释放的影响因素及其机理进行研究,可为富营养化水体的治理提供理论依据。  相似文献   
172.
对环境保护国际化给WTO规则的冲击进行了分析,并提出相关的对策。  相似文献   
173.
Double dividend hypothesis, golden rule and welfare distribution   总被引:3,自引:0,他引:3  
This paper analyzes the double dividend issues within the framework of overlapping generations models. We characterize the necessary conditions for obtaining a double dividend, i.e. an improvement of environmental and non-environmental welfare when the revenue from the pollution tax is recycled into a change in the labor tax rate. We show that, depending on the initial capital stock and on the intertemporal elasticity of substitution, conditions may be defined to simultaneously allow (i) the obtaining of a long-term double dividend, (ii) the economy to move closer to the modified golden rule and (iii) in the short term, an improvement in the welfare of the two present generations.  相似文献   
174.
三峡库区沿江堆存垃圾浸泡污染物COD溶出规律研究   总被引:1,自引:0,他引:1  
三峡库区沿江两岸堆存了大量的生活垃圾,随着三峡工程二期蓄水的I临近,二期水位以下的垃圾必须得到清理。为了科学有效的治理库区的生活垃圾,达到环境效益,社会效益和经济效益三者的最优结合,本文通过浸泡生活垃圾污染负荷浸出理论分析和动态冲刷实验研究,建立了理论模型和实验模型,并且对二者进行了对比分析。结果表明实验和理论模型能较好的反映垃圾污染物的溶出规律,将为三峡库区库底生活垃圾对水环境的影响预测和其清理提供基础和决策依据。  相似文献   
175.
线性溶剂化能相关方法应用及参数估算   总被引:1,自引:0,他引:1  
简要介绍了线性溶剂化能相关方法的原理,回顾了该方法在溶解度、辛醇/水分配系数和生物毒性预测中的成功应用,重点讨论了参数估算规则,以利于该方法进一步推广。  相似文献   
176.
Double Allee Effects and Extinction in the Island Fox   总被引:3,自引:0,他引:3  
Abstract:  An Allee effect (AE) occurs in populations when individuals suffer a decrease in fitness at low densities. If a fitness component is reduced (component AE), per capita population growth rates may decline as a consequence (demographic AE) and extinction risk is increased. The island fox ( Urocyon littoralis ) is endemic to six of the eight California Channel Islands. Population crashes have coincided with an increase in predation by Golden Eagles ( Aquila chrysaetos ). We propose that AEs could render fox populations more sensitive and may be a likely explanation for their sharp decline. We analyzed demographic data collected between 1988 and 2000 to test whether fox density (1) influences survival and reproductive rates; (2) interacts with eagle presence and affects fox fitness parameters; and (3) influences per capita fox population trends. A double component AE simultaneously influenced survival (of adults and pups) and proportion of breeding adult females. The adult survival AE was driven by predation by eagles. These component AEs led to a demographic AE. Multiple-component AEs, a predation-driven AE, and the simultaneous occurrence of both component and demographic AEs in a mammal are all previously unreported processes. Populations below 7 foxes/km2 could have suboptimal population growth rates due to the demographic AE, and AEs may have contributed to the dramatic declines in three fox populations. Because fox densities in critically endangered populations are well below this level, removing Golden Eagles appears necessary to prevent a predation-driven AE. Conservationists should also be aware of AEs when planning the release of captive foxes. More generally, our findings highlight the danger of overlooking AEs in the conservation of populations of rare or threatened species.  相似文献   
177.
依法做好地震应急是减轻地震灾害的关键环节   总被引:2,自引:0,他引:2  
原廷宏 《灾害学》1995,10(2):94-96
本文结合当前地震形势及地震灾害的突发性、社会性、广泛性,对《破坏性地震应急条例》作了阐述,进而论证了依法搞好地震应急总工作是减轻地震灾害的重要环节。  相似文献   
178.
ABSTRACT: Different allocation and delivery performance ratios are used to assess operations performance in a large scale public irrigation system in Indonesia. Results from this analysis indicate that field management practices deviate substantially from the official operating procedures. The lack of application of a single, standardized procedure for planning water allocations represents a serious constraint to effective monitoring and evaluating system performance. Underestimated and unrealistic planned allocations becomes the justification for overdiversion of water, and has the effect of undermining the resolve of managers to see to it that actual flows meet planned flows. Miscalculating planned allocations, poor matches between planned flows and actual deliveries, overdiversion and misreporting have economic consequences as well. For example, strict adherence to the standard operating rule during the second dry season of 1987 would have resulted in 19,070,000 m3 less water diverted into the irrigation system from the Brantas River or, at a conservative estimate of $1.78 per 100 m3 water, a savings of $339,500. Scope exists for making improvements in management by closer adherence to the standard delivery rule, which will also facilitate proper monitoring and evaluation.  相似文献   
179.
本文揭示了安岳县城大气二氧化硫污染特征及其变化规律。针对大气环境质量存在的问题,从宏观上提出了防治大气污染的对策。  相似文献   
180.
周成  杨国录  陆晶  李茂兵  陈澍 《环境工程》2016,34(5):113-117
结合国内外的研究,对温度、pH值、溶解氧等环境因素影响污染物释放的机制进行了综述。其中,温度的升高会促进底泥中氮磷的释放;随着溶解氧含量的增多,污染物越发不易释放;但pH值对底泥中的氮磷以及重金属的释放影响规律则各有不同。此外,结合国内外工程案例及试验研究,对污染底泥的治理技术进行了总结,分析了物理、化学和生物处理方法的利弊。联合处理方法则综合了多种方法的优点,具有良好的应用前景。  相似文献   
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