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871.
放射性核素污染及监测   总被引:2,自引:5,他引:2       下载免费PDF全文
由于发达国家的核试验和核电站的建设,放射性核素对环境的污染已引起世界各国的关注。我国目前实施对放射性强度的监测,而对核素监测相对比较薄弱。文章介绍了核设施泄露事故对大气、水和水生生物造成的污染及污染的削减过程,综述了目前发达国家的放射性核素污染水平、监测的核素种类和监测方法。  相似文献   
872.
The biological effects of contaminants in British estuaries and coastal waters have been studied for over 100 years. Until the 1970s. the major pollution impact on estuarine organisms was probably caused by poorly treated sewage which led to severe oxygen deficits and consequent asphyxiation of many water-breathers. However, since the introduction of improved sewage treatment in the last 30 years, a number of continuing impacts have come to light which represent true toxic effects of micro-contaminants. Sublethal changes observed in various bioassays and biomarkers are widespread in both fish and invertebrates, and in the most urbanised and industrialised estuaries, these effects are probably having impacts at the population and community levels. For example, there is good evidence to show that tributyltin from some antifouling paints has not only affected the sexuality and reproductive success of individual estuarine and coastal molluscs, but has also damaged some benthic communities of which molluscs are but a part. Although there are data to show that some contaminant concentrations are now declining, we do not yet have enough data in most cases to decide whether organisms have also begun to recover. This paper reviews the entire field of contaminant effects in UK estuarine and marine waters, focusing especially on the years 1985-2000, and makes some recommendations for future research and monitoring programmes.  相似文献   
873.
传统的道路交通监测存在不足之处 ,相应的路口自动监测力量犹显薄弱。对诸如闯红灯 ,闯单禁行线 ,超速等交通违章行为缺乏现代化的监测、取证等必要手段。笔者提出基于Internet的道路交通违章监测系统 ,有效地利用先进的通信及计算机技术 ,为提高交通道口的管理水平 ,确认违章事故提供了手段 ,并对此系统进行深入地分析和设计 ,同时通过实例证明 ,该系统违章监测和事故确认具有的有效性和可操作性。  相似文献   
874.
通过有效运行的环境监测质量管理体系和实施监测全过程质量管理对虹口区环境监测站质量管理现状进行分析,提出了对策及建议,结果,通过建立数学分析模型对监测数据进行综合分析,实验室工作逐步做到熟练地应用测量不确定度,使环境监测站质量管理水平进一步提高,更好的为环境管理服务.  相似文献   
875.
The assessment of management effectiveness in protected areas, i.e., the evaluation of whether management strategies are actually helping to achieve stated goals, is becoming a priority. In any such evaluation, accurate information concerning the dynamics of the managed system is required—information that is gathered through monitoring. Few protected areas, however, have well-developed monitoring plans, and reserve managers are faced with a shortage of protocols for their design. This paper proposes a methodology, applicable to a wide range of situations, for designing such plans. The process begins with the precise definition of the aims of the monitoring plan, followed by the identification of key ecological processes and management objectives for the area, and finally the selection of a reduced set of indicators. These indicators are represented at three levels of growing complexity, allowing the plan to be followed in a modular fashion and in agreement with available resources.  相似文献   
876.
应用时域边界元法 ,研究了单侧接触埋置结构与瞬态SH液 (剪切横波 )的动力相互作用 ,当入射SH波足够强时 ,界面会出现局部滑移并假设摩擦遵守库仓定理。笔者从实际情况出发 ,提出了新的数学模型和计算方法 ,计算了埋置矩形结构与瞬态SH波的动力相互作用问题 ,由于对此类问题的深入研究 ,为评估和预测埋置结构在动荷载下的安全性及疲劳寿命提供了重要的理论价值  相似文献   
877.
本文分析了基本抽样程序,并用来解决环境监测的抽样优化问题。抽样过程形成马尔可夫链,通过划分接收水平和抽样区间建立抽样策略。计算每一组策略的目标函数的取值,找到备选策略中最小成本抽样策略即最优抽样策略。  相似文献   
878.
Ten intertidal salt marshes along the Rhode Island coast were sampled and compared in terms of the relative standing crop and height of tallSpartina alterniflora, density of shoots, seed production and size, fish populations, and the abundance of grass shrimp, fiddler crabs, insects, and birds. The marshes ranged from 0.49 to 52.61 hectares (1.2 to 130 acres) and included fringe marsh in dense urban developments as well as unspoiled waterfowl preserves in rural isolation. Large variation in most parameters made it impossible to separate the sites with statistical significance using either univariate or multivariate techniques. Moreover, there was little meaningful intercorrelation among the parameters. Although more intensive sampling might make it possible to separate individual marshes with statistical rigor, these results suggest that the necessary effort may be too great to allow comparative field sampling to play a practical part in wetlands evaluation programs. The results also indicate that there is little, if any, correlation between visual esthetic perceptions of a marsh and its ecological characteristics. This work suggests that the development of ecological rating systems will not provide a reliable tool for the management of coastal wetlands.  相似文献   
879.
/ Roxborough State Park in Colorado's Front Range was established in 1975 following a history of cattle and sheep ranching by private ownership. Survey work conducted from 1979 to 1995 resulted in the documentation of 93 species of butterflies. A variety of factors are responsible for the composition of the butterfly community: (1) overgrazing and its effect on the presence or absence of specific butterfly host plants; (2) habitat differences resulting from topographical and geological features; and (3) ecological and historical biogeography. This study provides data on community sampling adequacy, along with estimates of effort needed to monitor trends in abundance by using a community self-similarity curve and power analysis. An annual monitoring plan is proposed to assess trends in community composition. The plan includes collection of presence/absence and abundance data for select butterflies based on natural history information.KEY WORDS: Butterfly communities; Grazing; Inventory; Monitoring; Natural history  相似文献   
880.
根据三峡工程对长江中游湖泊的生态环境影响,优选出了其监测因子,以期通过这些因子的监测,可以较全面、准确地反映长江中游湖泊的生态环境状况与动态变化趋势。  相似文献   
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