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71.
The lower Roanoke River in North Carolina, USA, has been regulated by a series of dams since the 1950s. This river and its floodplain have been identified by The Nature Conservancy, the US Fish and Wildlife Service, and the State of North Carolina as critical resources for the conservation of bottomland hardwoods and other riparian and in-stream biota and communities. Upstream dams are causing extended floods in the growing season for bottomland hardwood forests, threatening their survival. A coalition of stakeholders including public agencies and private organizations is cooperating with the dam managers to establish an active adaptive management program to reduce the negative impacts of flow regulation, especially extended growing season inundation, on these conservation targets. We introduce the lower Roanoke River, describe the regulatory context for negotiating towards an active adaptive management program, present our conservation objective for bottomland hardwoods, and describe investigations in which we successfully employed a series of models to develop testable management hypotheses. We propose adaptive management strategies that we believe will enable the bottomland hardwoods to regenerate and support their associated biota and that are reasonable, flexible, and economically sustainable. 相似文献
72.
地震预报与活断层分段 总被引:1,自引:0,他引:1
丁国瑜 《防灾减灾工程学报》1993,(1)
文章回顾分析了地震预报的经验与问题,对地震短期预报需进行新的探索与研讨,才能更快地前进。文章重点论述了地震预报和地震危险性评估方面有关的断层分段性问题。如何在众多的活断层上确定近期可能发生强震的地段,是地震预报中突出的重要问题之一。有关活断层分段性问题是近年来十分引人注目的课题。段是断层的破裂单元,断层的分段就是对断层进行独立的破裂单元的划分。断层分段有4种,当前讨论的主要是活断层破裂分段。 相似文献
73.
山东省旱,涝,地震灾害的时序特征及其相互关系 总被引:1,自引:0,他引:1
分析了山东地区历史干旱、洪涝和地震灾害时间分布特征及其相互关系,发现旱涝与地震灾害一样具有不同时间尺度的准周期活动特征,且地震与旱涝具有一定相关关系.如内陆大地震多与干旱活动相继发生,海域地震多发生在洪涝活动时期;破坏性地震前多发生干旱,震后又常有洪涝相随等。进而对山东旱涝活动进行了初步分期。文中还对上述现象的成因作了简单分析。 相似文献
74.
Climate skeptics typically argue that the possibility that global warming is exogenous, implies that we should not take additional action towards reducing emissions until we know what drives warming. This paper however shows that even climate skeptics have an incentive to reduce emissions: such a directional change generates information on the causes of global warming. Since the optimal policy depends upon these causes, they are valuable to know. Although increasing emissions would also generate information, that option is inferior due its irreversibility. We show that optimality can even imply that climate skeptics should actually argue for lower emissions than believers. 相似文献
75.
Among both forest practitioners and the general public, “forest health” has become an issue of contention. Whereas the debate
over which treatments will best achieve healthy forests has been framed largely by the popular media and politicians as a
struggle between industry and environmentalists, the views of the general public remain unexplored. Survey results from Oregon
and Washington residents were used to assess the relationships between respondents’ self-described environmental or economic
priorities and the following two variables: (1) acceptability of forest management practices and (2) perceived threats to
forest health. Findings indicate that active management was generally accepted by a majority of respondents regardless of
their environmental or economic orientation. Disagreement emerged, however, when the appropriateness of specific management
practices within specific forest conditions was examined. Additionally, strong evidence was found for a relationship between
self-described environmental or economic orientation and perceived threats to forest health. Those with an environmentally
oriented viewpoint tended to perceive human-caused factors as the largest threats, whereas those with an economic orientation
saw naturally occurring processes as the greatest threats. These findings suggest that the issue of contention is not active
management per se. Rather, the major divisions in the forest health debate are defined by specific contexts and circumstances,
as well as the management practices used. 相似文献
76.
MapObjects在城市道路交通噪声管理中的应用 总被引:6,自引:0,他引:6
从Visual Basic控件技术出发,介绍了建立在对象链接与嵌入技术基础上由美国ESRI公司的采用GIS控件MapObjects的运行机制及特点。结合该控件在城市道路交通噪声信息管理系统开发中的应用,对系统的建设目标、结构及开发模式做了介绍;以对北京市道路交通噪声信息管理系统的开发为例,对系统的功能作了简要说明。 相似文献
77.
讨论了城市污水经过A/O工艺处理时活性污泥的二次污染问题。所采用的方法是将原水、处理后的出水及活性污泥用乙酸丁酯萃取、萃取相经过真空浓缩后,采用GC/MS测定了样品中的有机化合物。结果表明,在A/O工艺处理城市污水过程中,活性污泥的吸附作用是主要的,降解作用是次要的:A/O工艺所排放的活性污泥仍然是一种危险的污染物。 相似文献
78.
介绍了大气污染生物主动监测中监测植物的选择原则:适宜的监测方法;合适的监测时间及监测植物的标准化问题。讨论了监测中应注意的几个问题如放样点距地在及排放点的合适距离。在监测中植物的朋肥供应等,并介绍了自掣是简易植物计。 相似文献
79.
阐述了氡的来源、在环境中的分布状况及其对人体的危害。用主动式活性炭盒采样和高纯锗探测器伽玛射线谱仪对样品进行测量,具有灵敏度高、精度好、易于操作等特点。 相似文献
80.
Adamo P Giordano S Sforza A Bargagli R 《Environmental pollution (Barking, Essex : 1987)》2011,159(6):1620-1628
A biomonitoring of airborne trace elements was performed in 2006 in Naples urban area through the exposure of devitalised Hypnum cupressiforme for 10 weeks at 4 m height. In one street, the moss was exposed at different heights to assess vertical gradients of element concentrations. Results were compared with those of a 1999 biosurvey. Correlations among Al, Fe and Ti suggested a soil particles contribution to element uptake. Cu, Mo and Fe were related with traffic flows. Long-range transport contributed to Cd, Cu and Mo accumulation in moss at higher heights. As in 1999, the airborne element load was higher in coastal sites, more affected by marine aerosols and traffic. In all sites, contents of Cd, Fe, Pb, Ni and V in moss were remarkably lower than in 1999, indicating a positive effect of actions set up in recent years to reduce the traffic and to improve the city air quality. 相似文献