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41.
This paper brings together institutional theories of polycentricity and critical human geography theory on scalar politics to advance understanding of the form and function of nested, polycentric regimes for the governance of large-scale common pool resources. We focus on institutional changes associated with a national marine protected area network in Palau through which national government and NGOs gain influence in local decision-making processes. Influence is gained through an attempt to scale up common-pool resource governance to an ecologically-relevant spatial scale in an effort to protect coral reef resilience and biodiversity across Palau. An institutional approach informed by scalar politics brings into focus potential tradeoffs between organizing governance reform around ecologically versus institutionally relevant scales. Our analysis suggests that prioritization of ecologically-relevant scales in institutional reform resulted in more nested but less polycentric institutional arrangements governing the network. We conclude that less distributed decision-making in the overall nested governance system could threaten the sustainability and resilience of coral reefs in the long-term by constraining institutional innovation and diversity. Results demonstrate the potential for interdisciplinary dialog to advance the research frontier on multi-level governance for large common pool resources. 相似文献
42.
于2018年10月9日~11月1日采集西太平洋表层海水,通过营养盐添加船基培养实验,研究了不同营养盐条件下浮游植物的生长及其释放挥发性卤代烃(VHCs)含量的动态变化规律.结果表明,与对照组相比,氮磷营养盐的添加对叶绿素a(Chl-a)的含量和三氯乙烯(C2HCl3),四氯乙烯(C2Cl4),一氯二溴甲烷(CHBr2Cl),三溴甲烷(CHBr3)的释放量表现出显著促进作用,但促进程度与添加氮磷营养盐的浓度及比值密切相关.高浓度氮更有利于浮游植物的生长及C2HCl3和C2Cl4的释放.N/P比符合Redfield比值更有利于CHBr2Cl和CHBr3的释放.相比NO3--N,NH4+-N的添加更有利于4种VHCs释放. 相似文献
43.
TGM measurements on board ships have proved to provide valuable complementary information to measurements by a ground based monitoring network. During the third China Arctic Research Expedition (from July 11 to September 24, 2008), TGM concentrations over the marine boundary layer along the cruise path were in-situ measured using an automatic mercury vapor analyzer. Here we firstly reported the results in Japan Sea, North Western Pacific Ocean and Bering Sea, where there are rare reports. The value ranged between 0.30 and 6.02 ng/m3 with an average of (1.52 ± 0.68) ng/m3, being slightly lower than the background value of Northern Hemisphere (1.7 ng/m3). Notably TGM showed considerably spatial and temporal variation. Geographically, the average value of TGM in Bering Sea was higher than those observed in Japan Sea and North Western Pacific Ocean. In the north of Japan Sea TGM levels were found to be lower than 0.5 ng/m3 during forward cruise and displayed obviously diurnal cycle, indicating potential oxidation of gaseous mercury in the atmosphere. The pronounced episode was recorded as well. Enhanced levels of TGM were observed in the coastal regions of southern Japan Sea during backward cruise due primarily to air masses transported from the adjacent mainland reflecting the contribution from anthropogenic sources. When ship returned back and passed through Kamchatka Peninsula TGM increased by the potential contamination from volcano emissions. 相似文献
44.
西南地区地形复杂,极端降水极易形成山洪并引发地质灾害,1998年夏季西南降水达709.3 mm,超出平均降水约23.9%。经使用水汽追踪模型WAM2layers和ERA-Interim再分析资料等大数据追踪西南降水水汽来源,发现西南夏季降水主要有四个源区,分别是西南季风区、西风带区、本地和东南季风区,1998年夏季分别贡献了330.1 mm、110.0 mm、104.8 mm和65.6 mm水汽,约占所追踪降水的52.2%、17.4%、16.6%和10.4%。西南季风区作为最大源区,贡献了超过一半的降水水汽。增加的降水其水汽主要来自西南季风区、西风带区和本地,比平均分别多贡献80.1 mm、29.3 mm和27.1 mm,合占所增加降水的99.9%;其中又以西南季风区贡献占主导。进一步发现,1998年夏季太平洋副高向西南延伸,并在北孟加拉湾和我国南海形成两个高压中心异常,导致西南季风向我国西南地区的水汽输送异常强劲,从而造成西南地区降水异常增多。 相似文献
45.
Steven M. Wondzell Mousa Diabat Roy Haggerty 《Journal of the American Water Resources Association》2019,55(1):116-132
Simulations of stream temperatures showed a wide range of future thermal regimes under a warming climate — from 2.9°C warmer to 7.6°C cooler than current conditions — depending primarily on shade from riparian vegetation. We used the stream temperature model, Heat Source, to analyze a 37‐km study segment of the upper Middle Fork John Day River, located in northeast Oregon, USA. We developed alternative future scenarios based on downscaled projections from climate change models and the composition and structure of native riparian forests. We examined 36 scenarios combining future changes in air temperature (ΔTair = 0°C, +2°C, and +4°C), stream discharge (ΔQ = ?30%, 0%, and +30%), and riparian vegetation (post‐wildfire with 7% shade, current vegetation with 19% shade, a young‐open forest with 34% shade, and a mature riparian forest with 79% effective shade). Shade from riparian vegetation had the largest influence on stream temperatures, changing the seven‐day average daily maximum temperature (7DADM) from +1°C to ?7°C. In comparison, the 7DADM increased by 1.4°C with a 4°C increase in air temperature and by 0.7°C with a 30% change in discharge. Many streams throughout the interior western United States have been altered in ways that have substantially reduced shade. The effect of restoring shade could result in future stream temperatures that are colder than today, even under a warmer climate with substantially lower late‐summer streamflow. 相似文献
46.
47.
通过剖析浮游植物生长特征和其集群结构与Si的重要性、Si的输入过程和生物地球化学过程以及Si限制浮游植物时间,揭示了在北太平洋的近岸水域,从秋天的雨季结束(11月)到春天的雨季开始(5月)之前,Si都限制浮游植物的生长,在北太平洋的远离近岸水域,浮游植物生长一直都受到Si的限制;探讨北太平洋风场变化的基本特点和规律与中国的沙尘暴发生、频率和强度,首次提出了北太平洋水域Si的提供系统,并且用框图模型说明了提供系统在运行过程中的每个流程。当北太平洋缺少Si时,该系统就向其水体输入大量的Si,来维持了北太平洋海洋生态系统的持续发展;为了补充输送到海洋的Si量减少,该系统提高了运行能力,造成内陆干旱、沙化面积扩大、沙尘暴强度增大。研究结果表明,在北太平洋水域,北太平洋的季风与北太平洋边缘的雨季在时间上密切相嵌,顺利完成近岸洪水和河流的输送与大气的输送之间的相互转换,一直保持向大海的水体输入大量的Si。而且,沙尘暴与北太平洋Si的缺乏在时间上紧密配合,其强度大小与Si缺乏的严重程度相一致。因此,人类在制定应对自然灾害的政策和战略时,要从人类的角度和地球的角度来共同考虑,有利于人类的健康生存,更应该有利于地球生态系统的持续发展。 相似文献
48.
以2007年西北太平洋海域Argo海表面温度、经纬度、深度为输入参数,利用LM-BP神经网络,构建了西北太平洋海水温度模型。将均方根差以及Pearson相关性系数作为检验指标,利用2008年和2009年的Argo数据对模型进行了检验。检验结果为:2008年均方根误差为0.714 0℃,Pearson相关性系数为0.996 8;2009年均方根误差为0.761 5℃,Pearson相关性系数为0.9965。表明所建立的基于LM-BP神经网络的Argo数据西北太平洋海水温度模型是可行的。 相似文献
49.
Courtland L. Smith Jennifer Gilden Brent S. Steel Karina Mrakovcich 《Environmental management》1998,22(5):671-681
/ Emerging ecosystem science builds on adaptive management as an approach to dealing with salmon problems in the Pacific Northwest. Adaptive management brings scientific and democratic processes together. However, managers, the public, resource users, and scientists differ in their views on the causes of salmon decline. Managers emphasize habitat loss and over-harvest as the primary causes; commercial fishers point to habitat loss, management practices, and predators; and the public gives greatest weight to water pollution and ocean drift nets. Scientific studies of salmon often produce results that seem contradictory or unclear to the public. For adaptive management to be effective, scientists' and the public need to better understand one another's perspectives.KEY WORDS: Perception; Fishery management; Salmon; Pacific Northwest; Science 相似文献
50.
Rusidan Lubis Michael V. Martin B. Starr McMullen 《Journal of the American Water Resources Association》1987,23(4):673-680
ABSTRACT: Grain transportation is a major economic activity on the multiple use Snake-Columbia River System. Congress is currently considering increased transportation user fees aimed at recapturing federal expenditures for waterway operations and maintenance. Three types of fee structure and four levels of cost recovery are evaluated using a network program model. In each case traffic is diverted away from the river to other Puget Sound ports via truck and rail transport modes. Grain shippers in the region will be adversely affected by a higher transport bill. The Lower Columbia River port economic activities will be negatively affected; however, competitive uses of the river, recreation, and hydroelectric generation will likely benefit modestly. 相似文献