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891.
Uwe Dornbusch Cherith Moses David A. Robinson Rendel Williams 《Journal of Coastal Conservation》2008,11(4):193-200
Shore platform erosion is considered a driving mechanism for cliff recession on many rocky coasts and, in the vicinity of
sea defence structures, a threat to their stability, yet the spatial pattern of platform erosion, as well as the rate of lowering,
is poorly documented. Measurements based on techniques such as the micro-erosion metre or laser scanner, though highly accurate
for short time scales and specific locations, are difficult to extrapolate in space and time. They also fail to record mesoscale
changes such as block removal. This paper describes a technique to quantify spatial and temporal changes and presents first
results. 相似文献
892.
Abstract: The existence of the Gulf of Mexico dead zone makes it clear that marine ecosystems can be damaged by terrestrial inputs. Marine and terrestrial conservation planning need to be aligned in an explicit fashion to fully represent threats to marine systems. To integrate conservation planning for terrestrial and marine systems, we used a novel threats assessment that included 5 cross-system threats in a site-prioritization exercise for the Pacific Northwest coast ecoregion (U.S.A.). Cross-system threats are actions or features in one ecological realm that have effects on species in another realm. We considered bulkheads and other forms of shoreline hardening threats to terrestrial systems and roads, logging, agriculture, and urban areas threats to marine systems. We used 2 proxies of freshwater influence on marine environments, validated against a mechanistic model and field observations, to propagate land-based threats into marine sites. We evaluated the influence of cross-system threats on conservation priorities by comparing MARXAN outputs for 3 scenarios that identified terrestrial and marine priorities simultaneously: (1) no threats, (2) single-system threats, and (3) single- and cross-system threats. Including cross-system threats changed the threat landscape dramatically. As a result the best plan that included only single-system threats identified 323 sites (161,500 ha) at risk from cross-system threats. Including these threats changed the location of best sites. By comparing the best and sum solutions of the single- and cross-system scenarios, we identified areas ideal for preservation or restoration through integrated management. Our findings lend quantitative support to the call for explicitly integrated decision making and management action in terrestrial and marine ecosystems. 相似文献
893.
Seasonal and spatial character of PCBs in a chemical industrial zone of Shanghai,China 总被引:1,自引:0,他引:1
Ma J Cheng J Xie H Hu X Li W Zhang J Yuan T Wang W 《Environmental geochemistry and health》2007,29(6):503-511
As one of China’s great metropolises, Shanghai is suffering from the impact of manufacture and the use of chemical industrial
products, and it faces serious pollution from polychlorinated biphenyls (PCBs). Therefore, in this study, in order to assess
the seasonal and spatial character of contamination from chemical industrial zones, the concentrations of PCBs have been measured
in various environmental media, including soil, leaves, and atmospheric particulate samples collected in a chemical industrial
zone of Shanghai and compared with samples from presumably unpolluted sites of rural areas. In soils, the PCB concentrations
ranged from 0.5 ng g−1 (unpolluted site) to 586.85 ng g−1 (chlor-alkali industry site). The concentrations of PCBs in evergreen leaves ranged from 0.3 ng g−1 to 32.46 ng g−1, and more chlorinated biphenyls congeners, such as penta-biphenyls and hexa-biphenyls, were the dominant contributors in
winter and spring. Seasonal differences and the constitution patterns of congeners might be affected by the temperature and
industrial activities. The PCB concentrations in the leaves of deciduous trees increase over time as the leaves grow. The
PCB concentration in atmospheric particulates was in the range of 9.22–14.15 × 103 pg m−3, which might be the result of influence from climate and industrial activities. The relativity of PCB contents among the
environmental media was discussed. The results in this paper provide an important profile of the current contamination status
of a key chemical industrial zone in China. 相似文献
894.
有机污染物在包气带中迁移转化试验研究 总被引:3,自引:0,他引:3
采集一定浓度的有机物废水 ,在试验室内进行了静态吸附、静态降解和动态土柱试验 ,对COD在包气带中迁移转化规律进行研究 ,提出了描述COD在包气带中迁移转化规律的数学模型。结果表明 :包气带对COD的吸附过程是线性的 ,可用亨利吸附模式s =Kdc +s0 表示 ,吸附系数Kd=0 .0 6 93;包气带对COD的降解曲线基本符合一级动力学方程c =c0 e-k1 t,降解系数k1=0 .0 4 99d-1;弥散试验测得弥散系数D =0 .0 0 2 4 2m2 /d。COD在包气带中的迁移转化过程是弥散、吸附、降解等多种作用共同作用的结果。 相似文献
895.
郝家兴 《中国安全生产科学技术》2020,16(7):75-81
为确定大采高综采面高抽巷的合理位置,以李村煤矿1303工作面为研究背景,采用理论分析、数值模拟及现场监测等研究方法,对1303工作面覆岩裂隙发育特征、高抽巷空间位置对其围岩稳定性与抽采效果的影响规律进行系统研究。研究结果表明:高抽巷宜布置在覆岩裂隙发育区,远离回风巷道采动应力影响的位置;1303工作面覆岩破坏范围随推进距离增加,呈现先急剧增大后趋于稳定的趋势,工作面推进距离为300 m时,裂隙带高度稳定在50 m左右,形成瓦斯抽采的优势通道;高抽巷距离煤层顶板、回风巷越近,越易失稳,不利于长期抽采,综合考虑高抽巷不同位置时的瓦斯抽采效率及围岩稳定性,确定其合理位置分别是距离回风巷平距为35 m,垂距为45 m;结合现场瓦斯浓度监测结果,得出上隅角、工作面、回风巷瓦斯浓度最大值分别为0.42%,0.24%,0.33%,远低于瓦斯超限标准1%,进一步证明高抽巷层位的合理布置,可以提高瓦斯抽采效果。 相似文献
896.
东营市海岸带区域综合承载力评估 总被引:1,自引:0,他引:1
随着人类对海岸带开发强度的不断提高,海岸带资源、环境问题日益突出,海岸带可持续发展成为人类共识,海岸带区域综合承载力研究作为该区域可持续发展的基础性研究,可以为海岸带区域合理开发与管理提供重要理论支撑。本文选取东营市海岸带为研究区域,以海岸带湿地遥感解译数据、浅海水质监测数据及社会经济统计数据为数据源,运用状态空间法计算了研究区2010—2014年海岸带区域的综合承载力;对东营市与潍坊市、滨州市的海岸带区域综合承载力进行了比较分析;预测了2016—2020年东营市海岸带区域综合承载力;依据研究结果探讨了海岸带可持续利用的未来途径。结果表明:在过去的2010—2014年和预测的2016—2020年东营市海岸带区域综合承载力均处于超载状态,但总趋势是向好的;同时,2010—2014年东营市海岸带在吸引外资、港口发展、海岸带生态系统服务价值、浅海海域水环境方面具有明显优势,但社会公共服务投入不平衡、不稳定。与2016—2020年东营市海岸带区域综合承载力预测结果相比较而言,2011年东营市海岸带区域综合承载力超载最明显,与该年环境压力大和社会投入不足有关。2014年东营市各县区海岸带区域综合承载力均处于超载状态,广饶县超载最明显;同时各县区自然、社会、经济发展水平差异较大,市辖区社会经济指标优于各县区。东营市海岸带区域综合承载力相比潍坊市、滨州市在资源、环境、生态方面具有明显优势,但在社会支撑方面投入不足,因此可以通过保持资源、生态优势,弥补社会投入不足等措施提高东营市海岸带可持续利用水平。 相似文献
897.
国家间自贸区的设立,将更加有利于各签约国资源环境利用效率的提升。本文采用贸易指数测算方法,分析了中、挪、韩在海水产品生产、加工及贸易流通中的各自优势。挪威因丰富的渔业资源和先进的渔业技术,在海水产品养殖及加工领域中具有全球引领作用;韩国有相对更加严格的海水产品安全检疫检验体系,可以确保海水产品的品质安全。随着中韩自贸区的实施及中挪重启双边自贸协定谈判,三国海洋渔业彼此间将进入自贸型竞争态势。如何运用自贸区效应,积极促进渔业资源开发比较潜能的发挥,进一步融入全球化,对于我国,尤其是对山东省渔业实现跨越式发展都是一个亟待破解的课题。山东省作为中国第一渔业大省,在继"海上山东"战略实施基础上,又率先提出"海上粮仓"建设规划设想。针对目前山东省渔业发展中存在的瓶颈问题,本文结合全球贸易分析模型(GTAP)的模拟,在中挪、中韩自贸区背景下对各方海水产品贸易的影响进行了系统分析,提出:在当前海水养殖产量大于捕捞产量的格局下,山东"海上粮仓"建设应以自贸区制度所形成的倒逼机制为互动机理,切实落实海产品养殖生产的安全标准底线和生态系统水平提升的两个基准维度,全面践行可持续健康的渔业资源开发理念,在全国先行完成开放型"海上粮仓"示范体系的建设,以推动我国海水产品生产与加工从量到质的转型,实现海水资源开发与生态环境保护并举,提升我国海洋渔业的国际竞争力。 相似文献
898.
Xiaojun Pan Kurt C. Kornelsen Paulin Coulibaly 《Journal of the American Water Resources Association》2017,53(1):220-237
This study investigates the feasibility of artificial neural networks (ANNs) to retrieve root zone soil moisture (RZSM) at the depths of 20 cm (SM20) and 50 cm (SM50) at a continental scale, using surface information. To train the ANNs to capture interactions between land surface and various climatic patterns, data of 557 stations over the continental United States were collected. A sensitivity analysis revealed that the ANNs were able to identify input variables that directly affect the water and energy balance in root zone. The data important for RZSM retrieval in a large area included soil texture, surface soil moisture, and the cumulative values of air temperature, surface soil temperature, rainfall, and snowfall. The results showed that the ANNs had high skill in retrieving SM20 with a correlation coefficient above 0.7 in most cases, but were less effective at estimating SM50. The comparison of the ANNs showed that using soil texture data improved the model performance, especially for the estimation of SM50. It was demonstrated that the ANNs had high flexibility for applications in different climatic regions. The method was used to generate RZSM in North America using Soil Moisture and Ocean Salinity (SMOS) soil moisture data, and achieved a spatial soil moisture pattern comparable to that of Global Land Data Assimilation System Noah model with comparable performance to the SMOS surface soil moisture retrievals. The models can be efficient alternatives to assimilate remote sensing soil moisture data for shallow RZSM retrieval. 相似文献
899.
Iwan Le Berre Marius Thériault Adeline Maulpoix Françoise Gourmelon 《Journal of Land Use Science》2017,12(4):271-291
Laws and bylaws are regularly challenged for their effectiveness in containing urbanisation sprawl and, conversely, for the constraints they put on development projects. From a French case study, we used survival analysis to disentangle a complex mix of influences on the distribution of residential construction over a 42-year observation period at plot scale when almost everything changes simultaneously. We found that integrated laws and bylaws can slow down coastal urbanisation but do not stop it. Although land planning is becoming more effective, it still provides ample opportunity for residential development because other factors, like distance to existing infrastructure, exert a far stronger influence than the protection of coastal areas. Therefore, this article contributes to filling a knowledge gap about the founding role of public policies on land use dynamics. 相似文献
900.
开发区土地集约利用评价方法是全面客观评价开发区土地集约利用状况的关键要素。以南京市12个开发区为实证对象,尝试采用物元分析法和多因素综合评价法对开发区土地集约利用水平进行评价对比分析,并与土地集约利用效率评价结果对比分析,以期探求更合适的土地集约利用水平评价方法。研究结果表明:(1)南京各开发区集约用地主要限制因子各不相同,主要是企业用地容积率、企业用地建筑密度、建设用地投入强度和建设用地产出强度;南京各开发区之间的集约用地水平呈现出明显的差异,国家级开发区集约等级相对高于省级开发区,高新技术开发区集约等级相对高于传统经济类开发区;(2)相较于多因素综合评价法,物元分析法不但能反映研究对象的综合信息还能反映单个指标分异情况以及研究对象所处状态的稳定性,反映的信息更丰富;土地集约利用水平评价结果与土地集约利用效率评价结果排序具有一定差异,表明未来开发区不但要提高其集约利用水平更要提高集约利用效率。 相似文献