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911.
江湖关系变化对鄱阳湖沉积物重金属分布及生态风险影响 总被引:8,自引:4,他引:4
选取不同水情下鄱阳湖表层沉积物,研究江湖关系变化对其重金属Cu、Pb、Zn、Cr和Cd的分布及生态风险影响,结果表明:①鄱阳湖沉积物受不同程度重金属污染,入湖河流颗粒物输入是鄱阳湖沉积物重金属的主要来源,其中Cu和Pb是主要污染因子.各重金属污染程度排列次序为:Cu>Pb>Zn>Cr>Cd,丰水期沉积物各重金属含量的变化范围为Cu 13.1~108.1 mg·kg-1、Pb 37~119.1 mg·kg-1、Zn 29.9~129.9 mg·kg-1、Cr 13.3~98.6 mg·kg-1和Cd 0.19~2.77 mg·kg-1;枯水期为Cu 3.05~69.7 mg·kg-1、Pb 27.5~105 mg·kg-1、Zn 18.8~95.4 mg·kg-1、Cr 7.34~70 mg·kg-1与Cd 0.033~0.406mg·kg-1;高值区域集中在"五河"尾闾水域和鄱阳湖入长江的湖口水域.②丰水期鄱阳湖沉积物重金属高风险区主要集中在五河尾闾区;枯水期,沉积物重金属高风险区面积扩大,不仅局限于五河尾闾区,且向北部进一步扩散,湖口区域的风险较大,但全湖生态风险总体上丰水期大于枯水期.③随着鄱阳湖与长江江湖关系进一步发生变化,丰水期水位抬高且维系时间缩短、枯水期提前、湖泊由"湖相"至"河相"的转变进程加快、河流特性增强,将导致全湖沉积物重金属生态风险相应降低,但高风险区域的范围进一步向北扩大. 相似文献
912.
The magnitude of the environmental and social consequences of soil erosion and land degradation in semiarid areas of the Mediterranean
region has long been recognized and studied. This paper investigates the interrelationship between land use/cover (LULC) changes
and land degradation using remotely sensed and ancillary data for southeastern Spain. The area of study, the Xaló River catchment
situated in the north of the Alicante Province, has been subjected to a number of LULC changes during the second half of the
20th century such as agricultural abandonment, forest fires, and tourist development. Aerial photographs dating back to 1956
were used for the delineation of historic LULC types; Landsat ETM+ data were used for the analysis and mapping of current
conditions. Two important indicators of land degradation, namely, susceptibility to surface runoff and soil erosion, were
estimated for the two dates using easily parametrizable models. The comparison of 1956 to 2000 conditions shows an overall
“recuperating” trend over the catchment and increased susceptibility to soil erosion only in 3% of the catchment area. The
results also identify potential degradation hot-spots where mitigation measures should be taken to prevent further degradation.
The readily implemented methodology, based on modest data requirements demonstrated by this study, is a useful tool for catchment
to regional scale land use change and land degradation studies and strategic planning for environmental management. 相似文献
913.
Watson A Glaspell B Christensen N Lachapelle P Sahanatien V Gertsch F 《Environmental management》2007,40(6):880-888
Many public land management agencies are committed to understanding and protecting recreation visitor experiences. Parks Canada
is deeply committed to that objective for visitors to Canada’s National Parks. This 2004 study, informed by a 2003 qualitative
study of visitor experiences and influences on those experiences at Auyuittuq National Park in Nunavut, worked to bring 50
potential elements of visitor experiences down to five articulated dimensions of the experience that is currently being received
at this remote eastern arctic park. A hypothesized set of 17 influences on experiences, also reduced to just two factors with
similar response patterns, and with some items that did not flow into the two factors, were used in a regression analysis
to understand the relationship between experiences and factors of influence. A sample of 61.8% (84) of the total recreation
visitor population 16 years of age or older was surveyed during deregistration after the trip. Knowledge about the dimensions
of the experiences currently received and factors of influence on those experiences can be used to guide selection of indicators
for describing objectives and prescribing monitoring protocol. 相似文献
914.
The accurate assessment of trends in the woody structure of savannas has important implications for greenhouse accounting and land-use industries such as pastoralism. Two recent assessments of live woody biomass change from north-east Australian eucalypt woodland between the 1980s and 1990s present divergent results. The first estimate is derived from a network of permanent monitoring plots and the second from woody cover assessments from aerial photography. The differences between the studies are reviewed and include sample density, spatial scale and design. Further analyses targeting potential biases in the indirect aerial photography technique are conducted including a comparison of basal area estimates derived from 28 permanent monitoring sites with basal area estimates derived by the aerial photography technique. It is concluded that the effect of photo-scale; or the failure to include appropriate back-transformation of biomass estimates in the aerial photography study are not likely to have contributed significantly to the discrepancy. However, temporal changes in the structure of woodlands, for example, woodlands maturing from many smaller trees to fewer larger trees or seasonal changes, which affect the relationship between cover and basal area could impact on the detection of trends using the aerial photography technique. It is also possible that issues concerning photo-quality may bias assessments through time, and that the limited sample of the permanent monitoring network may inadequately represent change at regional scales. 相似文献
915.
916.
Guangyu Qiao 《中国人口.资源与环境(英文版)》2013,11(4):324-329
In global climate change politics, China and India have worked closely with each other, representing two big emitters from the developing world. This article reviews Sino-Indian cooperation during four UN climate change negotiations from 2009 to 2012. Their collaboration echoed the perception of neorealism in international relations (IR) studies that states will seek “external balancing” for maximizing national “relative gains”. China and India are expected to continue their cooperation on climate change issues when sharing the same structural position as big economies and big emitters, the same pressure in carbon emission reductions, and the same goal of improving living standards for their citizens. Encountering the devastating impacts of climate change and the deadlock in responsibility division in current global climate change governance, this work seeks to shed light on the evolving multilateral governance environment and its complex implications for Sino-Indian relations from an IR perspective. 相似文献
917.
We analyze the impact of Regulation (EC) No 1080/2006 on separate collection rate of Italian regions. We exploit longitudinal data for 20 NUTS-2 Italian regions and eighteen years (from 1996 to 2013). We identify regions which are exposed to “Convergence” objective as the treatment group and regions which are not exposed to this objective as the control group and use a Difference in differences estimation. The estimates suggest that the Regulation (EC) No 1080/2006 has not influenced the convergence process among the Italian regions. The main policy implications are discussed. 相似文献
918.
Numerous empirical and simulation-based studies have documented or estimated variable impacts to the economic growth of nation states due to the adoption of domestic climate change mitigation policies. However, few studies have been able to empirically link projected changes in economic growth to the provision of public goods and services. In this research, we couple projected changes in economic growth to US states brought about by the adoption of a domestic climate change mitigation policy with a longitudinal panel dataset detailing the production of outdoor recreation opportunities on lands managed in the public interest. Joining empirical data and simulation-based estimates allow us to better understand how the adoption of a domestic climate change mitigation policy would affect the provision of public goods in the future. We first employ a technical efficiency model and metrics to provide decision makers with evidence of specific areas where operational efficiencies within the nation's state park systems can be improved. We then augment the empirical analysis with simulation-based changes in gross state product (GSP) to estimate changes to the states’ ability to provide outdoor recreation opportunities from 2014 to 2020; the results reveal substantial variability across states. Finally, we explore two potential solutions (increasing GSP or increasing technical efficiency) for addressing the negative impacts on the states’ park systems operating budgets brought about by the adoption of a domestic climate change mitigation policy; the analyses suggest increasing technical efficiency would be the most viable solution if/when the US adopts a greenhouse gas reduction policy. 相似文献
919.
北京市丰台区土地利用变化及社会经济驱动力分析 总被引:2,自引:0,他引:2
近十年来.北京城市化水平大幅度提升.建设用地不断向外扩展。城市边缘区土地利用变化异常明显。丰台区作为北京城市边缘区的重要组成部分。土地利用变化特征具有典型性,在分析丰台区12年间土地利用的类型变化、数量变化、程度变化和区域变化特征基础上。对形成这种土地利用变化的驱动力从社会经济方面进行了剖析,并在统计软件SPSS的支持下对土地利用变化驱动力指数进行了计算。结果表明.研究时段内土地利用变化幅度大。土地利用程度增加;耕地、园地和未利用地净减.而建设用地和林地净增.土地利用变化的社会驱动力主要是人口增长、经济发展和城市化水平提高.并且这些因素的驱动力指数是逐年增加的。政策的干预作用也不容忽视。 相似文献
920.
Recent years have seen a gradual adoption of a “catchment-scale” approach to flood risk management into European policy-making which, amongst other objectives, promotes rural land use change to reduce flood risk. While some exploratory studies of land managers’ attitudes exist, research is lacking on how public policies can be mobilised locally to implement these ideas. Two local initiatives were analysed in the transboundary River Tweed basin in Scotland and England during which public authorities negotiated with land managers. A combination of documents (N = 21) and interviews (N = 63) forms the basis of the data analysed. The results showed that implementation is highly dependent on the local policy framework, the activities of implementers, and land managers’ responses to (combination of) policy instruments. Several factors were identified influencing implementation such as devolution arrangements (i.e. from national to regional/local), the level of local interest on flood risk, local attitudes to compromise and collaboration, available policy instruments, and the existence of participatory catchment organisations. With limited scope for stand-alone regulatory action or funding in the short term, synergies and measures promoting co-benefits in flood risk management should be further sought in the Water Framework Directive River Basin Management Plans, as well as in cross-compliance and the new agri-environment-climate strategies of the common agricultural policy. 相似文献