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21.
汉江堵河流域地表水质时空变化特征 总被引:4,自引:0,他引:4
对汉江堵河流域9个点位为期1年的地表水水质理化特性进行时空特征分析,应用〖WTBX〗t〖WTBZ〗检验进行水质季节性变化分析,聚类分析进行空间相似性分析以确定空间尺度的分类情况,判别分析识别显著性指标,并以此反映上述空间聚类分析结果的差异性。结果表明:①Cl-、总溶解性固体(TDS)及浊度(Turbidity) 3项指标没有表现出显著的时间差异性;②温度、pH、NO-3、TP表现为丰水季显著大于枯水季,而SO2-4、HCO-3、NH+4、 DO则表现出相反的变化趋势,即枯水季显著大于丰水季;③空间聚类分析将采样点分为4类;④判别分析体现出良好的指标降维能力,仅需4个指标(NO-3、TDS、SO2-4、HCO-3)即可反映整体水质的空间差异性。 相似文献
22.
简要总结国内外农业循环经济发展概况及成功经验,简要介绍"十二五"期间,大连发展农业循环经济的主要途径与模式,为我国农业循环经济发展提供参考借鉴。 相似文献
23.
24.
F. Andrew. Schoolmaster 《Journal of the American Water Resources Association》1992,28(3):495-505
ABSTRACT: Texans participate directly in water policy decision-making through a referendum process involving amendment of the state's constitution. Prior to 1985, Texans voted on eight amendments. Five of these were ratified (1957, 1962, 1966, 1971, 1976), and collectively resulted in the creation of the Water Development Fund, with an authorization level of $600 million, and the Texas Water Development Board, the organization charged with administering the fund. Three other amendments were defeated in 1969, 1976, and 1981 by ever-increasing margins. From 1985 to 1991, six additional amendments were proposed and subsequently ratified, resulting in a $1.8 billion increase in Water Development Fund authorization and the creation of an agricultural water conservation fund and bond insurance program. County-level electoral data for the 1985–1991 referenda were mapped to assess sectional and regional factors underlying public opinion regarding these water resource development and funding programs. Regional contrasts were most pronounced for the 1989 and 1991 referenda that targeted economically distressed areas across the state, particularly the colonias located along the Rio Grande, and the 1989 amendment that removed a time limit on the issuance of agricultural water conservation bonds. As a specific case study, the Texas experience could serve as a guide in California where similar constitutional restrictions require tax and spending programs to be approved by voters, and in other states that may be considering the development of similar state-level financial programs for water projects. 相似文献
25.
Some of the literature pertinent to the interactions of birds of flight and man made obstacles, such as transmission lines is reviewed here. Some birds use these towers, poles, and buildings for nesting and perches. They also collide with them. Original observations presented here suggest that the environmental impacts of these types of obstacles on birds, and vice-versa, seem not due to the inability of the birds to perceive the obstacles, but rather that the birds are apparently distracted from a safe flight pattern by their own species, or by others.
Editor's Note: Although this paper is quite specialized in comparison with many other articles published in Environmental Management, I feel it is a very useful overview of the problems and the literature related to bird collisions with manmade obstacles. It is hoped that the information presented by the Willards will be helpful to other workers who are perhaps engaged in preparing environmental impact statements concerning structures that could invite bird collisions. 相似文献
26.
Assessment of population exposure to particulate matter pollution in Chongqing, China 总被引:1,自引:0,他引:1
Wang S Zhao Y Chen G Wang F Aunan K Hao J 《Environmental pollution (Barking, Essex : 1987)》2008,153(1):247-256
To determine the population exposure to PM(10) in Chongqing, China, we developed an indirect model by combining information on the time activity patterns of various demographic subgroups with estimates of the PM(10) concentrations in different microenvironments (MEs). The spatial and temporal variations of the exposure to PM(10) were illustrated in a geographical information system (GIS). The population weighted exposure (PWE) for the entire population was 229, 155 and 211 microg/m(3), respectively, in winter, summer and as the annual average. Indoor PM(10) level at home was the largest contributor to the PWE, especially for the rural areas where high pollution levels were found due to solid fuels burning. Elder people had higher PM(10) exposure than adults and youth, due to more time spent in indoor MEs. The highest health risk due to particulate was found in the city zone and northeast regions, suggesting that pollution abatement should be prioritized in these areas. 相似文献
27.
Nutrient transfer functions: the site of integration between feeding behaviour and nutritional physiology 总被引:6,自引:0,他引:6
Summary. We describe and extend a graphical approach to quantitative nutrition that focuses on the interplay between behavioural and
physiological components of nutritional regulation. The site of integration is the nutrient transfer function, which is the
function describing the time course of nutrient transfer between serially connected nutritional compartments (e.g., from the gut to the blood). The relationship between the shape of the nutrient transfer function and the temporal patterns
of feeding determines the values of two key quantitative parameters of nutrition: the rate ('power') and the efficiency of nutrient acquisition. The approach can be extended to consider, in addition to the short-term behavioural and physiological
decisions made by animals, some ecological determinants and longer-term, life history consequences of such decisions. Most
importantly, this category of models can provide insights into the interplay among the various nutrients in an animal's diet.
We illustrate this using hypothetical examples, and also present preliminary data for the power-efficiency relationships of
protein and digestible carbohydrates in locusts. Finally, we consider existing evidence for the various means available to
these and other insects for regulating such relationships.
Received 24 September 1997; accepted 9 December 1997. 相似文献
28.
基于能值分析的武穴市耕地利用效益时空特征分析 总被引:1,自引:0,他引:1
开展耕地利用效益评价,对实现农业生态文明和耕地高效持续利用具有指导意义。结合能值分析、自相关等方法,评价和分析了2002~2011年武穴市耕地利用效益的时空演变特征。结果表明:近10a来武穴市耕地利用效益的能值投入和产出处于上升趋势,增长速度分别达58.17%和61.29%;能值投入中工业能值所占比重最大,超过总量的70%以上,2011年达到82.17%;耕地集约度增加6.60×1015sej的同时环境压力也在变大,耕地环境负载率由2002年的2.88上升至2011年的4.61;农业生产能力和农民生活水平不断提高;空间自相关结果显示武穴市各乡镇单位面积耕地能值投入和产出具有较明显的东高—南低—西平的聚集特征。研究结果对优化武穴市农业生产物化投入结构、提高产出效果,实现耕地高效持续利用具有一定的指导意义。 相似文献
29.
绿色发展是旅游业可持续发展理念的重要组成部分,是旅游业奉行以人为本、生态至上和全面发展的新价值观。在梳理旅游业绿色发展概念及内涵基础上,构建旅游业绿色发展效率评价体系,运用SBM-Undersirable模型、核密度估计、空间马尔科夫链等方法,探讨2008—2018年中国31个省(市、自治区)旅游业绿色发展效率(TGDE)时空演化特征及影响机理。研究发现:(1)时间和空间变化方面,TGDE总体处于中等偏下水平,时间上呈“W”型变化形态,“下降—上升—调整”阶段特征显著;空间呈“东—中—西”递减分布,内部差异为西部地区>东部地区>中部地区,低、中、高效率由“金字塔”向“菱形”结构转变,高效率地区集中于东部沿海,中等效率多分布于中西部地区,低效率位于胡焕庸线两侧。(2)动态演进方面,TGDE始终存在两极分化现象,但区域协调性逐步增强,具有较强平稳性,难以实现跨越式发展,空间向上转移省份比较集中,以中西部为主,向下调整省份较少,且存在明显的空间溢出效应,溢出影响具有不对称性。(3)影响机理方面,总体上,经济水平、产业结构、政府规制、教育水平和旅游资源影响因子与TGDE间存在显著的正向关系,对外开放程度的作用不显著,但各因子的影响程度、作用机理及条件具有较强地域性。 相似文献
30.
山区农村居民点时空格局演变特征及蚁群仿真优化——以重庆澄江镇为例 总被引:2,自引:0,他引:2
山地农村居民点系统因受自然因素及人类活动等多重扰动而处于深刻转型中,探索山区农村居民点时空格局特征及其优化策略,对于优化山区国土空间格局、推进山区国土空间综合治理与乡村振兴具有重要意义。基于构建理论框架,集成运用景观格局指数法、栅格权重叠加评价法、改进蚁群算法(ACO)等,以重庆澄江镇为例,探索山区农村居民点时空格局演变特征及优化过程,提出优化调控策略。结果表明:(1)研究区农村居民点空间格局演变特征呈现集中、靠拢的演化发展趋势,总体呈现匀质、线状、向心、院落四种分布形态;同时高程、坡度、水域、城镇、道路、基础设施等自然—经济社会因素均对山区农村居民点时空格局演化产生重要影响。(2)改进蚁群算法优化后,研究区农村居民点斑块面积(CA)减少10.07%,居民点斑块数量(NP)和密度(PD)分别减少83.12%和81.16%,平均斑块面积(MPS)增加了4.3倍,平均最近邻体距离(MENN)增加了42.82%。优化后69.1%的农村居民点斑块都集中在适宜区和较适宜区内,且重点向交通便利、公共设施完善、生产便利和中心村庄集中。优化后的农村居民点空间格局更加紧凑有序,土地集约节约效率更高。(3)基于仿真优化结果,综合考虑村庄振兴“产业—人口—土地”互动耦合机制,提出城郊融合、产业集聚、景村融合、搬迁撤并四类农村居民点格局优化方案,助推山区乡村振兴。(4)优化结果同时表明改进的蚁群算法非常适用于复杂环境条件下的较小尺度要素空间布局优化,能够为山区国土空间规划编制提供技术支撑。 相似文献