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91.
Indigenous people play an integral role in shaping natural environments, and the disruption to Indigenous land management practices has profound effects on the biosphere. Here, we use pollen, charcoal and dendrochronological analyses to demonstrate that the Australian landscape at the time of British invasion in the 18th century was a heavily constructed one—the product of millennia of active maintenance by Aboriginal Australians. Focusing on the Surrey Hills, Tasmania, our results reveal how the removal of Indigenous burning regimes following British invasion instigated a process of ecological succession and the encroachment of cool temperate rainforest (i.e. later-stage vegetation communities) into grasslands of conservation significance. This research provides empirical evidence to challenge the long-standing portrayal of Indigenous Australians as low-impact ‘hunter-gatherers’ and highlights the relevance and critical value of Indigenous fire management in this era of heightened bushfire risk and biodiversity loss.  相似文献   
92.
当前,我国国土空间规划自上而下试图从宏观层面尽可能解决或缓解自改革开放以来所面临的生态环境问题、资源约束、人地关系冲突、多头管理、规划权威性等关键问题。我国国土规划的体系、架构和技术条例等迄今已形成相对科学合理的“共性”规范,但在战略层面讨论面向未来国家安全背景下的地域“个性”问题仍较缺乏。面对国家需求和西部特殊情境,应考虑建立基于国家安全考量的跨省区、跨流域的西部国土空间规划。在战略层面,为保障国家安全,此规划应着重考虑:(1)理论上,基于国家安全视角应建立跨省区、跨流域的西部国土空间规划体系;(2)实践中,建议制定西部空间尺度的以生态区、自然保护区为核心的“西部国土空间规划—生态安全”专项规划,以边境线、支撑线为规划脉络的“西部国土空间规划—生存安全”专项规划(或在规划中明确“国防安全细则”),依托主要交通线以城镇体系为组织脉络的“西部国土空间规划—生活安全”专项规划(或在规划中明确“西部和谐社会建设细则”),遵循主体功能区且以区域性中心城市、城市群等为中心的“西部国土空间规划—生产安全”专项规划(或“西部经济高质量发展规划”),重构生态空间、生存空间、生活空间、生产空间;(3)特别建议强化边疆城镇/村寨建设,设立新时代“大三线建设”——西部“环青藏高原重点建设带”,以应对后疫情时期有限全球化和“双循环”现实的可能的国家安全需求。整体上,西部情境特殊,其国土空间规划与东中部应有差异,切忌一刀切。  相似文献   
93.
以滇西重金属地质高背景区为研究区,系统采集了4193件表层土壤样品,分析测试了As、Cd、Cr、Cu、Hg、Ni、Pb和Zn 8种重金属元素的含量,综合运用相关分析、主成分分析和单因素方差分析等经典统计方法探讨了土壤重金属来源和土壤重金属含量与成土母质、土地利用方式之间的关系,并利用地统计方法对重金属的空间分布特征进行了分析.结果表明:①研究区8种重金属含量平均值均超过全国土壤背景值,但是低于农用地污染风险筛选值;与云南省土壤背景值相比,As、Cd、Cu、Ni、Pb和Zn含量平均值与云南省背景值相当,Hg和Cr的平均含量分别是其背景值的2.35和1.60倍,土壤重金属存在不同程度累积现象.②Cr、Cu和Ni主要受成土母质的控制;Cd、Zn和Pb主要受人类活动影响,人为来源主要为铅锌矿开采选冶、交通运输和煤炭燃烧,Cd、Zn在一定程度上受成土母质的影响;As和Hg以人为来源为主,受汞矿采选、农业活动及煤炭燃烧的影响.③不同成土母质和土地利用方式的土壤中重金属含量差异显著.Cd、Cr、Cu、Hg和Ni在沉积岩母质区土壤中平均含量最高;草地中As、Cd、Cr、Cu、Hg、Ni、Zn平均含量最高.④Cu、Ni、Cr高值区与沉积岩母质区及区内分布的铜矿和铁矿空间耦合性良好;Pb、Cd和Zn的高值区与区内的铅锌矿分布范围基本一致;As和Hg高值区与区内汞矿等热液型金属矿的分布具有较高的空间一致性,在人类活动密集地区也呈高背景分布.  相似文献   
94.
To explore the complexity of temporal and spatial dynamics of an agricultural landscape under various external and internal driven scenarios, SimKat, an agent-based model, has been developed with the simulation computer program CORMAS. This model combines simplified bio-physical processes of land cover, regional dry-land salinity changes, rainfall impact on productivity, farm profitability and the complexity of land-use decisions of individual farmers in a dry-land agricultural catchment (no irrigation). In this model, simulated farmers formulate individual decisions dealing with land-use changes based on the combined performance of their past land cover productivity and market returns. The willingness to adapt to market drivers and the ability to maximize returns vary between farmers. In addition, farmers in the model can demonstrate various attitudes towards dry-land salinity mitigation as a consequence of experiencing and perceiving salinity on their farm, in the neighborhood or across the entire region. Consequently, farmers can adopt land cover strategies aimed at reducing dry-land salinity. Aggregating the simulated individual behavior of farmers combined with historical rainfall and market price records, reproduced similar aggregated trends of land-cover changes, regional salinity change and farm number decline as observed in the last 20 years in the subject region (Katanning, Western Australia). Using the model in an initial exploratory study on the impact of rainfall variability and change highlighted the importance of average rainfall decline and the widespread willingness of farmers to adapt perennial vegetation in their farming systems to combat regional dry-land salinity. Rainfall decline, as one of the observed consequences of climate change in this region, can also lead to prolonged sequences of dry seasons in the future. Adaptation by farmers to sequences of dry and wet seasons, rather than an average trend in rainfall, seems to be critical for farm survival in this region. Intensifying cropping during wet seasons to maximize farm returns can increase vulnerability in subsequent periods of dry seasons, in particular where alternative income from pasture and sheep production has been lost in the adaptation process.  相似文献   
95.
采用平衡解吸法研究了西辽河沉积物不同粒径微团聚体磷的解吸特征.结果表明,不同粒径团聚体磷的解吸比例为黏粒(0.20)<粉粒(0.28)<细砂(0.45)<粗砂(0.93);其原因为:细粒级微团聚体中腐殖质含量远远高于粗粒级;细粒级微团聚体中有机质是通过可溶有机质与黏土矿物相互结合形成复合体而富集,在其所形成的复合体团聚结构中引起的团聚体结构不可逆形变是导致磷的解吸比例降低,解吸迟滞性指数增大的根本原因;西辽河冲泻质泥沙黏粒和粉粒级微团聚体所携载的可解吸态磷(NAP)入海后可分别为上覆水提供磷(212.93±38.60)mg/kg,(159.45±31.44)mg/kg.沉积物黏粒级和粉粒级微团聚体所携载的NAP是磷素循环的重要组成部分.  相似文献   
96.
松嫩平原西部农田径流中有机氯农药的分布特征   总被引:10,自引:1,他引:9  
闫百兴  汤洁  何岩 《环境科学》2003,24(2):82-86
松嫩平原西部水田回归水、旱田地表径流中BHC、DDT主要异构体或代谢物的可溶态、颗粒吸附态的分析表明,回归水中BHC、DDT的含量均较低,BHC以β-BHC为主,占73.5%~99.5%,呈β>α>γ>δ规律;DDT中仅检出p,p'-DDT.BHC(β-BHC除外)、DDT以溶解态为主,悬浮颗粒物的粒径大小是影响回归水中农药含量的重要因素;悬浮物中DDT的生态风险很低,而BHC有潜在的生态风险.  相似文献   
97.
Environmental problems are a function of the process of economic development and the ability to mitigate the problems through regulation. An historical analysis helps to show how the problems have been solved thus far. The objective of this investigation is to present an overview of environmental problems and the corresponding regulations in Western Europe during the 1980s. Environmental problems for 18 Western European countries were identified from abstracts from a data base on environmental literature. The 1977 findings were systematized on the basis of 20 key words according to source and impact, and a new data base was established. The data showed that the main environmental problems in Western Europe were: energy production/acid rain, nuclear power/waste, air pollution/climate, heavy metals, pesticides, water pollution, solid waste, and unforeseen accidents. Many environmental problems are common to most European countries. Regulatory measures differ significantly. In some countries environmental regulations are largely limited to the implementation of European Economic Community (EEC) directives. We have supplemented the national analyses with an examination of existing and proposed EEC regulations along with interviews with civil servants in the EEC Commission. In the 1980s, EEC environmental regulations were similar to environmental regulations in some member states. It is expected that future EEC regulations will be less reflective of those of individual member states.  相似文献   
98.
ABSTRACT: Problems of water quality and quantity are critical to development of the energy resources of the Western U. S. Based on a number of independent measures, the Upper Colorado River Basin will experience severe water availability problems in a few decades if projected energy and agricultural development occurs. Given the impending collision between the competing interests of various Western water users, water resource management and conservation deserves the utmost attention. Substantial opportunities for conservation exist in energy and agricultural development. Selection of both conversion and cooling technologies and careful siting decisions can sharply reduce the water requirements of energy development. Agricultural water conservation strategies include improving irrigation and cultivation practices, removing phreatophytes, removing marginal lands from production, and changing crop patterns. In order to accomplish significant conservation, however, there must be changes in those aspects of Western water law that remove conservation incentives from the water use system.  相似文献   
99.
干旱区水资源短缺,生产用水、生态用水与人民群众的生活用水矛盾突出。针对和田地区农村改水的地下饮用水状况的分析和评价,结果表明,地下饮用水的色度、浑浊度以及砷、泵、镉、铬、铅、硝酸盐等超标率均为零。总硬度、Cl^-、SO4^2-及F^-等指标的超标率较高,而这些物质的存在对于水质的理化性状影响较大,并因此而引发人体健康教育改变。和田地区总体饮用I级水的人口数量多,但局部的超标水依然存在。应通过对区域自然地理状况和人文因素的系统研究和科学论证,加强水源保护,改进卫生条件和卫生观念,建立农村饮水监测网,加强系统监测、监督和管理,以保障人民群众安全的生活用水。  相似文献   
100.
由于形成山地灾害的多种自然因素具有垂直地带性,尤其作为主要动力因素的水,超过一定高度后由液态成为固态,从而造成了山地灾害的垂直地带性。山地灾害从高到低可分为冰雪带、冻融带和流水(古地下水,裂隙水)带,高低两带之间主体界线在南水北调西线工程及其邻近地区为4900m和3500m。各带均有其特点,其中对西线第一期工程及其下游地区可能造成重大影响的有:大型的冰崩、雪崩、冰湖崩决、滑坡或古滑坡复活、泥石流、泥石流坝或滑坡坝溃决。但这些大型山地灾害在该地区不很严重.今后出现的可能性小,只要引起重视,妥善处理,可以避免或减轻其危害。  相似文献   
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