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81.
放射性碳同位素加速器质谱(ASM14C)测年法是湖泊沉积物定年的主要方法,并且是全新世年代学研究的热点。随着对全新世古气候与环境变化研究的深入,选取不同介质定年可能对年代模型的准确性造成误差,进而影响到气候指标的解译。本文选取贵州东北部梵净山九龙池沉积物中树枝、树叶、树皮、种子等植物残体和全样有机质作为测年介质,利用ASM14C进行定年。结果表明,相比全样有机质,使用植物残体定年可以在一定程度上避免碳库效应的影响。但相比于原位沉积且生长年限较短的叶片,树枝的定年结果偏老,不是一种理想的定年介质。另外,根据定年结果及总有机碳含量重建了全新世九龙池的碳累积速率,发现碳累积速率可以指示该地区亚洲夏季风强度的变化历史。 相似文献
82.
在遥感图像基础上,利用GIS技术从景观指数方面定量分析了唐家河自然保护区主要植被类型在东西、南北和西北至东南3个方向上的梯度变化。结果表明:次生落叶阔叶林、常绿落叶阔叶混交林、针阔叶混交林与针叶林的梯度变化明显,并且在各方向上具有不同的变化特征。其中,常绿落叶阔叶混交林从西北至东南方向的梯度变化最为复杂, 斑块数量与面积分别呈“升—降—升—降”与“升—降—升”的波动变化趋势,而边界密度与平均最近距离呈先升后降的变化趋势,两端破碎度高但连接性好,中部相反。针叶林从北至南的梯度变化最为简单,斑块面积减少,破碎度与复杂度降低,南北两端分布较多,中部较少。唐家河自然保护区植被景观格局在不同方向上的梯度变化研究为地震后该地区的植被保护与管理提供重要指导意义。 相似文献
83.
Further to the European Waste Electrical and Electronic Equipment (WEEE) Directive, setting up efficient collection schemes is necessary to ensure the recovery targets set. Following the subsidiary principle, the WEEE Directive defines only the general requirements for mandatory collection and recycling objectives. The modalities of the logistics and the organisation of the take-back schemes are left to the choice of Member States. In this paper, the implementation of the WEEE Directive and the development of the WEEE recovery infrastructure in Finland are described and the challenges to the effective management of the WEEE recovery system in Finland are expressed. It can be said that the implementation of the WEEE Directive has succeeded in Finland and, at the same time, the legislative basis has been enacted. In addition, a functional WEEE recovery infrastructure has been built and, the collection requirements of the WEEE Directive have been exceeded in a relatively short time. However, the paper outlines that some inefficient practices still exist, particularly in the registration and WEEE collection stages. It is concluded that raising awareness would lead to a more environmentally sound behaviour and would, ultimately, improve WEEE recovery efficiency. 相似文献
84.
田至美 《中国ISO14000认证》2009,(2):11-15
主体功能区划主要在于解决区域问题,用科学发展观协调区域发展。本文从区域发展的整体性出发,用空间发展的相互作用理论分析了北京山区各主体功能区协调发展的区域背景。 相似文献
85.
Benjamin K. Sovacool 《Environment, Development and Sustainability》2007,9(2):187-201
Contrary to claims from American politicians, lobbyists, and oil and gas executives, allowing energy development in the Alaskan
Arctic National Wildlife Refuge (ANWR) will harm the environment, compromise international law, erode the social significance
of wilderness protection, and ultimately fail to␣increase the energy security of the United States. After exploring a brief
history of the ANWR controversy, this piece argues that the operation of oil and gas refineries in ANWR will release discharged
solids, drilling waste, and dirty diesel fuel into the ecosystem’s food-chain, as they have from oil operations in Prudhoe
Bay. Less obvious but equally important, oil and gas exploration in ANWR will violate a number of international treaties on
biodiversity protection. In the end, development in ANWR will threaten the concept of wilderness protection, and will do little
to end US dependence on foreign sources of energy.
About the Author: Benjamin K. Sovacool is a doctoral candidate in the Department of Science and Technology Studies at the Virginia Polytechnic
Institute & State University in Blacksburg, Virginia. He works as a research analyst for the Consortium on Energy Restructuring
and is a Senior Research Fellow for the Virginia Center for Coal and Energy Research. He also just completed a Graduate Fellowship
in Energy Policy at the Oak Ridge National Laboratory in Oak Ridge, Tennessee.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
86.
福建太姥山龙潭洞地质环境与景观资源特征 总被引:1,自引:0,他引:1
本文系统论述了福建太姥山龙潭洞所在地域的自然地理、区域地质及环境地质条件,并对龙潭洞的规模形态、形成机制及景观资源特点进行讨论,为龙潭洞旅游资源的开发利用及总体规划设计提供参考依据。 相似文献
87.
通过对鸡东防山洪项目工程概况介绍,对所在地区周围环境概况进行调查和分析,确定本项目开发建设活动的特征、污染源及污染程度,提出有针对性的污染防治措施,并从技术、经济等方面论证该措施的可行性,预测该项目建设期和服务期可能对周围环境产生的影响,并作出相应的分析和评价。 相似文献
88.
ABSTRACT: Toxicity testing is a means of establishing the environmental risk of a uranium tailings release. It is valuable in designing tailings containment structures because it assists in setting acceptable levels of risk for the design. This paper presents details of toxicity tests of the tailings from Ranger Uranium Mine, Northern Territory, Australia. The results suggest that the non-radiological toxicity of the tailings is low. The environmental risk of a tailings release is more likely to be related to the physical impacts of the tailings, including infilling of billabongs and changes in the sedimentology of riparian ecosystems rather than their biogeochemical impact. Two major results were: (1) water from treatment with washed tailing fines were not toxic to Hydra viridissima, and (2) mixtures of washed tailings fines and natural floodplain sediment (overlying water or elutriates) were not toxic to Hydra viridissima or Moinodaphnia macleayi. 相似文献
89.
An ecological survey was carried out to determine the sediment concentrations of nutrients and heavy metals and bioaccumulation of heavy metals in fish and shrimp including tilapia (Oreochromis mossambicus×O. nilotica), grey mullet (Mugil cephalus), gei wai shrimp (Metapenaeus ensis) and caridean shrimp (Macrobrachium nipponensis) in the traditional tidal shrimp ponds (gei wais) of Mai Po Nature Reserve, Hong Kong. The sediments collected from the landward sites contained higher nutrient contents, as well as zinc (Zn), chromium (Cr), copper (Cu), nickel (Ni) and cadmium (Cd) than those collected from the seaward sites, but vice versa for lead (Pb) and mercury (Hg). However, the concentrations of all metals were exceptionally high in the two sites located outside the reserve, suggesting that waters from Deep Bay might be the possible source of metal contamination affecting the reserve. All metals studied seemed to accumulate in the viscera of fish. Body size was the determining factor for the accumulation of heavy metals in caridean shrimp and gei wai shrimp but not fish. Concentrations of the metals studied in tissues of grey mullet and gei wai shrimp were found to be safe for human consumption. Concentrations of Cr in tilapia whole body (0.68–1.10 mg kg−1 wet weight) were close to or over the guideline value of 1 mg kg−1 set by the Food Adulteration (Metallic Contamination) Regulations of Hong Kong. Tilapia flesh and small caridean shrimp collected from gei wais were contaminated by Cr and Pb but still fit for human consumption. Caution is required if large caridean shrimp is to be consumed in large amounts continuously because the concentration of Pb exceeded the maximum permitted concentration (6 mg kg−1). The rather high Cr concentrations in tilapia whole body should not be overlooked as the fish will serve as a food source for migratory birds visiting the site. 相似文献
90.
Nowadays, more people tend to spend their recreational time in large national parks, and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health. To investigate the pollution levels, potential sources and health risks of trace metal(loid)s in road soils, a total of eight trace metal(loid)s (including As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China. The results showed that the concentrations of As, Cd, Pb, Zn and Hg appeared different degrees of pollution compared with their corresponding background values. According to the pollution indices, Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk. Combining principal component analysis and positive matrix factorization model, the results showed that traffic, industrial, agricultural and natural sources were the potential origins of trace metal(loid)s in this area, with contribution rates of 39.93%, 25.92%, 10.53% and 23.62%, respectively. Non-carcinogenic risks were all negligible, while the carcinogenic risk of As was higher than the limit (1 10−6). Moreover, children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation. The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults, while traffic and industrial sources have a significant impact on health risks. This study will give more insights to control the environmental risks of trace metal(loid)s in national parks. 相似文献