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<正> According to the leading national classification of the climate of China, given by B. Huang (revised version 1986), Hainan falls into the tropical climatic realm, subdivided into a "peripheral tropical" type for the northern part and a "middle tropical" type for the southern part of the island. While all-year-round frost-free conditions define the tropics in general, the 20t-isotherm for the coldest month represents the boundary between the peripheral tropical and middle tropical types. Compared to the tropical climate in general, Hainan experiences distinctly lower winter temperatures which thus result in a larger annual temperature variation. In terms of precipitation, Hainan records a long rainy season through the southwest monsoon and typhoon seasons from May until October while winter precipitation is comparably lower. Representing two agroclimatic hazards, strong typhoon winds and cold waves seriously affect Hainan. Although to be defined as "marginal tropica-1", the climatic conditions on Hainan 相似文献
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Policy forums are lightly institutionalized and stable forms of governance networks that include administrative authorities, interest groups, and scientists. They are said to produce different types of outputs, from simple actor coordination to position papers and implementation documents, but their productivity has also been questioned. Metagovernance strategies can improve the capability of policy forums to produce outputs. To determine how different metagovernance strategies influence the capability of forums to produce joint position papers, 29 policy forums in the Swiss environmental sector are compared through a qualitative comparative analysis. Results indicate that metagovernance strategies such as state actors as forum members or majority decision rules need to be combined with small forum size or low actor heterogeneity. Furthermore, forum foundation by the state complicates the production of position papers. 相似文献
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Aggregating the benefits of environmental improvements: distance-decay functions for use and non-use values 总被引:3,自引:0,他引:3
One of the main problems in using environmental cost-benefit analysis is deciding on the relevant population: whose benefits should we count? This is important since aggregate benefits depend on both per-person benefit and the number of beneficiaries. Yet this latter term is often hard to evaluate. Distance-decay functions are one way of addressing this problem. In this paper, we present estimates of distance-decay functions for a particular environmental improvement, namely a reduction in low flow problems on the River Mimram in Southern England. We do this both for users and non-users, in the context of a contingent valuation study of the benefits of improving low flow conditions. We test whether distance-decay effects for mean Willingness to Pay are stronger for a single environmental good (the River Mimram, in this case) than for a more inclusive set (here, all rivers in Thames region which suffer from low flow problems). Finally, we explore the impact on part-whole bias, in terms of the relationship between WTP for an individual site and WTP for a more inclusive group of sites, of allowing for distance-decay effects. 相似文献
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The transformation of the former blast-furnace site “Hermannhütte” in Dortmund-Hoerde into commercial, residential and service parks, called PHOENIX East and PHOENIX West involves some unusual challenges concerning the water management. The retention of sediments and nutrients plays an important role. To achieve the objectives, various management measures are being used. The installation of an artificial lake in PHOENIX East, which is groundwater- and rainfed, has different requirements than the conventional purification and retention of surface water in PHOENIX West. Both conventional methods such as storm water sedimentation tank and -reservoirs as well as soil filtration, phosphates elimination, Biodyozon®-plant and biomass management ensure good water quality. 相似文献
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Jurvelin J Edwards R Saarela K Laine-Ylijoki J De Bortoli M Oglesby L Schläpfer K Georgoulis L Tischerova E Hänninen O Jantunen M 《Journal of environmental monitoring : JEM》2001,3(1):159-165
Personal exposures and microenvironment concentrations of 30 target VOCs were measured for 401 participants living in five European cities as a part of the EXPOLIS (Air Pollution Exposure Distributions within Adult Urban Populations in Europe) study. Measurements in Basel used an active charcoal (Carbotech) adsorbent as opposed to the Tenax TA used in the other study centres. In addition, within each centre, personal and microenvironment VOC sampling required different sampling pumps and, because of different sampling durations, different sampling flow rates. Thus, careful testing of the sampling and analysis procedures was required to ensure accuracy and comparability of collected data. Monitor comparison tests using Tenax TA showed a mean VOC concentration ratio of 0.95 between the personal and microenvironment monitors. The LODs for the target VOCs using Tenax TA ranged from 0.7 to 5.2 microg m(-3). The LODs for the 14 target compounds quantifiable using Carbotech ranged from 0.9 to 3.2 microg m(-3). Tenax TA field blanks showed no remarkable contamination with the target VOCs, except benzaldehyde, a known artefact with this adsorbent. Thus, the diffusion barrier system used prevented contamination of Tenax TA samples by passive diffusion during non-sampling periods. Duplicate and parallel evaluations of the Tenax TA and Carbotech showed an average difference of < 17% in VOC concentrations within the sampling methods, but a systematic difference between the methods (Tenax TA: Carbotech concentration ratio = 1.18-2.36). These field evaluations and quality assurance tests showed that interpretation and comparison of the results in any VOC monitoring exercise should be done on a compound by compound basis. It is also apparent that carefully planned and realised QA and QC (QA/QC) procedures are needed in multi-centre studies, where a common sampling method and laboratory analysis technique are not used, to strengthen and simplify the interpretation of observed VOC levels between participating centres. 相似文献
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Klaus T?pfer 《生态毒理学报》2002,(4):3
对于许多人来说 , 生态旅游是一个 “ 术语 “ . 它是一个经常被误用或误解的词 . 正如这期 < 产业与环境 > 特刊中一些文章的作者所指出的那样 , 对生态旅游的定义仍在发展变化 . 但是 , 生态旅游总的目标应该是为发展旅游业同时把其负面影响降到最小提供一个机遇 . 生态旅 游作为一种可持续旅游手段 , 可以在与当地居民分享经济利益的同时避免环境的恶化 . …… 相似文献