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SAGAR V. KRUPA 《Environmental monitoring and assessment》1997,46(1-2):73-88
Our knowledge of global climate change has many uncertainties.Whether global air temperature will increase, by how much, and when,are subject to debate, but there is little doubt that troposphericconcentrations of several trace gases are increasing. While possibleincreases in the average air temperature is a product of these changes,the increases in the trace gases alone will have an effect on agriculture.Increases in the ambient concentrations of carbon dioxide are expectedto have a positive net effect on crop production. In contrast, anyincreases in the penetration of surface-level ultraviolet-B (280–320 nm)radiation, and known increases in surface ozone concentrations, areconsidered to have adverse effects on certain crops. Our presentknowledge of the joint effects on crops of elevated levels of carbondioxide, ultraviolet-B radiation and ozone, and possible alterations in airtemperature and precipitation patterns, is virtually zero. Therefore, anypredictions of the effects of global climate change on agriculture aresubject to significant uncertainties. In contrast, coupling of climatechange (only temperature and precipitation) models to crop productionhas led to a number of future scenarios. In spite of theirpresent limitations, results from these efforts can be useful in planningfor future agriculture. 相似文献
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Travis CC Obenshain KR Regens JL Whipple CG 《Environmental monitoring and assessment》2001,71(1):51-60
The United States currently is engaged in a complex,multi-billion dollar effort to cleanup a legacy ofboth privately- and federally-owned hazardous wastesites. Decisions regarding the best approach forremediation of these sites often are based on theanalysis of potential risks to human health and theenvironment. A cornerstone of such analysis is thefrequent use of computerized multimedia environmentaltransport models, to evaluate the large quantities ofinformation necessary to understand the present andfuture implications of contamination at a site. Onebarrier to wide-spread use of this analyticalprocedure is the view that results obtained usingcomputer models are highly dependent on user input,and therefore, subject to manipulation. It is widelyrecognized that for decisions to be both credible andimplementable, the public must have confidence in boththe scientific basis for judgments involved and thedecision processes employed (NRC, 1983). Our purposein this article is to overview the difficultiesassociated with application of multimedia models toreal world problems and the contribution these modelscan make to technically sound estimates of exposure and risk. 相似文献
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温室气体对气候环境的影响预测及其不确定性 总被引:1,自引:1,他引:1
随着温室气体排放量的增加,联系温室气体特有的保温效应,大气平均气温将升高。在采用气候模式对未来近百年的气候变化做出一定预测的基础上,分析未来可能出现的气候变化所造成的对气候环境方面的影响。详细分析了现阶段预测未来气候环境变化存在的不确定性,正是这些不确定性影响了预测的可信度。 相似文献
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微小流量大气采样器自动检定装置的研究 总被引:2,自引:0,他引:2
介绍了微小流量大气采样器自动检定装置的检测原理 ,给出了该检定装置用于计算的数学模型 ,主要通过对各分量标准不确定度进行分析和计算 ,得到该检定装置测量的扩展不确定度 ,并证明建立该自动检定装置适用于微小流量大气采样器的检定工作 相似文献
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从基线波动、气泡干扰、相分离膜干扰及试剂和标准的干扰等4个方面,总结了流动注射分析法在挥发酚测定中的不确定因素,并提出了有效的改进建议。 相似文献
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Julien Dron Aude Ratier Annabelle Austruy Gautier Revenko Florence Chaspoul Emmanuel Wafo 《环境科学学报(英文版)》2021,33(11):193-205
The bioaccumulation of PAHs and metal elements in the indigenous lichens Xanthoria parietina was monitored during two years at a quarterly frequency, in 3 sites of contrasted anthropic influence. The impact of the meteorological factors (temperature, relative humidity, rainfall, wind speed) was first estimated through principal component analysis, and then by stepwise multilinear regressions to include wind directions. The pollutants levels reflected the proximity of atmospheric emissions, in particular from a large industrial harbor. High humidity and mild temperatures, and in a lower extent low wind speed and rainfall, also favored higher concentration levels. The contributions of these meteorological aspects became minor when including wind direction, especially when approaching major emission sources. The bioaccumulation integration time towards meteorological variations was on a seasonal basis (1–2 months) but the wind direction and thus local emissions also relied on a longer time scale (12 months). This showed that the contribution of meteorological conditions may be prevalent in remote places, while secondary in polluted areas, and should be definitely taken into account regarding long-term lichen biomonitoring and inter-annual comparisons. In the same time, a quadruple sampling in each site revealed a high homogeneity among supporting tree species and topography. The resulting uncertainty, including sampling, preparation and analysis was below 30% when comfortable analytical conditions were achieved. Finally, the occurrence of unexpected events such as a major forest fire, permitted to evaluate that this type of short, although intense, events did not have a strong influence on PAH and metals bioaccumulation by lichen. 相似文献
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土壤作为陆地生态系统最大的碳库和碳循环过程的关键环节,其源、汇的变化直接影响全球碳平衡,因此,土壤有机碳储量估算成为生态领域的重要研究内容之一。通过比较不同研究者在不同研究尺度上报道的有机碳储量的研究结果,发现这些研究结果较不一致。分析认为导致土壤有机碳储量评估结果存在较大差异的原因,主要是来自于采样过程中人类干扰以及气候变化等环境要素的波动,特别是研究者所采取的不同估算方法和背景资料。从环境要素(外因)和估算方法(内因)两个角度出发,提出了土壤有机碳储量的研究意义,阐述了造成土壤有机碳储量估算的不确定性和目前研究中存在的问题,并在此基础上,对其未来研究方向和重点进行了展望。 相似文献
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Jacob von Oelreich Annika Carlsson-Kanyama Åsa Svenfelt Per Wikman-Svahn 《Local Environment》2015,20(4):459-473
A warmer climate leads to rising sea levels. Despite uncertainties about how rapid and substantial future sea-level rise (SLR) will be, society needs to prepare and adapt. This study examines the state of planning for future SLR in Sweden by surveying 33 coastal municipalities in southern Sweden and interviewing local, regional and national authorities with relevant accountability. The results reveal that there are considerable gaps in current planning for SLR. Almost one-third of municipalities lack guiding planning documents for SLR, and more than two-thirds do not discuss SLR beyond 2100. We argue that the prevailing uncertainty and ambiguity in assessments of future SLR is problematic within a traditional “predict-then-act” paradigm, and that robust approaches, such as scenario planning, can reduce many of these problems. 相似文献
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针对湖泊水体富营化评价方法具有的不确定性问题,提出了湖泊富营养化组合评价的真值次数加权法.该法的建立步骤分为3步:首先,根据富营养化评价标准,随机生成1000组富营养化水质指标样本,分别用灰色关联法、模糊评价法、打分统计法、经验频率法、贝叶斯方法、向量评价法6种单项方法进行富营养化评价;然后统计1000组样本中各单项方法的评价值与真值相同的次数,据此计算各单项评价方法在组合评价方法中所占的权重;最后利用权重值对6种单项评价值进行加权平均组合,从而得到真值次数加权法的组合评价结果.将真值次数加权法应用于全国30个湖泊的水体富营养化评价,结果表明,该法能有效降低单项评价方法的不确定性. 相似文献