Distribution of 137Cs in soil along Ta-han River Valley in Tau-Yuan County in Taiwan

Environmental 137Cs contamination was suspected from accidents at spent fuel storage pits of a research reactor site in the Ta-han River valley in Taiwan. In order to further characterize this contamination, soil samples were collected and measured by a gamma-spectroscopy system in 1999. It was found that 137Cs contamination is distributed up to 4 km from the reactor in an area covered mostly by rice and plant fields. 137Cs concentration in the topsoil ranged up to about 1000 Bq kg-1, as compared with soil beyond the contaminated area, which does not exceed 15 Bq kg-1. Spatial distribution of 137Cs was characterized by strong non-uniformity, which complicated our understanding of the distribution pathway of the radionuclides. The highest concentrations of 137Cs, up to more than 1000 Bq kg-1, were found within a few rice fields. The relative location of these rice fields and the water supplies from local streams suggested that the 137Cs was distributed along water pathways in the valley.     

“两控区”内燃煤火电厂烟气脱硫成本的转移

运用环境经济学、环境法学方面的知识研究了如何解决“两控区”内燃煤火电厂的烟气脱硫成本问题．结果表明,只要电能消费者消费了酸雨和SO₂污染控制区内燃煤火电厂的火电,就应最终承担燃煤火电厂的烟气脱硫成本电能消费者的负担标准为火电厂依靠经济上可实现的最佳可得控制技术生产单位电能所耗费的平均脱硫成本费用;烟气脱硫成本转移的最佳时间和方式为电网经营者把平均脱硫成本分摊给电能消费者,收取电费后再补贴给火电厂．     

依靠科技进步，实现跨越式发展

结合西部地区的科技现状,分析了科技创新的内在要求,探讨了实现跨越式发展的途径和对策。     

整装反应器无反应条件下的传热

研究整装反应器在反应点火之前的传热行为以及反应器参数对基体热响应的影响。建立了起燃阶段反应器的传热模型,通过数值计算,分析和讨论了固相轴向热传导性能及各种设计参数对基体热响应的影响。比较了基体采用金属体或陶瓷体时热响应的不同。结果表明,当无量纲导热系数∧＜1时,固相轴向导热性能对基体热响应无明显影响,金属体具有好的热响应性能,参数分析有助于反应器的设计和建模。     

南京市不同功能区PM10中多环芳烃的污染特征

PM10是衡量大气环境质量好坏的重要指标之一;多环芳烃(PAHs)是具有强烈致癌性的有机污染物,大多吸附在粒径小于10 μm颗粒物上.利用长期定位实验采集了南京市两典型功能区--大厂地区和山西路的PM10样品,对其PAHs质量浓度进行了分析测定,研究了不同功能区PM10中PAHs的时空污染特性.研究结果表明:南京市PM10污染比较严重,其质量浓度变化范围在0.1157 mg·m-3～0.3913 mg·m-3之间;经分析PM10中16种优控多环芳烃(PAHs)发现,全年大厂地区的PAHs的质量浓度与山西路PAHs的质量浓度没有明显的高低之分;PAHs总质量浓度的空间变化不明显,时间变化也没有规律性;比较PM10与PAHs的月平均质量浓度变化趋势,两者之间的变化没有相关性,各自的质量浓度变化也没有规律性,分析其结果可能是由于PAHs的不稳定性造成的.     

根瘤菌、丛枝菌根（AM）真菌与宿主植物共生的分子机理

丛枝菌根(AM)真菌和根瘤菌是两类重要的共牛微生物,分别能够与宿主植物形成丛枝菌根和根瘤,其中,对二者共有的宿主植物--豆科植物而言,则能够形成AM真菌-豆科植物-根瘤菌三重共生体.两类微生物与宿主植物共生关系建立的关键是二者之间的相互识别以及随后的侵染,其相互识别过程就是它们相互交换信号分子、相互作用的过程,而这两类微生物与宿主植物的识别过程具有许多相似之处.本文就根瘤菌、AM真菌与宿主植物在分子水平上的共生机理进行了综述,在对宿主植物分泌信号分子识别的基础上,提出植物根系对两类微生物侵染的感应机制,分析了共生体形成过程中相关基因的转录与表达,进而阐明了共生体的形成过程,并对本领域的未来发展提出了建议.     

Drainage affects tree growth and C and N dynamics in a minerotrophic peatland

The lowering of the water table resulting from peatland drainage may dramatically alter C and N cycling in peatland ecosystems, which contain one-third of the total terrestrial C. In this study, tree annual ring width and C (delta(13)C) and N (delta(15)N) isotope ratios in soil and plant tissues (tree foliage, growth rings, and understory foliage) in a black spruce-tamarack (Picea mariana-Larix laricina) mixed-wood forest were examined to study the effects of drainage on tree growth and C and N dynamics in a minerotrophic peatland in west-central Alberta, Canada. Drainage increased the delta(15)N of soil NH4+ from a range of +0.6% per hundred to +2.9% per hundred to a range of +4.6% per hundred to +7.0% per hundred most likely through increased nitrification following enhanced mineralization. Plant uptake of 15N-enriched NH4+ in the drained treatment resulted in higher plant delta15N (+0.8% per hundred to +1.8% per hundred in the drained plots and -3.9% per hundred to -5.4% per hundred in the undrained plots), and deposition of litterfall N enriched with 15N increased the delta15N of total soil N in the surface layer in the drained (+2.9% per hundred) as compared with that in the undrained plots (+0.6% per hundred). The effect of drainage on foliar delta(13)C was species-specific, i.e., only tamarack showed a considerably less negative foliar delta(13)C in the drained (-28.1% per hundred) than in the undrained plots (-29.1% per hundred), indicating improved water use efficiency (WUE) by drainage. Tree ring area increments were significantly increased following drainage, and delta(13)C and delta(15)N in tree growth rings of both species showed responses to drainage retrospectively. Tree-ring delta(13)C data suggested that drainage improved WUE of both species, with a greater and more prolonged response in tamarack than in black spruce. Our results indicate that drainage caused the studied minerotrophic peatland to become a more open ecosystem in terms of C and N cycling and loss. The effects of forested peatland drainage or drying on C and N balances deserve further research in order to better understand their roles in future global change.     

Designing environmental monitoring networks to measure extremes

This paper discusses challenges arising in the design of networks for monitoring extreme values over the domain of a random environmental space-time field {X _ij } i = 1, . . . , I denoting site and j = 1, . . . denoting time (e.g. hour). The field of extremes for time span r over site domain i = 1, . . . ,I is given by \(\{Y_{i(r+1)}=\max_{j=k}^{k+n-1} X_{ij}\}\) for k = 1 + rn, r = 0, . . . ,. Such networks must not only measure extremes at the monitored sites but also enable their prediction at the non-monitored ones. Designing such a network poses special challenges that do not seem to have been generally recognized. One of these problems is the loss of spatial dependence between site responses in going from the environmental process to the field of extremes it generates. In particular we show empirically that the intersite covariance Cov(Y _i(r+1),Y _i′(r+1)) can generally decline toward zero as r increases, for site pairs i ≠ i′. Thus the measured extreme values may not predict the unmeasured ones very precisely. Consequently high levels of pollution exposure of a sensitive group (e.g. school children) located between monitored sites may be overlooked. This potential deficiency raises concerns about the adequacy of air pollution monitoring networks whose primary role is the detection of noncompliance with air quality standards based on extremes designed to protect human health. The need to monitor for noncompliance and thereby protect human health, points to other issues. How well do networks designed to monitor the field monitor their fields of extremes? What criterion should be used to select prospective monitoring sites when setting up or adding to a network? As the paper demonstrates by assessing an existing network, the answer to the first question is not well, at least in the case considered. To the second, the paper suggests a variety of plausible answers but shows through a simulation study, that they can lead to different optimum designs. The paper offers an approach that circumvents the dilemma posed by the answer to the second question. That approach models the field of extremes (suitably transformed) by a multivariate Gaussian-Inverse Wishart hierarchical Bayesian distribution. The adequacy of this model is empirically assessed in an application by finding the relative coverage frequency of the predictive credibility ellipsoid implied by its posterior distribution. The favorable results obtained suggest this posterior adequately describes that (transformed) field. Hence it can form the basis for designing an appropriate network. Its use is demonstrated by a hypothetical extension of an existing monitoring network. That foundation in turn enables a network to be designed of sufficient density (relative to cost) to serve its regulatory purpose.     

流域生态补偿机制研究

由于流域生态服务的公共物品属性,政府需要建立流域生态补偿机制以提供足够的流域生态报务。本研究提出流域生态补偿机制的主要模式是公共支付体系,财政转移支付体系,自发组织的私人协议和自由贸易体系。模式的决定要素是流域尺度和产投明晰程度,其组成要素是补偿标准,实际补偿量,组织实施和竞争机制的使用．     

城市生态环境与可持续发展评价指标体系研究

本文从探讨城市生态环境与可持续发展的战略关系入手,在进行调查研究的基础上,提出了城市生态环境与可持续发展评价指标体系,旨在为城市的全面、协调、可持续发展提供一点科学管理依据。