东北地区城市水资源环境问题及其对策

对东北三省区城市水资源环境问题及其控制对策与措施进行了分析和探讨。面临的主要问题有：水资源相对短缺和供需矛盾突出、地表水环境污染严重、地下水环境受破坏和污染、尚未形成节水型的社会生产生活与管理体系等。针对区域城市水资源环境问题提出了相应的控制对策与措施。     

水资源困境与生态城市建设路径的政策研究

我国目前面临着水资源短缺、产业结构配置和污水处理能力等严重问题,文章从生态城市建设的现状和问题出发,提出我国生态城市建设中合理利用水资源的政策途径,包括城市水系统规划、产业布局调整、提高节水技术以及培育城市水权市场等。     

“絮凝专辑”的卷首语

随着我国水资源短缺及水污染问题加剧,已明显地制约了我国经济的可持续发展。因此,水资源的再生利用是目前亟待解决的大问题。水资源再生利用是指对微污染的水源水以及城市、工业废水进行深度处理而使之能够达到重复利用的目的,即水质深度净化处理。它主要涉及当前亟待解决的饮用水水源微污染、城市、工业废水以及油田回注水中的各种纳微米级颗粒污染物去除难的问题。     

天津城市化发展趋向与水资源可持续利用

分析了新时期天津城市化发展趋向，从城市人口增长、城市工业结构、城市化进程等诸方面，探讨了城市化进程与水资源利用之间的关系，提出了适应城市化发展的水资源可持续利用战略。     

21世纪初石家庄市生态环境建设与可持续发展战略

分析了石家庄市目前存在的水资源危机、地表水严重污染、大气污染严重、固体废物围城、绿地不足、热岛现象加重等一系列环境问题。这些问题已影响到城市的社会、经济发展。根据石家庄市特点，提出了石家庄市生态城市建设的基本框架，全方位、多层面地论述了生态城市建设与可持续发展的途径与对策。     

天津市工业废水污染控制问题的研究

本文对天津市的水环境质量现状和存在的主要环境问题进行了系统分析,根据天津市污染防治长期规划,从建设工业水污染防治体系的目标出发,提出了解决城市工业废水污染控制问题的对策,方法和相应措施。并针对水资源严重匮乏地区的经济与环境协调发展问题,进行了研究和探讨。     

天津可持续发展的水资源约束与对策

天津是资源型缺水城市，水资源严重短缺、水质污染以及过量开采地下水导致的地面沉降等问题成为天津社会经济快速发展的制约因素。在对天津水资源现状及相关问题分析基础上，提出建立节水型经济结构、建立健全水资源行政管理体系等水资源可持续利用的对策。     

城市水资源合理利用分析与水资源承载力研究—以本溪市为例

本文以辽宁省重工业城市本溪市为例，运用指数评价模型，进行城市工业用水变化情况分析；同时采用系统动力学模型，预测城市水资源系统发展趋势。在此基础上，探讨水资源承载力的定量表示，提出可比较的区域不同策略的水资源承载力，从而为制定水资源的经济发展决策提供理论依据。     

城市水循环途径及影响分析

通过对城市水循环途径及人类对自然界水循环影响因素分析，确定城市水资源优先开发、利用次序，提出城市水资源形成良性循环的必要条件。     

黄河流域农业水资源与水环境问题及技术对策

对黄河流域农业水资源与水环境现状和存在问题进行了分析,并针对这些问题,提出了改善黄河流域农业水资源利用与水环境安全的技术对策。研究指出,黄河流域水资源贫乏、水质污染严重、灌溉水水质劣化、农业水资源供需矛盾突出,水环境日趋恶化,产生了严重的生态环境问题;而目前我国缺乏有效的农业水资源和水环境监测预警系统,节水农业和水污染防治技术水平低,基础设施落后,信息平台建设不够,农业种植结构和水资源不匹配。今后应加快建立农业水资源与水环境监测预警系统与信息平台,积极推进农业水资源高效利用技术升级,全面提高农业污染防控技术水平,加强农业水环境保护,调整种植结构,建立节水高效种植制度。     

基因芯片在鼻咽癌研究中的应用

鼻咽癌是我国南方及东南亚地区常见的恶性肿瘤,严重威胁人类健康．鼻咽癌的发生、发展是一个多因素、多基因和多阶段的过程,其基因的异常要远远先于形态改变．进行鼻咽癌发生发展中分子机制及相关基因的研究,为,临床上寻找病因、早期诊断及病理分型等方面提供重要的理论依据．基因芯片作为近几年发展起来的一项新兴分子生物技术,具有高通量、准确、高效信息检测的特点,能够研究细胞内所有基因的表达谱,同时获得成千上万个基因活化的模式,为肿瘤临床诊断和治疗提供了强有力的工具．参15．     

甲苯二异氰酸酯(TDI)致癌性的综合评估

甲苯二异氰酸酯(TDI)被数家机构分类为可能的人类致癌物,其主要依据为动物实验发现对啮齿动物经灌胃暴露TDI后肿瘤发生率升高。基于研究结果的可靠性以及一致性,综合评估了现有研究数据是否支持这一分类。结果显示现有的流行病学数据不足以有力证明TDI为人类致癌物。动物实验研究表明,吸入接触TDI并不导致肿瘤发生。经灌胃暴露后观察到的肿瘤很可能是由于TDI转化为已知的啮齿动物致癌物甲苯二胺(TDA)所致。在TDI吸入暴露的体内实验中,当由TDI转化生成的TDA不能达到具有显著生物学效应的浓度时,TDI对啮齿动物或人类都没有遗传毒性。由于哺乳动物在生理性接触条件下TDI不能转变成TDA,所以对人类而言,TDI接触与致癌效应之间无直接的显著因果关系。因此虽然在如灌胃等非生理暴露的条件下,TDI可能的人类致癌物的分类是正确的,但本文对其致癌研究数据的合理评估和正确理解有助于将产品监管力度集中于与职业暴露更相关的有害健康效应上。     

The effects of the risk of fire on the optimal rotation of a forest

The effects of the risk of fire or other unpredictable catastrophe on the optimal rotation period of a forest stand are investigated. It is demonstrated that when fires occur in a time-independent Poisson process, and cause total destruction, the policy effect of the fire risk is equivalent to adding a premium to the discount rate that would be operative in a risk-free environment. Other cases are also investigated and in each a modified form of the Faustmann formula is derived and a “marginal” economic interpretation given.     

On the nature and role of protein constituents of the cuticle of crustaceans in relation to permeability of the cuticle

The chemical composition of the cuticle in regions which are permeable and impermeable to water in 4 crustaceans (Ocypode platytarsis, Metapenaeus monoceros, Emerita asiatica, Ligia exotica) was investigated, with special reference to the protein components. It was found that the cuticle which is permeable lacks the outer epicuticle or the entire epicuticle compared to the cuticle in the impermeable regions. The permeable cuticle is distinguished by the absence of a fuchsinophil protein, which is a precursor of tanning. Permeability of the cuticle is also associated with the presence of a simple protein, positive to the biuret test, and with a protein containing sulphydryl groups. It is considered that the cuticle protein may play a role in conferring permeability properties to the cuticle itself.     

Prediction of potential areas of species distributions based on presence-only data

We introduce a methodology to infer zones of high potential for the habitat of a species, useful for management of biodiversity, conservation, biogeography, ecology, or sustainable use. Inference is based on a set of sites where the presence of the species has been reported. Each site is associated with covariate values, measured on discrete scales. We compute the predictive probability that the species is present at each node of a regular grid. Possible spatial bias for sites of presence is accounted for. Since the resulting posterior distribution does not have a closed form, a Markov chain Monte Carlo (MCMC) algorithm is implemented. However, we also describe an approximation to the posterior distribution, which avoids MCMC. Relevant features of the approach are that specific notions of data acquisition such as sampling intensity and detectability are accounted for, and that available a priori information regarding areas of distribution of the species is incorporated in a clear-cut way. These concepts, arising in the presence-only context, are not addressed in alternative methods. We also consider an uncertainty map, which measures the variability for the predictive probability at each node on the grid. A simulation study is carried out to test and compare our approach with other standard methods. Two case studies are also presented.     

6种观赏植物吸收甲醛能力比较研究

城市住宅的室内空气污染十分严重,甲醛已经成为中国目前室内空气中的首要污染物.在已有的报道中,盆栽观赏植物吸收甲醛的效果并未排除盆土的净化能力,由此植物净化效果显然缺乏科学性.选用6种常用室内观赏植物,将盆土与茎叶部分隔开,放入自行研制的甲醛熏蒸箱中,对植物进行熏蒸实验.测得熏蒸前后甲醛的变化量和植物叶面积,以净吸收率及单位叶面积甲醛减少量来比较6种植物吸收甲醛能力的大小.主要结论如下:(1)甲醛质量浓度是国际标准(0.08 mg·m~(-3))23倍情况下,6种观赏植物均能吸收空气中的甲醛,且因种类不同吸收能力大小不一.吸收甲醛能力排序为:广东万年青(Aglaonema modestum)>绿萝(Epipremnum aureum)>垂叶榕(Ficus benjamina)>虎尾兰(Sansevieria trifasciata)>龟背竹(Monstera deliciosa)>四季秋海棠(Begonia semperflorens-hybr.).单位叶面积植物吸收甲醛量依次为:广东万年青绿萝>虎尾兰>龟背竹>垂叶榕>四季秋海棠.(2)甲醛质量浓度是国际标准(0.08mg·m~(-3))57倍情况下,6种观赏植物吸收甲醛能力排序为:垂叶榕>虎尾兰>绿萝>广东万年青>龟背竹>四季秋海棠.单位叶面积植物吸收甲醛量依次为:虎尾兰>垂叶榕>龟背竹>广东万年青>绿萝>四季秋海棠.(3)根据净吸收率及单位叶面积吸收甲醛量的差异,将植物的吸收能力分为两类,吸收甲醛能力较强的植物有:广东万年青、绿萝、虎尾兰、龟背竹、垂叶榕(与空白组相比有显著性差异(P<0.05));较低的植物有:四季秋海棠(与空白组相比无显著性差异).     

Biological Sustainability of Live Shearing of Vicuña in Peru

Abstract:  The vicuña's ( Vicugna vicugna ) fiber is highly valued as an export product that is made into luxury fabric and clothing. The price of fiber in 2004 was $566/kg, which makes the fiber a potentially important source of income for Andean agropastoral communities and serves as an incentive to allow vicuña grazing on high-elevation Andean landscapes. It is presumed that a shorn vicuña has little value for poachers, so shearing vicuñas could serve as a disincentive to poaching. Thus, the supply of vicuña fiber may be sustainable if it is procured through live shearing, which should serve as a powerful conservation tool. We evaluated the effects of capture and shearing on the demography of vicuña in one site located in the Salinas Aguada Blanca Reserve, Arequipa, Peru, where vicuñas were captured and shorn in spring and then returned to the wild. We conducted fixed-width line-transect censuses from 1997 to 2003 of this population. We compared the proportion of young born to females that were shorn versus females that were unshorn for the 3 years in which shearing occurred. We evaluated the effect of capture and shearing on proportion of young born to shorn and unshorn females at a second site, Picotani, Puno. The wild population in Arequipa that underwent capture and shearing showed a steady increase in total population and average density between 1997 and 2003. No significant difference was found between the proportion of young per female for shorn and unshorn females at either site. We conclude that in spring, capture and live shearing of vicuñas can be biologically sustainable. Further research is needed to determine whether shearing during winter months is biologically sustainable.     

四环素对铜绿微囊藻光合作用和抗氧化酶活性的影响

以铜绿微囊藻(Microcystis aeruginosa)为试验材料,研究了四环素暴露对铜绿微囊藻光合作用和抗氧化酶活性的影响。结果显示,0.80~35.00 mg.L-1四环素暴露胁迫4 d时,铜绿微囊藻的叶绿素荧光和潜在最大电子传递速率(Re,t,max)受到抑制,抑制作用随ρ(四环素)的增加而增强,最大抑制率分别为39.95%和44.08%;暴露7 d时,2者最大抑制率分别升高至59.48%和91.90%。抗氧化酶系统也受到四环素的影响,暴露4和7 d时,超氧化物歧化酶(SOD)活性分别下降30.36%~35.92%和25.03%~35.51%,不同四环素浓度组间差异不显著;过氧化物酶(POD)活性升高,在7 d内呈现诱导现象。可见,四环素暴露能够阻碍铜绿微囊藻光合作用,破坏抗氧化酶系统平衡,抑制藻类生物量的增长。     

The just rate of depletion of a natural resource

The optimal pricing and use of a natural resource is reconsidered with respect to intergenerational equity considerations. It is assumed that in a just economy, each generation chooses the plan that maximizes its own utility, subject to the constraint that the plan should not be exploitative in the sense that each generation does not take advantage of its earlier point in time with respect to future generations. It is shown that if the cost of production of an alternative energy source (e.g., solar) is sufficiently high relative to the stock of naturally stored energy, the constraints of justice result in a lower rate of energy use initially, but a higher rate later.