长江白鱀豚的保护

白鱀豚是我国特有的珍稀淡水哺乳动物,仅分布于长江中下游,目前长江白鱀豚的种群数量仅约200头,濒临灭绝。造成白鱀豚濒危的主要威胁来自长江鱼类资源的减少、有害渔具的广泛使用、航运事业的发展、河道的大规模整治、水电工程的建设、水体污染以及白鱀豚自身的生理特征。通过我们多年的研究,提出了建立半自然白鱀豚保护区、人工饲养下白鱀豚的繁殖,和建立长江白鱀豚自然保护区等三大措施。在各级政府和科研部门的共同努力下,三项措施正在落实,为保护白鱀豚创造了良好的条件,但面临的困难还很多,任务十分艰巨,我们希望开展广泛的国际合作,为保护白鱀豚共同努力。     

Analysis of microcystins in cyanobacteria blooms and surface water samples from Meiliang Bay,Taihu Lake,China

Taihu Lake is the third largest freshwater lake in China. In recent years, the water pollution of cyanobacteria blooms has become a severe problem in this area. Microcystins (MCs) are an important group of toxic compounds mainly produced by some cyanobacteria species and have both acute and chronic hepatotoxic effects on animals and humans. This paper presents the first data on the identification and detection of MCs in both natural occurring cyanobacteria blooms and surface water samples (0-0.5 m), collected from Meiliang Bay, Taihu Lake, China. A conventional method for extraction and isolation of MCs from cyanobacteria blooms was applied. High-performance liquid chromatography (HPLC) analysis showed that the main toxic component in the cyanobacteria materials was MC-LR. The monoclonal antibody (mAb) against MC-LR produced by hybridoma technique was employed for direct competitive ELISA to detect the concentrations of MCs in bloom and water samples collected in 2001. The results not only revealed the presence of MCs but also temporal variations of MCs levels of three sampling stations in Meiliang Bay in 1 year. It is obvious that the MC contents were relatively higher during warm months and related with the status of eutrophication. Our study indicates the threat associated with MCs in water body of Taihu Lake. To prevent the MCs potential hazard on public health in this area, some necessary measures of monitoring and control of growth of cyanobacteria are urgently needed.     

汞(Ⅱ)和砷(Ⅲ)在草炭土胡敏酸上的吸附

为研究汞和砷在胡敏酸上的吸附特性,从辽宁彰武采集了草炭土并用稀碱法提取胡敏酸。研究胡敏酸对Hg（Ⅱ）和As（Ⅲ）吸附作用,探讨温度（15、25、35、45℃）、pH（3,5,7,9）和离子强度（Ca2+,H2PO4-）对该吸附的影响,并计算吸附活化能。结果表明：温度与胡敏酸对Hg（Ⅱ）的吸附呈显著正相关,而对胡敏酸吸附As（Ⅲ）的影响较小;pH对胡敏酸吸附Hg（Ⅱ）也呈正相关,而胡敏酸对As（Ⅲ）的吸附以中性最好,酸性、碱性下吸附量均降低;Ca2+对Hg（Ⅱ）的吸附有明显的抑制作用,H2PO4-对As（Ⅲ）的吸附影响很小。对等温吸附实验结果拟合证明,胡敏酸对Hg（Ⅱ）和As（Ⅲ）等温吸附更符合Freundlich模型。对动力学吸附实验结果拟合证明,准二级动力学方程能很好地描述胡敏酸对Hg（Ⅱ）和As（Ⅲ）的吸附。Hg和As（Ⅲ）在胡敏酸的吸附活化能分别为23.06 kJ·mol-1和2.65 kJ·mol-1,表明Hg（Ⅱ）在胡敏酸上的吸附以化学吸附为主,As（Ⅲ）在胡敏酸上的吸附以物理吸附为主。     

Ecological plasticity of nest-building behavior of the redwing (<Emphasis Type="Italic">Turdus iliacus</Emphasis> L.) in Karelia according to individual marking data

The placement of 1918 redwing nests has been analyzed, including 214 nests of 90 marked females (2–8 known nests per female). A high level of intraspecific and individual variation in utilization of different types of nest supports is described. It is shown that redwings choose nest sites without regard to previous experience (either positive or negative) or to the placement of their parent nest. Under conditions of the northern taiga, such behavior provides for significant reduction of chick mortality by the end of the season. This is con- firmed by comparison with the song thrush (T. philomelos), which nests mainly on spruce trees.     

揭开武汉东湖蓝藻水华消失之谜

水华（亦称湖靛）是湖泊富营养化最恶劣的表征之一。武汉东湖７０年代至１９８４年间每年夏季出现蓝藻水华,１９８５年起突然消失,至今已有１４年没有重现,原因何在？通过三次设在湖里的围隔试验,证明鲢鳙的大量放养,是水华消失的决定性因素。     

岷江上游山地生态系统的退化及其恢复与重建对策

阐述了岷江上游山地生态系统的主要特征及主要由人类活动引起的森林、草地、农用地和整个山地生态系统环境退化现状。在此基础上，提出了岷江上游退化山地生态系统恢复与重建的对策，即加强资源和环境的合理利用和保护，提高全民环境保护意识；分区分类治理；不同区城不同退化亚系统采取不同的技术方法。同时，就恢复与重建过程中应注意的几个问题出提出了解决的思路和方法。     

环境污染事故灾害的特点与影响分析

环境污染事故灾害现已成为环境灾害中不可忽视的灾种之一，严重威胁着人们生命与财产的安全，并制约着环境经济社会的持续稳定发展。本文根据山东省近几年环境污染事故灾害的状况，系统分析了其特点与环境影响，并提出了相应的防减灾对策。     

火灾中均布荷载作用下钢筋混凝土方板的极限分析

本文利用有限差分法确定了火灾时钢筋混凝土板的温度分布，并基于塑性铰线理论确定了火灾时钢筋混凝土方板的破坏机制，根据高温下混凝土和钢筋的力学性能对火灾过程中塑性铰截面的弯矩及板的极限荷载进行了分析，可为建筑结构的耐火设计提供依据。     

Externalities, Floating Population and Spatial Agglomeration

With the further development of socialist market economy, the mobility of factor markets in China, especially the labor market, is strengthened. Externalities interacts with the agglomeration of productive factors. Under the framework of new economic geography, this article presents a theoretical model involving the endogenous population density affected by urban externalities. Results show that the population density is more concentrated around the center because the degree and extent of interaction between individuals intensifies when the distance from the center decreases. When there are several externalities resources, the aggregation of externalities changes the configuration of spatial factor allocation. These results fit well with the empirical facts about the decreasing density of floating population along the cities of Guangzhou, Dongguan and Shenzhen in Guangdong Province which is situated in the eastern coast of the Pearl River Delta. We fred that under the impacts of externalities released from Hong Kong into the coast, floating population was more concentrated around Shenzhen and Dongguan, which are more adjacent to Hong Kong compared with Guangzhou City.     

陕西大暴雨时空分布特征及减灾对策

通过对陕西１９５７～１９９８年共４２年９７个测站的逐日降水量中大暴雨资料进行时间和空间尺度分析，总结归纳出陕西灾害性大暴雨的天气气候基本特征和规律性，并提出相应的减灾对策。