Ammonia production and kinetic properties of glutamate dehydrogenase in the sipinculid Phascolosoma arcuatum exposed to anoxia

The amounts of total NH ₄ ⁺ detected in the external media in which Phascolosoma arcuatum had been exposed to various periods of anoxia were significantly greater than those in which the worms were exposed to normoxia for a similar period. The increased NH ₄ ⁺ production by P. arcuatum during anoxic exposure was unlikely to be due to an increased catabolism of adenine nucleotides or urea. In contrast, there were significant decreases in the concentrations of several free amino acids in the coelomic plasma and body tissues of individuals during the 48 h of anoxic exposure. The amount of NH ₄ ⁺ produced by the anoxic P. arcuatum could be accounted for by the decreases in the concentrations of aspartate or glycine. Increases in the catabolism of free amino acids (FAA), leading to the increased production of NH ₄ ⁺ , in P. arcuatum during anoxia were supported by the detection of significant changes in the kinetic properties of glutamate dehydrogenase (GDH), in the deaminating direction, from worms exposed to anoxia for 48 h. The apparent increase in the affinity of GDH from the anoxic worm to glutamate would bring about a greater deaminating activity at physiological concentrations of ths substrate. P. arcuatum used in these experiments were collected from the mangrove swamp at Mandai, Singapore between 1990 and 1993.     

青岛工业与资源灰色关联分析

本文应用灰色关联分析方法研究了青岛地区主导工业对资源的依赖状态及不同工业行业之产出对各类资源投入的反应程度,以灰关联树反映工业经济与资源复合系统之整体及不同层次子系统的耦合关系,定量揭示工业经济效益主导变量与各类资源变量的动态联系,从资源高效利用的角度探讨了青岛工业产业结构调整和优化的方向及区域经济与环境效益相协调的可能途径。     

Coping with riverbank erosion hazard and displacement in bangladesh: survival strategies and adjustments

As a deltaic plain, Bangladesh annually experiences riverbank erosion hazard due to sudden and rapid channel shifting, particularly in the major floodplain areas of the country. Consequently, valuable cultivable land is lost; also village settlements, markets and towns are destroyed, displacing tens of thousands of people. This paper examines the magnitude of river channel migration and encroachment on land, and the nature of human adjustment systems in the Brahmaputra–Jamuna floodplain, by investigating aspects of the social and cultural dynamics of resettlement of the displaced people. Some policy measures are recommended to improve the ability of the people in the floodplain to cope with these hazards.     

Fractionation of butyltin species during sample extraction and preparation for analysis

Solvent extraction and evaporative concentration steps are often used in procedures for the measurement of butyltins in environmental samples. As part of a larger study utilizing radiolabeled butyltins, the loss and fractionation of butyltins during sample preparation was investigated. TBT, DBT, and MBT were extracted from acidified seawater by hexane with efficiencies of about 95–99, 50–60 and 11% respectively. In addition, losses of about 70% of DBT were found during evaporative concentration of hexane. A variety of sediment extraction procedures were tested and none were found to be highly efficient for total butyltin extraction.     

模拟消落带水华暴发行为的数值沙堆模型

以长江最大支流汉江近年来水华污染的现场资料为例,通过氮磷浓度、水温、流速和光照等实测数据构建了消落带开放水域环境体系的数值沙堆模型,描述了藻类生长及水华暴发的动力学机制;利用数值沙堆系统崩塌行为反映出的频率-尺度幂律关系作为判断消落带水域是否暴发水华以及规模大小的依据,采用有限尺度标度分析从不同侧面验证了水华暴发系统的自组织临界性,并揭示出各种拟合参数与水华暴发规模之间的定量关系.研究表明,沙堆模型如果存在良好的幂律关系,相应的消落带水域将暴发水华,且幂律指数越大,水华污染程度越严重.     

柱撑粘土材料的环境化学行为

柱撑粘土是一种新型的复合材料，国内外近年来进行了广泛和深入的，本文系统评述了国内外柱撑粘土复合材料的环境化学行为，吸附重金属离子，吸附苯酚类物质，吸附磷类物质，吸附废水中的COD，大气污染等方面，揭示该种新材料在各种污水处理中具有广阔的应用前景。     

木质素降解酶及其调控机理研究的进展

近年来有关木质素降解微生物和木质素降解酶的产与调控机理的研究表明，腐霉和细菌在木质自然降解中起着重要作用，腐霉的降解作用发生在次级代谢阶段，而细菌发生在初级代谢阶段，影响木质素降解酶的产生酶活力高低的因素有碳氮的选择与限制；诱导物的添加；表面活性剂的使用；某些金属离子浓度水平的改变；菌丝的固定化，温度和摇床转速的变换等。     

日本八大公害案件裁决后的日本环境法发展及对中国环境法发展之借鉴

分析了日本八大公害案件的裁决对日本环境法发展的影响，如法制思想的转变，判例的应用，民事责任制度的发展以及环境管理机构的完善等，讨论了其对中国环境法制建设的借鉴。     

对今后我国海洋环境保护工作的几点设想

本文比较全面地阐述了近年来我国海洋环境保护工作所取得的主要成就，并针对未来沿海经济的迅速发展将给海洋环境带来的压力，探讨深入开展海洋环境保护工作。