泰国和越南的产业改革和养虾业通向生态、社会及经济可持续发展的道路

越南的养虾业正处在对生产体系的基础改造,使其转变成一个重要产业的过程中.该地区其他国家的经验,特别是高投入生产体系占主导地位的泰国的经验表明,现在正是通过干预使养虾业改道进入在生态、社会和经济上更可持续的道路.在泰国,实施强化的体系和复杂的产业组织的多年经验并没有获得可持续的解决办法.这里所面临的任务是使社会重新赢得控制并沿着更有效和良性发展的道路改变改革的发展方向.我们的分析结果表明,这两个国家的现行方法不可能使养虾业可持续的发展,需要对整个对虾的生产、喂养、加工、供销及管理的方式进行全面改革.     

Carbon Dioxide Balance of Wood Substitution: Comparing Concrete- and Wood-Framed Buildings

In this study a method is suggested to compare the net carbon dioxide (CO₂) emission from the construction of concrete- and wood-framed buildings. The method is then applied to two buildings in Sweden and Finland constructed with wood frames, compared with functionally equivalent buildings constructed with concrete frames. Carbon accounting includes: emissions due to fossil fuel use in the production of building materials; the replacement of fossil fuels by biomass residues from logging, wood processing, construction and demolition; carbon stock changes in forests and buildings; and cement process reactions. The results show that wood-framed construction requires less energy, and emits less CO₂ to the atmosphere, than concrete-framed construction. The lifecycle emission difference between the wood- and concrete-framed buildings ranges from 30 to 130 kg C per m² of floor area. Hence, a net reduction of CO₂ emission can be obtained by increasing the proportion of wood-based building materials, relative to concrete materials. The benefits would be greatest if the biomass residues resulting from the production of the wood building materials were fully used in energy supply systems. The carbon mitigation efficiency, expressed in terms of biomass used per unit of reduced carbon emission, is considerably better if the wood is used to replace concrete building material than if the wood is used directly as biofuel.     

环烷酸脱油工艺的实验研究

以锦州化工二厂生产的２＃环烷酸为原料，采用减压蒸馏──初馏分皂化萃取脱油工艺，可制得中性油含量分别低于１０％和５％的一级品环烷酸．该工艺具有流程简单、物料消耗少、产品收率高等优点．通过实验，初步探讨了蒸馏真空度、氢氧化钠浓度及用量、乙醇用量、萃取剂用量等工艺条件对脱油效果及产品质量的影响。     

SO2污染对小鼠骨髓细胞微核的诱发作用

在SO2吸入慢性染毒条件下,小鼠骨髓嗜多染红细胞（PCE）的微核细胞率与微核率均显著增加,且雌雄差异显著。结果也表明,SO2对阳性致突变剂乌拉坦航发微核的作用有显著抑制效应。本研究模拟SO2空气污染,从整体水平直接证实了SO2是哺乳类细胞染色体断裂剂、SO2与阳性致突变剂的联合作用是复杂的结论。     

以运行费用函数为基础制定超标污水收费标准

根据现行的上海市和国家的超标污水征收标准的特点，提出制定新标准的５项原则。新标准的制定方案中，确定以ｙ＝ａ．ｘ＾β费用函数基础；用数理统计等方法，通过对污染排放标准，处理深度和处理费用３者关系的处理，得出二类污染物中，１级收费标准比现行２级收费标准上升３０％、２级收费采用现行标准、３级收费标准比现行标准下降２０－３０％；并提出污染物收费的计算公式，经对方案的论证和测算，说明其有效好的可行性。     

Effect of soil solids concentration in batch tests on the partition coefficients of organic pollutants in landfill liner-soil materials

 The effect of the soil solids concentration in batch tests on the measured values of the partition coefficient (K _p) of organic pollutants in landfill liner-soil material was investigated. Since this study was based on the results of batch and column tests conducted independently, there were limitations to the conclusions derived. The organic compounds tested were benzene, methylene chloride, toluene, trichloroethylene, and p-xylene. The results of this study showed that as soil solids concentrations increased, the measured K _p values of these organic compounds strongly decreased. The observed values of K _p stabilized when the soil solids concentration was above a certain value. Typical K _p values obtained from batch tests conducted under high soil solids concentrations were close to those obtained from column tests. It was concluded that the K _p values of organic compounds measured under low soil solids concentrations, i.e., less than 100 g/l, may not correctly simulate the field situation. Consequently, the values of K _p obtained with low soil solids concentrations can result in an overestimation of the retardation factor of the landfill liner material. Received: March 14, 2002 / Accepted: August 25, 2002     

STREAM DISCHARGE PREDICTION VIA A GRID BASED SOIL WATER ROUTING WITH PADDY FIELDS1

ABSTRACT: A grid based daily hydrologic model for a watershed with paddy fields was developed to predict the stream discharge. ASCII formatted elevation, soil, and land use data supported by the GRASS Geographic Information System are used to generate distributed results such as surface runoff and subsurface flow, soil water content, and evapotranspiration. The model uses a single flow path algorithm and simulates a water balance at each grid element. A linear reservoir assumption was used to predict subsurface runoff components. The model was applied to a 75.6 km² watershed located in the middle of South Korea, and observed stream flow hydrographs from 1995 and 1996 were compared to model predictions. The stream flow predictions of 1995 and 1996 generally agreed with the observed flow, resulting in a Nash‐Sutcliffe efficiency R² of 0.60 and 0.62, respectively. The hydraulic conductivity for percolating water through the saturated layer affected baseflow generation. The levee height of the paddy influenced the time and magnitude of the surface runoff, depending on irrigation management. The model will be used for making low flow management decisions by evaluating the role of each land use to stream flow, especially in case of paddy decrease by gradual urbanization of a watershed.     

Enhanced production of poly(3-hydroxybutyrate) by filamentation-suppressed recombinantEscherichia coli in a defined medium

Fed-batch cultures of recombinantEscherichia coli strains were carried out for the production of poly(3-hydroxybutyric acid) (PHB) in a chemically defined medium. TheE. coli strains used were XL1-Blue, harboring pSYL105, a stable high-copy number plasmid containing theAlcaligenes eutrophus polyhydroxyalkanoate (PHA) genes, and XL1-Blue, harboring pSYL107, which is pSYL105 containing theE. coli ftsZ gene to suppress filamentation. With XL1-Blue(pSYL105) the final cell mass and PHB concentration obtained in 62 h were 102 and 22.5 g/L, respectively. Fed-batch culture of XL1-Blue(pSYL107) under identical conditions resulted in a final cell mass and PHB concentration of 127.5 and 48.2 g/L, respectively. The PHB contents obtained with XL1-Blue(pSYL105) and XL1-Blue(pSYL107) were 22.1 and 37.8%, respectively. Therefore, PHB was more efficiently produced in a defined medium by employing filamentation-suppressed recombinantE. coli.     

Design of a representative and cost-effective sampling programs for industrial wastewater with examples from bleached kraft pulp and paper mills

The diagram constructed for selection of sampling methods indicates that, for a systematic error, E ≤ 13%, grab sampling (GS) may be used to characterize effluents with variation coefficient of flow ≤ 120% and of contaminant concentrations ≤ 10%. For the whole studied range of variation coefficient of contaminant concentrations (2–82%), time-proportional compositing (TC) method may be applied with E ≤ 10% for effluents characterized by variation coefficients in flow < 90%. The more complicated flow-proportional compositing (FC) method is required only for effluents with larger variation coefficients or to produce more precise results. The diagram constructed for selection of sampling frequencies indicates that sequential sampling at intervals of approximately 60 min may be applied with E ≤ 10% for effluents characterized by variation coefficients ≤ 30%. Practical application of the diagrams, constructed using normal series, was checked against monitoring data from two pulp and paper mills in Vietnam. The two diagrams provided results on sampling methods and frequencies in good agreement with those obtained from actual monitoring data with percentages of agreement cases of 80 and 75%, respectively. The approach was applied in design of a monitoring program at the Bai Bang integrated pulp and paper mill in Vietnam.