PESTICIDES IN GROUND WATER: DO ATRAZINE METABOLITES MATTER?1

ABSTRACT: Atrazine and atrazine-residue (atrazine + two metabolites - deethylatrazine and deisopropylatrazine) concentrations were examined to determine if consideration of these atrazine metabolites substantially adds to our understanding of the distribution of this pesticide in groundwater of the midcontinental United States. The mean of atrazine.residue concentrations was 53 percent greater than that of atrazine alone for those observations above the detection limit (> 0.05 μg/l). Furthermore, a censored regression analysis using atrazine-residue concentrations revealed significant factors not identified when only atrazine concentrations were used. Thus, knowledge of concentrations of these atrazine metabolites is required to obtain a true estimation of risk of using these aquifers as sources for drinking water, and such knowledge also provides information that ultimately may be important for future management policies designed to reduce atrazine concentrations in ground water.     

A COMPARATIVE STUDY OF A SWEDISH AND A CHINESE HYDROLOGICAL MODEL1

ABSTRACT: There are a large number of conceptual hydrological models available today. It is not easy to immediately identify the similarities and differences between the different models. The Swedish HBV model and the Chinese Xinanjiang model are two examples of conceptual, semi-distributed, rainfall-runoff models. The Xinanjiang model was designed for use in humid and semi-humid regions, with no routine for the snowmelt runoff, whereas the snow routine is an important part of the HBV model in many applications. The model structures of the two models may be described in four routines, compared in this paper. The integral structures of them are similar, but there are some differences, especially in the runoff production routine. The physical significance and physical definitions of some model parameters were analyzed. Both models were tested in two basins. Both models gave similar results, and both models performed well in the application. The similarity of the results obtained by different model structures leads to the following two conclusions. First, more effort should probably be spent on the improvement of input data quality and coverage than on the development of more detailed model structures only. Second, inference about basin behavior and characteristics from the values of calibrated model parameters must be made with great caution.     

用灰色模型预测我国铁路水害发展趋势

根据近１５ａ来我国铁路水害年断道时间和断道次数的数据特点，将不同程度水害年分为三个等级。在此基础上，建立了铁路水害的灰色预测模型。并用此模型预测了近期铁路水害大小和远期的发展趋势。这对于我国铁路水害防治的宏观决策具有指导意义。     

土氡测量在地质灾害勘测中的干扰实验研究

对土氡勘测中来自测量过程、勘测场地条件、气象因素方面的常见干扰进行了实验研究，探讨了干扰机理，指出了定性及部分定量排除干扰的方法。     

北京地区15000年以来环境变迁中灾害性气候突变事件的讨论

通过高分辨率孢粉分析及烧失量、炭屑实验结果的统计分析，结合１４Ｃ、古地磁等，对北京房山东甘池１５０００ａ以来植被变化和环境变迁进行了较为深入的研究，特别强调气候变化的灾害性突变事件。初步得知约在１４１００～１４０００ａＢ．Ｐ．前后曾出现与哥得堡反转相对应的事件，在１００００ａＢ．Ｐ．左右出现类似与新仙女木事件相对应的事件，在大约５７７０ａＢ．Ｐ．和４５６０ａＢ．Ｐ．左右及２８５０～２６５０ａＢ．Ｐ．出现了大暖期的突然降温事件。     

人为泥石流灾害严重等级的定量模糊综合评判

根据神府－东胜矿区人为泥石流的调查分析，选择１５个因素（含５个主控因素）作为其严重程度的评价因子，确定了四值逻辑（严、中、轻、否）评判的定量标准。应用模糊综合评判和分层定量模糊综合评判两种方法对该煤田６５条泥石流沟的严重等级进行综合判别，准确性达９３．１％，它为保护该地煤田建设和工农业生产提供了重要的科学依据。     

Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends

In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially oriented films showed an increase in tensile strength, modulus, and strain-at-break.     

施工企业安全文化的核心——保护员工的安全与健康

分析了企业安全文化的发展和施工安全的特点，围绕企业目标、市场占有率、生产成本、企业形象、经济效益等内容，论述了保护员工安全与健康是施工企业安全文化的核心     

地质勘探巷道的通风新方法探讨

探讨了巷道通风的新方法，其中包括用间断风筒的通风、半循环通风、封闭式通风、高压通风机通风等，并就通风研究的发展方向提出了几点建议     

事故树定量分析与安全指标的数学模型的建立

阐述了在该课题研究过程中，提出的一些新概念、新定义和新方法