Approaches and terminology for causal analysis in land systems science

Research into land and social-ecological systems science could benefit from improved clarity in the terminology used for causal analysis and a structured way to make causal inferences. Here I identify two aspects of causality, i.e. causal effects and causal mechanisms, and discuss explanation in historical sciences. I then propose definitions for the major terms used for causal relations, including driver, (spatial) determinant, location and contextual factor, proximate and underlying factors. Finally, I discuss the contribution of various operational approaches, including time series and counterfactual approaches for assessing causal effects and process-tracing approaches for establishing causal mechanisms. Having a coherent concept of causality, agreeing on a precise vocabulary and harnessing our tools with the clear purpose of establishing both causal effects and causal mechanisms should strengthen causal explanations for single cases, for drawing policy-relevant lessons and for theoretical development in relation to land and, more broadly, social-ecological systems processes.     

地下水NH4+-15N同位素测试技术进展

本文根据铵离子的物理化学性质,建立了各种测试分析技术.传统的NH4+_-15N同位素测试过程包括样品中NH4+的收集、转化为适于质谱分析的气态N2以及用15N同位素质谱进行分析.其中NH:的收集方法较多,包括蒸馏法、扩散法、离子交换柱法和沸石萃取法等.适于质谱分析气态N2的转化方法可分为化学湿法和干燃烧法.笔者就同位素分析测试过程中NH4+的收集、转化及15N测试各个步骤加以总结,分析各自方法的优缺点和适用范围,寻求问题的解决途径.并评述了最近出现的色谱-质谱联合分析法和叠氮法.最后对地下水NH4+-15N同位素测试技术的发展进行了展望,以期能够更广泛地应用于环境和水文地质领域.     

汽车塑料饰件电镀工艺及其性能检测

本文重点讲述了汽车塑料电镀工艺以及其可能存在的各种问题,进一步介绍了相关问题的解决方法.参照目前国际上各大整车厂的性能检测方法,论述了如何对汽车塑料电镀成品件进行性能测试来确定其质量.随着各国对环保要求的提高,希望我国汽车塑料电镀工艺能紧追和应用先进工艺,减少对环境的污染.     

Effect of environmental parameters on the degradability of polymer films in laboratory-scale composting reactors

Previous research in our laboratory reported a convenient laboratory-scale composting test method to study the weight loss of polymer films in aerobic thermophilic (53°C) reactors maintained at a 60% moisture content. The laboratory-scale compost reactors contained the following synthetic compost mixture (percentage on dry-weight basis): tree leaves (45.0), shredded paper (16.5), food (6.7), meat (5.8), cow manure (17.5), sawdust (1.9), aluminum and steel shavings (2.4), glass beads (1.3), urea (1.9), and a compost seed (1.0) which is designated Mix-1 in this work. To simplify the laboratory-scale compost weight loss test method and better understand how compost mixture compositions and environmental parameters affect the rate of plastic degradation, a systematic variation of the synthetic mixture composition as well as the moisture content was carried out. Cellulose acetate (CA) with a degree of substitution (DS) value of 1.7 and cellophane films were chosen as test polymer substrates for this work. The extent of CA DS-1.7 and cellophane weight loss as a function of the exposure time remained unchanged when the metal and glass components of the mixture were excluded in Mix-2. Further study showed that large variations in the mixture composition such as the replacement of tree leaves, food, meat, and sawdust with steam-exploded wood and alfalfa (forming Mix-C) could be made with little or no change in the time dependence of CA DS-1.7 film weight loss. In contrast, substituting tree leaves, food, meat, cow manure, and sawdust with steam-exploded wood in combination with either Rabbit Choice (Mix-D) or starch and urea (Mix-E) resulted in a significant time increase (from 7 to 12 days) for the complete disappearance of CA DS-1.7 films. Interestingly, in this work no direct correlation was observed between the C/N ratio (which ranged from 13.9 to 61.4) and the CA DS-1.7 film weight loss. Decreasing moisture contents of the compost Mix-2 from 60 and 50 and 40% resulted in dramatic changes in polymer degradation such that CA DS-1.7 showed an increase in the time period for a complete disappearance of polymer films from 6 to 16 and 30 days, respectively.Guest Editor: Dr. Graham Swift, Rohm & Haas.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

总氮测定中应注意的几个问题

对总氮测定中影响空白值偏高的因素进行了实验和分析,并提出了改进意见。     

基于预测有效度一致的城市生活垃圾产生量预测

提出了基于预测有效度一致的城市生活垃圾产生量最优组合预测模型,该模型在组合预测之前利用Kendall一致性检验法对参加组合的单项预测模型值的拟合精度进行一致性检验,在通过检验之后再利用方差倒数法求解最优组合权重,建立组合预测模型。通过实例分析,表明其预测精度高于参加组合的各单项模型预测值,在城市生活垃圾产生量的预测工作中有一定的应用价值。     

可变径管道漏磁检测有限元仿真与实验研究

为了更好地支持压力管道检验,降低事故率,本文基于漏磁检测原理,利用有限元分析软件建立了管道外漏磁检测模型,对管道漏磁检测进行了仿真计算,得到了缺陷处漏磁场特征曲线,模拟了圆柱形缺陷对管道外壁漏磁场的影响,得出了不同参数缺陷对漏磁场的影响规律,并且基于理论和有限元计算结果试制了可变径管道外漏磁检测仪的样机,利用该检测仪对壁厚为8mm的带有人工缺陷的管道进行扫描检测,研究不同参数缺陷对漏磁场信号的影响规律。结果表明,所得结果与有限元仿真的结果吻合良好,且缺陷检测精度及效果满足要求,另外,检测装置对内外壁缺陷检测同样可行有效,适合特种设备（压力管道）检测的工程应用。     

芳纶在阻燃防护服中的应用及检测

本文介绍了间位芳纶和对位芳纶的性能,并对利用其性能制作的阻燃防护服进行了检测。     

湖北省油菜测土配方施肥下N2O减排潜力估算

以油菜种植大省-湖北省为案例地,在分析农田氮肥施用与油菜籽产量的基础上,依据氮肥利用率变化,估算测土配方施肥技术在湖北省全面推广的情况下,带来的N2O减排潜力.结果表明,在湖北省油菜种植中,测土配方施肥技术的推广将带来646.32ktCO2-eq的理论减排.以2012年湖北省油菜测土配方推广情况为基础,进一步全面实施该项技术,将产生173.91ktCO2-eq的减排量,占油菜种植因氮肥使用而产生的N2O排放总量的13.98%.测土配方施肥通过优化营养元素配比,提高油菜氮肥利用效率,是一项控制与减少农业N2O排放、减少氮素在环境中盈余量的有效措施.     

Analysis of the toxicity of glyphosate and Faena® using the freshwater invertebrates Daphnia magna and Lecane quadridentata

With the present contribution an evaluation of the toxicity of the pure herbicide glyphosate and its commercial formulation Faena® is reported using the cladoceran Daphnia magna Strauss and the rotifer Lecane quadridentata Ehrenberg. LC₅₀, EC₅₀, NOEC, and LOEC values for each toxicant and for both test organisms are obtained. Regarding acute toxicity, Faena was 11-fold more toxic to L. quadridentata than pure glyphosate and slightly more toxic to D. magna (1.7-fold). Inhibition of esterase activity in L. quadridentata by glyphosate was the most sensitive end-point; the EC₅₀ was 1500-fold smaller than the LC₅₀. The implications of these results and their comparison with established international and national limit values for glyphosate are discussed.