标准系列加入回归法测定燃油中微量氮

对燃油中含氮量的测定方法进行了研究，提出了一种分析测定燃油中微量氮的简便方法。在待测柴油中加入一系列不同体积的吲哚标准溶液后，让油样在亚硒酸催化作用下，经浓硫酸预消解——稀硫酸回流消解、碱性条件下蒸馏及馏出液用稀硫酸接收，使其中的有机氮变为无机氮，继而转化成为可分析试样，最后用麝香草酚比色法一线性回归法算出柴油中的总氮。该分析方法的回收率在98．0％～100．2％之间，相对标准偏差小于2．14％。     

质量流量比法配制标准气体

介绍了一种利用控制气体质量流量比率的方法配制标准气体的动态配气装置。其特点是所配制的标准气体浓度值不受气温和气压的影响,显示直观,是一种精度高、稳定性好、耐腐蚀并可长期连续供气的配气设备。     

原子吸收法测定降水中的钾、钠、钙、镁的改进

对标准分析方法中的K、Na、Ca、Mg分开测定改进为混合测定。改进法与标准法的校准曲线、精密度与准确度均较为一致。改进法简化了操作程序，提高了工作效率。     

危险废物分级管理方法研究

危险废物因具有毒性、易燃性、腐蚀性和反应性等多种危害特性,如果暴露于环境中将会对人类健康和生态环境造成很大威胁.深入分析了欧美等一些国家对危险废物进行分级管理的方法,针对中国目前危险废物的产生现状和管理现状,提出了综合考虑危险废物的产生量和活性大小等各个方面,借助风险评价对危险废物进行分级管理的方法和原则,以及相应的分级管理程序的建议,为完善中国的危险废物管理体系提供参考.     

Predicting tree species presence and basal area in Utah: A comparison of stochastic gradient boosting,generalized additive models,and tree-based methods

Many efforts are underway to produce broad-scale forest attribute maps by modelling forest class and structure variables collected in forest inventories as functions of satellite-based and biophysical information. Typically, variants of classification and regression trees implemented in Rulequest's^© See5 and Cubist (for binary and continuous responses, respectively) are the tools of choice in many of these applications. These tools are widely used in large remote sensing applications, but are not easily interpretable, do not have ties with survey estimation methods, and use proprietary unpublished algorithms. Consequently, three alternative modelling techniques were compared for mapping presence and basal area of 13 species located in the mountain ranges of Utah, USA. The modelling techniques compared included the widely used See5/Cubist, generalized additive models (GAMs), and stochastic gradient boosting (SGB). Model performance was evaluated using independent test data sets. Evaluation criteria for mapping species presence included specificity, sensitivity, Kappa, and area under the curve (AUC). Evaluation criteria for the continuous basal area variables included correlation and relative mean squared error. For predicting species presence (setting thresholds to maximize Kappa), SGB had higher values for the majority of the species for specificity and Kappa, while GAMs had higher values for the majority of the species for sensitivity. In evaluating resultant AUC values, GAM and/or SGB models had significantly better results than the See5 models where significant differences could be detected between models. For nine out of 13 species, basal area prediction results for all modelling techniques were poor (correlations less than 0.5 and relative mean squared errors greater than 0.8), but SGB provided the most stable predictions in these instances. SGB and Cubist performed equally well for modelling basal area for three species with moderate prediction success, while all three modelling tools produced comparably good predictions (correlation of 0.68 and relative mean squared error of 0.56) for one species.     

平均综合污染指数在地面水污染分级中的应用

根据对污染物污染分担率，在确定地面水体主要污染物的基础上，计算相应水体不平均综合污染指数、对地面水污染程度进行分级。     

Social determinants of soil and water conservation in rural Kenya

Soil erosion is a major environmental problem and threat to rural development in Kenya. Numerous attempts to address the problem have apparently had little success. There are however some districts that have been very successful, notably Machakos. In this study we search for the factors that determine successful development in soil conservation such as social capital, human capital and market integration. One of our main results is that social capital measures are significant determinants of investment in soil conservation. A better understanding of the relevant mechanisms is essential for developing policies targeting improvement in natural resource management.

钢铁企业水系统实现节能减排的技术措施

很多钢铁企业面临着工业污水量远大于回用水量,处理后的工业污水因缺少用户只能外排而同时还需引入大量的工业新水的尴尬局面。节能减排不只是减少工业新水用水量和全部工业污水处理回用,更重要的是要实现工业污水排放量和回用水量之间的平衡。结合某钢铁公司的实际情况,就钢铁企业水系统实现节能减排的技术措施进行了探讨,作为工程实践的一种参考。     

水中轮状病毒实时定量PCR外标准品的构建

采用细胞培养和T-A克隆技术,在轮状病毒主要结构蛋白VP7基因序列上设计合成引物,经PCR扩增后将特异性产物连接入pGEM-T-easy载体中,经过酶切鉴定和测序分析获得轮状病毒cDNA标准品.利用常规PCR和实时定量PCR方法对所获得的cDNA标准品进行特异性、稳定性和重复性指标的检验.结果表明,利用此标准品制备的标准曲线具有较高的扩增效率和良好的线性关系(斜率为-3.353,R2=0.995);实时定量PCR熔解曲线分析表明,温度在81℃±0.5℃的PCR产物是轮状病毒VP7序列上的特异性产物,表明此标准品是轮状病毒特异性的;同时,所制备的标准品在实时定量PCR检测中具有较大的线性范围(9×100～9×1011 copies/μL,每个反应最低可以检测到9个拷贝数的轮状病毒cDNA,表明利用该标准品进行实时定量PCR分析时具有较高的检测灵敏性;此外,该标准品具有较高的稳定性和重复性(3次独立实验CV值在0.2%～0.9%之间),可长期稳定保存.构建的标准品可用作检测水环境中轮状病毒的实时荧光定量PCR的外标准品.     

气相色谱法对本底大气氧化亚氮浓度的标气定量方法研究

利用气相色谱-电子捕获检测器法(GC-ECD)测量大气中氧化亚氮(N_2O)浓度是目前广泛使用的方法,但ECD分析N_2O时存在线性范围较窄的缺点,因此,标气数量和定量方式是决定分析结果的关键因素.基于此,本文对比分析了单点线性校正法(S)、多点线性拟合法(D)、单瓶标气近似校正法(SA)、单瓶标气比值校正法(SC)对N_2O检测分析结果的差异.结果表明,SA定量相对误差最小,对测试使用的6瓶标气定值平均误差为0.09×10~(-9).根据本底大气N_2O观测精度要求,以及我国大气N_2O浓度变化范围较大的特征,推荐选用SA法对大气中N_2O浓度进行定值.依据所选方法对黑龙江龙凤山本底站大气N_2O浓度进行观测(2015年1—12月),结果显示,黑龙江龙凤山站大气N_2O浓度最高值出现在4—5月,平均值超过330×10~(-9).该站大气N_2O浓度主要受人为活动排放的影响.