龙口市海水入侵动态系统分析与防治对策

海水入侵已成为全球普遍关注的地下水环境问题,它不仅严重地威胁着人类淡水资源,而且破坏生态环境平衡,制约着社会经济可持续发展。以山东省龙口市为靶区,通过分析研究衡量海水入侵重要因子－氯离子浓度时空分布规律及其影响因素,探索海水入侵动态系统规律,提出防治海水入侵的措施和对策。     

Carrousel氧化沟单个表曝机流态的模型试验和分析比较

对仅安装1个倒伞形表面曝气机(简称表曝机)的Carrousel氧化沟模型进行了水力学测定,通过颗粒动态分析仪(PDA)系统分析流出和流入表曝机一侧的液体流动速度、沉降速度,以及固体含量分布.结果表明,流出表曝机一侧,距表曝机较近的x轴位置流速较大;沉降速度沿y轴有个转折点,位于沟壁与挡板的中间;远离单个表曝机,固体含量逐渐增大.并将单个表曝机的测量结果与氧化沟内安装2个表曝机的流动试验进行比较,发现2个表曝机所产生的流场与单个表曝机产生的流场差别较大,且2个表曝机所产生的流场更稳定.      

Does industrial waste taxation contribute to reduction of landfilled waste? Dynamic panel analysis considering industrial waste category in Japan

Waste taxes, such as landfill and incineration taxes, have emerged as a popular option in developed countries to promote the 3Rs (reduce, reuse, and recycle). However, few studies have examined the effectiveness of waste taxes. In addition, quite a few studies have considered both dynamic relationships among dependent variables and unobserved individual heterogeneity among the jurisdictions. If dependent variables are persistent, omitted variables cause a bias, or common characteristics exist across the jurisdictions that have introduced waste taxes, the standard fixed effects model may lead to biased estimation results and misunderstood causal relationships. In addition, most existing studies have examined waste in terms of total amounts rather than by categories. Even if significant reductions in total waste amounts are not observed, some reduction within each category may, nevertheless, become evident.Therefore, this study analyzes the effects of industrial waste taxation on quantities of waste in landfill in Japan by applying the bias-corrected least-squares dummy variable (LSDVC) estimators; the general method of moments (difference GMM); and the system GMM. In addition, the study investigates effect differences attributable to industrial waste categories and taxation types. This paper shows that industrial waste taxes in Japan have minimal, significant effects on the reduction of final disposal amounts thus far, considering dynamic relationships and waste categories.     

电感耦合等离子体质谱法测定土壤样品中的痕量硒元素

随着电感耦合等离子体质谱技术的发展,准确测定环境样品中的痕量硒元素含量越来越受到关注。质量数76、78、80和82的硒元素受氩的多原子干扰非常严重,必须进行校正才能得到满意的结果。利用动态反应池模式对土壤样品的测定条件进行条件优化,将Cell Gas从0.3～0.7ml/min步幅0.1ml/min、RPQ从0.45～0.7步幅0.05进行同步优化,最终确定针对消解样品的Cell Gas为0.5ml/min,RPQ为0.45,78Se是最佳的测定同位素。通过石墨电热赶酸仪赶酸,适当稀释控制可溶性固体量,在线加入103Rh内标来克服基线漂移,提高了分析方法的准确性。2%甲醇的加入提高了硒在电感耦合等离子体中的离子化强度,在一定程度上增强了低浓度的响应值。根据国家标准参考物质的分析结果评价方法的准确性,证实所建立的方法简便、准确、快速。     

顶空-毛细管柱气相色谱法测定气样中甲醇

对自动顶空进样器与气相色谱法联用技术测定环境空气和废气中甲醇的方法进行了研究。结果表明：当样品加入4g氯化钠，顶空平衡温度为80℃，平衡时间为20min，用HP—FFAP毛细管柱分离，氢火焰离子化检测器检测时，得到甲醇标准曲线方程为y=23415x＋237．2，相关系数（R）0．9994；检出限为0．002mg／m2，相对标准偏差（n=6）为0．5％，加标回收率为98．9％。该方法简单、灵敏、分离度好、检出限低。     

Mutual effects between dynamic leakage behavior and the pressure/temperature in a LNG tank with external heat fluxes

The objective of this work is to investigate and model the mutual effects between the dynamic pressure/temperature in the LNG tank and the leakage behavior with external heat fluxes. The results suggest that the pressure and temperature in tank during leakage change with the comparison results between the heat flux consumed in liquid boil-off and the external heat flux supplied. At the liquid leakage stage, when the external heat flux is not very high, the pressure in tank tends to increase significantly, even results in tank explosion. It increases more and more heavily with higher and higher external heat fluxes. At the vapor leakage stage, large amount of vapor spray out, which results in a high generation rate of vapor by the liquid boil-off. The pressure in tank normally decreases to be low, which is unfavorable for the LNG tank explosion. Therefore, at this vapor leakage stage, blocking the leakage hole as soon as possible is not always a right choice for fire fighters. Finally, it is suggested that reducing the heat flux into the tank, either at the liquid leakage stage or in vapor one, is key to the tank safety.     

What is the acceptable margin of error for the oxygen uptake method in evaluating the reactivity of organic waste?

The acceptable margin of error for the organic waste reactivity measured by the oxygen uptake method was assessed. Oxygen uptake was determined by the Dynamic Respiration Index (DRI) (mgO₂/kgVS h). The composed uncertainty (uC) of the experimental set up used for the DRI test was evaluated and the uncertainty (u) of all the components of the apparatus was evaluated. A procedure for calculating the uC of the apparatus is proposed. The components affecting the uC of the DRI to a more significant extent were the one of the oxygen mass rate and the u of the amount of VS in the sample analyzed. For a confidence level of 99.73%, the extended uC (UC) interval for a DRI = 1024 mgO₂/kgVS h was ±440 mgO₂/kgVS h, whereas for a DRI = 3489 mgO₂/kgVS h, the UC interval was ±1288 mgO₂/kgVS h. When oxygen consumption and VS content become lower than 600 mgO₂/h and 0.9 kg, respectively, the UC interval is similar to the measured DRI.     

松花江哈尔滨段主干流常规污染物动态衰减速度系数的测算研究

采用2011—2013年松花江哈尔滨段各断面水质监测数据和老头湾水文数据,运用实测资料反推法和河流一维水质模型对该段干流的COD、BOD5、NH3-N的衰减速度系数K进行测算,结果表明:1—12月朱顺屯—大顶子山的KCOD、KBOD5、KNH3-N分别在0.035 d-1~3.372 d-1、0.368 d-1~5.459 d-1和0.245 d-1~5.600 d-1之间;冰封期各污染物K值小于明水期,夏季(6—8月)K值大于其他季节。以2013年阿什河口下—呼兰河口下河段上、下游各断面的监测数据对测算的各污染物动态K值进行率定,实际监测值与预测浓度年内变化趋势基本一致,相对误差在25%以内,水质验证结果较满意。     

基于环境一号卫星CCD数据的巢湖叶绿素a的动态监测

环境一号卫星CCD数据具有获取周期短、空间分辨率高等特点,能够及时准确地监测叶绿素a的浓度变化和分布,其在内陆湖泊水质遥感监测方面具有良好的应用前景。文章通过星地同步地面实验,建立起巢湖水体的叶绿素a浓度遥感反演模型,利用2009年4月至2010年3月的环境一号卫星CCD数据,分季节对巢湖叶绿素a行动态监测和分析。结果表明,巢湖叶绿素a具有明显的时空分布特征,夏季叶绿素a浓度最高,冬季最低,秋季高于春季;西半湖湖区叶绿素a浓度一般高于东半湖湖区,西北部和中部湖区空间变化比较大,东部湖区变化较小。     

Accident modelling and analysis in process industries

Accident modelling is a methodology used to relate the causes and effects of events that lead to accidents. This modelling effectively seeks to answer two main questions: (i) Why does an accident occur, and (ii) How does it occur. This paper presents a review of accident models that have been developed for the chemical process industry with in-depth analyses of a class of models known as dynamic sequential accident models (DSAMs). DSAMs are sequential models with a systematic procedure to utilise precursor data to estimate the posterior risk profile quantitatively. DSAM also offers updates on the failure probabilities of accident barriers and the prediction of future end states. Following a close scrutiny of these methodologies, several limitations are noted and discussed, and based on these insights, future work is suggested to enhance and improve this category of models further.