EXAMPLES OF LANDFILL-GENERATED PLUMES IN LOW-RELIEF AREAS,SOUTHEAST FLORIDA1

ABSTRACT: Areas of low topographic relief have low water-table gradients and make the direction of movement of contaminants from land fills in the ground water difficult to predict from regional gradients alone. The landfill, nearby free-flowing ditches or canals, variations in hydraulic conductivity, and the influence of nearby pumping wells can all affect the direction of flow. In low-gradient areas the concepts of “upgradient” and “downgradient” are less useful in planning the location of monitoring wells than in areas of higher relief. Low-relief areas also may be affected by the discharge of mineralized water from deeper aquifers, naturally or through irrigation, which can mask geochemical surveys intended to detect landfill leachate. Examples of effects of low topographic relief are noted in southeast Florida where water-table gradients are 7×10^?-⁴ to 5×10^?-⁴ feet per foot. Water-table mounding beneath the landfill and the drainage effects of nearby ditches and well have created multiple leachate plumes in Stuart where one plume migrated in a direction opposite to the apparent regional gradient. In Coral Springs analysis suggests a bifurcating plume migrating along two narrow zones. In Fort Pierce it was difficult to detect leachate because of mineralized irrigation water and fertilizer runoff from an adjacent citrus grove.     

煤中微量元素的环境效应

以华北某电厂燃煤为例,探讨了煤中微量元素的环境效应评价方法。通过电感耦合等离子体原子发射光谱(ICP-AES)等方法测定了电厂循环流化床炉原煤、飞灰、底灰中F,Pb,Hg,等11种微量元素的含量,通过淋滤实验测得了原煤及底灰中Pb、Hg、Cr等7种微量元素的淋出率,并测定了煤堆附近土壤中Cd、Hg、Cr等6种微量元素的含量,计算出了煤中微量元素对大气、水和土壤环境的污染因子。结果表明,燃煤中元素F、Hg、Se、Cl挥发性较强,燃煤中微量元素对大气环境的综合污染因子达3.5,属重污染。元素Hg、As的淋出率较高,原煤和底灰中微量元素对水环境的综合污染因子分别为0.71和0.88,污染程度属微污染。土壤对Cd、Hg、Pb等元素的富集程度很高,煤中微量元素对土壤环境的综合污染因子为0.98,属微污染。     

船运液态二氧化碳储罐爆炸事故的原因分析

在分析船运液态二氧化碳储罐爆炸事故的基础上,近似计算了其物理爆炸的能量,并采用TNT当量计算方法,分别估算了事故的人员死亡区域、重伤区域、轻伤区域的半径和建筑物毁灭性破坏区域的半径;同时根据事故容器设计参数的验算,指出由于对事故容器归属"低温压力容器"和"低温低应力压力容器"的错误划分造成制造材料选用的错误,以及违规使用,从而导致了事故的发生;并针对事故的原因,提出了应引起的反思。     

CO中毒的环境气象因子分析及预测方法研究

利用2006年9月~2007年3月全国CO中毒病例资料,选取日发病人数为8人以上的CO中毒事件发生日作为样本,对CO中毒的气象条件进行了分析研究.结果表明,微风或者静风、大气层结稳定的气象条件不利于CO气体的扩散,同时,气温变幅较小、气压下降、云量多和气体湿度大也可能间接导致CO中毒事件的发生.用风速、大气稳定度、24h变温、24h变压、总云量和相对湿度作为预报因子,利用阈值加权平均的方法,初步建立了区域性CO中毒气象潜势预报模型.     

垃圾渗滤液变组分浓度污染物运移耦合模型

基于非饱和溶质运移理论,建立了水分运移和溶质对流-扩散的动力学耦合模型,通过室内土柱试验拟合了垃圾有机污染物衰减曲线,在充分考虑垃圾污染物浓度衰减,土壤水环境吸附解吸、生物降解作用基础上,进行了污染物运移的数值模拟,模拟结果较真实地反映了污染物的运移规律,该模型可为定量预测垃圾场土壤中有机污染物的时空分布提供一定的理论依据。     

Exploring the effects of multiple management objectives and exotic species on great lakes food webs and contaminant dynamics

A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter (Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies of dominant organisms) that should be corrected in order to make reliable management decisions.     

太原市冬季PM2.5水溶性组分污染特征分析

为了探讨太原市大气阴霾天气的主要污染物PM2.5中水溶性组分的污染特征,于2011年12月~2012年1月,采用美国Thermal Anderson公司的大流量PM2.5颗粒物采样器进行了PM2.5样品采集,共获得样品56个.通过采样前后滤膜的重量变化计算PM2.5的质量浓度.并采用微波提取技术,用TOC/TN分析仪研究了水溶性TOC和水溶性TN等的污染特征.研究结果表明,太原市冬季采暖期PM2.5污染严重,并且比北京、天津、广州、南京、西安的污染水平都高.对PM2.5主要影响因素风速、相对湿度、温度和昼夜变化等的分析表明,风速大小与PM2.5的浓度大小呈负相关(r=-0.4693,α=0.05),相对湿度与PM2.5浓度呈正相关(r=0.4092,α=0.05),而温度与其浓度变化关系不明显;采样期间PM2.5浓度的昼夜变化规律不明显.水溶性TOC对PM2.5贡献较高,占PM2.5总量的13.2%~57.7%;NO3-、SO42-也与水溶性TOC有重要的相关关系.     

土石混合体REV尺度数值方法研究

土石混合体是一类较为复杂的宏观二元介质不连续岩土体,不同的块体分布情况及不同的试件尺度导致其具有不同的等效强度特性。基于随机集合体构造(RA S)方法构建了土石混合体的随机模型,编制程序实现了随机模型的输出和数值模型的生成。以西南某大型堆积体滑坡中的典型土石混合体为例,考虑含石量和不同粒径分布规律,建立多组不同尺寸随机模型,进行了大量的数值试验,得到了强度表征单元体积(REV)尺度,在此基础上得到了等效强度参数,并分析了土石混合体受力性能和渐进破坏模式。研究结果表明,土石混合体存在REV尺度,案例所得的REV尺度为1.0 m×1.0 m,不同尺度数值计算结果有一定差别,基于REV尺度的力学参数才符合工程意义。