澜沧江流域沉积物间隙水-上覆水营养盐特征与交换通量分析

为分析澜沧江梯级水库建设对澜沧江流域沉积物-水界面交换过程的影响,于2016年2~3月对澜沧江云南段间隙水-上覆水氮、磷营养盐进行了调查与分析.结果表明,澜沧江自然河道沉积物间隙水总氮(TN)均值为15.254 mg·L~(-1),显著高于水库均值6.577 mg·L~(-1);但其总磷(TP)均值为0.654 mg·L~(-1),低于水库区域的1.432 mg·L~(-1).澜沧江流域沉积物间隙水氮、磷浓度均高于上覆水浓度,上覆水-间隙水垂向TN浓度在表层沉积物处达到最大值,且自然河道总溶解氮(DTN)扩散通量均值为2.117 mg·(m~2·d)~(-1),高于水库的均值0.785 mg·(m~2·d)~(-1);但其总溶解磷(DTP)扩散通量为0.044 mg·(m~2·d)~(-1),低于水库的均值0.053 mg·(m~2·d)~(-1),上覆水氮盐主要来源于沉积物间隙水.澜沧江梯级水库建设导致的沉积物组成差异与水体扰动差异是间隙水-上覆水界面交换差异的主要原因.     

巢湖西部河口区沉积物氮磷分布特征与原位扩散通量估算

选取巢湖西部重污染入湖河口区,研究表层沉积物氮磷污染特征,并运用Fick定律估算沉积物-水界面氮磷原位扩散通量.结果表明:南淝河、派河、十五里河河口表层沉积物总氮平均含量达到2208.17 mg·kg~(-1),氮形态以有机氮为主,占比达到90%以上.表层沉积物总磷平均含量为704.59 mg·kg~(-1),其中铁铝结合磷、活性有机磷和钙镁结合磷分别占比27%、28%和18%.河口区水体氨氮浓度从上覆水到孔隙水中总体呈上升趋势,沉积物表层(0~5 cm)孔隙水中氨氮平均浓度为25.42 mg·L~(-1),是上覆水中的7倍.沉积物孔隙水中硝氮与正磷酸盐浓度在垂向上随深度的增加呈先上升后降低的趋势,在沉积物-水界面附近达到浓度最高值.3个河口沉积物孔隙水中氮磷营养盐均向上覆水扩散,其中氨氮扩散通量分别为25.87、74.85与18.08 mg·m~(-2)·d~(-1).硝氮与正磷酸盐扩散通量较低,范围分别在1.38~2.78和0.011~0.024 mg·m~(-2)·d~(-1)之间.总体上看,巢湖西部河流入湖河口区表层沉积物氮污染严重,且存在较高的氮磷营养盐释放风险,应是巢湖富营养化控制过程中重点关注的区域.     

Impacts of ocean CO2 disposal on marine life: II. Probabilistic plume exposure model used with a time‐varying dose‐response analysis

A method to evaluate aquatic mortality given a pollutant distribution is presented and applied to several sample low pH plumes representing various ocean CO₂ disposal schemes. The method is an improvement over current analysis because it integrates the mortality due to timevarying exposure to low pH with the probabilistic experiences of passive organisms subject to turbulent lateral diffusion as they pass through the plume. For the examples presented, the plume was discretized laterally into lanes and longitudinally by time steps, and a random walk model accounting for the scaledependent nature of relative diffusion was used to simulate the organism pathways over one time step. From these simulations, the probability that an organism will be in a given lane, , one time step after it starts from an initial lane, , was determined for all combinations of and . These probabilities were used to find the number of organisms following each of the possible pathways, and the mortality to the organisms due to their time varying exposure to low pH was determined by using the toxicity model described in part I of this paper. The integrated method allows the impact of the plume to be described in terms of total organism mortality as well as spatial deficit of organisms.     

Heavy Metal Tolerance in Chromogenic and Non-Chromogenic Marine Bacteria from Arabian Gulf

A simple method – direct agar diffusion assay – was optimised for rapid assessment of heavy metal toxicity to marine chromogenic and non-chromogenic bacteria. The procedure involved spotting of a 10 microliter test solution on the seeded agar plate and incubation of the plates at 30°C to accelerate bacterial growth. Under optimum conditions, test results were obtainable within 12–18 hr instead of 96 hr incubation time generally required for a marine bacterial assay by conventional agar plate methods. A range of sixteen heavy metals, each at 5 different concentrations was tested. Toxicity was demonstrated by the formation of a clear zone of growth inhibition around the point of application. Toxicity of tested chemicals could be easily demonstrated at concentrations as low as 0.1 g per spot on the agar plate. A dose dependent relation between metal concentration (g/spot) and the diameter of the clear zone on agar plate was observed, suggesting potential of this method as an easy and economical tool in quantitative toxicology studies.     

A Novel Technique for Monitoring Contaminant Transport Through Soils

An experimental setup which is capable of simulation as well as monitoring contaminant transport through soil mass has been developed. Efficiency of the experimental setup has been demonstrated by comparing the results obtained from the argentometric method. Reynolds number (R_e) and the Peclet number (P_e) have been found to be less than unity. This indicates that flow of the solute through soil mass is laminar and the dominant contaminant transport mechanism is diffusion.     

关于河流污染事故的若干数学估计

为了预报突发河流污染事故的环境影响,对污染物迁移的相关估计和研究是非常必要的.以一维河流中的污染物迁移扩散模型为基础,讨论了几种不同情况下污染物浓度随空间的分布和随时间的变化.通过相应的数学推导,得到了若干简洁的估计公式:如污染物浓度的最大值点、达到某一浓度限值所经历的时间等.在获取足够的数据进行具体的数值模拟之前,由这些估计式可以得到污染物迁移过程中的一些重要特征量.     

氧化塘水力特性模型研究

氧化塘是一种被广泛应用且运行费用较低的污水处理设施，其流型有多种模型可供采用，但主要模型参数纵向扩散系数（D）和扩散因素（d）均难准确预测，为了满足这些模型的通用性就需要建立所需参数的预测方程。通过氧化塘模型研究，利用示踪实验技术测定了水力逗留时间分布，提出了一种计算氧化塘模型纵向扩散系数D的经验公式，为求取扩散因素d或扩散传质准数Pe提供了简便方法。用所得经验公式求得胜利油田桩西联采油废水氧化塘Pe值，与实测值较好吻合，相对偏差为6．61％。     

危险气体泄漏扩散的实验方法研究

综述了研究危险气体事故泄漏扩散的3种实验方法,即全规模大型现场实验、实验室模拟和小型现场实验,详细讨论该3种试验方法在实施和应用中的优缺点。对小型现场实验的无量纲长度、速度、时间、大气稳定度、大气湍流、液滴的尺寸分布和沉降、源动量通量比例等重要参数的确定方法重点进行分析和阐述。小型试验法特别适用于模拟化学性质活泼的危险气体的泄漏扩散研究,可为安全评价、应急救援提供有价值的参考数据。     

公共大空间建筑生化恐怖模式和通风技术分析

公共大空间建筑生化恐怖模式主要有制造火灾产生毒性气体、爆炸毒气弹分散毒性物质和人工直接布洒毒性物质。分析表明:火灾烟气受热浮力作用,在建筑物上部出现明显的烟气层,采用自然或机械排烟能有效地减缓或控制烟气层下降;爆炸分散毒性物质,除了爆炸点周边区域外,毒气扩散受热气流诱导,以及浓度差引起的运动;不考虑室内对流气流的影响,人工布洒毒性物质产生的毒性气体,其扩散主要是由浓度差引起的。不同类型恐怖袭击产生的毒性气体受室内对流气流的控制,合适的通风方式能够控制毒性气体的扩散和输运过程。但能否采用某一形式的通风系统兼备防范不同类型的恐怖袭击,需要对通风系统的通风量、气流组织和控制方式做更深入的研究。     

Excel在环境评价中污染物扩散模式上的应用

Excel是办公自动化的重要软件，利用Excel编制程序，结合《环境影响评价技术导则》给出的扩散模式，可方便快捷地计算出环境影响评价中污染物扩散浓度和分布特征，结果准确可靠。这一方法，可供环境影响评价人员参考，以免除环评人员烦琐的运算过程。