A Database for Volatile Organic Compounds

The database for volatile organic compounds (VOC data base) was created with the aim of providing an overview of tropospheric hydrocarbon measurements. The data base contains 202 substances, for which atmospheric and useful kinetic data such as rate coefficients, photolysis frequencies, mixing ratios, emission data and ozone formation potentials are compiled from available literature. The database file can be downloaded without charge from http://www.physchem.uni-wuppertal.de/voc-database. Registered users will be informed about the appearance of updates.     

湖北一次冰雹天气过程的落区诊断分析和预报

利用欧洲中心和T106数值预报产品，分析常规气象资料，对湖北省1998年3月20～25日历史上罕见的连续性强对流天气过程进行诊断分析，揭示了产生强对流天气的环流形势和影响系统，并从短期角度对连续性强对流天气过程归纳出天气模型和预报指标，得出了强对流天气落区及降水性质与各要素之间的关系，为更好地提高预报强对流天气的准确率提供一定的参考。     

表层底泥翻耕对太湖藻源性湖泛的预控作用

表层底泥已被证实是引发或诱发太湖湖泛发生的主要因素,但能否通过像控制湖泊内源污染的翻耕方式对湖泛形成预控,则有待与过程有关的实验研究.模拟研究太湖易发湖泛区底泥翻耕对藻源性湖泛的控制作用,跟踪监测不同翻耕深度和翻耕后时长,对照和处理组上覆水的视觉、嗅觉、营养盐和挥发性硫化物浓度,以及表层底泥理化性质的变化.结果表明,未翻耕的对照组在模拟实验中发生了湖泛,翻耕10 cm和翻耕20 cm差异不大,但翻耕后时长对湖泛发生影响较大.刚翻耕后(1 d)即进行藻源性湖泛模拟的处理组发生了湖泛,但在程度和持续时间上均低于对照组;翻耕180 d和540 d的处理组,10 cm和20 cm翻耕深度均未发生湖泛.合理选择翻耕的施工时间,可以有效预防和控制湖泛的发生.     

挥发份在夕卡岩型和斑岩型矿床形成中的作用

通过总结多年来对夕卡岩型和斑岩型矿床的研究所获得的成果，作者认识到挥发相在这些矿床形成过程中的重要地位和意义。文章系统讨论了在花岗质岩浆中挥发相的形成和时空演化、挥发相的组成及其与硅酸盐熔融体的不相溶性，提供了挥发相在夕卡岩型和斑岩型矿床中存在的证据，提出挥发相对花岗质岩体顶部和邻近围岩的微细裂隙、爆破角砾岩、夕卡岩、碱质硅酸盐交代岩和富含挥发份矿物的形成，以及在矿质的迁移富集等各个过程中都具有十分重要的意义。     

The mass estimation of volatile emission during 1199-1200 AD eruption of Baitoushan volcano and its significance

On the basis of the study of volcanic products during 1199-1200AD eruption of Baitou Mountain (Baitoushan), the released volatile content was estimated by comparing Cl, F, S, H2O concentrations of undegassed glass inclusions with those of degassed matrix glasses. The calculations show that volatile yields, released from the melt, are 109.88×106 ton of HCl, 196.80×106 ton of HF, 1477.84×106 ton of H2O, 23.14×106 ton of SO2, which could have formed 35.43×106 ton of H2SO4 aerosol in the atmosphere. They could have substantial effect on paleoclimate and paleo-environment.     

土壤中挥发性污染物迁移转化的两区模型研究

分析了挥发性污染物在土壤中迁移转化机制以及耕作层土壤的特点,在考虑耕作层土壤大孔隙流的特点基础上,以质量守恒原理为基础,建立了挥发性污染物在土壤中迁移转化的两区数学模型,并给出了模型的数值解法。以典型的挥发性污染物为例,对其在土壤中的迁移转化的动力学行为进行分析,认为农药的挥发性以及不动水区含水率是农药在土壤中浓度分布的主要影响因素,验证了土壤中农药挥发性数学模型的应用更符合其发生机制以及所建立的两区模型的正确性。这对于预测挥发性污染物释放对环境污染的变化趋势和控制挥发性污染物对环境的污染具有重要意义,并为土壤中挥发性污染物的安全评价提供了手段。     

与铁相关的几种渗透反应格栅材料性能的比较

挥发性氯代有机化合物为地下水和饮用水中最常见的挥发性有机污染之一。文中对日益引人注意的渗透反应格栅(PRB:permeable reactive barrier)材料进行了研究。主要在实验室条件下,利用中国现有的实用性材料———铸铁的铁屑、实验室合成双金属和纳米双金属作为反应介质,对反应的脱氯效果和机理、还原性脱氯的反应动力学和影响因素进行初步的研究,以寻求一种可以大量得到的廉价而高效的材料,研究它对氯代烃的降解效率。在研究中选择最有代表性的CT和PCE作为目标污染物,讨论粒状铁、双金属以及纳米双金属对氯代有机物的降解速率,确定气相色谱法测定水溶液中的氯代有机物浓度的最佳实验条件,比较3 类反应介质的特点和应用范围。     

水中挥发性有机物分析的影响因素和常见问题解决办法

应用吹扫捕集-气相色谱-质谱法测定水中挥发性有机物,多种因素影响着定量分析的准确性,包括样品瓶的清洗及标准配制、样品和标准溶液的保存、载气气源的纯度、仪器状态检查及参数选择、分离度及积分方式。本文提出在分析过程中样品瓶必须清洗干净,以免污染样品;样品和标准溶液的保存时间过长会降低目标物的回收率;载气和吹扫气会带入杂质;分离度的大小将影响峰高和峰面积测量的准确度。针对分析中氯乙烯的回收、二氯甲烷的交叉污染、浑浊样品的处理等常见问题提供了解决方案,推荐采用选择扫描方式进行分析,并根据样品基体的情况来选择定量离子,将分析的初始温度降至40℃以下并保持2~3 min,以保证氯乙烯的回收率;实验室保持良好的通风环境,避免二氯甲烷交叉污染;色谱柱的最高温度升至220℃以上并保持2~3 min,可以排除萘及分子烷烃的干扰,保证分析的连续性;对于浑浊样品,推荐在野外取样时进行在线过滤或直接采用静态顶空方式进行测定。     

胶州湾养殖海区沉积物中酸可挥发性硫的研究

沉积物中酸可挥发性硫化物（AVS）的含量对控制重金属在沉积物/间隙水中的分配和重金属的生物可利用性方面有重要意义，也是海洋养殖业的重要指标之一，研究改正目前《海洋监测规范》中沉积物酸可挥发硫化物的测定方法基础上，建立了一套简单易行的仪器装置和分析程序，讨论了N2流量、反应时间、酸强度、硫总量4个方面对测定结果的影响，给出了胶州湾海区沉积物中AVS的定量数据，表明胶州湾养殖海区沉积物中AVS的含量显著高于非养殖海区和其它海湾沉积物中AVS的定量数据，表明胶州湾养殖海区沉积物中AVS的含量显著高于非养殖海区和其它海湾沉积物中AVS的含量，探讨了应用AVS归一化沉积物中二价有毒金属评价其化学活性和生物可用性的可能性。     

TECHNICAL NOTE An experimental investigation of air flow patterns in saturated soils during air sparging

Air sparging is an emerging method used to remediate saturated soils and groundwater that have been contaminated with volatile organic compounds (VOCs). During air sparging, air is injected into the subsurface below the lowest known depth of contamination. Due to buoyancy, the injected air will rise through the zone of contamination. Through a variety of mechanisms, including volatilization and biodegradation, the air will serve to remove or help degrade the contaminants. The contaminant-laden air will continue to rise towards the ground surface, eventually reaching the vadose zone, where the vapours are collected and treated using a soil vapour extraction (SVE) system.Air sparging performance and ultimately contaminant removal efficiency is highly dependent on the pattern and type of subsurface air flow. This paper presents the results of a laboratory experimental study which investigated the injected air flow pattern development within an aquifer simulation apparatus. The test apparatus consisted of a tank measuring 61 cm long by 25.4 cm wide by 38.1 cm high. The apparatus was equipped with one air injection well and two vapour extracton wells. Three different soils were used to simulate different aquifer conditions, including a sand, a fine gravel and a medium gravel. Experiments were performed with different injected air pressures combined with different vacuum and groundwater flow conditions. Experiments were also conducted by injecting air into simulated shallow aquifers with different thicknesses. The air flow patterns observed were found to depend significantly on the soil type, groundwater flow conditions and system controls, including injected air pressure, flow rate and applied vacuum. © Rapid Science Ltd. 1998