柴油机排气微粒冷却演变特性的实验研究

对柴油机排气微粒在冷却条件下的演变特性进行了实验研究.结果表明,排气的冷却作用对微粒的质量浓度具有重要的影响.引起微粒质量浓度变化的主要原因是排气中气态碳氢的冷凝,从而增加了微粒的质量浓度.排气的冷却促使柴油机微粒增大,分布在0.01～1.0 μm粒径范围内的微粒数量有所减少,特别是小于0.1 μm以下的小微粒,微粒数量下降的幅度相对较大,并且冷却温度越低,变化越明显.排气冷却后,0.1-1.0 μm粒径范围内的微粒体积浓度呈减少的趋势.此外,流速对排气冷却条件下的微粒演变特性亦有一定的影响,随排气流速的降低,0.01～1.0 μm粒径范围内的微粒数量浓度和体积浓度减小.     

北京夏季典型天气TSP组成和来源对比

于2005年7月选择分别受北方冷空气、海上高压和地方性山谷风影响的3个天气过程条件下,在北京市区和郊区采集了23个大气总悬浮颗粒物(TSP)样品,并采用扫描电镜-X射线能谱技术,根据单颗粒尺度、形貌、特征化学组成解析出各类源对颗粒数浓度的贡献.结果发现:有机/碳质颗粒(占总颗粒数的31.3%,下同)和矿物颗粒(占29.5%)为优势种类,二次源颗粒占10.6%,燃煤飞灰占7.2%,燃煤、机动车排放和建筑施工产生的3类颗粒占4.1%～6.5%.3种天气下颗粒组成特征鲜明,来源差别明显:①冷空气影响下空气质量最好,TSP样品中粒径小于1.0 μm和大于5.0 μm颗粒较多,一次源处于绝对主导地位(占90%);②海上高压控制天气下,粒径为1.0～2.5 μm的颗粒大幅度增加,有大量的次生粒子生成(占10%～20%);③地方性天气中颗粒质量浓度偏高,粒径小于1.0 μm和1.0～2.5 μm颗粒所占比例均较高,但有机/碳质颗粒比例减少, 其他次要种类颗粒增多.市区人为源颗粒的种类最多,对郊区影响明显.      

铅在植物-环境体系中的吸收、分布和迁移规律的稳定同位素示踪法研究

以低浓度的稳定铅同位素为示踪剂,采用电感耦合等离子质谱法,通过盆栽实验,考察了在不同的pH值环境和不同铅源引入方式下,茶树植株对铅的吸收情况以及铅在植株体内的分布及迁移规律.结果表明:茶树植株对大气铅源污染的反应比土壤铅源污染灵敏;大气铅源污染有往顶端(芽)迁移的趋势,而土壤铅源污染则主要聚集在根部;低pH条件增强植株对铅的吸收且能促使植株体内的铅的往高处迁移.本实验方法危害小,更接近植株承受低浓度污染的实际情况,能区分实验引入铅源和环境引入铅源.     

天津地区土壤中微量元素含量的纵向分异

根据80个土壤剖面13种微量几素及有关理化参数实测结果,研究了大津地区土壤中微量元素含量的纵向分异结果表明,天津土壤中绝大多数微量元素含量高于全国平均含量由于淋溶较弱,发育时间较短,各微量元素含量在土壤纵向的分异不明显与受市区影响较小的远郊相比,天津近郊土壤中各微量元素含量具有明显的升高趋势,其中汞的增幅最大大津地区冲积母质土壤中微量元素含量与残积母质土壤中相应含量的比值大多在1～15之间。冲积过程中的粒径分选作用是形成这一现象的根本原因空间分析的结果证明,母质是影响天津土壤中微量元素含量的主导因素,面人为影响也一定程度上改变了土壤中微量元素含量及其空间分布     

玉龙雪山冰川公园的旅游资源特色及其保护

本文总结了云南省玉龙雪山以现代冰川和古冰川遗迹为主的旅游资源特色,探讨了现代冰川和古冰川遗迹的旅游观赏价值,并结合全球气候变化的趋势,提出了保护冰雪旅游资源和建立国家冰川公园的建议     

论城市室内环境中气溶胶污染问题

本文全面评述了室内环境中气溶胶的种类来源,化学组成,形成和自然清除机理。空气环境中气溶胶大致可分为：１．燃烧型气溶胶,主要包括各类燃料燃烧产生的烟雾和烟草烟雾等;２．矿物型气溶胶,包括粉尘,飞灰,石棉及其它天然纤维尘等;３．生物型气溶胶,包括植物生气溶胶,如动物皮屑及各类微生物等。     

石墨探针直接收集、石墨探针炉原子吸收法测定APM中痕量银

本文采用一定气孔性的石墨探针直接收集大气颗粒物（APM）,然后用石墨探针炉原子吸收法直接测定收集在探针上的APM中痕量银。实验表明:峰面积吸光度与银的浓度在0—120ng·ml~(-1)范围内呈线性关系,银的特征量为6.75pg,检测限（3σ）为11.74pg,RSD（n=11）为3.92％,分析标准物质NBS1648（城市颗粒物）,其回收率和RSD（n=5）分别为90.2—105.0％和6.0％,证明此法准确、灵敏、快速、简便。     

Influence of fly ash aided phytostabilisation of Pb, Cd and Zn highly contaminated soils on Lolium perenne and Trifolium repens metal transfer and physiological stress

Due to anthropogenic activities, large extends of soils are highly contaminated by Metal Trace Element (MTE). Aided phytostabilisation aims to establish a vegetation cover in order to promote in situ immobilisation of trace elements by combining the use of metal-tolerant plants and inexpensive mineral or organic soil amendments. Eight years after Coal Fly Ash (CFA) soil amendment, MTE bioavailability and uptake by two plants, Lolium perenne and Trifolium repens, were evaluated, as some biological markers reflecting physiological stress. Results showed that the two plant species under study were suitable to reduce the mobility and the availability of these elements. Moreover, the plant growth was better on CFA amended MTE-contaminated soils, and the plant sensitivity to MTE-induced physiological stress, as studied through photosynthetic pigment contents and oxidative damage was lower or similar. In conclusion, these results supported the usefulness of aided phytostabilisation of MTE-highly contaminated soils.     

Mg/Al水滑石对水中痕量邻苯二甲酸酯的吸附动力学和热力学

研究了Mg／A1水滑石对水中痕量邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二（2一乙基己基）酯（DEHP）和邻苯二甲酸二辛酯（DnOP）的吸附动力学和热力学特性。结果表明,在所研究的浓度范围内,3种邻苯二甲酸酯的吸附动力学曲线均符合准二级速率方程,DMP、DEHP和DnOP分别在600、200和200min基本达到吸附平衡;3种邻苯二甲酸酯的吸附等温线基本符合Langmuir和Freundlich吸附等温方程;在283～308K范围,pH=6．36,3种邻苯二甲酸酯初始浓度均为50μg／L时,吸附过程△H为负值且绝对值为5～12kJ／mol,表明吸附为放热过程,以表面物理吸附为主,邻苯二甲酸酯在Mg／Al水滑石上的吸附是色散力、诱导力、取向力和氢键力等多种作用力协同作用的结果。     

Granulometric and Metal Distributions for Post‐Katrina Surficial Particulate Matter Recovered From New Orleans1

Bhadha, Jehangir H., Casey Schmidt, Robert Rooney, Paul Indeglia, Ruben Kertesz, Elizabeth Bevc, and John Sansalone, 2009. Granulometric and Metal Distributions for Post‐Katrina Surficial Particulate Matter Recovered From New Orleans. Journal of the American Water Resources Association (JAWRA) 45(6):1434‐1447. Abstract: Hurricane Katrina and the resulting failure of the levees that surrounded and protected New Orleans generated a significant detained volume of stormwater within the urban area of New Orleans. Between the inundation resulting from levee failure and eventual pumped evacuation of stormwater from the urban area of New Orleans, a large mass of storm‐entrained particulate matter (PM) was deposited in the inundated areas. This study examined the granulometry and granulometric distribution of metals for post‐Katrina surficial PM deposits recovered from 15 sites (10 inundated and 5 non‐inundated) in New Orleans. Results of this examination were compared to pre‐Katrina data from New Orleans. While post‐Katrina analysis of PM indicates that Pb, Zn, and Cu concentrations for PM are reduced for all sites, inundated sites had higher Cu, Pb, and Zn concentrations for the settleable (～25‐75 μm) and sediment (>75 μm) size fractions. A comparison between total metal concentration and the bioavailable (leachable) fraction for PM reveals that inundated sites had up to 19% higher leachable metal concentration compared to non‐inundated sites. The reduction in PM‐bound total metal concentrations for recovered PM can be explained through a combination of scouring (and therefore change in granulometry from pre‐Katrina) that resulted from transport of suspended PM by storm flows and pumped evacuation; as well as leaching and PM‐based redistribution from extended contact with rainfall and during stormwater detention. New Orleans has been exposed to elevated levels of metals through decades of activities that include vehicular transportation, chemical, industrial, and oil production facilities resulting in higher metal concentrations for urban soil‐residual complexes. As a result, the influent storm flows associated with Katrina as an episodic event cannot solely explain the distribution and fate of PM‐associated metal concentrations.