2008年北京采暖开始前后大气颗粒物化学成分及来源研究

为了系统反映北京采暖开始前后大气颗粒物的特征,于2008年10月底到12月初在北京北三环内城区使用分级式撞击采样仪进行了大气颗粒物采样,并用质子激发X射线荧光分析(PIXE)方法对其中16种化学元素浓度进行了分析.结果表明,采暖开始后16种元素总浓度较采暖期前增长3%,As、Cu在采暖期间的浓度增幅在30%以上,采暖开始后细粒子中Pb浓度增长为27%.富集因子分析结果表明,Cu、As、Pb等元素细粒子的富集因子比1999年同期有明显减小,说明北京近年来实行的环保措施较为有效.     

珠海海洋大气中甲磺酸粒子与季节变化的相关性

文章主要利用检测单个粒子的薄膜法,探讨了中国珠海海洋大气中甲磺酸(MSA)粒子的数量浓度、粒子百分数、大小和酸性(pH值)及其一般变化规律。根据在2005年1月至2005年12月间采集的样品的分析结果表明:甲磺酸粒子在大气中的数量浓度在8.6×10-11～26.6×10-11nmol/m3之间变化,粒子百分数在11.4%～34.8%之间变化,当量直径在1.0964～1.5171μm之间变化,酸性(pH值)在1.86～2.71之间变化;甲磺酸粒子的数量浓度、粒子百分数、当量直径和pH值的变化与季节变化具有明显的相关性;甲磺酸粒子的数量浓度、占总粒子的百分数随气温的升高和海洋生物生长的旺盛而增大,在夏季达到最大值,而随着气温的降低和空气湿度的增大,甲磺酸粒子的当量直径增大、酸性增强,在春季和空气湿度较大时,其当量直径具有最大值、pH值则具有最小值;1天当中,MSA粒子的浓度在下午时达到最大,早晨最小。     

鼎湖山PM2.5中化学元素的组成及浓度特征和来源

为研究珠江三角洲大气颗粒物的污染特征及其来源,于2006年6～12月,在鼎湖山利用大流量颗粒物采样仪进行PM_2.5样品的采集,并利用ICP-MS分析其中的元素浓度.结果表明, Pb、V、Cu、As、Zn、Se元素平均浓度为216.24、 15.40、 60.56、 31.81、 432.06和8.12 ng·m^-3,处于高污染浓度水平.因子分析表明,化石燃料的燃烧、金属冶炼工业、扬尘和海盐是该地区PM_2.5的主要来源.     

大气颗粒物化学质量平衡源解析方法研究

对基于化学质量平衡原理（CMB）的大气颗粒物来源解析方法中各步骤的研究情况进行综述。重点对土壤尘、煤烟尘、尾气尘、道路尘、城市扬尘、建筑水泥尘、海盐粒子等污染源样品采集方法,环境空气中颗粒物样品采集用滤膜及采样器,样品中各组分分析方法,以及采用cMB模型进行源解析拟合计算软件的发展情况进行了介绍,同时针对目前源解析中存在的问题提出了一些建议。     

广州地区秋冬季细颗粒物PM_(2.5)化学组分分析

本文对广州地区2009~2010年秋冬季节大气中PM2.5进行采样,并分析PM2.5样品的水溶性离子、重金属元素、有机碳/元素碳(OC/EC)、有机酸、多环芳烃浓度和粒径分布。通过分析初步掌握了广州地区秋冬季节大气中PM2.5的化学组分和特点:广州地区秋冬季PM2.5呈现城区高于城郊,PM2.5中有机质(OM)是最主要的成分,其次是硫酸根离子、硝酸根离子和铵根;PM2.5中有机碳和元素碳的空间分布特征相似,并受一次源排放影响;PM2.5中铝、锌、铅是含量最高的重金属,且城区重金属浓度高于城郊;PM2.5中17种多环芳烃、苯并a芘(BaP)均为城郊浓度最高。     

沿海城市灰霾天气与海盐氯损耗机制的关系

随着经济规模迅速扩大和城市化进程加快,大气气溶胶污染日趋严重,由细粒子气溶胶造成的能见度恶化事件越来越多,这些人类活动排放的污染物,可形成灰霾天气致使能见度下降。尤其值得注意的是沿海城市灰霾天气增长较快,沿海城市灰霾天气增多与海盐气溶胶粒子的氯损耗机制关系密切。我国30年前在粉尘污染时代建立的空气质量评价体系,已经远远不能描述新型复合空气污染类型,尤其是不能描述细粒子污染的情况,能见度的恶化主要与细粒子的浓度关系比较大,而与气溶胶的质量浓度关系不大。能见度与PM2.5尤其是PM1有非常好的关系,因而目前用能见度来描述灰霾天气是最好的指标。     

春季黄海边界层内海盐细粒子氯亏损及混合状态研究

为了解海盐气溶胶和亚洲出流污染物的相互影响,对2001年春季黄海边界层内观测的气溶胶细粒子可溶离子浓度(AGE-Asia中NCAR C-130飞机航测)进行了研究.所分析的6个航段(航段1～航段6)都位于黄海中部(124.0°E～125.1°E,34.3°N～36.4°N)的大气边界层内.离子摩尔比和相关分析表明,在所...     

Solubilization and degradation of perchloroethylene （PCE） in cationic and nonionic surfactant solutions

Solubilization of perchloroethylene (PCE) in a nonionic (Triton X-100) and a cationic (cetyltrimethylammonium bromide (CTAB)) surfactant solutions and the degradation of surfactant solubilized PCE using fine to nanosize Fe and bi-metallic Fe-Ni particles were investigated. Micelle partition coefficients (Km) and molar solubility ratio (MSR) for PCE in 10 g/L of surfactant solutions have been quantified and the solubility of PCE (100 mg/L in water) in the surfactant solutions increased by about ten fold. Of the two surfactants studied, Triton X-100 solubilized the higher amount of PCE per gram of surfactant. To degrade solubilized PCE, both iron and bimetallic Fe-Ni particles were used in continuously stirred batch reactors. The iron and bi-metallic particles were synthesized using the solution method and the particles were characterized using the SEM, EDS, TEM and XRD. The PCE solubilized up to 500 mg/L in both surfactant solutions were totally degraded at various rates by 200 g/L of bi-metallic Fe-Ni particles in less than 20 hr, which is the highest concentration of PCE degraded in the shortest time compared to data in the literature. The degradations of PCE solubilized in surfactant solutions were represented by nonlinear kinetic relationships which depended on the type of surfactant used for solubilizing the PCE.     

Humic acid and metal ions accelerating the dechlorination of 4-chlorobiphenyl by nanoscale zero-valent iron

Transformation of polychlorinated biphenyls (PCBs) by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl (4-ClBP) by nanoscale zero-valent iron (NZVI) in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-ClBP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the dechlorination efficiencies of 4-ClBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-ClBP in the first 4 hr, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2+, Cu2+, and Ni2+, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-ClBP. The dechlorination percentages of 4-ClBP in the presence of 0.1 mmol/L Co2+, Cu2+ and Ni2+ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-ClBP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.     

Characterization of condensed phase nitric acid particles formed in the gas phase

The formation of nitric acid hydrates has been observed in a chamber during the dark reaction of NO2 with O3 in the presence of air. The size of condensed phase nitric acid was measured to be 40–100 nm and 20–65 nm at relative humidity (RH) 6 5% and RH = 67% under our experimental conditions, respectively. The nitric acid particles were collected on the glass fiber membrane and their chemical compositions were analyzed by infrared spectrum. The main components of nitric acid hydrates in particles are HNO3 3H2O and NO3?? xH2O (x> 4) at low RH, whereas at high RH HNO3 H2O, HNO3 2H2O, HNO3 3H2O and NO3?? xH2O (x> 4) all exist in the condensed phase. At high RH HNO3 xH2O (x 6 3) collected on the glass fiber membrane is greatly increased, while NO3?? xH2O (x > 4) decreased, compared with low RH. To the best of our knowledge, this is the first time to report that condensed phase nitric acid can be generated in the gas phase at room temperature.