Dependency of polycyclic aromatic hydrocarbon concentrations on particle size distribution in Tehran atmosphere

In this work, the airborne particulate matter with an aerodynamic diameter less than 10 µm (PM₁₀) was fractionated in a six-stage high-volume cascade impactor to identify particulate size distribution in Tehran atmosphere. The study was conducted at 15 sites located in the north, south, east, west, and central parts of Tehran in 2005. Air samples were analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) by HPLC. The daily PM₁₀ concentrations at the peak of traffic in roadside areas were found to be 106–560 µg m^?3. The cumulated concentration sum of PAHs, based on 16 species, was found to have an average concentration of 380 ng m^?3. Furthermore, it was found that more than 60% of PAHs belonged to the small particulate size range, having sizes of less than 0.49 µm, some containing benzo(ghi)perylene and indeno(123cd)pyrene (high molecular weight) with average concentrations of 8 and 6 ng m^?3 and fluorene, phenanthrene, and fluoranthene (low molecular weight) with average concentrations of 14, 13, and 19 ng m^?3, respectively. In addition, the results revealed that the lighter three- and four-ring PAH compounds were the most abundant pollutants in the air collected at all the sampling sites.     

Distribution,levels, and risk assessment of polycyclic aromatic hydrocarbons in the soot of some kitchens in the Cape Coast Metropolis of Ghana

The effect of using firewood for cooking, baking, and heating in poorly ventilated kitchens on the formation of polycyclic aromatic hydrocarbons (PAH) in kitchen soot in the Cape Coast Metropolis of Ghana has been studied. The kitchens in Ghana, especially those in the rural areas, are simple clay hut structures with small doors. The kitchens have little or no openings for ventilation and, as a result, the cook is exposed directly to high doses of smoke containing different compounds including PAH. In this study, a total of 42 soot samples were collected for 6 weeks from seven kitchens and analyzed using gas chromatography with flame-ionization detection (GC/FID). The average PAH concentration in the kitchen soot samples ranged from 0.7 to 445 µg kg^?1. The unit risk of PAH associated with the dermal contact/inhalation of the kitchen soot occurred at 7.4 × 10^?3 in children and at 4.8 × 10^?5 in the adults, showing the impact. However, the high level of PAH measured in this work especially that of benzo[a]pyrene (B[a]P) may cause cancer in the women who are exposed to the smoke. The study was therefore designed to find out the level of PAH in kitchen soot and their contributions as the monitoring tools in the assessment of risks and hazards of PAH in Ghana.     

采用实验和密度泛函理论计算揭示吸光性环境介质对多环芳烃光降解的影响机制

多环芳烃(PAHs)在环境中的光降解动力学受环境介质吸光组分的影响.为揭示介质吸光组分对PAHs光降解影响的内在机制,以吸光很弱的甲醇和吸光较强的丙酮和二甲基亚砜(DMSO)为模拟环境介质,考察不同吸光性溶剂介质对3种PAHs(菲、芘和苯并[a]芘)光解的影响;并采用密度泛函理论(DFT)计算,分析了溶剂分子光敏化能量/电子转移反应对PAHs光解的影响机制.结果表明,激发态的丙酮分子抑制了菲和芘的光解,而加快了苯并[a]芘的光解;激发态的DMSO分子抑制了菲的光解,促进了芘和苯并[a]芘的光解.过滤掉DMSO所吸收的部分光谱频段后,PAHs在DMSO中的光解速率与甲醇中的接近.DFT计算表明,激发态的丙酮或DMSO主要作为电子受体与PAHs发生光敏化电子转移反应,是影响PAHs光解的内在原因.     

Chemical characterization of Tan‐Sui River sediment in North Taiwan

Surface sediment samples from four downstream sites of Tan‐Sui River in Taipei metropolitan area were collected from 1997 to 1999. The semivolatile organic pollutants present in the sediments were screened by GC/MSD. Several target compounds including sixteen polycyclic aromatic hydrocarbons (PAHs), seven chlorobenzenes, two phthalates and the total amount of C8‐C32 aliphatic hydrocarbons were quantified. The concentration of the 16 PAHs ranges from 0.21 to 5.69 μg/g of which fluoranthene, pyrene and phenanthrene were the highest. The concentration of the total chlorobenzenes ranged from 0.04 to 5.85 μg/g. The concentration of bis(2‐ethylhexyl)phthalate ranges from 3.8 to 35.3 μg/g and that of the total C8‐C32 aliphatic hydrocarbons ranges from 0.94 to 10.6 μg/g. Some of these values are higher than similar sediment survey in Japan in the eighties. The concentration of bis(2‐ethylhexyl)phthalate is much higher than the no‐effect level (0.184 μg/g) set by McDonald. Some of the PAHs have already reached the level of biological effects. As compared with the sediment samples collected from Tou‐Chien River and Pu‐Ze River located at the west of Taiwan, the chlorobenzene concentrations of sediments in Tan‐Sui River are 5–6 times higher, the PAHs are 6–10 times higher and the phthalates are 11–20 times higher. Nonylphenol was also commonly found in the Tan‐Sui River sediment. There is a decreasing tendency of PAHs and phthalates concentration from surface to bottom for the core sample at Taipei Bridge site. Such tendency is less obvious for chlorobenzenes.     

湿地生态系统硅生物地球化学循环研究进展

硅在地壳中的丰度仅次于氧,是地球表面大多数土壤和岩石的一种基本成分,也是水生植物（特别是硅藻类）以及多种作物生长所必需的营养元素,还是控制陆地、海洋、沿海和内陆水生态系统机能的重要营养元素。目前关于全球硅的生物地球化学循环的研究多集中在陆地和海洋两大生态系统,而湿地生态系统中硅的循环过程、储存量尚不清楚。虽然在河口湿地开展一些关于硅的相关研究,但是硅在湿地的循环机制研究不够全面,尤其相比碳、氮、磷等元素,硅素研究甚少。而且,国内关于硅的相关研究更为匮乏。本文在总结国内外关于湿地生态系统硅素研究的基础上,综述硅在湿地生态系统的存在形态与分布特征,阐述硅在湿地生态系统中的基本循环过程,列举影响硅在湿地生态系统中循环的主要因素,如：湿地类型、水淹时间、季节变化、人类干扰等;提出在今后研究工作中应进一步探索硅在湿地生态系统中迁移、转化的机制,加深研究人类活动对湿地生态系统硅循环的影响,特别是应该加强研究河口潮汐湿地和沿海湿地生态系统硅的生物地球化学循环过程和储存量,有助于明确湿地生态系统对于硅的截留量;并弄清湿地中碳与硅含量之间的关系,从水文学角度分析湿地中排水、蒸发、洪期及滞留时间等因素对硅循环的影响,从而试图建立湿地硅循环模型,有助于预测湿地生态系统硅循环对沿海地区赤潮等富营养化现象和全球气候变化的影响。     

国Ⅳ柴油机颗粒物与颗粒态多环芳烃排放特征

针对一台轻型柴油机,采用国Ⅳ柴油,在不使用和使用后处理装置的条件下,进行ESC循环工况(分别记为ESC-0、ESC-DP)和ETC循环工况(分别记为ETC-0、ETC-DP)下的发动机台架测试.每次测试用一对滤膜采集颗粒物,采样前后分别称重以确定颗粒物质量,进而计算排放因子.用气相色谱-质谱联机(GC-MS)分别分析每张滤膜上颗粒物的多环芳烃(PAHs)组分.ESC-0、ESC-DP、ETC-0、ETC-DP的颗粒物排放因子分别为0.12,0.05,0.48,0.16 g/(kW·h);相应的PAHs排放因子分别为69,35,174,76 μg/(kW·h).后处理分别使颗粒物和PAHs减排56%~68%和49%~56%.总PAHs中,三环PAHs占比重最大(64%±9%).PHE在总PAHs中占比重最大(54%±9%).PAHs的分布与其物理化学特性、柴油中的芳烃含量有关.PAHs特征比值FA/(FA+PY)为0.37~0.51.     

黄海硅的分布与收支研究

基于2012年在黄海的综合调查,对黄海水体和沉积物中溶解硅和生物硅的含量和分布及主要影响因素进行了分析,并结合历史数据建立了黄海硅收支与循环的模型.结果表明,黄海水体溶解硅和生物硅在秋季均高于春季,生物硅占活性硅的22%,陆源输入、初级生产和底界面扩散对硅的含量和分布的影响较为突出.收支表明,底界面扩散是黄海水体溶解硅的主要来源,占外部输入的48%,其次是东海的输入,占32%,河流贡献为9%,地下水贡献为6%,地表径流(非河流部分)贡献为3%,渤海贡献为1.5%,大气仅贡献0.5%;黄海水体溶解硅的支出主要是通过生物的吸收与随后的沉积埋藏和向东海的输出,其比例分别为72%和27%,黄海向渤海输出比例仅为1.0%;黄海沉积物是水体溶解硅的源,同时黄海体系还具有潜在汇的特性;黄海硅的净埋藏量约为55×109mol/a,占当年生物硅总量的7.2%,高于全球海洋的平均比值(3%),是外部输入硅总量的47%.本研究量化了黄海硅循环的主要过程,初步揭示了硅的源-汇特征以及陆地输入对近海硅收支与循环的影响.     

植物收割对人工湿地去除多环芳烃的影响

人工模拟北京市清河水质,研究模拟人工湿地中植物收割对PAHs去除效果的影响.结果显示:植物和填料对PAHs的去除均有一定的贡献率.湿地种植芦竹并添加填料后对2环萘、3环菲、4环芘和5环苯并[a]芘的去除率平均提高了34.82%、47.92%、19.70%和7.78%.湿地植物收割后,对萘、菲、芘和苯并[a]芘的平均去除率分别提高了11.31%、10.42%、21.21%和12.22%,且在收割后第2周期达到最大.植物收割后,第1周期的相对生长率最低(0.03~0.04cm/d),第2周期的相对生长率最高(0.47~0.51cm/d),第4周期的相对生长率恢复正常水平(0.17~0.23cm/d);对PAHs的去除率在第4周期恢复正常水平.     

Isolation and identification of fungi tolerant to polycyclic aromatic hydrocarbons and coal tar from different habitats in Lithuania

A group of 36 fungal strains, belonging to the Lithuanian mycobiota, was collected and isolated from different locations, habitats, and matrices, including creosote-treated wood in storage yards for crosstie wastes. The eight most perspective strains selected according to preliminary assessment of tolerance to coal tar were subsequently identified combining taxonomical evaluation and molecular techniques. The tolerance of the eight identified fungal species (five basidiomycetes and three ascomycetes) to the presence of various concentrations of coal tar, and for the four most perspective fungal strains (Pleurotus sp., Schizophyllum sp., Irpex lacteus, Bjerkandera adusta) to polycyclic aromatic hydrocarbons was evaluated. The ligninolytic enzymatic activity assay of the isolated strains resulted in a good correspondence between the tolerance to pollutants and the capability to produce ligninolytic enzymes indicating that this group of white-rot fungi is perspective for further investigation and eventual usage for mycoremediation of polycyclic aromatic hydrocarbons polluted substrates.     

曹妃甸和黄骅港近岸海域表层水体中PAHs的分布、来源及风险评价

曹妃甸和黄骅港是河北省近海工业布局和港口分布较密集的区域,对其近岸海域海水水质进行监测具有重要意义。2014年9月采集研究区近岸海域表层海水,并利用GC-MS对其中16种优先控制PAHs进行测定。结果表明,曹妃甸和黄骅港近岸海域表层海水中∑PAHs含量分别为52.6~192.1 ng·L~(-1)和85.4~156 ng·L~(-1),平均含量分别为74.59 ng·L~(-1)和121.45 ng·L~(-1)。黄骅港近岸海域∑PAHs含量高于曹妃甸近岸海域的含量,但PAHs的种类没有差异。对比其他研究区域水体中PAHs的含量,本区域表层海水中PAHs的含量处于中等水平,属于轻污染。异构体比值结合该区域现状分析初步判断,研究区表层海水中PAHs来源于石油污染和煤、生物质等的燃烧。应用风险商值法(RQ)对研究区域表层海水中PAHs的生态风险进行评价,结果表明该海域存在低生态风险,需采取措施控制PAHs的污染。