Enhanced chemical oxidation of aromatic hydrocarbons in soil systems

Fenton's destruction of benzene, toluene, ethylbenzene, and xylene (BTEX) was investigated in soil slurry batch reactors. The purpose of the investigation was to quantify the enhancement of oxidation rates and efficiency by varying process conditions such as iron catalyst (Fe(II) or Fe(III); 2, 5, and 10mM), hydrogen peroxide (H2O2; 30, 150, 300 mM), and metal chelating agents (l-ascorbic acid, gallic acid, or N-(2-hydroxyethyl)iminodiacetic acid). Rapid contaminant mass destruction (97% after 3h) occurred in the presence of 300 mM H2O2 and 10 mM Fe(III). An enhanced removal rate (>90% removal after 15 min and 95% removal after 3h) was also observed by combining Fe(III), N-(2-hydroxyethyl)iminodiacetic acid and 300 mM H2O2. The observed BTEX mass removal rate constants (3.6-7.8 x 10(-4)s(-1)) were compared to the estimated rate constants (4.1-10.1 x 10(-3)s(-1)). The influence of non-specific oxidants loss (by reaction with iron hydroxides and soil organic matter) was also explored.     

Atmospheric concentrations of PM2.5 trace elements in the Seoul urban area of South Korea

Fine particles (PM2.5) were collected during all four seasons, from April 2001 to February 2002, in Seoul, South Korea, using an annular denuder system. Elemental compositions of ambient PM2.5 were analyzed using the proton-induced X-ray emission method. The greatest contributors (> or = 2%) to the PM2.5 mass were sulfur (S), silicon (Si), chlorine (Cl), aluminum (Al), and iron (Fe) in the spring; S in the summer; and S and Cl in the fall. S, Cl, and Si were the major elements in the winter. S was the most abundant species among the elements, ranging from 5.3 to 7.9%, followed by Si and Cl. From analysis of variance, PM2.5 mass, Al, Si, potassium, calcium, and Fe showed significant seasonal differences during the four seasons (p < 0.001). Enrichment factor (EF) analysis was carried out to identify the sources affecting the aerosol in the Seoul area. On the basis of the mean EF values, elemental S, copper, zinc, and lead may be emitted from anthropogenic sources (EF > 50). Elemental Al, Si, titanium, and Fe may be emitted from crustal sources (EF < 3). Additionally, a correlation analysis was carried out for source identification. The results of the correlation analysis were confirmed by the results of the EF analysis.     

Volatile organic compounds in some urban locations in United States

Volatile organic compounds (VOCs) have been determined to be human risk factors in urban environments, as well as primary contributors to the formation of photochemical oxidants. Ambient air quality measurements of 54 VOCs including hydrocarbons, halogenated hydrocarbons and carbonyls were conducted in or near 13 urban locations in the United States during September 1996 to August 1997. Air samples were collected and analyzed in accordance with US Environmental Protection Agency-approved methods. The target compounds most commonly found were benzene, toluene, xylene and ethylbenzene. These aromatic compounds were highly correlated and proportionally related in a manner suggesting that the primary contributors were mobile sources in all the urban locations studied. Concentrations of total hydrocarbons ranged between 1.39 and 11.93 parts per billion, by volume (ppbv). Ambient air levels of halogenated hydrocarbons appeared to exhibit unique spatial variations, and no single factor seemed to explain trends for this group of compounds. The highest halogenated hydrocarbon concentrations ranged from 0.24 ppbv for methylene chloride to 1.22 ppbv for chloromethane. At participating urban locations for the year of data considered, levels of carbonyls were higher than the level of the other organic compound groups, suggesting that emissions from motor vehicles and photochemical reactions strongly influence ambient air concentrations of carbonyls. Of the most prevalent carbonyls, formaldehyde and acetaldehyde were the dominant compounds, ranging from 1.5-7.4 ppbv for formaldehyde, to 0.8-2.7 ppbv for acetaldehyde.     

翅片式防爆柴油机排气冷却器烟气侧数值分析

建立了翅片式防爆柴油机排气冷却器的计算模型,通过FLUENT软件对其烟气侧进行了仿真分析,探讨了防爆柴油机排气冷却器烟气内部的流场及温度场分布规律,仿真结果与热平衡试验结果基本一致,表明建立的数值分析模型准确,为翅片式排气冷却器的设计优化提供了理论指导。     

Risk of motor vehicle accident death among 1.3 million veterans of the Iraq and Afghanistan wars

Objective: We conducted a cohort study of recent wartime veterans to determine the postservice mortality risk due to motor vehicle accidents (MVAs).

Methods: Veterans were identified from the Defense Manpower Data Center records. Deployment to te Iraq or Afghanistan war zone was determined from the Contingency Tracking System. Vital status of 317,581 deployed and 964,493 nondeployed veterans was followed from their discharge dates between 2001 to 2007 until earlier of date of death or December 31, 2009. Underlying causes of death were obtained from the National Death Index Plus.

Results: Based on 9,353 deaths (deployed, 1,650; nondeployed, 7,703), of which 779 were MVA deaths as drivers (166; 613), both cohorts had 25 to 24% lower mortality risk from all causes but had 44 to 45% higher risk of MVA deaths relative to the U.S. general population. The higher MVA mortality risk was not associated with deployment to the war zone. After controlling for age, sex, race, marital status, branch of service, and rank, the risk for deployed veterans was comparable to that of nondeployed veterans (hazard ratio = 0.91; 95% confidence interval, 0.77–1.09).

Conclusions: Veterans exhibit significantly higher risk of MVA deaths compared to the U.S. general population. However, deployment to the Iraq or Afghanistan war was not associated with the excess risk.     

Aerosol Composition Change due to Dust Storm: Measurements between 1992 and 1999 at Gosan,Korea

Aerosol composition change between dust storm and non duststorm periods is studied using the TSP (Total SuspendedParticulate) data measured at Gosan, Korea between 1992 and1999. The concentrations of elements measured between 1993and 1996 and those of ions between 1992 and 1999 duringdust storms are compared with those during non-dust stormperiods in spring (March, April, and May). Among theanalyzed ions, the concentrations of crustal species(potassium, calcium, magnesium, and chloride) andanthropogenic species (nitrate and non-sea salt (nss)-sulfate) increased when dust storm occurs while those ofammonium and sodium did not increase. Among the analyzedelements, the concentrations of crustal species (Fe, Al,Ca, Ti, and Zn) increased when dust storm occurs whilethose of anthropogenic species (Mn, V, Ni, Cu, Cd, and Cr)did not increase. The only anthropogenic element of whichconcentration increased during dust storm periods was Pb.It was found that the concentrations of nitrate and nss-sulfatewere highest during spring. Also, the ratio of theyearly average concentrations of nitrate to nss-sulfateincreases, probably due to the emission trend change innortheast Asia, especially, in China.     

全氟辛酸诱导斑马鱼脾脏损伤及白细胞介素表达紊乱的免疫毒效应研究

全氟辛酸(PFOA)是新型持久性有机污染物,在水生生态系统多介质环境中广泛分布,其对水生生物的致毒机理备受关注.本文应用透射电镜和实时荧光定量PCR技术,研究了PFOA(0.05、0.1、0.5和1 mg·L-1)在7 d和14 d两个不同暴露时间段对斑马鱼脾脏的损伤效应及对白介素指标IL-1β、IL-4和IL-21表达的影响.结果表明,PFOA能够明显导致斑马鱼脾脏损伤,脾脏细胞呈现细胞膜皱缩和空泡化等特征.PFOA能够明显干扰斑马鱼脾脏白介素的表达.对于7 d暴露组,IL-1β和IL-4在m RNA水平的相对表达量随着暴露剂量的增加呈现出明显的先上升后下降的趋势;而IL-21的相对表达量随着暴露剂量的增加不断上升.对于14 d暴露组,IL-1β和IL-21在m RNA水平的相对表达量随着暴露剂量的增加呈现出明显的先上升后下降的趋势;而IL-4的相对表达量随着暴露剂量的增加不断上升.线性相关性分析表明,当暴露时间为7 d时,IL-1β表达量与IL-4表达量的相关系数为0.53;当暴露时间为14 d时,IL-1β表达量与IL-21表达量的相关系数为0.50,这说明PFOA诱导不同时间段后,斑马鱼脾脏IL-1β的表达量分别受IL-4和IL-21表达的影响.综上,本研究证实全氟辛酸能够通过诱导白介素表达的紊乱而导致斑马鱼免疫系统损伤,存在明显的剂量-效应特征.白介素IL-1β、IL-4和IL-21可以作为监测PFOA对水生生物健康风险评价研究的重要生物标志物.     

基于卫星遥感数据(AOD)估算PM2.5的研究进展

雾霾天气的频繁出现,不断向人们警示中国大气环境污染的严重性.细颗粒物PM2.5作为空气质量评价指标之一,由于粒径小、为有毒性物质提供载体的特性,对人们的健康和生活产生很大的负面影响.近年来,PM2.5的相关研究引起了世界各国研究者的广泛关注,通过地基手段获得PM2.5质量浓度受到环境、地理等因素的限制,而利用卫星遥感技术估算地面PM2.5质量浓度,覆盖面广、估算精度可靠,对环境污染监测和治理具有重要意义.在综合了国内外关于气溶胶光学厚度(AOD)估算PM2.5文献的基础上,对AOD和PM2.5的数据源和估算的方法及手段作了简要介绍,分析总结了AOD与PM2.5相关性与PM2.5遥感估算的模型,并展望了未来PM2.5研究的发展方向.     

两相法筛选高效除磷菌的研究

利用模拟除磷菌生存环境的两相法,设计厌氧-好氧两相交替条件,配合厌氧相含底物无磷培养基和好氧相含磷无底物培养基,进行高效除磷菌的筛选和菌株除磷能力检测.两相法包括前期富集、筛选、检测前驯化和检测共四个阶段.采用两相法从运行良好的SBR反应器中筛得15株菌,所有菌株均具有除磷能力,菌株除磷能力强.两相法筛选除磷菌具有针对性强,工作量小,筛选获得的菌株多样性好和高效除磷菌比例高等优点.