The impact of wood smoke on ambient PM2.5 in northern Rocky Mountain valley communities

During the winters of 2006/2007 and 2007/2008, PM_2.5 source apportionment programs were carried out within five western Montana valley communities. Filter samples were analyzed for mass and chemical composition. Information was utilized in a Chemical Mass Balance (CMB) computer model to apportion the sources of PM_2.5. Results showed that wood smoke (likely residential woodstoves) was the major source of PM_2.5 in each of the communities, contributing from 56% to 77% of the measured wintertime PM_2.5. Results of ¹⁴C analyses showed that between 44% and 76% of the measured PM_2.5 came from a new carbon (wood smoke) source, confirming the results of the CMB modeling. In summary, the CMB model results, coupled with the ¹⁴C results, support that wood smoke is the major contributor to the overall PM_2.5 mass in these rural, northern Rocky Mountain airsheds throughout the winter months.     

Compound specific carbon and hydrogen stable isotope analyses of volatile organic compounds in various emissions of combustion processes

This study presents carbon (δ¹³C) and hydrogen (δD) isotope values of volatile organic compounds (VOCs) in various emission sources using thermal desorption-gas chromatography-isotope ratio mass spectrometry (TD-GC-irMS). The investigated VOCs ranged from C6 to C10. Samples were taken from (i) car exhaust emissions as well as from plant combustion experiments of (ii) various C3 and (iii) various C4 plants. We found significant differences in δ values of analysed VOCs between these sources, e.g. δ¹³C of benzene ranged between (i) −21.7 ± 0.2‰, (ii) −27.6 ± 1.6‰ and (iii) −16.3 ± 2.2‰, respectively and δD of benzene ranged between (i) −73 ± 13‰, (ii) −111 ± 10‰ and (iii) −70 ± 24‰, respectively. Results of VOCs present in investigated emission sources were compared to values from the literature (aluminium refinery emission). All source groups could be clearly distinguished using the dual approach of δ¹³C and δD analysis. The results of this study indicate that the correlation of compound specific carbon and hydrogen isotope analysis provides the potential for future research to trace the fate and to determine the origin of VOCs in the atmosphere using thermal desorption compound specific isotope analysis.     

城市河涌受污染底泥的固化/稳定化处理

为了给河涌疏浚底泥的资源化提供技术支持,以广州市车陂涌表层受污染底泥为研究对象,用水泥、石灰、粉煤灰、膨润土等材料对底泥进行固化/稳定化处理实验。通过无侧限抗压强度、污染物在模拟自然条件下(中性)的释放特征、毒性浸出实验(酸性条件)对固化/稳定化处理效果进行综合分析。结果表明:经合适的处理后,固化体抗压强度能高于300 kPa;固化体自然条件下重金属的释放量明显减少,固化/稳定化处理能够有效减缓和减少固化体的二次污染;毒性浸出实验结果表明,河涌底泥经固化/稳定化处理后其重金属浸出能力显著降低。     

PDA的制备及其对水体中邻苯二甲酸二甲酯的去除性能

以二甲基二烯丙基氯化铵(DMDAAC)和丙烯酰胺(AM)为原料,Span-80和Tween-80为乳化剂,液体石蜡为分散相,采用分批加料法,反相乳液聚合制备二甲基二烯丙基氯化铵与丙烯酰胺的共聚物(PDA)。研究内容包括单体配比、引发剂配比、油水体积比和pH值对产物特性粘度的影响。研究获得的优化聚合条件为:单体质量比(DMDAAC∶AM)为2∶8,引发剂质量比(NaHSO3∶K2S2O8)为5∶3,油水体积比为1∶1.2,pH值为8。选用自制PDA用于去除水中邻苯二甲酸二甲酯(DMP)时,在絮凝剂PDA的投加量为0.60 mg/L,pH值为10时,DMP的去除效果最好,去除率达到98.31%。     

GIS-based source identification and apportionment of diffuse water pollution: perfluorinated compound pollution in the Tokyo Bay basin

To efficiently reduce perfluorinated compound (PFC) pollution, it is important to have an understanding of PFC sources and their contribution to the pollution. In this study, source identification of diffuse water pollution by PFCs was conducted using a GIS-based approach. Major components of the source identification were collection of the monitoring data and preparation of the corresponding geographic information that was extracted from a constructed GIS database. The spatially distributed pollution factors were then explored by multiple linear regression analysis, after which they were visually expressed using GIS. Among the 35 PFC homologues measured in a survey of the Tokyo Bay basin, 18 homologues were analyzed. Pollution by perfluorooctane sulfonate (PFOS) was explained well by the percentage of arterial traffic area in the basin, and the 84% variance of the measured PFOS concentration was explained by two geographic variables, arterial traffic area and population. Source apportionment between point and nonpoint sources was conducted based on the results of the analysis. The contribution of PFOS from nonpoint sources was comparable to that from point sources in several major rivers flowing into Tokyo Bay. Source identification and apportionment using the GIS-based approach was shown to be effective, especially for ubiquitous types of pollution, such as PFC pollution.     

Determination and analysis of PM10 source apportionment during episodes of air pollution in Central Eastern European urban areas: The case of wintertime 2006

Source apportionment of air pollution due to particulate matter with an aerodynamic diameter <10 μm (PM₁₀) was investigated in Central Eastern European urban areas. A combination of four methods was developed to distinguish long-range transport (LRT) and regional transport (RT) from local pollution (LP) sources as well as to discern the involvement of traffic or residential sources in LP. Sources of PM₁₀ events of pollution were determined in January 2006 in representative Polish cities using monitored air quality and meteorological data, backward air mass trajectories, correlation and principal component analysis (PCA). Daily patterns of PM₁₀ levels show that several peak episodes were registered in Poland; January 21–30th being the most polluted days. Air mass back-trajectory analysis shows that all cities were under the influence of LRT from North-eastern origins (Russia–Belarus–Ukraine), most were also under LRT from Southern origin (Slovakia, Czech Republic), and northern cities were under national RT influence. PCA analysis shows that ion-sums of secondary inorganic aerosols account for LRT pollution while arsenic and chromium represents markers of RT (industrial) and LP (residential) sources of PM₁₀, respectively. Determination of several ratios (REG/UB, REG/TRAF, TRAF/UB) calculated between PM₁₀ levels measured at regional background (REG); urban background (UB) and traffic (TRAF) monitoring sites shows that, with ratios REG/UB ≥ 0.57, PM₁₀ episodes in both Szczecin and Warsaw bore a marked RT origin. The lower REG/UB ≤ 0.35 in the Southern cities of Cracow and Zabrze indicates that LP was the main contributor to the observed episodes. Only PM₁₀ episodes in Southern-western Poland (Jelenia Góra) were clearly of LP origin as characterized, by the lowest REG/UB ratio (<0.2). The high TRAF/UB ratios obtained for all cities (close to 1) indicate that there was a great uniformity of PM levels on an urban scale owing to the meteorologically stagnant conditions. A high correlation between PM₁₀, NO₂ and CO confirms that traffic emission represented a common and an important LP source of urban pollution in most Polish cities during January 2006. On the other hand PM₁₀ which is also highly correlated with SO₂ in 4 cities out of 6, indicates that coal combustion through domestic heating or industrial activities was also an important LP source of PM₁₀. Finally, extremely unfavourable meteorological conditions caused by the influence of a Siberian high-pressure system were found to be associated with the occurrence of severe PM₁₀ episodes of pollution.     

Effect of powdered activated carbon on Chinese traditional medicine wastewater treatment in submerged membrane bioreactor with electronic control backwashing

Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors （SMBRs） operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR （CSMBR） while the other was dosed with powdered activated carbon （PAC） （PAC-amended SMBR, PSMBR）. The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d （576 h） was 5.87 L/h with average hydraulic residence time （HRT） of 5.97 h and that of PSMBR during a steady periodic state of 30 d （720 h） was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand （COD） removal efficiency of CSMBR was 89.29% with average organic loading rate （OLR） at 4.16 kg COD/（m^3.d） while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/（m^3.d）. COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry （300 mg/L）. Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.     

合肥市冬季灰霾天气PM_(2.5)源解析

于2016年12月30日—2017年2月4日,利用单颗粒气溶胶飞行时间质谱仪(SPAMS),对合肥市PM_(2.5)开展来源解析连续监测,共捕捉到4次较为明显的灰霾过程,对颗粒物种类及质谱特征进行了分析。结果显示,监测期间合肥市主要颗粒物成分为元素碳(EC)(31. 9%)、富钾(K)(16. 6%)、有机碳(OC)(16. 0%)及混合碳颗粒(ECOC)(15. 0%)等。主要污染源为机动车尾气源(24. 5%)、工业工艺源(22. 7%)、燃煤源(14. 1%)、二次无机源(13. 5%)等。污染天气发生时,工业工艺源占比上升2. 2个百分点,生物质燃烧和燃煤源占比分别下降1. 7和2. 7个百分点,机动车尾气和扬尘源基本持平,表明此次污染过程主要受到工业工艺源的累积影响。     

高温中植筋胶拉伸抗剪强度试验研究

为了研究高温中植筋胶的拉伸抗剪强度,进行了57个植筋试件在不同温度下的拉拔试验。试验温度共11个,温度范围为25～350℃。采用电炉加热升温,当到达设定温度后立即进行拉拔实验,每个温度下做5组试件。试验中量测电炉温度,植筋试件温度,植筋滑移和拉拔力。试验结果表明:随着温度升高,植筋胶的拉伸抗剪强度显著下降,当温度高于350℃后,植筋胶基本丧失承载力,约为常温下的4%左右。     

储罐爆炸抛射碎片对目标储罐的破坏概率研究

化工储罐爆炸产生的抛射碎片击中并破坏相邻罐体后,将引发多米诺效应。N guyen破坏概率模型认为,当罐壳受撞击后,残余壁厚小于某个临界值时就会被破坏,并假设该临界残余壁厚为定值,存在不合理之处。本文基于储罐壳体损失面积安全评价方法AP I 579,把撞击形成的复杂凹坑简化为圆锥形,分别针对圆柱储罐、球罐推导出圆锥形凹坑剩余强度系数的求解方法,并根据塑性失效理论确定了罐壳的临界剩余强度系数,由此建立了新的破坏准则。在此基础上,采用蒙特卡罗法进行模拟,建立了新的爆炸碎片对目标储罐的破坏概率模型,与N guyen模型相比,得出的破坏概率偏大,结果更为安全保守。通过对剩余强度系数与无量纲撞击深度和凹坑锥角的变化关系进行分析,证明N guyen模型中临界残余壁厚为定值的假设并不合理,而新的基于剩余强度系数计算的破坏概率更为准确合理。