极性基湿润剂与矿岩类粉尘颗粒的作用机理

根据矿岩类粉尘微颗粒的表面性质和极性基湿润剂的特性，应用分子热力学和表面物理化学理论探讨了湿润型抑尘剂与矿岩类粉尘之间的相互作用机理。矿岩类粉尘吸附水的本质是由于它们之间的相互吸引作用，是分子之间的短程相互作用力和长程作用力共同作用的结果。当矿岩类粉尘与水相碰撞时，只有当吸引力大于排斥力时，水分子才能牯附于矿岩类粉尘，表面张力和体系自由能足够小时，水才能湿润矿岩类粉尘。分析了湿润剂对水和矿岩类粉尘的表面改性的原理，它增加水和矿岩类粉尘之间的相互作用力，减小了界面表面张力和体系自由能，使矿岩粉尘被水湿润能自由地进行。     

Discriminate Analysis for Dust Storm Prediction in the Gobi and Steppe Regions in Mongolia

A discriminate analysis method for probability forecast of dust storms in Mongolia has been developed. The prediction method uses data recorded at 23 meteorological stations in the Gobi and steppe regions of Mongolia, including surface air pressure and geo-potential height at the 500-hPa level on grid points, and weather maps from 1975 to 1990. Weather elements such as air temperature, pressure, geo-potential height etc, which influence the formation of dust storms, are prepared as predictors. To select the most informative/important predictors (variables), we used a mean correlation matrix of variables together with the Mahalonobis distance, and correlation coefficients between dust storms and predictors with an orthogonalization for removing correlated predictors. The most informative predictors for dust storm prediction are intensities of surface cyclones and migratory anticyclones, passage of cold fronts, the horizontal gradients of the surface air pressure in the cold frontal zone, cyclonic circulations from the ground surface up to the 500-hPa level, the geo-potential height at 500-hPa level and its temporal changes. Selected predictors are used in discriminate analysis for formulating dust storm prediction equations. Sandstorm data have been classified into three classes, viz., strong, moderate and weak dust storms, depending on their intensities, durations and areas covered. Predictions of the probabilities of dust storm occurrence use the prediction equations for each class. The prediction is made from 12 hours to 36 hours. Verification of the probability forecasts of dust storms is also shown. The accuracy of forecasts is 72.2–79.9% with the data used for developing equations (dependent variables), in contrast to 67.1–72.0% with unrelated data for deriving equations (independent variables).     

Analysis of Roadside Inhalable Particulate Matter (PM10) in Major Korean Cities

A data analysis of three major Korean cities was conducted to assess roadside inhalable particulate matter 10 μm or smaller in aerodynamic diameter (PM₁₀), including temporal and meteorological variations, over a recent period of 4 to 6 years. The yearly roadside PM₁₀ concentrations presented a well-defined increasing trend or no trend depending on the roadside monitoring station. Most mean values exceeded or approximated the Korean standard of 70 μg/m³ per year for PM₁₀. A representative roadside diurnal trend was characterized by a distinct morning maximum. In most cases, the Sunday roadside concentrations were similar to or somewhat lower than the weekday concentrations, and the PM₁₀ concentrations presented a well-defined seasonal variation, with the maximum concentration in March. The monthly maximum concentrations observed in March were most likely attributable to Asian dust storms. In two metropolitan cities (Seoul and Busan), the frequency of days with roadside PM₁₀ concentrations exceeding the standard of 150μg/m³ per 24 h was much lower for the roadside monitoring stations than for the residential monitoring station, whereas in the third city (Daegu), this result was reversed. Interestingly, the average maximum concentrations observed for the roadside sites in Seoul and Busan during March were higher than those for the residential sites, suggesting that the roadside concentrations responded more to the dust storms than the residential areas. The relationship between the pollutant concentrations and five important meteorological parameters (solar radiation, wind speed, air temperature, relative humidity, and precipitation) showed that the number and type of meteorological variables included in the equations varied according to the monitoring station or season. Finally, the current results confirmed that attention should be given to the PM₁₀ exposure of residents living near roadways.     

Effects of particle thermal characteristics on flame microstructures during dust explosions of three long-chain monobasic alcohols in a half-closed chamber

To reveal clearly the effects of particle thermal characteristics on flame microstructures during organic dust explosions, three long-chain monobasic alcohols, solid at room temperature and similar in physical-chemical properties, were chosen to conduct experiments in a half-closed chamber. In the experiments, the dust materials were dispersed into the chamber by air to form dust clouds and the hybrids were ignited by an electrical spark. A high-speed optical schlieren system was used to record the flame propagation behaviors. A fine thermocouple and an ion current probe were respectively used to measure the flame temperature profile and the reaction behaviors of the combustion zone. Based on the experimental results, combustion behaviors and flame microstructures in dust clouds with different thermal characteristics were analyzed in detail. As a result, it was found that the dust flame surfaces were completely covered by cellular structures that significantly increased the flame frontal areas. Flame propagated more quickly and the number of the cellular cells increased as increasing the volatility of the particles. On the contrary, maximum temperature and the thickness of the preheated zone decreased as increasing the volatility of the particles. According to the ion current profile, the particles in the preheat zone were pyrolyzed to intermediate radicals and the radicals' fraction in the higher volatile dust flame was higher than that in the lower volatile dust flame.     

福建省重点城市路面尘负荷及化学组成研究

采集并分析了福建省重点城市厦门、漳州、泉州和莆田城区具有代表性的57个地面扬尘和16个土壤样品的26种无机元素、8种水溶性离子和碳成分等组成.不同城市粒径≤100μm的路面尘负荷平均值在6.99 g.m-2与10.11 g.m-2之间,而粒径≤2.5μm的路面尘(PM2.5)负荷平均值在4.0 mg.m-2和12.5 mg.m-2之间.不同城市土壤尘和路面尘PM2.5中浓度最高的元素都是Si、Ca、Al、Fe和K,路面尘中Ca元素明显富集,而主要人为来源的重金属元素如Cu、Pb、Zn、Cr在路面尘PM2.5中的浓度显著高于土壤尘.漳州城区路面尘PM2.5中二次离子NH4+、NO3-和SO24-的含量明显高于其它地区,厦门、漳州和泉州城区路面尘PM2.5中Mg2+和Ca2+之间都存在显著的正相关关系.四城市路面尘中有机碳(OC)的含量均高于济南、石家庄以及北京地面扬尘OC的含量,元素碳(EC)的含量均低于北京地区路面扬尘EC的含量.泉州和莆田两地OC和EC的相关性较好,说明路面尘中OC和EC有相同或相似的来源.质量平衡结果显示泉州和莆田路面尘PM2.5中含量最高的是土壤尘,其次为有机物.按化学组成特征对路面尘PM2.5进行聚类解析,得到受大气沉降影响、受土壤尘影响、受大气沉降和土壤尘共同作用以及受土壤尘和建筑尘共同作用4类样品.     

重庆市夏秋季VOCs对臭氧和二次有机气溶胶生成潜势的估算

为估算重庆市夏秋季VOCs（挥发性有机物）对O₃和SOA（二次有机气溶胶）的生成潜势,利用在线GC-MS/FID在2015年8月22日-9月23日对重庆市区点和郊区点VOCs开展了为期一个月的实时观测,获得市区点和郊区点$ \varphi $（TVOCs）（总挥发性有机物）分别为41.35×10-9和22.72×10-9,其中市区点以烷烃（35.2%）和烯炔烃（25.2%）为主,郊区点以含氧挥发性有机物（oxygenated volatile organic compounds,OVOCs）（30.6%）和烷烃（26.0%）为主.结合最大增量反应活性量化市区点和郊区点VOCs的OFPs（臭氧生成潜势）分别为149.11×10-9和71.09×10-9,市区点OFPs最大的是乙烯、丙烯、甲苯、C8和C9的芳香烃等,郊区点OFPs最大的VOCs是丙烯醛、异戊二烯和甲基乙烯基酮.结合气溶胶生成系数量化郊区点和市区点VOCs对SOA的生成贡献分别为0.36和1.26 μg/m3,相比国内其余城市VOCs的SOAP（二次有机气溶胶生成潜势）较小,主要以甲基环己烷、正壬烷、正葵烷和十一烷等高碳烷烃,以及甲苯、苯、二甲苯和乙苯等芳香烃的SOAP为主.研究显示,控制烯炔烃和芳香烃的浓度有助于控制重庆市O₃的生成,控制高碳烷烃和芳香烃则有助于控制重庆市SOA的生成.      

北京市铺装道路降尘污染特征及来源

为研究北京市道路降尘在不同季节的污染特征及来源,选取北京市4条典型道路得到64个采样点的道路尘样品,采集的道路尘样品经过预处理得到75 μm以下的颗粒物,经过再悬浮及实验室分析得到PM_2.5的粒径分布和化学成分谱.结果表明:不同采样高度及不同道路类型的颗粒物粒径大体分布规律一致,颗粒物质量频率存在三个峰值,分别为0.75 μm（微粒径）、2.50 μm（小粒径）、4.50 μm（大粒径）;各季节的降尘颗粒物的化学组分中质量分数最大的是元素,主要元素（含量>1%）季节变化为冬季>春季>秋季>夏季,元素富集因子法得到污染元素为Cr、Cd、Sn、Cu、Zn、Pb、As,双重元素为Bi、Ti、Ni、W、Mg、Ca、TI、Mo、V、Fe、Zr、Ba,其余16种为非富集元素;颗粒物中离子质量分数在夏季最大为9.31%,春季、秋季、冬季的离子质量分数相差不大,其中Ca2+、NO₃-、Cl-、SO₄2-占总离子质量的80%左右;碳素中w（OC）和w（EC）的季节变化均为夏季>秋季>春季>冬季,OC/EC[w（OC）/w（EC）]的季节变化规律为冬季>春季>秋季>夏季.不同季节w（OC）和w（EC）的相关性大小为夏季>秋季>春季>冬季.对PM_2.5中化学组分来源分析表明,污染元素受机动车和建筑尘影响较大,与机动车尾气相比,机动车磨损造成的污染也不容小视;燃煤影响一直存在,但供暖期污染有所改善.机动车尾气、建筑尘及土壤尘对离子均有贡献,在夏季土壤尘、建筑尘、二次反应的综合影响较大,春季土壤尘影响更为突出.碳在夏秋季节受汽车尾气和建筑尘的影响较大,夏季二次反应影响不大;冬季除气象因素外,燃煤和生物质燃烧也不可忽视;春季土壤尘影响较为突出.      

铁炭内电解垂直流人工湿地对污水厂尾水深度脱氮效果

针对污水厂尾水总氮(TN)含量偏高、微生物可利用碳源低的问题,构建铁炭内电解垂直流人工湿地(ICIE-VFCW)装置,研究了ICIE-VFCW对尾水的处理效果,并采用紫外-可见光光谱(UV-VIS)、凝胶过滤色谱(GFC),进一步探讨了ICIEVFCW强化脱氮机制.结果表明,ICIE-VFCW可提高系统对尾水中COD的去除,出水COD可稳定在30 mg·L~(-1)以下,全年、暖季、寒季COD平均去除率较普通垂直流人工湿地分别可提高10.16%、9.81%、11.22%.系统出水TN可维持在10 mg·L~(-1)以下,全年、暖季、寒季TN平均去除率较普通垂直流人工湿地分别提高13.72%、12.90%、16.17%.经过人工湿地处理后,污水中有机物的腐殖度、芳香度及相对分子质量(Mr)均有所下降,且ICIE-VFCW中Mr下降更为明显.湿地基质掺杂铁炭可促进尾水中大分子有机物转化为小分子,为微生物提供更多可利用碳源,从而提高脱氮效率.     

道路灰尘中有机磷阻燃剂污染特征及人体暴露

利用气质联用仪(GC-MS)定量分析了苏州市25个道路灰尘样品中4种有机磷阻燃剂(organophosphate flame retardants,OPFRs)的含量水平和分布特征,并估算了成人、儿童和环卫工人灰尘摄入和呼吸暴露两种不同途径的日暴露量.结果表明,在灰尘样品中4种OPFRs均有不同程度检出,总OPFRs的含量范围为ND~8 901.66 ng·g~(-1),中位值为1 039.21 ng·g~(-1).三(1-氯-2-丙基)磷酸酯[Tris(1-chloro-2-propyl)phosphate,TCPP]、磷酸三(丁氧基乙基)酯[Tris(2-butoxyethyl)phosphate,TBEP]、磷酸三(1,3-二氯-2-丙基)酯[Tris(1,3-dichloro-2-propyl)phosphate,TDCPP]和磷酸三(2-氯乙基)酯[Tris(2-chloroethyl)phosphate,TCEP]含量范围分别为0~6 931.46、0~2 021.15、0~788.44和0~62.16 ng·g~(-1).在高暴露情景下,成人、儿童和环卫工人通过摄入灰尘暴露ΣOPFRs的日均暴露量分别是125.68、915.78和6 314.16 pg·kg~(-1),儿童的暴露量比普通成人高6倍;而成人、儿童和环卫工人通过呼吸途径暴露ΣOPFRs的日均暴露量分别为3.07E-02、1.89E-02和1.54E-01 pg·kg~(-1).因此灰尘中OPFRs对于儿童和环卫工人的潜在危害更大.     

Homogeneous and heterogeneous reactions of anthracene with selected atmospheric oxidants

The reactions of gas-phase anthracene and suspended anthracene particles with O3 and O3-NO were conducted in a 200-L reaction chamber, respectively. The secondary organic aerosol (SOA) formations from gas-phase reactions of anthracene with O3 and O3-NO were observed. Meanwhile, the size distributions and mass concentrations of SOA were monitored with a scanning mobility particle sizer (SMPS) during the formation processes. The rapid exponential growths of SOA reveal that the atmospheric lifetimes of gas-phase anthracene towards O3 and O3-NO are less than 20.5 and 4.34 hr, respectively. The particulate oxidation products from homogeneous and heterogeneous reactions were analyzed with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). Gas chromatograph/mass spectrometer (GC/MS) analyses of oxidation products of anthracene were carried out for assigning the time-of-flight (TOF) mass spectra of products from homogeneous and heterogeneous reactions. Anthrone, anthraquinone, 9,10- dihydroxyanthracene, and 1,9,10-trihydroxyanthracene were the ozonation products of anthracene, while anthrone, anthraquinone, 9-nitroanthracene, and 1,8-dihydroxyanthraquinone were the main products of anthracene with O3-NO.