Characterization of atmospheric aerosol (PM10 and PM2.5) from a medium sized city in São Paulo state, Brazil

Air pollution causes deleterious effects on human health with aerosols being among the most polluting agents.The objective of this work is the characterization of the PM_(2.5) and PM_(10) aerosol mass in the atmosphere.The methods of analysis include WD-XRF and EDS.Data were correlated with meteorological information and air mass trajectories(model HYSPLIT)by multivariate analysis.A morphological structural analysis was also carried out to identify the probable sources of atmospheric aerosols in the city of Sao Jose do Rio Preto,Brazil.The mean mass concentration values obtained were 24.54 μg/m~3 for PM_(10),above the WHO annual standard value of 20 μg/m~3 and 10.88 μg/m~3 for PM_(2.5) whose WHO recommended limit is10 μg/m~3.WD-XRF analysis of the samples revealed Si and Al as major components of the coarse fraction.In the fine fraction,the major elements were Al and S.The SEM-FEG characterization allowed identifying the morphology of the particles in agglomerates,ellipsoids and filaments in the PM_(10),besides spherical in the PM_(2.5).The analysis by EDS corroborated WD-XRF results,identifying the crustal elements,aluminosilicates and elements of anthropogenic origin in the coarse fraction.For the fine fraction crustal elements were also identified;aluminosilicates,black carbon and spherical particles(C and O) originating from combustion processes were predominant.The use of multivariate analysis to correlate air mass trajectories with the results of the morpho-structural characterization of the particulate matter allowed confirmation of the complex composition of the particles resulting from the combination of both local and long-distance sources.     

重庆金佛山降雪中飞灰单颗粒特征及来源解析

大气降雪能够保存大气环境信息,是研究区域环境的良好介质.位于渝黔交接带的金佛山海拔2 251.1 m,冬季降水以降雪的形式出现,周边区域人类活动强烈.关于该区域大气气溶胶中的飞灰单颗粒特征的研究比较缺乏.本研究采集了金佛山5个降雪样品,运用扫描电镜及X能谱分析联用系统(SEM-EDS)对样品中的132个飞灰进行单颗粒形貌、化学组成分析.结果表明,研究区降雪中存在大量球形飞灰,包含光滑颗粒、粗糙颗粒及聚合体颗粒3种形态,分别占统计颗粒的80.31%、14.39%和5.30%;平均粒径1.64μm,平均环度1.09.按主导化学元素分为富硅类、富碳类、富铁类、富铝类及富钛类5种,所占比例分别为34.09%、49.24%、12.88%、2.27%和1.52%.结合气象资料、气团后向运移轨迹和飞灰性质,推测富碳类飞灰可能主要来自于生活排放源和工业活动;富硅类飞灰可能来自于渝西、黔北、湘中、浙赣一带及粤西的火力发电厂等高温燃煤工业;富铁类及富钛类飞灰则可能来源于渝西和黔北、湘中的钢铁厂、轧钢厂等金属冶炼活动.     

高钙特征焚烧飞灰的加速碳酸化处理及对重金属浸出特性的影响

针对生活垃圾焚烧飞灰的高钙含量特征,在室温下采用CO2对焚烧飞灰在液固比(L∶S)为0.25∶1的条件下进行加速碳酸化处理,考察加速碳酸化处理对焚烧飞灰中重金属(As、Cd、Cu、Zn、Sb、Pb)浸出特性的影响.焚烧飞灰XRD分析表明,加速碳酸化处理后飞灰中的Ca(OH)2和CaClOH衍射峰消失,而CaCO3的衍射峰增多,且强度增加.加速碳酸化处理后飞灰中铅的形态发生了改变,并且能够检测到铜的化合物.TG/DTA分析表明,焚烧飞灰在440℃之前增重达到5.70%,SEM-EDS分析证实了Ca(OH)2(s)+CO2(g)→CaCO3(s)反应的发生.焚烧飞灰加速碳酸化处理后的TCLP浸出实验表明,碳酸化时间在2 h内,重金属的浸出浓度除Cd保持不变外都显著下降;而当碳酸化时间超过50 h后,重金属的浸出浓度除Pb外普遍高于飞灰未经碳酸化处理时的浸出浓度.     

武汉城市污水中微塑料的分离、鉴定及其微观特征分析

为研究武汉城市污水中微塑料的分布特点及其表面形貌特征,采用以连续浮选分离装置为基础进行改进设计的微塑料提取装置对污水中微塑料进行分离,通过用65%硝酸和30%过氧化氢混合液（体积比为1:3）对污水样品进行消解,并采用筛网（300、600、1 000目）（100目=0.147 mm）和滤膜（1 μm玻璃纤维滤膜和20 nm氧化铝滤膜）分离技术建立起对水体微塑料和纳米塑料的分离富集方法.通过傅里叶变换红外光谱（FTIR）、扫描电镜-X射能谱分析联用（SEM-EDS）等方法对所提取微塑料颗粒的组成成分、赋存特征、表面形貌特征进行分析.结果表明:①提取装置的平均回收率在92%以上.②污水中微塑料类型主要为碎片类、泡沫类、薄膜类和纤维类.③FTIR结果证实,该方法所提取的微塑料颗粒中有聚乙烯、聚丙烯等成分,且发现了羰基、聚酯类物质存在,说明提取到的微塑料中可能有可降解塑料颗粒.④SEM-EDS结果显示,各类微塑料表面粗糙、撕裂程度不同,存在不同程度的风化痕迹,并在其表面发现Si、Cu、O、Al、Na、Ca、Ba等元素的富集.研究显示:改进的微塑料分离方法能够实现对污水中微塑料的高效提取;同时,明确了武汉城市污水微塑料的表面形貌特征及赋存特征,为未来武汉城市污水中微塑料污染的针对性治理提供理论依据.      

A comparison of SEM-EDS with ICP-AES for the quantitative elemental determination of estuarine particles

Suspended particulate matter (SPM) is a key component regulating the biogeochemistry of natural and contaminant moieties in estuaries. Individual particle analyses can complement conventional bulk analyses of SPM, but are rarely undertaken. This study used scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS) of particles to quantify a range of elements in the reference estuarine sediment PACS-2. This approach was compared with a bulk SPM analysis based on inductively coupled plasma-atomic emission spectrometry (ICP-AES). The median concentrations of Al, Fe, Mg, and Ca for the two approaches were similar, and accuracy for both methods was good. SEM-EDS analysis was also satisfactory for K. Agreement was poorer for Mn and Ti, which were present at trace concentrations. Increasing the number of particles examined by SEM-EDS should improve the analysis. SEM-EDS analysis of SPM from the Tamar Estuary, UK, revealed marked geochemical differences between particle sub-populations.Selected article from 6th European Meeting on Environmental Chemistry, Belgrade, 2005, organised by Prof. Dr. Branimir Jovancicevic and the European Association of Chemistry and the Environment (ACE, www.research.plymouth.ac.uk/ace)     

大肠杆菌与水体中U(Ⅵ)的作用行为和产物研究

通过批次吸附实验及介观和谱学等表征方法,研究了大肠杆菌(E.coli)粉末对水体中U(Ⅵ)的富集行为和吸附模型,并对其作用产物进行了详细分析.结果表明:大肠杆菌对初始浓度为50mg/L U(Ⅵ)溶液(pH＝5)的吸附容量可达到276.89mg/g.Langmuir等温模型和准二级动力学方程能较好的描述其吸附过程. FTIR、SEM-EDS、XRD分析结果表明:在与水体中U(VI)作用后,大肠杆菌表面检测出UO₂²⁺的红外特征峰(876.16cm^-1)和U的能谱吸收峰(结合能=2.4~4.4keV).UO₂²⁺主要与菌体表面的烷基、氨基、羧基、分子间氢键发生作用,重点与PO₂-、P(OH)₂、PO₄^3-以及PO₃^-等含P基团进行络合配位,最终产物以CaU(PO₄)₂、Ca(UO₂)₂(PO₄)₂·xH₂O、NaUO₂(PO₃)₃等铀的磷酸盐形式存在.     

Optimization of the removal of chromium and lead by Penicillium chrysogenum using 2k factorial experiments

This study aims to prepare a low-cost, environmentally friendly, and alternative, biosorbent to remove chromium Cr (III) and lead Pb (II) from polluted water and to find out the highest removal efficiencies using 2^k factorial experiments. The Cr (III) and Pb (II) tolerant fungal strain identified as Penicillium chrysogenum was isolated from ceramic industrial sludge. The impact of process variables on biosorption of Cr (III) and Pb (II) by P. chrysogenum was first evaluated with the Taguchi screening design. Factors and levels were determined to optimize Cr (III) and Pb (II) removal efficiency. According to this, five factors; initial concentration, pH, biosorbent dose, temperature, and inactivation methods were determined for both metals, each factor defined as a fixed factor with two levels. Optimization of the parameters affecting the removal process was determined by the Taguchi method and the signal-to-noise (S/N) ratios are calculated. The maximum removal efficiency (99.92%) was observed at pH 7, biosorbent 1 mg L^–1, inactivation with autoclaving, and at 20°C with an initial metal concentration of 50 mg L^–1 Cr (III). On the other hand, the maximum removal efficiency (98.99%) was observed at pH 4, biosorbent 5 mg L^–1, inactivation with autoclaving, and at 20°C with an initial metal concentration of 50 mg L^–1 Pb (II). Furthermore, metal ions removal by P. chrysogenum was also confirmed by scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectrometer (EDS). The presence of functional groups on fungal cells of metal binding was investigated by Fourier transform infrared (FT-IR).     

Properties of agricultural aerosol released during wheat harvest threshing, plowing and sowing

This study shows for the first time a chemical and morphological characterization of agricultural aerosols released during three important agricultural operations： threshing, plowing and sowing. The field campaigns were carried out in the eastern part of the Po Valley, Italy, in summer and autumn 2009. The aerosol particles were sampled on quartz fiber filters and polytetrafluoroethylene membranes in order to allow Inductively Coupled Plasma Mass Spectrometry （ICP-MS） analysis and Scanning Electron Microscopy equipped with an Energy Dispersive X-ray Spectrometer （SEM-EDS） investigations, respectively. The organic carbon mass concentrations were measured with a Sunset Laboratory Dual-Optical Organic Carbone/Elemental Carbon （OCEC） Aerosol analyzer. The morphological and chemical analyses by SEM-EDS allowed recognizing four main particle classes： organic, silica, calcite and clay minerals. The organic particles contribute to both fine and coarse aerosol fractions up to ca. 50% for all three agricultural activities. This was also confirmed by OCEC analysis for fine fraction. Most of the agricultural aerosols, about 60%, were single particles and the remaining 40% were agglomerations of particles. The ICP-MS results showed that threshing and plowing produce more aerosol particles than sowing, which was characterized by important amounts of clay minerals produced from land soils.