Characterization of Aerosols Containing Zn, Pb, and Cl from an Industrial Region of Mexico City

Department of Chemistry and Biochemistry, University of California, San Diego, California 92093-0314, USA.
Environmental Science and Technology (Impact Factor: 5.48). 11/2008; 42(19):7091-7. DOI: 10.1021/es7030483
Source: PubMed

ABSTRACT Recent ice core measurements show lead concentrations increasing since 1970, suggesting new nonautomobile-related sources of Pb are becoming important worldwide (1). Developing a full understanding of the major sources of Pb and other metals is critical to controlling these emissions. During the March, 2006 MILAGRO campaign, single particle measurements in Mexico City revealed the frequent appearance of particles internally mixed with Zn, Pb, Cl, and P. Pb concentrations were as high as 1.14 microg/m3 in PM10 and 0.76 microg/m3 in PM2.5. Real time measurements were used to select time periods of interest to perform offline analysis to obtain detailed aerosol speciation. Many Zn-rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2 x 6H2O. The internally mixed Pb-Zn-Cl particles represented as much as 73% of the fine mode particles (by number) in the morning hours between 2-5 am. The Pb-Zn-Cl particles were primarily in the submicrometer size range and typically mixed with elemental carbon suggesting a combustion source. The unique single particle chemical associations measured in this study closely match signatures indicative of waste incineration. Our findings also show these industrial emissions play an important role in heterogeneous processing of NO(y) species. Primary emissions of metal and sodium chloride particles emitted by the same source underwent heterogeneous transformations into nitrate particles as soon as photochemical production of nitric acid began each day at approximately 7 am.


Available from: Vaithiyalingam Shutthanandan, Jun 03, 2015
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    ABSTRACT: For a better understanding of metal particle morphology and behaviors in China, atmospheric aerosols were sampled in the summer of 2012 in Beijing. The single-particle analysis shows various metal-bearing speciations, dominated by oxides, sulfates and nitrates. A large fraction of particles is soluble. Sources of Fe-bearing particles are mainly steel industries and oil fuel combustion, whereas Zn- and Pb-bearing particles are primarily contributed by waste incineration, besides industrial combustion. Other trace metal particles play a minor rule, and may come from diverse origins. Mineral dust and anthropogenic source like vehicles and construction activities are of less importance to metal-rich particles. Statistics of 1173 analyzed particles show that Fe-rich particles (48.5%) dominate the metal particles, followed by Zn-rich particles (34.9%) and Pb-rich particles (15.6%). Compared with the abundances among clear, haze and fog conditions, a severe metal pollution is identified in haze and fog episodes. Particle composition and elemental correlation suggest that the haze episodes are affected by the biomass burning in the southern regions, and the fog episodes by the local emission with manifold particle speciation. Our results show the heterogeneous reaction accelerated in the fog and haze episodes indicated by more zinc nitrate or zinc sulfate instead of zinc oxide or carbonate. Such information is useful in improving our knowledge of fine airborne metal particles on their morphology, speciation, and solubility, all of which will help the government introduce certain control to alleviate metal pollution. Copyright © 2014 Elsevier B.V. All rights reserved.
    Science of The Total Environment 12/2014; 511C:369-380. DOI:10.1016/j.scitotenv.2014.12.071 · 3.16 Impact Factor
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    ABSTRACT: PM2.5 were collected in March 2006 during the MILAGRO campaign (Megacities Initiative: Local and Global Research Observations) carried out in the northern region of the Mexico City Metropolitan Area (MCMA), in order to realize an individual characterization of particulate matter through scanning electron microscopy coupled with an energy-dispersive X-Ray analyzer (SEM-EDX), acquiring information from around 6 000 particles about their morphology, size and superficial chemical composition. Measurements of the aerosol were obtained at a site located in the northern part of Mexico City (T0) and also at a site located 30 km northeast (T1) in four time intervals 6: 00 - 9: 00; 11: 00 - 14: 00; 16: 00 - 19: 00 and 21: 00 - 0: 00 hrs. Employing backscattered electron detector (BSD) anthropogenic phases were analyzed with the EDX and elemental composition of individual particles showed mainly elemental composition of Fe-O (24% relative abundance) with spherical morphology congruent to emissions from metal-mechanic industrial process and soil re-suspension. Twenty percent of the aerosol was "Pb-rich" particles identified as agglomerations of nanometric spheres of individual size distributions among 1.0 - 600 nm and they are related to high temperature industrial emissions. The "Ba-rich" particles (16%) presented chemical associations of Ba-S-O and irregular morphologies and they were related to emissions from the mineral phase of barite that constitutes the asbestos of the automobile pieces. "C-rich" group was the fourth most abundant (12%) one with predominant morphology corresponds to nanometric spheres (between 600 and 800 nm) of compact and continuous surface, this kind of particles are mainly related to vehicle exhaust emissions and their temporal distribution presented a clear decrease during weekends when vehicle traffic is reduced on the MCMA. Elements like Ca, Zn, Cu, Sr, Sn, Al, Sb, Na and W were also detected in less relative abundance (28% of the total), and their individual morphology and possible source emissions are described. (c) Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
    Atmospheric Pollution Research 07/2012; 3(3). DOI:10.5094/APR.2012.032 · 1.23 Impact Factor