Analysis of Air Particulate Emissions Collected Downwind of an Automobile Shredding Operation: Implications for the Envi
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Analysis of Air Particulate Emissions Collected Downwind of an Automobile Shredding Operation: Implications for the Environment and Human Health Kennedy Nguyen and Valerie J. Leppert School of Engineering, University of California, Merced 5200 North Lake Road, Merced, CA 95343, USA ABSTRACT The disposal of materials at the end of their lifecycle, especially for complex manufactured products, presents challenges in terms of both protecting the environment and human health. In particular, used automobiles are disposed of by removal of various component parts, followed by shredding. In this study, air particulates were collected over several days by DRUM impactor downwind of an automobile shredding plant, size separated, and analyzed by scanning and transmission electron microscopy (SEM and TEM), and energy-dispersive x-ray spectroscopy (EDXS), in order to determine their particle size distribution and corresponding chemical composition. Results for larger particles, ranging in size from 2.5 to 10.0 μm, showed mainly diatoms and salts, from the plant’s ocean side location, and aluminosilicates, consistent with geological sources. As particle size decreased from 10 µm to 0.09 µm, particle loading decreased, and composition shifted to mainly oxygen and sulfur, indicative of sulfates, which along with nickel and vanadium that were detected, could be attributed to emissions from nearby shipping traffic. Iron was found to be present, including in spherical particles that were ~ 2 µm in diameter, indicating they originated from a high temperature process. Spherical iron particles also were found to correlate with plant operations, making them a useful “tracer” material for plant emissions. Lead, cerium, barium, chromium and zinc were also detected and their possible correlation to plant feedstocks is discussed. The implications of these results for the environment, particularly soil and water deposition, and for human health as a result of inhalation, are discussed. INTRODUCTION In 2008 and 2009, an investigation was conducted of particulate matter collected in Wilmington, CA, downwind of an automobile shredding plant. An 8 stage Davis rotating universal-size-cut monitoring (DRUM) impactor[1] was used to collect a time series of sizeseparated particulate samples that were subsequently analyzed by synchrotron-induced x-ray fluorescence (S-XRF) for elemental composition[2]. Here, we report the results from a separate investigation of the different aerodynamic size fractions using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging, and energy dispersive x-ray spectroscopy (EDXS) for elemental composition. The implications of these results for the environment and human health are discussed. EXPERIMENTAL DETAILS Particulate samples were collected using an 8 stage DRUM impactor in August to September of 2008. The 8-stage collector size separated particles into different size ranges between 10.0 µm to 0.09 µm based on aerodynamic diameter, as listed in Table 1. Separated size fractions were then c
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