AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Development and Field Evaluation of an Online Monitor for Continuous Measurement of Metals in Coarse Particulate Matter
MOHAMMAD SOWLAT, Dongbin Wang, Giulia Simonetti, Martin Shafer, James Schauer, Constantinos Sioutas, University of Southern California
Abstract Number: 23 Working Group: Instrumentation and Methods
Abstract This study presents a novel system for online, field measurement of three toxicologically relevant redox-active metals (Fe, Mn, and Cr) in ambient coarse particulate matter (PM). This new system utilizes two virtual impactors combined with a modified liquid impinger (BioSampler) to collect coarse PM directly as concentrated slurry samples. The concentrations of target metals in the collected slurries are subsequently measured using a Micro Volume Flow Cell (MVFC) coupled with spectrophotometry to quantify the light absorption of colored complexes resulting from the reaction between the target metals and analytical reagents. In the field evaluations, very good agreements for total concentrations of target metals were obtained between online spectrometer-based measurements and those analyzed by means of inductively coupled plasma mass spectrometry (ICP-MS). Moreover, this coarse PM metal monitor was deployed in the field for continuous operations and measurements for three months. Diurnal variations of the target metals and their associations with meteorological parameters were also explored in the current study. The average concentration of Fe, Mn and Cr in coarse PM obtained in this study is 57.8±2.5, 15.0±0.6, and 6.9±0.6 ng/m3, respectively. All three metals represent similar diurnal variations, with peak values observed during 8-10AM and lowest levels observed during midnight (10PM to 2AM) throughout the sampling campaign. Metal concentrations are also affected by other meteorological parameters such as wind speed and relative humidity. Results from this study suggest that it is an effective technology for characterization of three important metals in ambient coarse PM.