Real-time measurement of total and water-soluble organic carbon with developed online monitors 

Abstract

In this study, two online monitoring systems were developed for measuring total organic carbon (TOC) and water-soluble organic carbon (WSOC) in fine and coarse airborne particles. The performance of these monitoring systems was assessed through field experiments to confirm their capability for real-time measurement. For collecting fine airborne particles, a versatile aerosol concentration enrichment system (VACES) coupled with an aerosol-into-liquid sampler (AILS) were utilized. On the other hand, the collection of coarse particles was conducted by two virtual impactors (VIs) in tandem with a modified BioSampler. These particle collection setups were connected to a Sievers M9 TOC analyzer to provide hourly readings of TOC and WSOC levels in water-based samples. Hourly average concentrations of TOC in fine and coarse particles were found to be 5.17 ± 2.41 µg/m³ and 0.92 ± 0.29 µg/m³, respectively. A parallel comparison was made with a Sunset Lab EC/OC analyzer, and a high degree of correlation in TOC readings was observed with R2 values of 0.89 and 0.85 for fine and coarse PM, respectively. Field tests were also performed to represent diurnal variations in WSOC levels bound to fine particles. The observed average WSOC concentrations for winter and summer were found to align closely with prior studies conducted in Los Angeles. In summary, validation was provided for the reliability of the novel developed monitors in the real-time measuring of TOC and WSOC, establishing their utility for future studies aimed at identifying pollution sources and their health impacts.