Elemental Characterization of Ambient Particulate Matter for a Globally Distributed Monitoring Network: Methodology and Implications

XUAN LIU, Randall Martin, Jay R. Turner, Washington University in St. Louis

     Abstract Number: 187
     Working Group: Identifying and Addressing Disparate Health and Social Impacts of Exposure to Aerosols and Other Contaminants across Continents, Communities, and Microenvironments

Abstract
Global ground-level measurements of elements in ambient particulate matter (PM) can provide valuable information to understand emission sources of dust and trace elements, assess their health impacts, and improve atmospheric models. We use Energy-dispersive X-ray Fluorescence to characterize the elemental composition of PM collected from 24 globally distributed sites in the Surface PARTiculate mAtter Network (SPARTAN) over 2018−2022. Consistent protocols are applied to collect all samples and analyze them at one central laboratory which ensures the comparability of data across sites around the world. Reference materials that mimic filter material and mass loadings of typical PM samples are applied to calibrate the instrument. Routine quality control measures are implemented to monitor instrument stability and acceptance testing is conducted to ensure filter quality. Background levels from both lab and field are considered to calculate method detection limits. Additive and proportional uncertainties are estimated to provide overall measurement uncertainties. Long-term concentrations of dust and trace element oxides (TEO) are determined from the elemental dataset for SPARTAN sites. In addition to sites in arid regions, high dust concentration (6 μg/m³) in PM2.5 is also observed in Dhaka (Bangladesh) with a high TEO level (6 μg/m³). High carcinogenic risk (>1 cancer case per 100,000 adults) from airborne arsenic is observed in Dhaka, Kanpur (India), and Hanoi (Vietnam). Common emission sources including dust, traffic, and coal combustion are identified for these sites, with coal combustion likely the major arsenic source as indicated by principal component analyses.