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

Abstract

Global ground-level measurements of elements in ambient particulate matter (PM) can provide valuable information to understand the distribution of dust and trace elements, assess health impacts, and investigate emission sources. We use X-ray fluorescence spectroscopy to characterize the elemental composition of PM samples collected from 27 globally distributed sites in the Surface PARTiculate mAtter Network (SPARTAN) over 2019−2023. Consistent protocols are applied to collect all samples and analyze them at one central laboratory, which facilitates comparison across different sites. Multiple quality assurance measures are performed, including applying reference materials that resemble typical PM samples, acceptance testing, and routine quality control. Method detection limits and uncertainties are estimated. Concentrations of dust and trace element oxides (TEO) are determined from the elemental dataset. In addition to sites in arid regions, a moderately high mean dust concentration (6 μg/m 3 ) in PM 2.5 is also found in Dhaka (Bangladesh) along with a high average TEO level (6 μg/m 3 ). High carcinogenic risk (>1 cancer case per 100000 adults) from airborne arsenic is observed in Dhaka (Bangladesh), Kanpur (India), and Hanoi (Vietnam). Industries of informal lead-acid battery and e-waste recycling as well as coal-fired brick kilns likely contribute to the elevated trace element concentrations found in Dhaka.

Global Spatial Variation in the PM2.5 to AOD Relationship Strongly Influenced by Aerosol Composition

“…SPARTAN also provides filter based PM2.5 chemical composition, which is initially described in Snider et al, (2016). Subsequent developments to the sampling and analysis procedure of SPARTAN include an upgrade to the AirPhoton SS5 sampling station to use a cyclone inlet, an automated weighing system (MTL AH500E) to improve precision and throughput, additional black carbon analysis by Hybrid Integrating Plate/Sphere (White et al, 2016), trace metal elements measured by X-ray Fluorescence (Liu et al, 2024) and a global mineral dust equation (Liu et al, 2022). We require 50 days of coincident PM2.5 and AERONET AOD measurements for a SPARTAN site to be included in our analysis.…”