In-air micro-particle-induced X-ray emission imaging and spectroscopy of air-borne particles collected hourly from an automated sampling unit of the atmospheric environmental regional observation system

Particulate matter (PM) collected hourly by an automated sampling unit of the Atmospheric Environmental Regional Observation System (AEROS) was characterized by external micro-particle-induced X-ray emission (PIXE) analysis and imaging. Micro-PIXE analysis revealed the overall elemental composition and differences in the elemental composition ratios of PM2.5 and PM2.5-10 collected as individual spots on Teflon tape filters from the unit, and the blank Teflon tape showed a clean background. Moreover, micro-PIXE imaging visualized regions with different elemental compositions in PM2.5 and PM2.5-10. Accumulation of PM2.5 particles was found frequently on tape filters which accounted approximately for 70% of particular elemental composition including heavy metals like iron, compared to that from whole area. The results suggest that PIXE effectively reveals elemental composition of hourly-collected PM by AEROS system for futuristic application for source apportionment of those over Japan