Figure 2
From: Large global variations in measured airborne metal concentrations driven by anthropogenic sources
(a) Crustal enrichment factors (EF) for PM2.5 relative to crustal ratios of the given element and iron (Eq. 1), and (b) replacing measured iron with measured PMc (Eq. 2). Elements are sorted by mean enrichment factor across all sites; sites are listed alphabetically. Singapore is not shown in the bottom plot due to unavailable PMc data.
