Fig. 1.

Information on field measurements of chemically-aged dust particles and reactive acidic gases in East Asia. (A) Location of the measurement sites. Red contour lines show the regions where calcium nitrate formation involving dust particles tends to be strongly activated (28). (B) Relative atomic ratios of Ca∶Cl∶(Al + Si + Fe) for dust particles collected at Beijing (22), and SEM images of typical Ca-free and Ca-rich particles taken using 10 kV electron beam (Scale bar: 3 μm). The relative atomic ratios for dust particles collected at Chuncheon (25) are also shown for reference. (C) Same as Fig. 1B, but for the particles collected at Kanazawa (26). (D) Ground-based measurements of gaseous HNO₃ and HCl at Kanghwa (n = 13), Imsil (n = 12), Primorskaya (n = 6), Oki (n = 7), Sado-seki (n = 7), and Tappi (n = 7) from March to May 2007 (means ± standard deviations).