Fig. 1

The proportion of PMCs in each source. Abbreviations: PMC, particulate matter components; Br, bromine; Ca, calcium; Cu, copper; EC, element carbon; Fe, iron; K, potassium; Ni, nickel; NO₃-, nitrate; OC, organic carbon; Pb, lead; Si, silicon; SO₄²-, sulfate; V, vanadium; Zn, zinc