Characteristics and source apportionment of atmospheric aerosols at the summit of Mount Tai during summertime

Abstract. To investigate the long-range transport of air pollutants in North China, aerosol samples were collected at the summit of Mount Tai (Shandong province) in June of 2006. Water-soluble ion and metal element concentrations were analyzed using ion chromatography (IC) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. Results showed three different size distributions for the ions and metal elements characterized, including masses in: (i) the accumulation mode, with a peak at 0.43 to 1.1 μm (SO₄²⁻, NH₄⁺, K⁺, Pb, Zn, Ti); (ii) the coarse particle mode, with a peak at 4.7 to 5.8 μm (Ca²⁺, Mg²⁺, Ca, Mg, Fe, Al, Ba, Mn); and (iii) a bimodal distribution, with peaks at 0.43 to 0.65 μm and 4.7 to 5.8 μm (NO₃⁻, Na⁺, Cl⁻, Na, Co, Ni, Mo, Cu). When SO₄²⁻ was in high concentration, the mass median diameter was between 0.5 μm and 0.8 μm, belonging to the "drop mode". The concentrations of SO₄²⁻, NO₃⁻, NH₄⁺, and K⁺ were quite variable. Interestingly, SO₄²⁻, NO₃⁻, and NH₄⁺ reached their highest concentrations when the humid air mass was coming from the south. Furthermore, crustal element concentrations increased when the air mass came from the north and pollution element concentrations were elevated when the air mass came from the south.