which was likely the result of mixing of the regional emissions and the long-range transported pollutants. Specifically,the ratios of Cd/Al, Cu/Al, Zn/Al in PD_HN were evidently more close to those of PD_BJ while much higher than those of PD_SH. In contrast,the ratios of K
þ
/Al and As/Al in PD_HN were about half of those in PD_BJ although they were higher than those in ND_HN.