Size-resolved samples were collected using a 14-stage impactor during four seasons in Zhengzhou and analyzed for 26 elements to calculate the health risks from atmospheric particle-bound metals. High concentrations of heavy metals were observed in ultrafine (10.2 (Ni)-66.9 (Cd) ng m-3) or submicrometer (11.4 (Ni)-134 (Pb) ng m-3) mode in winter. Two size-dependent models were used to estimate the deposition of inhaled toxic metals in various regions of the human respiratory system. Results show that heavy metals deposited in the alveolar region ranged from 7.6 (As)-375 (Al) ng m-3 and were almost concentrated in ultrafine and fine modes. Cd (2.2-8.6) may cause accumulative non-carcinogenic health effects on children, and Cr (1.0 × 10-4-2.2 × 10-4) may lead to carcinogenic health risks for nearby residents around the sampling site. The major sources by principal component analysis that contributed to Cr and Cd in ultrafine and fine particles were coal combustion, vehicular and industrial emissions. The atmospheric dry deposition fluxes of Cr and Cd were between 0.7 and 1.9 μg m-2 day-1 calculated by a multi-step method. From the environmental and public health perspective, environmental agencies must control the emission of heavy metals in the atmosphere.
Keywords: Dry deposition; Health risks; Inhalation exposure; Size distribution; Sources.
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