Distribution and Health Risk Assessment of Heavy Metals in Atmospheric Particulate Matter and Dust

Abstract

In order to study the concentration, distribution characteristics, and health risk assessment of toxic heavy metals, Cu, Mn, Pb, Ti, V, Cd, Cr, Co, Mo, and Ni, in atmospheric particulate matter (PM) and dust, the PM and dust samples were collected in all four seasons in 2014 in Beijing using two high volume air samplers (Echo Tecora Inc., Italy) and a dust tank, respectively. Selected metals were quantified by ICP-MS. Annual average concentrations of PM2.5 and PM10 were 153.40 μg·m-3 and 232.93 μg·m-3, which were five and three times higher than the Ambient Air Quality Standard values (GB 3095-2012), respectively. The average PM2.5/PM10 was 0.74, implying that PM2.5 predominated the particulate matter concentrations. The results of backward trajectory analysis suggested that exogenous particles originated from the northwest, north-northeast, southeast, and southeast-northwest during winter, spring, summer, and autumn, respectively. The order of annual average concentrations of selected metals in PM2.5 and PM10 was Ti > Mn > Pb > Cu > Cr > Ni > V > Cd > Mo > Co. The sum of the concentrations of Ti, Mn, Pb, Cu, and Cr accounted for 91.93% and 92.49% of the total concentration of target metals in PM2.5 and PM10, respectively. The metal content of dust followed the order of Ti > Mn > Pb > Cu > Ni > Cr > V > Co > Mo > Cd and Ti (2561.48 μg·g-1) accounted for 72.57% of the total metal content of dust. The geo-accumulation index (Igeo) of Cd, Pb, Cu, and Ni were 4.03, 2.49, 1.33, and 0.43, which represented the states of heavily to extremely contaminated, moderately to heavily contaminated, moderately contaminated and uncontaminated to moderately contaminated, respectively, indicating that dust in the target area included significant amounts of Cd, Pb, and Cu. The health risk assessment suggested that non-carcinogenic and carcinogenic risks of selected metals in PM10 and dust were within safe limits, but their long-term impact cannot be ignored.