Abstract
Spherical black carbon aggregates were frequently observed in dust dry deposition in Daejeon, Korea. They were tens of micrometers in diameter and presented a mixture of black carbon and several mineral phases. Transmission electron microscopy (TEM) observations with energy-dispersive X-ray spectroscopy (EDS) and selected area diffraction pattern (SADP) analyses confirmed that the aggregates were compact and included significant amounts of lead chromate (PbCrO4). The compositions and morphologies of the nanosized lead chromate particles suggest that they probably originated from traffic paint used in roads and were combined as discrete minerals with black carbon. Based on Pb isotope analysis and air-mass backward trajectories, the dust in Daejeon received a considerable input of anthropogenic pollutants from heavily industrialized Chinese cities, which implies that long-range transported aerosols containing PbCrO4 were a possible source of the lead and hexavalent chromium levels in East Asia. Lead chromate should be considered to be a source of global atmospheric Pb and Cr(VI) pollution, especially given its toxicity.
Highlights
High levels of Pb and Cr and their seasonal variations are detected in the air in Korea[1,2], China[3,4,5] and Japan[6]
Leaded gasoline was traditionally considered as a major source of Pb in the air, and in China and Korea, leaded gasoline was banned in the year 2000 and 1993, respectively
The blood lead levels of children in China are higher than those in developed countries, and childhood lead poisoning remains a grave public health concern in China[19]. This fact indicates that sources other than leaded gasoline contribute to the airborne lead in China
Summary
High levels of Pb and Cr and their seasonal variations are detected in the air in Korea[1,2], China[3,4,5] and Japan[6]. The lead and chromium levels did not show a distinct annual variation in 2007–2008, but gradually increased from summer to winter and remained at a relatively high level in the spring[1] Both AD and NAD samples showed high levels of Pb and Cr1,7. These high levels of lead and chromium in airborne particulates are of great concern due to their negative impacts on air quality and human health. The blood lead levels of children in China are higher than those in developed countries, and childhood lead poisoning remains a grave public health concern in China[19] This fact indicates that sources other than leaded gasoline contribute to the airborne lead in China.
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