Specific sources of health risks caused by size-resolved PM-bound metals in a typical coal-burning city of northern China during the winter haze event

摘要

High particulate matter (PM) pollution frequently occurs in winter over northern China , resulting in threats to human health. To date, there are limited studies to link source apportionments and health risk assessments in the different size-resolved PM samples during high PM events. In this study, size-segregated PM samples were collected in Linfen, a typical coal-burning city, in northern China during a wintertime haze pollution. In addition to water-soluble ions and carbon contents, metallic elements in the different size-segregated PM samples were also determined for health risk assessments by inhalation of PM. During the sampling period, the average concentration of PM_(10) was 274 ± 57 μg m~(-3) with a major fraction (73%) of organic material and secondary-related aerosols, and an insignificant portion of trace elements (TEs, ～ 3%). The size distribution showed that As and Se, markers of coal combustion, exhibited a mono-modal distribution with a major peak at 0.4-0.7 μm and the others mostly possessed mono-/bi-modal patterns with a major peak at 3.3-5.8 μm. The cancer risk (CR) resulted from PM_(10) metals by inhalation was estimated to be 2.91 × 10~5 for children and 7.75 × 10~(-5) for adults while non-cancer risk (NCR) was 2.10 for children and 0.70 for adults. Chromium (Cr) was the dominant species (～89%) of cancer risk in PM_(10). Road dust was a major fraction (～65%) to total metals in coarse PM (dp ＞ 3.3 μm) whereas coal combustion was a dominant source (～55%) in submicron (dp ＜ 1.1 μm) PM metals. However, traffic emissions (40%) and coal combustion (36%) were the dominant sources of CR since both emissions contributed major fractions (74%) to Cr, especially in submicron PM which exhibited high deposition efficiency of TEs into respiratory tracts, resulting in high CR in Linfen City.