Isotopic signatures and source apportionment of Pb in ambient PM2.5

Control priority based on source-specific DALYs of PM2.5-bound heavy metals by PMF-PSCF-IsoSource model in urban and suburban Beijing

To determine the priority control sources, an approach was proposed to evaluate the source-specific contribution to health risks from inhaling PM2.5-bound heavy metals (PBHMs). A total of 482 daily PM2.5 samples were collected from urban and suburban areas of Beijing, China, between 2018 and 2019. In addition to the PMF-PSCF model, a Pb isotopic IsoSource model was built for more reliable source apportionment. By using the comprehensive indicator of disability-adjusted life years (DALYs), carcinogenic and noncarcinogenic health risks could be compared on a unified scale. The study found that the annual average concentrations of the total PBHMs were significantly higher in suburban areas than in urban areas, with significantly higher concentrations during the heating season than during the nonheating season. Comprehensive dust accounted for the largest contribution to the concentration of PBHMs, while coal combustion contributed the most to the DALYs associated with PBHMs. These results suggest that prioritizing the control of coal combustion could effectively reduce the disease burden associated with PBHMs, leading to notable public health benefits.

Investigation of source and infiltration of toxic metals in indoor PM2.5 using Pb isotopes during a season of high pollution in an urban area

Lead (Pb) isotope ratio has been applied in source investigation for particulate matter in size < 2.5 μm. However, arsenic (As) and cadmium (Cd) are carcinogenic to human and their isotope analysis is difficult. This study investigated whether the Pb isotope ratio was a useful indicator in identifying the sources of As and Cd indoors and investigating its influencing factors. This study also calculated the infiltration factor (Finf) for metals to assess the influences of indoor- and outdoor-generated metals to indoor air. The As and Cd concentrations in indoor air were 0.87 ± 0.69 and 0.19 ± 0.15 ng/m3, respectively; the corresponding values for outdoor air were 1.44 ± 0.80 and 0.33 ± 0.19 ng/m3. The Finf of As and Cd were 0.60 ± 0.37 and 0.58 ± 0.39, and outdoor was a predominant contributor to indoor As and Cd. The Pb isotopes ratio indicated that traffic-related emission was a major contributor to Pb. The Pb concentration was associated with those of As and Cd in indoor or outdoor air, as was the 208Pb/207Pb ratio in outdoor air. Significant correlations between indoor 208Pb/207Pb values and As and Cd concentrations in indoor air were found only in study houses with air change rate > 1.5 h-1. These findings suggested that traffic-related emission was identified as a major source of As and Cr. The 208Pb/207Pb is a useful indicator in investigating the source of As and Cd; however, the air change rate influences the applicability of this approach on source identification.

Monsoon climate controls metal loading in global hotspot region of transboundary air pollution

Eastern Asia is a major source of global air pollution. The distribution and intensity of these emissions are becoming well characterized, but their impact on the earth surface considering regional hydroclimatological settings has yet to be quantified. Here we show high-resolution spatiotemporal trace metal distributions of precipitation samples collected throughout the Japanese archipelago in 2013, when the world's coal consumption was the greatest, to depict the mass transportation and deposition of pollution. The results show that metals emitted through coal combustion transported from the continent via prevailing wind were intensively deposited along the western coast of the archipelago during winter due to heavy snowing, resulting in lead (Pb) concentration of precipitations exceed the critical level (> 10 μg l^-1). About 1497 tons of Pb of continental origin loaded through wet deposition accounted for over ca. 87% of the total annual flux in 2013, which constituted ca. 18.5% of the total emissions from China in 2012. This study presents the first detailed picture of monsoon climate-controlled atmospheric metal transportation and loading in the hotspot region after the phase-out of leaded gasoline in the twentieth century. The dataset can serve as a base for evaluating the effect of countermeasures implemented recent year.