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• In Beijing's super sandstorm 2021, 5700 amplicon sequence variants were detected. • Airborne bacteria in sandstorms were compared with the after-storm and haze days. • The sandstorm newly brought 10 pathogenic bacterial genera to the atmosphere. • Small bioaerosols (0.65–1.1 µm) were still suspended after the sandstorm subsided. Sandstorm, which injects generous newly emerging microbes into the atmosphere covering cities, adversely affects the air quality in built environments. However, few studies have examined the change of airborne bacteria during severe sandstorm events. In this work, we analyzed the airborne bacteria during one of the strongest sandstorms in East Asia on March 15th, 2021, which affected large areas of China and Mongolia. The characteristics of the sandstorm were compared with those of the subsequent clean and haze days. The composition of the bacterial community of air samples was investigated using quantitative polymerase chain reaction (qPCR) and high-throughput sequencing technology. During the sandstorm, the particulate matter (PM) concentration and bacterial richness were extremely high (PM 2.5 : 207 µg/m3; PM 10 : 1630 µg/m3; 5700 amplicon sequence variants/m3). In addition, the sandstorm brought 10 pathogenic bacterial genera to the atmosphere, posing a grave hazard to human health. As the sandstorm subsided, small bioaerosols (0.65–1.1 µm) with a similar bacterial community remained suspended in the atmosphere, bringing possible long-lasting health risks. [Display omitted] [ABSTRACT FROM AUTHOR]

Air quality has significantly improved in China; however, new challenges emerge when dust weather is combined with haze pollution during spring in northern China. On March 15, 2021, an extremely severe sandstorm occurred in Beijing, with hourly maximum PM 10 and PM 2.5 concentrations reaching 5267.7 μg m−3 and 963.9 μg m−3, respectively. Continuous sandstorm events usually lead to complicated pollution status in spring. Three pollution types were identified disregarding the time sequence throughout March. The secondary formation type was dominant, with high ratios of PM 2.5 /PM 10 (mean 74%) and PM 1 /PM 2.5 (mean 52%). This suggests that secondary transformations are the primary cause of heavy pollution, even during the dry seasons. Sandstorm type resulted in dramatic PM 10 levels, with a noticeable decrease in PM 2.5 /PM 10 levels (27%), although PM 2.5 levels remain high. The transitional pollution type was distinguished by an independent increase in PM 10 levels, although PM 2.5 and PM 1 levels differed from the PM 10 levels. Throughout March, the sulfur oxidation rate varied considerably, with high levels during most periods (mean 0.52). A strong correlation indicated that relative humidity was the primary variable promoting the formation of secondary sulfate. Sandstorms promote heterogeneous reactions by providing abundant reaction surfaces from mineral particles, therefore aggravating secondary pollution. The sandstorm air mass from the northwest passing through the sand sources of Mongolia carried not only crustal matter but also organic components, such as bioaerosols, resulting in a sharp increase in the organic carbon in PM 2.5. [Display omitted] • Three types of air pollution were identified: secondary formation, sandstorm and transitional pollution. • Haze mixed with sandstorms caused more severe air pollution in Beijing. • Air masses from Mongolia with high bioaerosol burden led to increased organic carbon concentrations. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in sandstorm depositions in Beijing, China. The PAH concentrations in 13 samples collected in Beijing ranged from 0.18 to 3.52 μg g−1. Analysis of the sources of contamination revealed that the PAHs were derived from a coal combustion source, although various effects of traffic emissions were also observed. Furthermore, the PAH levels in Beijing tended to be higher in the southeast. Finally, the nemerow composite index revealed that the degree of pollution in the sandstorm depositions varied widely among sampling sites. [ABSTRACT FROM AUTHOR]

Sandstorms which distribute a great number of particles are a special atmospheric occurrence and are uncommon in northern China. This study was conducted to determine, for the first time, the concentration of organochlorine pesticides (OCPs) in sandstorm depositions. Samples were collected from urban areas of Beijing and a total of eight OCPs were measured. All samples contained OCP residues. The total hexachlorocyclohexane (HCHs) concentration ranged from 20.6 to 59.8ng g−1 and the total dichlorodiphenyltrichloroethane (DDTs) concentration ranged from 12.0 to 14.3ng g−1. Furthermore, increasing HCH contamination was observed from the northwest to the southeast and a uniform distribution of DDT contamination was discovered in Beijing. Analysis of the sources of contamination showed that HCHs in the sandstorm depositions were derived from a relatively old source of lindane, and DDTs mainly originated from an old source of dicofol in Beijing. The preliminary pollution assessment of the samples indicated that HCH levels might be categorized as low pollution and DDT levels might be categorized as no pollution. The present study suggests that sandstorm depositions may not produce the special risk of adverse health effect from OCPs for the residents of Beijing, China. [ABSTRACT FROM AUTHOR]

In China, sandstorms play an important role in the long-range atmospheric transport and deposition of hexachlorobenzene (HCB). Concentrations of HCB in sandstorm depositions sampled from Beijing and the origination region were measured to reveal HCB levels during atmospheric transport. The results suggested a constant level of HCB during atmospheric transport. The values were close to environmental background values indicating that no potential source of HCB existed along the transport route. A tendency for HCB levels in Beijing to increase from north to east was also observed, which was probably due to the influence of wind speed and industrial zone distribution. [ABSTRACT FROM AUTHOR]