Mineralogy and geochemistry of Asian dust: dependence on migration path, fractionation, and reactions with polluted air

Abstract

Abstract. Mineralogical and geochemical data are essential for estimating the effects of long-range transport of Asian dust on the atmosphere, biosphere, cryosphere, and pedosphere. However, consistent long-term data sets of dust samples are rare. This study analyzed 25 samples collected during 14 Asian dust events occurring between 2005 and 2018 on the Korean Peninsula and compared them to 34 soil samples (<20 µm) obtained from the Mongolian Gobi Desert, which is a major source of Asian dust. The mineralogical and geochemical characteristics of Asian dust were consistent with those of fine source soils in general. In dust, clay minerals were most abundant, followed by quartz, plagioclase, K-feldspar, calcite, and gypsum. The trace element contents were influenced by the mixing of dust with polluted air and the fractionation of rare earth elements. Time-series analyses of the geochemical data of dust, combined with satellite remote sensing images, showed a significant increase in the Ca content in the dust crossing the Chinese Loess Plateau and the sandy deserts of northern China. Calcareous sediments in the sandy deserts and pedogenic calcite-rich loess are probable sources of additional Ca. Dust-laden air migrating toward Korea mixes with polluted air over East Asia. Gypsum, a minor mineral in source soils, was formed by the reaction between calcite and pollutants. This study describes not only the representative properties of Asian dust but also their variation according to the migration path, fractionation, and atmospheric reactions.

PM2.5 at a semi‐rural site near Beijing, China

“…Back trajectories calculated with the HYSPLIT model 35 confirm that most of the days the air masses were coming from the north and likely include dust from the Gobi desert, mixed with regional and local particles, local soil, and dust. In a mineralogy study by Jeong 36 high amounts of S were shown in dust events in the area, in addition to the mineral dust elements. The low contribution of V and BC indicates that heavy fuel oil combustion is not a major contributor to factor 1.…”

Aerosol Iron from Metal Production as a Secondary Source of Bioaccessible Iron

“…The data coverage of the mineralogical database for East Asia is not satisfactory as much of the information for this region is compiled in Chinese language publications . Indeed, the Fe content is relatively enriched in Asian dust (5.27 ± 0.25%) compared to the global average . Thus, the regionally averaged Fe content (35–50°N, 70–120°E) for each Fe species in clay-sized soils was scaled to that in the clay-sized fraction of Chinese desert sediments .…”

“…50 Indeed, the Fe content is relatively enriched in Asian dust (5.27 ± 0.25%) compared to the global average. 53 Thus, the regionally averaged Fe content (35−50°N, 70−120°E) for each Fe species in clay-sized soils was scaled to that in the clay-sized fraction of Chinese desert sediments. 54 The scaling factors of the Fe content, which were used to estimate lithogenic emissions of Fe from clay-sized soils in the simulations, are presented in the Supporting Information (Table S4).…”

Measurement report: Stoichiometry of dissolved iron and aluminum as an indicator of the factors controlling the fractional solubility of aerosol iron: Results of the annual observations of size-fractionated aerosol particles in Japan

“…Iron-bearing particles derived from mineral dust and anthropogenic Fe have different chemical compositions and mineralogy. Mineral dust is mainly composed of crystalline aluminosilicates (Jeong and Achterberg, 2014;Jeong, 2020). Fly ash emitted from anthropogenic high-temperature combustion processes can be categorized into two groups: non-magnetic and magnetic particles.…”