Characteristics of ¹⁴C and ¹³C of carbonate aerosols in dust storm events in China

In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the ¹⁴C and ¹³C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ¹³C of the dryland dust samples considerably varied in a range of -9.7 to -5.0‰, which partly overlapped the desert dust carbonate δ¹³C ranges. The ¹⁴C content of the dryland dust carbonates showed a narrow range of 60.9±4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting ¹⁴C showing of 28.8±3.3pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of ¹⁴C (33.5±5.3pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of ¹⁴C contents (46.2±5.0pMC, n=7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.