Contribution of dust in northern China to PM concentrations over the Hexi corridor.

Four main dust sources and dust events that affected the Hexi Corridor were defined, and the HYSPLIT model was used to trace the dust that originated during the dust episodes of 2015-2017 and to quantify the contributions of dust sources to PM. On this basis, an algorithm that quantified the contribution of dust sources to PM was proposed in this study. The results showed that the main dust sources affecting the Hexi Corridor are generally located in the northern part of Xinjiang, which is mainly dominated by the Gurbantunggut Desert (source A); the Taklimakan and Kumtag Deserts and their surrounding areas (source B); both Qaidam Basins (source C); and the Badain Jaran Desert, Tengger Desert, Hobq Desert, Ulan Buh Desert, and Mu Us Sandy Land and their surrounding areas (source D). The occurrence time of dust and the frequency of PM exceeded the daily concentration standards and showed significant characteristics of being high in the spring and low in the autumn. The higher concentration of PM in the winter was mainly due to anthropogenic sources from heating process. The contribution of source area D to PM concentration was the greatest (42%). Source area B was one of the main dust sources (with a contribution rate of 23%); however, approximately 63% of the dust in this area originates from the Kumtag Desert. The contribution of source area A is lower than that of the study area due to greater precipitation and higher vegetation coverage (22% contribution rate). Source area C has the lowest contribution to the research area due to obstruction by the Qilian Mountain (13% contribution rate).