Characterization of sources and emission rates of mineral dust in Northern China

Northern China, covering many deserts, gobi-deserts and and loess-lands, is one of the world's largest sources of atmospheric dust. In this study, we estimate the dust annual mean emission rates and perform comparative characterization of dust sources in Northern China by combining the geographical, pedological and 30-year (1951-1980) climatological data. Multi-year averaged emission rates of PM(50), PM(30) and PM(10) (i.e., dust particulates smaller than 0.05, 0.03 and 0.01 mm in diameter, respectively) were calculated using the modified US EPA empirical formulas. We demonstrate that the main dust sources in Northern China are the Taklimakan Desert (the annual mean PM(10) emission rate, Q(10), is some 0.38 ton/ha yr), the Central gobi-desert (Q(10) = 0.24 ton/ha yr), and the deserts located on the Alxa Plateau (Q(10) = 0.05 ton/ha yr). The Loess Plateau appears to be a weak dust source. We identify and characterize three broad types of dust sources in Northern China: Type 1. Deserts in dry-agricultural areas, Type 2. Gobi-deserts and deserts located on the plateaus, and Type 3. Deserts and gobi-deserts located in topographical lows. Types 1-3 sources contribute 1%, 35% and 64%, respectively, to the total annual mean emission of PM(10) dust. Although the maximum of dust emission occurs in spring, each source type has a distinct seasonal cycle. The analysis of both the seasonal cycle pattern and spatial distribution of dust emission rates demonstrates that a. combination of extreme aridity and strong winds is a key factor governing the dust emission in Northern China. (C) 2002 Elsevier Science Ltd. All rights reserved.