Dust emission from desertified lands in the Heihe River Basin,Northwest China |
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| Authors: | Tao Wang Wanquan Ta Lichao Liu |
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| Institution: | (1) Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Institute, Chinese Academy of Sciences, Lanzhou, Gansu Province, 730000, People’s Republic of China |
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| Abstract: | The annual and seasonal dust emissions were calculated for eight types of desertified lands at 120 sites in the Heihe River
Basin of northwestern China. The results showed that dust emission rates increased from the middle to the lower reaches of
the river by a factor of up to 103. There two strongest areas of dust emission are the dried-up Gaxun Lake with a dust emission rate of 1.6 t ha−1 year−1, and the desertified grassland areas around the abandoned Heicheng City, with a dust emission rate of 0.6–0.7 t ha−1 year−1. The total annual dust emissions with their particle diameters less than 50, 30, and 10 μm were 1.71 × 106, 1.11 × 106, and 0.555 × 106 t, respectively. Dust emission rates showed striking seasonal variations, with the maximum value (45%) occurring in spring
and the minimum value (13.5%) in summer. The mineral aerosol-size distributions were also measured and the results showed
that the size distributions for dust and non-dust events were both trimodal, in contrast with the widely accepted view that
primary particles such as aeolian dust are coarse, whereas particles less than 1 μm in diameter are mainly secondary particulate
substances such as ammonium nitrate, ammonium sulfate, and organic matter. |
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