Acta Geographica Sinica ›› 2007, Vol. 62 ›› Issue (11): 1153-1164.doi: 10.11821/xb200711004

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Distribution Pattern of Grain Size in Surface Sediments from Sugan Lake and Its Potential in Recording Aeolian Dust in Arid China

XIAO Shun, CHEN Fahu, QIANG Mingrui, ZHANG Jiawu, ZHOU Aifeng, SUN Donghuai   

  1. Center for Arid Environment and Paleoclimate Research (CAEP), Key Laboratory of Western China's Environment Systems, MOE, Lanzhou University, Lanzhou 730000, China
  • Received:2007-08-08 Revised:2007-09-22 Online:2007-11-25 Published:2007-11-25
  • Supported by:

    Chinese NSFC Innovation Team Project, No.40421101; Research Fund for the Doctoral Program of Higher Education, No.20060730003

Abstract:

Sediments from inland enclosed lakes in arid regions of northwestern China provide ideal documents in reconstructing high-resolution history of aeolian dust and aerosols. Sugan Lake in northern Qaidam Basin on the Tibetan Plateau is an enclosed shallow lake mainly fed by groundwater, in which annually laminated varves are well preserved since mid- and late Holocene. Surface sediments from Sugan Lake were collected and analyzed for grain size. Frequency curves of samples indicated multi-components in the surface sediments. Weibull function fitting employed to the grain size distribution suggested that there are four components from clay to sand in the surface sediments characterized by their respective modes. Super-fine component has mode size around 1 μm, fine-grained component has mode of 5-10 μm, coarse-grained component has mode of 50-100 μm, and the mode of sand component is about 500 μm. The main components in the surface sediments appear in fine or coarse grains. Particles trapped in the lake ice in winter and dust storms during the same period present the similar distribution pattern in grain size. The main component of aeolian dust from lake ice is composed of particles sized between 15 and 20 μm, and sand component (with mode size of 452.9 μm) appeared, indicating that sand particles were transported to Sugan Lake during the winter. Dust samples from dust storm period (May) or non-dust storm period (November) prevalently consist of three components without sand grains. During strong dust storm events, however, four components including sand are identified, the main component of which still has a size of 100-200 μm. Our results show that the sand component of the surface sediments in Sugan Lake has been transported by ambient strong dust storm activities; the coarse grains have most likely recorded the regional dust storm events; fine component seems to have indicated the intensity of water supply in the basin; super-fine component as extensively deposited in the Chinese loess, may have represented the background level of atmospheric dust and aerosols in the arid region of northwestern China. Therefore, the sediments from Sugan Lake have documented the regional aeolian dust and dust-storm events and have the potential in reconstructing the history of aeolian dust activities.

Key words: grain size distribution pattern, Weibull function, Sugan Lake, arid region, aeolian dust