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A high-resolution loess section in the western Chinese Loess Plateau, Yuanbao Section, was sampled for organic carbon isotopic analyses. The soil organic carbon isotope (δ 13Corg) varied between −22.6‰ and −27.5‰ during the last glacial at the section. During the last interstadial, the δ 13Corg values were more negative than those in both early and late periods of the last glacial by 4‰ The isotopic composition indicates a coupled response of the pure C3 plants to the temperature, precipitation and the concentration of atmospheric CO2. Decrease in temperature and the atmospheric CO2 concentration from the last interstadial to Last Glaicial Maximum (LGM) caused the organic carbon isotopes to become positive by 1.5‰–2.0‰ The amplitude of 4‰ in the δ 13Corg variation during the last glacial should be mainly caused by the precipitation change. Therefore, the δ 13Corg variations of the Yuanbao Section during the last glacial period documented the large-amplitude fluctuation of the monsoon precipitation, which is estimated to be 250–310 mm more during the last interstadial than that in the LGM, and 100 mm more than that during early last glacial. The rapid changes of the monsoon precipitation on millennial scale during the last glacial have also been recorded in the isotopic variations in Yuanbao loess section. As the isotopic composition varies complicatedly as shown in the loess-paleosol sequence, it cannot be simply attributed to the abundances of C3 and C4 plants or be used as an indicator of the summer monsoon variations.

To understand the role of atmospheric dust in the global climate system further, it is necessary that a longer sequence of dust storm history should be established using geological archives in dust provenance area. Hydrologically closed lakes in the arid regions of China could be ideal objectives to trace dust storm evolution since the most of Northwest China has been recognized as an important source area for global dust loading. Lake Sugan, a closed lake located at the northern margin of the Qinghai-Tibetan Plateau, would be employed to study on the dust storm history in the Qaidam Basin. Here, 8 elements and 11 rare-earth elements were analyzed for three different sediments/deposits in the Sugan Lake region, namely, the surface sediments of Lake Sugan, the settled sand dust including materials collected during dust storm durations, and the surface deposits of the region. The results show the element of Al has been enriched by 11% relative to the surface ground deposits. The composition of the element in lake sediments is nearly half of the settled dust, which may be diluted by the carbonate accounting for about 50% of the lake sediment. Two of Al, Fe and Sc exhibit apparent positive correlations in the lake sediments. Also, for one of the three elements positive correlation was found between the settled sand dust and the lake sediments. However, there are negative correlations between the catchment deposits and the settled sand dust, and between the catchment deposits and the lake sediment for Al and Sc. Variations in Fe and Sc compositions exhibit an apparent positive correlation not only with intensity of dust storm events, but also with frequency of the events. The Fe and Sc compositions seem to be changeless for the three kinds of sediments/ deposits. In addition, the results of rare-earth elements analyses show that the lake sediments, the settled sand dust and the surface ground deposits may derive from a homologous source. The elements of Al, Fe, Sc are most likely to be transported into lake through strong wind and dust storm processes. Therefore, sediments of Lake Sugan could he used to trace dust storm in this region, and the elements of Al, Fe, So could be applied in reconstruction of dust storm history.

23 ostracod species have been recorded from surface and short core samples from the Qilian Mountains, NW China. Brooks and rivers, small shallow meadow and oxbow pools and a lake were sampled at an altitude ranging from 2900 m to 3570 m asl. Brooks were dominated by Candona rawsoni , Ilyocypris cf. bradyi and/or Ilyocypris lacustris and Limnocythere inopinata . In river habitats Candona candida and Eucypris sp. were most abundant. Meadow pools with peaty, dystrophic waters mainly contained valves of Ilyocypris cf. bradyi and/or Ilyocypris lacustris and Eucypris sp. whereas the latter was replaced by Heterocypris incongruens in a shallow oxbow pool. Candona rawsoni , Cyclocypris ovum and Ilyocypris echinata were the most frequent species in the freshwater Lake Luanhaizi. The recorded taxa are mainly distributed in the holarctic realm but Fabaeformiscandona danielopoli and Ilyocypris echinata appear to be restricted to the cold mountainous region in China.

Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal sequence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the 210Pb, AMS 14C and conventional 14C dating methods. Carbon and oxygen isotopes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of δ18O values of surface water and air temperature observation data in the study area, it might be thought that the δ18O value of the carbonate indicates effective moisture, and the changes in δ13C values are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages: Warm-dry climate during 0–190 AD; cold-dry climate during 190–580 AD; warm-dry climate during 580–1200 AD (MWP); cold-wet climate during 1200–1880 AD (LIA); cold-dry climate during 1880–1950 AD; and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.