首页|A carbon- and oxygen-isotope record of recent environmental change from Qinghai Lake, NE Tibetan Plateau

A carbon- and oxygen-isotope record of recent environmental change from Qinghai Lake, NE Tibetan Plateau

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A c. 300-year oxygen and carbon isotope record derived from fine-grained and ostracod carbonate from Qinghai Lake testifies to dramatic interannual tointerdecadal limnological change. Fine-grained carbonates, which are mainly authigenic, are likely to have formed in the epilimnion of the lake and their isotopic composition reflects the summer temperature and, more importantly, the isotopic composition of the near-surface waters, which is mainly a function of evaporative concentration. Ostracod shells are secreted in the benthos of the lake, and their isotopic composition reflects summer bottom-water conditions, together with fractionation effects, which may differ between species. Differences betweencontemporaneous values from authigenic carbonates and ostracod shells may provide an indication of stratification within the lake and variations in effective precipitation over the northeast part of the Tibetan Plateau over the past 300 years. A period of moderate evaporative concentration, from about 300 to 100 yr BP, was interrupted by a marked wet phase from ～100 to 40 yr BP, which was in turnfollowed by a return to drier conditions in the most recent part of the record.The increase in ? 18O values in the latter part of the record accords well withinstrumental records of lake-level lowering and salinity increase since about 1955 AD.

Tibetan PlateauQinghai Lakestable isotopesostracodsmonsoon

A.C.G.Henderson、J.A.Holmes、ZHANG Jiawu、M.J.Leng、L.R.Carvalho

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Environmental Change Research Centre (ECRC), Department of Geography, University College London, 26 Bedford Way, London WC1H 0AP, UK

Center for Arid Environment and Paleoclimate Research, National Laboratory of Western China's Environmental Systems, Lanzhou University, Lanzhou 730000, China

NERC Isotope Geosciences Laboratory (NIGL), British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK

Present address: Centre for Ecology and Hydrology (CEH), Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK

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国家自然科学基金伦敦大学校科研和教改项目

40125001

2003

科学通报(英文版)
中国科学院

科学通报(英文版)

SCI
ISSN：1001-6538
年,卷(期)：2003.48(14)
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