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首页> 外文期刊>Chinese science bulletin >A carbon- and oxygen-isotope record of recent environ- mental change from Qinghai Lake, NE Tibetan Plateau
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A carbon- and oxygen-isotope record of recent environ- mental change from Qinghai Lake, NE Tibetan Plateau

机译：青藏高原东北部青海湖近期环境变化的碳氧同位素记录

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摘要

A c. 300-year oxygen and carbon isotope record derived from fine-grained and ostracod carbonate from Qinghai Lake testifies to dramatic interannual to interde-cadal 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 between contemporaneous 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 turn followed by a return to drier conditions in the most recent part of the record. The increase in δ~(18)O values in the latter part of the record accords well with instrumental records of lake-level lowering and salinity increase since about 1955 AD.
机译：c。来自青海湖的细粒碳酸盐和碳酸盐类碳酸盐的300年氧气和碳同位素记录证明，年际至年代际的湖泊学发生了巨大变化。细粒碳酸盐主要是自生的，很可能在湖泊的上层形成，其同位素组成反映了夏季的温度，更重要的是，反映了近地表水的同位素组成，这主要取决于蒸发浓度。鱼的贝壳被分泌在湖泊的底栖生物中，其同位素组成反映了夏季的底水状况，以及分馏效应，这在不同物种之间可能有所不同。自生的碳酸盐和成虫壳的同时期值之间的差异可能提供了过去300年以来湖泊内部分层和青藏高原东北部有效降水变化的迹象。大约300至100 yr BP的中等蒸发浓度时期被〜100到40 yr BP的明显湿相中断，随后又在记录的最近部分恢复到较干燥的条件。记录的后半部分δ〜（18）O值的增加与大约自公元1955年以来湖泊水位降低和盐分增加的仪器记录非常吻合。

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