Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-exp...Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.展开更多
The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the recon...The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the reconstruction of terrestrial ecosystems and global climate changes. It has also been widely used in paleolimnological studies in arid northwestern China. In recent years, however, an increasing number of studies have enriched the environmental significance reflected by the stable carbon isotope geochemistry of lakes;therefore, the interpretation of lake δ13 C variations in paleoenvironmental reconstructions should be carefully evaluated from various aspects. In this paper, previous studies from the past several decades on the lacustrineδ13 C variations in arid northwestern China were reviewed, and the possible mechanisms of the δ13 C variations were discussed.Our study will provide a reference for the application of carbon isotope geochemistry in paleoenvironmental reconstructions.展开更多
基金funded by Chinese Post-doctoral Research Fund (No. 2014T70951)the National Natural Science Foundation of China (Nos. 41201014, 41371028, 41402314)
文摘Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.
基金supported by the CAS Strategic Priority Research Program (Grant No. XDA05120400)
文摘The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the reconstruction of terrestrial ecosystems and global climate changes. It has also been widely used in paleolimnological studies in arid northwestern China. In recent years, however, an increasing number of studies have enriched the environmental significance reflected by the stable carbon isotope geochemistry of lakes;therefore, the interpretation of lake δ13 C variations in paleoenvironmental reconstructions should be carefully evaluated from various aspects. In this paper, previous studies from the past several decades on the lacustrineδ13 C variations in arid northwestern China were reviewed, and the possible mechanisms of the δ13 C variations were discussed.Our study will provide a reference for the application of carbon isotope geochemistry in paleoenvironmental reconstructions.
