气候变化领域集成服务门户(CCPortal): Stable isotopes and trace elements in modern ostracod shells: implications for reconstructing past environments on the Tibetan Plateau, China

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DOI	10.1007/s10933-017-9971-1
	Stable isotopes and trace elements in modern ostracod shells: implications for reconstructing past environments on the Tibetan Plateau, China
	Boerner, Nicole; De Baere, Bart; Akita, Lailah Gifty; Francois, Roger; Jochum, Klaus Peter; Frenzel, Peter; Zhu, Liping; Schwalb, Antje
通讯作者	Borner, N (通讯作者)
发表日期	2017
ISSN	0921-2728
EISSN	1573-0417
起始页码	191
结束页码	211
卷号	58 期号:2
英文摘要	Stable isotopes and trace elements in ostracod shells have been used widely in paleolimnological investigations of past lake hydrochemistry and climate because they provide insights into past water balance and solute evolution of lakes. Regional differences in lake characteristics and species-specific element fractionation, however, do not permit generalization of results from other regions or ostracod species to the southern Tibetan Plateau, in part because most common taxa from the southern Tibetan Plateau are endemic to the area. This study evaluated relations between present-day environmental conditions and the geochemical composition of modern ostracod shells from the southern Tibetan Plateau, to assess the suitability of using shell chemistry to infer hydrological conditions. We studied nine lakes and their catchments, located along a west-east transect in the south-central part of the Tibetan Plateau. Stable oxygen and carbon isotope values and trace element concentrations in recent shells from the four most abundant ostracod species (Leucocytherella sinensis, ?Leucocythere dorsotuberosa, Limnocythere inopinata, Tonnacypris gyirongensis) were measured, together with hydrochemical properties of host waters at the time of sampling. Results revealed significant between-species differences in stable isotope fractionation and trace element incorporation into shell calcite. Stable oxygen and carbon isotope values of ostracod shells were correlated significantly with the stable isotope composition of the respective water body , reflecting salinity and productivity, respectively. Offsets between delta O-18(shell) and delta C-13(shell) and inorganic calcite, the latter representing isotopic equilibrium, suggest shell formation of T. gyirongensis during spring melt. L. sinensis reproduces throughout the monsoon season until September and shows several consecutive generations, and L. inopinata molts to the adult stage after the monsoon season in August/September. The influence of pore water delta C-13 was displayed by L. inopinata, suggesting shell calcification within the sediment. Mg/Ca-shell is primarily influenced by water Mg/Ca ratios and salinity and confirms the use of this shell ratio as a proxy for precipitation-evaporation balance and lake level. In addition, Sr/Ca and Ba/Ca can be used to infer changes in salinity, at least in closed-basin lakes with calcite saturation. Observed effects of water Sr/Ca and salinity on Sr/Ca incorporation are biased by the presence of aragonite precipitation in the lakes, which removes bioavailable Sr from the host water, resulting in low Sr/Ca-shell values. Changes in carbonate mineralogy affect the bioavailability of trace elements, a process that should be considered in paleoclimate reconstructions. Oxygen isotopes and Mg/Ca-shell ratios were unaffected by water temperature. Positive correlations among Fe/Ca, Mn/Ca and U/Ca in ostracod shells, and their negative correlation with delta C-13, which reflects organic matter decay, show the potential to infer changes in redox conditions that can be used to reconstruct past oxygen supply to bottom waters and thus past water-circulation changes within lakes. The intensity of microbial activity, associated with organic matter decomposition, can be inferred from U/Ca ratios in ostracod shells. These findings highlight the value of fossil ostracod records in lake deposits for inferring paleoenvironmental conditions on the southern Tibetan Plateau.
关键词	TANGRA YUMCO NONMARINE OSTRACODS WATER SAMPLES LAKE CHEMISTRY OXYGEN TEMPERATURE RECORDS CALCITE CARBON
英文关键词	Ostracoda; Shell geochemistry; Hydrochemistry; Trace elements; Stable carbon and oxygen isotopes
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Geology ; Marine & Freshwater Biology
WOS类目	Environmental Sciences ; Geosciences, Multidisciplinary ; Limnology
WOS记录号	WOS:000404687500006
来源期刊	JOURNAL OF PALEOLIMNOLOGY
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/259059
推荐引用方式 GB/T 7714	Boerner, Nicole,De Baere, Bart,Akita, Lailah Gifty,et al. Stable isotopes and trace elements in modern ostracod shells: implications for reconstructing past environments on the Tibetan Plateau, China[J]. 中国科学院青藏高原研究所,2017,58(2).
APA	Boerner, Nicole.,De Baere, Bart.,Akita, Lailah Gifty.,Francois, Roger.,Jochum, Klaus Peter.,...&Schwalb, Antje.(2017).Stable isotopes and trace elements in modern ostracod shells: implications for reconstructing past environments on the Tibetan Plateau, China.JOURNAL OF PALEOLIMNOLOGY,58(2).
MLA	Boerner, Nicole,et al."Stable isotopes and trace elements in modern ostracod shells: implications for reconstructing past environments on the Tibetan Plateau, China".JOURNAL OF PALEOLIMNOLOGY 58.2(2017).