A 15.4-ka paleoclimate record inferred from δ¹³C and δ¹⁵N of organic matter in sediments from the sub-alpine Daping Swamp, western Nanling Mountains, South China

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• 作者：Wei Zhong ; Zhiqiang Wei ; Yu Chen ; Shengtan Shang ; Jibin Xue…
• 关键词：Paleoclimate ; South China ; Nanling Mountains ; Stable carbon isotopes ; Stable nitrogen isotopes
• 刊名：Journal of Paleolimnology
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：57
• 期：2
• 页码：127-139
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Paleontology; Sedimentology; Climate Change; Physical Geography; Freshwater & Marine Ecology; Geology;
• 出版者：Springer Netherlands
• ISSN：1573-0417
• 卷排序：57

文摘

We inferred past climate conditions from the δ13C and δ15N of organic matter (OM) in a sediment core (DP-2011-02) from the sub-alpine Daping Swamp, in the western Nanling Mountains, South China. In the study region, a 1000-m increase in altitude results in a ~0.75‰ decrease in δ13C and a ~2.2‰ increase in δ15N. Organic carbon stable isotope (δ13C) values of the dominant modern vegetation species, surface soils, and the core samples taken in the swamp exhibit a strong terrestrial C3 plant signature. Comprehensive analysis of the core indicates both terrestrial and aquatic sources contribute to the OM in sediment. Temperature and precipitation are most likely the critical factors that influence δ13C: warm and wet conditions favor lower δ13C, whereas a dry and cool climate leads to higher δ13C values. Higher δ15N values may result from greater water depth and increased primary productivity, promoted by large inputs of dissolved inorganic nitrogen, induced by high surface runoff. Lower δ15N values are associated with lower lake stage and reduced productivity, under drier conditions. Therefore, stratigraphic shifts in these stable isotopes were used to infer past regional climate. Measures of δ13C and δ15N in deglacial deposits, in combination with total organic carbon (TOC) and nitrogen (TN) concentrations, the TOC/TN ratio, coarse silt and sand fractions, dry bulk density and low-frequency mass magnetic susceptibility, reveal two dry and cold events at 15,400–14,500 and 13,000–11,000 cal a BP, which correspond to Heinrich event 1 and the Younger Dryas, respectively. A pronounced warm and wet period that occurred between those dry episodes, from 14,500 to 13,000 cal a BP, corresponds to the Bølling–Allerød. The δ13C and δ15N data, however, do not reflect a warm and wet early Holocene. The Holocene optimum occurred between ~8000 and 6000 cal a BP, which is different from inferences from the nearby Dongge cave stalagmite δ18O record, but consistent with our previous results. This study contributes to our understanding of climate-related influences on δ13C and δ15N in OM of lake sediments in South China.