A 1,100-year palaeoenvironmental record inferred from stable isotope and trace element compositions of ostracode and plant caryopses in sediments of Cattle Pond, Dongdao Island, South China Sea
A 1,100-year palaeoenvironmental record inferred from stable isotope and trace element compositions of ostracode and plant caryopses in sediments of Cattle Pond, Dongdao Island, South China Sea
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南海东岛牛塘沉积物介形类和植物颖果稳定同位素和微量元素组成推断1100年古环境记录
DOI：
10.1007/s10933-008-9211-9
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发表时间：
2008-11-01
影响因子：
2.1
通讯作者：
Wu, Xiaohong
中科院分区：
文献类型：
--
作者：
Liu, Xiaodong;Sun, Liguang;Wu, Xiaohong
南海东岛牛塘湖相沉积物中保存了丰富的陆生草介形壳类（Cyprinotus cingalensis）和尾草（Urochloa paspaloides）的壳类。本文对介形虫瓣和植物颖果的氧、碳同位素和元素（Ca、Mg）进行了分析。δ O-18（介形虫）和δ C-13（介形虫）呈显著正相关，且呈向沉积物层序顶部递减的趋势，并有一定的波动，表明有效水分逐渐增加。介形虫壳中Mg/Ca比值在上部样品中呈下降趋势，反映了湖泊盐度的逐渐降低。Mg/Ca比值通常被用来代表湖水盐度变化。沉积物上部14cm植物颖果的δ C-13（org）值低于底部沉积物的δ C-13（org）值，表明水分和盐度胁迫较小。这些结果表明，东岛的有效水分和降雨强度在过去的1100年中呈增加趋势。
Abundant ostracode valves (Cyprinotus cingalensis) and caryopses of Urochloa paspaloides, a terrestrial grass, were well preserved in the lacustrine sediments of the Cattle Pond on Dongdao Island, South China Sea. Oxygen and carbon isotopes, and elements (Ca, Mg) were analyzed on ostracode valves and plant caryopses in this study. The delta O-18(ostracode) and delta C-13(ostracode) exhibited a positive and statistically significant correlation, and showed a decreasing trend toward the top of sediment sequence with some fluctuations, indicating a gradual increase in effective moisture. The Mg/Ca ratios in the ostracode shells, generally used as a proxy for salinity changes in lake water, showed a trend toward lower values in the upper samples, reflecting a gradual decrease of salinity in the lake. The delta C-13(org) values in the plant caryopses of the upper 14 cm of sediment have lower values than those in the bottom sediments, suggesting less water and salinity stress. These results indicate increasing effective moisture and rainfall intensity over the past similar to 1,100 years on Dongdao Island.