Change of Organic C-13 in Ornithogenic Sediments of the Xisha Archipelago, South China Sea and its Implication for Ecological Development
Change of Organic C-13 in Ornithogenic Sediments of the Xisha Archipelago, South China Sea and its Implication for Ecological Development
复制标题
南海西沙群岛鸟类沉积物中有机C-13变化及其生态发展意义
DOI：
10.1111/1755-6724.13327
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发表时间：
2017
影响因子：
3.3
通讯作者：
Xu Liqiang
中科院分区：
文献类型：
--
作者：
Wu Libin;Liu Xiaodong;Xu Liqiang
沉积物中有机碳同位素常被用来识别有机质的来源。本文对西沙群岛广进岛和金庆岛两个受鸟粪影响的沉积物剖面进行了有机碳δ 13 C研究。鸟源珊瑚砂沉积物中有机质主要有鸟粪颗粒和植物残体两种来源，有机质δ 13 C（δ 13 COM）存在显著差异，鸟粪颗粒有机质δ 13 C远高于植物残体有机质δ 13 C，整体样品δ 13 COM介于两者之间。基于双端元混合模型，定量重建了大量样品中鸟粪源和植物源有机物的比例。结果表明，大约在公元1200-1400年左右，海鸟开始在岛屿上栖息，从那时起，鸟粪颗粒一直是土壤有机质的重要来源。随着鸟粪源营养物质的积累，近200年来，岛屿上的植物开始大量生长，这反映在沉积物上层植物源有机质的显著增加。然而，近几十年来，鸟粪衍生的有机物大大减少，表明海鸟数量迅速减少。研究结果表明，有机碳δ 13 C可有效地用于定量确定有机质对块状鸟源珊瑚砂沉积物的贡献。
Organic carbon isotopes in sediments have been frequently used to identify the source of organic matter. Here we present a study of organicδ13C on two sediment profiles influenced by guano from Guangjin and Jinqing islands in the Xisha Archipelago, South China Sea. Organic matter from ornithogenic coral sand sediments has two main sources, guano pellets and plant residues, and their organicδ13C (δ13COM) are significantly different Organic carbonδ13Cguanois much higher thanδ13Cplant, andδ13COMof bulk samples is intermediate. Based on a two‐end‐member mixing model, the proportions of guano‐ and plant‐derived organic matter in the bulk samples were reconstructed quantitatively. The results showed that seabirds began to inhabit the islands around approximately 1200–1400 AD, and that guano pellets have been an important source of soil organic matter since then. With the accumulation of guano‐derived nutrients, plants began to develop prosperously on the islands in the last 200 years, which is reflected by the significant increase of plant‐derived organic matter in the upper sediment layer. However, guano‐derived organic matter decreased greatly in recent decades, indicating a rapid decrease in seabird population. Our results show that organicδ13C can be effectively used to quantitatively determine different source contributions of OM to bulk ornithogenic coral sand sediments.