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| Carbon and nitrogen isotopes analysis and sources of organic matter in surface sediments from Sanggou Bay and its adjacent areas, China |
| 桑沟湾养殖区及其附近海域沉积物中碳氮同位素分析及有机质来源甄别 |
| Received:December 19, 2013 Revised:July 08, 2014 |
| DOI： |
| Key words:sanggou Bay organic matter sediment stable isotopes aquaculture shellfish seaweed |
| 中文关键词: 桑沟湾，有机质，沉积物，稳定同位素，养殖，贝类，海藻 |
| 基金项目:The State Oceanic Administration Project of China under contract NO. DOMEP (MEA)-01-01 and DOMEP (MEA)-02. |
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| Abstract: |
| Natural existed stable carbon and nitrogen isotopes play an essential role in studying sources of sedimentary organic matter. We determined the carbon and nitrogen isotopic compositions of organic matter in surface sediment from the Sanggou Bay and its adjacent areas, characterized by high-density shellfish and seaweed aquaculture, in order to identify the sources of sedimentary organic matter. In parallel, grain size, organic carbon (OC) and total nitrogen (TN) of surface sediment were measured. The results showed that sedimentary OC and TN ranged from 0.17% to 0.76%, from 0.04% to 0.14% in August, and from 0.23% to 0.87%, from 0.05% to 0.14% in November, respectively. There was a significant positive correlation between OC and TN (R = 0.98, P < 0.0001), indicating that OC and TN were homologous. The stable carbon and nitrogen isotopes of organic matter varied from -23.06‰ to -21.59‰, from 5.10‰ to 6.31‰ in August, and from -22.87‰ to -21.34‰, from 5.13‰ to 7.31‰ in November, respectively. This study found that the major sources of the sedimentary organic matter were marine shellfish biodeposition, seaweed farming, and soil organic matter. Using a three-end member mixed model, we estimated that the dominant source of sedimentary organic matter was shellfish biodeposition, with an average contribution rate of 65.53% in August and 43.00% in November, respectively. The shellfish farming had a significant influence on the coastal carbon cycles. |
| 中文摘要: |
| 天然存在的碳、氮稳定同位素对于研究海洋沉积物有机质的来源有非常重要的作用。本文于2012年8月和11月对桑沟湾养殖区及附近海域沉积物进行采样，分析了沉积物粒径以及有机碳、总氮、碳、氮同位素的分布特征，探讨了沉积物有机质的来源，并在此基础上估算了不同来源的贡献。结果表明，8月有机碳和总氮的含量范围分别是0.17%～0.76%和0.04%～0.14%；11月有机碳和总氮的含量范围是0.23%～0.87%和 0.05%～0.14%。TOC%与TN%呈极显著的正相关（R=0.98，P＜0.0001），表明沉积物有机碳和总氮具有同源性。8月有机质的碳、氮稳定同位素变化范围分别是-23.06‰～-21.59‰和5.10‰～6.31‰。11月有机质的碳、氮稳定同位素变化范围分别是-22.87‰～-21.34‰和5.13‰～7.31‰。有机质来源分析表明，贝类生物沉积、海藻养殖以及土壤有机质是沉积物有机质主要的三种来源。运用三元混合模型计算得出，8月和11月沉积物有机质主要来源是贝类生物沉积物，平均贡献率分别为65.53%和43.00%，这表明近海大规模贝类养殖对浅海碳循环具有显著的影响。 |
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