| 摘要: |
| 本文基于薄膜梯度扩散(DGT)和平面光电极(PO)两种原位监测方法,首次从μm尺度获取了南四湖四个湖区泥-水界面(SWI)的活性磷(P)以及亚铁(Fe+II)、亚硫(S-II)、pH和DO等密切因子精细化分布变化信息, 并初步探讨了南四湖SWI活性P变化特征与控制机制。结果直观揭示南四湖底泥剖面活性P的浓度分布呈现明显的空间异质性,变化范围为0.34 ~ 2.36 mg/L,均值为1.26 mg/L。水平空间分布上独山湖(NS2,1.41 ± 0.56 mg/L)和昭阳湖(NS3,1.97 ± 0.42 mg/L)活性P含量显著高于南阳湖(NS1,1.07 ± 0.20 mg/L)和微山湖(NS4,0.58 ± 0.24 mg/L)。南四湖大部分采样点底泥中的活性P与活性S、 Fe呈现正相关性,而NS3的活性P、Fe、S的相关性尤为显著(P< 0.001),表明在剧烈有机质矿化过程中,活性S可以通过与Fe的相互作用促进活性P 的释放。SWI界面pH和DO二维高分辨分布信息也显示,受上游大量有机质输入的影响,底泥有机质降解消耗大量DO并产生大量S-II,硫酸盐还原占据主导地位,促进铁结合P 的释放。以上结果表明南四湖底泥中P的形态转化受Fe 和S两类氧化还原敏感元素控制,支持了P、Fe、S的耦合释放机制,明确了S与Fe的生物地球化学循环共同控制泥中活性P的释放。 |
| 关键词: 泥-水界面 铁-磷-硫循环 原位 高分辨 平面光电极(PO) 薄膜梯度扩散(DGT) |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目）,国家科技攻关计划 |
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| Refined variations of labile phosphorus across the sediment-water interface of Lake Nansi |
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Sun Yu, Guo Xinyue, Bai Yang, Zhang Yunpeng, Han Chao
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: State Key Laboratory of Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing
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| Abstract: |
| Herein the refined distribution of labile phosphorus (P) and its related factors e.g. ferrous iron (Fe+II), sulfide (S-II), pH, and dissolved oxygen (DO) across the sediment-water interface (SWI) of Nansi Lake were simultaneously measured based on two emergent in situ methods of diffusive gradient in thin films (DGT) and planar optode (PO). We further explored the characteristics and controlling mechanisms of labile P changes across the SWI of Lake Nansi. The results intuitively revealed that the concentration distribution of labile P in the sediment profiles of Lake Nansi showed obvious spatial heterogeneity, with a range of 0.34 ~ 2.36 mg/L and a mean value of 1.26 mg/L. The horizontal spatial distribution of labile P was significantly higher in Dushan Lake (NS2, 1.41 ± 0.56 mg/L) and Zhaoyang Lake (NS3, 1.97 ± 0.42 mg/L) than in Nanyang Lake (NS1, 1.07 ± 0.20 mg/L) and Weishan Lake (NS4, 0.58 ± 0.24 mg/L). The positive correlation between labile P and labile S, Fe in the sediment of most of the sampling sites in Lake Nansi, and the correlation between labile P, Fe, and S in NS3 was particularly significant (P< 0.001), suggesting that the labile S can promote the release of labile P through the interaction with Fe during the process of drastic organic matter mineralization. High-resolution two-dimensional distribution information of pH and DO at the SWI indicates that the input of large amounts of organic matter from upstream affects the SWI, where the degradation of organic matter in the sediment consumes large amounts of DO and produces large amounts of S-II, dominated by sulfate reduction, which promotes the release of Fe-bound P. The above results indicate that the migration of P in the sediment of Lake Nansi is controlled by two types of redox-sensitive elements, Fe and S, which supports the coupled release mechanism of P, Fe and S, and clarifies that the biogeochemical cycles of S and Fe jointly control the release of reactive P in the sediment. |
| Key words: Sediment-water interface (SWI) planar optode phosphorus-iron-sulfur cycle in situ high resolution diffusive gradients in thin-films (DGT) |
