有机质与盐度对海岸咸水泻湖沉积物-水界面磷迁移转化的影响机制研究

Phosphorus is the limiting factor of eutrophication of water bodies, organic matter is an important component of sediment, salinity seasonal variation is an important feature of the lagoon. The influence mechanism of the migration process of organic matter and salinity on phosphorus is not clear. This project use the typical coastal brackish lagoon-Changli Qilihai lagoon as the research object, as the research focus on organic matter, salinity and sediment-water interface. Using organic component separation method, nuclear magnetic resonance, infrared spectroscopy to analyze the phosphorus composition, diffusion flux and the mineralization rate. The influence mechanism of organic matter and salinity to migration and transformation of phosphorus at sediment-water interface was studied. Through the study of changes in salinity effects on organic matter humification process, further reveal the influence mechanism of salinity migration on the transformation of phosphorus in the sediment-water interface. In this study, in-depth understanding of the phosphorus biogeochemical processes in the paralic zone, which has important theoretical and practical significance to predict, control coastal lagoon eutrophication.

磷是水体发生富营养化的限制性因子，有机质是沉积物的重要组分，盐度季节变化是泻湖这一海陆交互地带水体的重要特征。有机质和盐度对海陆交互水域磷迁移转化过程的影响机理尚不清晰。为此本项目以典型海岸咸水泻湖-昌黎七里海泻湖为研究对象，以有机质、盐度和沉积物-水界面磷为研究重点，运用有机组分分离方法、核磁共振、红外光谱等手段通过确定沉积物-水界面磷的组成、扩散通量和矿化速率等特征参数定量分析有机质和盐度对沉积物-水界面磷迁移转化过程的影响机制，并通过探讨盐度变化对有机质腐殖化过程组分的影响，进一步揭示盐度对沉积物-水界面磷迁移转化的影响机制。本研究对深入理解磷在海陆交互地带的生物地球化学过程以及海岸泻湖富营养化的预测、控制和修复方面具有重要的理论和实践意义。

本课题以昌黎七里海泻湖为研究对象，以有机质和沉积物-水界面磷为研究重点，分析了表层、柱状沉积物中氮磷赋存形态、空间分布特征以及相关性：表层沉积物中TN含量在88.52~1180.46mg/kg之间，表层沉积物中TP的含量在195.9~541.5mg/kg之间；柱状沉积物TN含量为42~1764mg/kg，TP含量为86.86~582.47mg/kg。表层沉积物对磷吸附特征的研究发现沉积物对磷的吸附过程主要发生在0-12h，符合一级动力学方程。盐度对沉积物的磷吸附和释放具有一定的影响。相关性分析表明，表层沉积物中TP与各形态磷间存在一定的相关性，TP在表层沉积物中的含量和分布主要由IP控制和制约，TOC能够影响沉积物对磷的吸附作用；沉积物轻质有机质（LFOM）影响磷的矿化量和矿化速率。各形态氮、TOC和各粒径含量分布的相关性差别较大，TN的含量和分布状况受非可转化态氮的控制，可转化态氮中SAEF-N、SOEF-N以硝态氮占优势。从统计特征来看，七里海泻湖南部区域受到一定程度的污染。该研究结果可为七里海泻湖氮磷污染控制提供理论依据，对滨海泻湖生态功能的恢复具有重要的指导价值。