底泥组合扰动下内源磷形态转化的诱发机制和行为过程机制

During the research on National Natural Science Foundation of China, sediment disturbance could promote the migration of phosphorus from the overlying water to the sediments and then enhance the immobilization of sedimentary phosphorus. It is attributed to the transformation of sedimentary phosphorus forms. However, the reason is not clear why the transformation of sedimentary phosphorus forms is induced and what the paths of the transformation are. Several key scientific problems have not yet been settled in the process of constructing migration and transformation theory system for water bodies. Physical and benthos combination disturbance was proposed in the project. The aim of the project is to clarify the inducing mechamism and behavior mechanism of transformation of sedimentary phosphorus. Emphasis will be focused on the regeneration and transformation of sedimentary phosphorus on the base of the characteristics of sediment micro interface and sediment micro environment under combination disturbance, in order to reach the following objectives. It is to clarify the essential cause of phosphorus regeneration and migration in the micro-level. It is to clarify the inducing mechanism of transformation of sedimentary phosphorus. It is to rebuild the mode used to estimate the regeneration and migration of sedimentary phosphorus. It is to research the interaction of the characteristics of sediment micro interface and sediment micro environment on the transformation of sedimentary phosphorus and then to identify the key inducing factors and controlling factors. It is to clarify the inducing mechanism and evolution mechanism of transformation of sedimentary phosphorus. It is to construct the quantitative relationship among combination disturbance and the characteristics of sediment micro interface and sediment micro environment and the regeneration and transformation of internal phosphorus. The aim is to reach the key breakthrough on transformation mechanism of sedimentary phosphorus. It is to provide the basic theory basis to construct the theory system of phosphorus migration and transformation in water bodies.

在青年基金的研究中发现：底泥扰动促进了上覆水中磷向底泥迁移，并强化了底泥对内源磷的固定。这主要源于内源磷形态间的相互转化。但我们尚不清楚内源磷形态“为什么”转化，并通过“怎样的途径”完成转化，这使得在构建水体磷迁移转化理论体系时遇到诸多困难。本项目提出了物理和底栖生物组合扰动模式，以“内源磷形态转化诱发机制和行为过程机制”为关键科学问题，在深入探讨组合扰动下底泥微界面特征和底泥微环境变化基础上，重点围绕组合扰动对内源磷再生和形态转化的协同作用机制，研究内源磷再生和迁移对组合扰动的响应规律，在微观层面上阐明内源磷再生和迁移的本质诱因；构建内源磷再生和迁移的估算模式；研究底泥微界面特征和底泥微环境的变化对内源磷转化的交互作用，阐明内源磷形态转化诱发机制和行为过程机制；构建组合扰动—底泥微界面特征和微环境变化—内源磷再生和形态转化响应的关系。为完善水体磷迁移转化理论体系提供基础理论依据。

浅水湖泊中，磷是水体发生富营养化的关键因子。在国家自然科学基金面上项目（编号：51278523）的资助下，课题组围绕底泥微界面和底泥微环境特征对组合扰动的响应规律、组合扰动对内源磷再生和迁移的交互作用、物理和底栖生物组合扰动对内源磷形态转化的协同作用机制，开展深层次的基础研究，重点突破组合扰动下内源磷形态转化的协同作用机制，以阐明扰动对内源磷再生和转化的影响、探明底泥微界面和底泥微环境特征对组合扰动的响应规律、描述内源磷转化途径和转化过程为研究内容，完成了课题的各项研究内容，深化了对浅水湖泊中内源磷迁移转化对组合扰动的响应的科学认识，达到了预期目标。.课题研究形成了以下主要成果：组合扰动下，沉积物的OPD、TOE、ORP、pH、含水率、孔隙度以及总微生物活性等底泥微环境和微界面参数一直处于较高水平；采用线性、多项式、指数3种拟合方式对相关数据进行曲线拟合，阐明了组合扰动对底泥微环境和底泥微界面具有“跃变式”叠加效应。解析了物理扰动、底栖生物扰动、藻类等多重扰动因素对磷在上覆水、间隙水、悬浮物、沉积物间流向的贡献率；颗粒态磷在扰动下最容易与其他形态磷发生相互转化，垂向微界面因其独特的界面特征可能是内源磷发生迁移转化的主要诱发区域；阐明了藻类与扰动共存体系下颗粒物质物理化学吸附与藻类生物吸收对水体中磷消失的贡献率；解析了不同扰动因素在内源磷转化中的贡献率；初步描述了内源磷在组合扰动下的转化途径和机理；阐明了物理扰动、底栖生物扰动、藻类等多重因素下内源磷转化的交互作用；初步描述了组合扰动对内源磷形态转化的协同作用机制；明确了底栖生物创造的垂向微界面是内源磷发生矿化和形态转化的“活性区域”，而生物矿化在内源磷形态转化中扮演了极为重要的角色。组合扰动对内源磷再生和转化的协同机制为：物理扰动胁迫摇蚊幼虫构筑更多更深的廊道；摇蚊幼虫构筑大量廊道改变了沉积物的含水率与孔隙度，强化了同等物理扰动剪切力对沉积物产生的效应。