富钙底质对岩溶湖滨湿地磷的截留效应及作用机制研究

Phosphorus retention and its activity mechanism by lakeshore wetland has been becoming a hot research direction over the world. Because of calcium-enriched base, Karst lakeshore wetland need to be achieved more attention by researchers. It’s still unclear whether calcium compound in Karst lakeshore wetland sediment could change phosphorus retention efficiency and activity mechanism or not. Focusing on calcium-enriched sediment of lakeshore wetland, phosphorus retention efficiency and its activity mechanism by this typical lakeshore wetland would be carried out in this research. The two key scientific problems need to be solved in this research as: (1) How calcium-enriched sediment change phosphorus retention efficiency and activity mechanism by Karst lakeshore wetland; and what are the key processes calcium-enriched sediment could change in Karst lakeshore wetland phosphorus retention efficiency; (2) What are the key affecting factor for changing phosphorus retention by calcium-enriched sediment of lakeshore wetland? Choosing the Karst lakeshore wetland, located at south-east of Yunnan province, as the typical object, the relative research work will be operated for the efficiency of phosphorus retention and its activity mechanism by calcium-enriched sediment of Karst lakeshore wetland. Through field monitoring, indoor simulating and field in-situ checking trials, the discovering results will be achieved on the efficiency of phosphorus retention efficiency and changing characters by calcium-enriched sediment of lakeshore wetland, and the impact factors will be determined. With the comparing, statistics and correlation analysis methods, the efficiency of phosphorus retention and activity mechanism by the factors of environmental conditions (temperature, pH, DO, Eh, etc.) and calcium form and concentrations of calcium-enriched sediment will be disclosed. The research predicted results will provide technical support for Karst lakeshore wetland management and designing.

湖滨湿地对磷的截留及机制是目前国内外研究热点，岩溶湖滨湿地因底质钙含量高的特点受到广泛关注，其对磷的截留效应和作用机制是否存在差异尚不清楚。本项目以湖滨湿地富钙底质为切入点，开展磷的截留效应及作用机制研究，拟重点解决两个科学问题：（1）揭示富钙底质对湖滨湿地磷截留关键过程；（2）识别影响富钙底质对湖滨湿地磷截留的主要因子。本研究拟以滇东南普者黑岩溶湖滨湿地为研究对象，重点开展富钙底质对湖滨湿地磷截留效应及影响机制研究。通过现场定期采样监测、室内模拟和野外原位验证等方法，找出湖滨湿地富钙底质中钙的形态与浓度特征及其对湖滨湿地磷截留效果时空分异特征；揭示富钙底质对岩溶湖滨湿地磷的截留关键过程、底泥中钙-磷平衡关系及磷的归趋；识别富钙底质对岩溶湖滨湿地磷截留的主要影响因子。项目研究成果可为岩溶湖滨湿地恢复与重建提供技术支撑，为其它同类地区湖滨湿地保护与恢复提供理论依据。

湖滨湿地对磷的截留及机制是目前国内外研究热点，岩溶湖滨湿地因底质钙含量高的特点受到广泛关注，本研究以滇东南普者黑岩溶湖滨湿地为研究对象，重点开展富钙底质对湖滨湿地磷截留效应及影响机制研究。通过调查湖滨湿地富钙底质中钙的形态与浓度特征及其对湖滨湿地磷截留效果时空分异特征，揭示了富钙底质对岩溶湖滨湿地磷的截留关键过程及富钙底质对岩溶湖滨湿地磷截留的主要影响因子。项目研究成果可为岩溶湖滨湿地恢复与重建提供技术支撑，为其它同类地区湖滨湿地保护与恢复提供理论依据。研究共培养研究生4名，发表学术论文9篇，获批专利和软著等知识产权7项。主要研究结果如下：.（1）岩溶湖滨湿地不同类型湿地沉积物磷素含量不同，水平分布上，湿季三种类型湿地沉积物TP含量的大小为农田＞湖滨湿地＞草甸，干季为农田＞草甸＞湖滨湿地，垂直分布上，湖滨湿地三种土层沉积物TP含量大小为表层＞中层＞底层。湿地沉积物TP含量存在明显的季节动态，主要表现为湿季显著大于干季（p＜0.05）。受农田面源污染的影响，三种类型湿地中，农田与植物、沉积物中的磷含量均有着极好的相关性。.（2）岩溶湿地典型挺水植物会表现出一定程度的钙抗逆性，主要通过减少单株叶片面积，降低株高，减少水分流失的方式来保证机体的正常生理功能。但超过一定的阈值，抗逆性会减弱，导致挺水植物出现生长抑制或者死亡现象。研究结果表明：狭叶香蒲有作为维护以及修复岩溶湿地以及喀斯特地区生态的潜力。.（3）岩溶湿地底泥对水体中磷吸附能力随挺水植物的生长时间而变化，但在沉积物中磷占水中总磷百分比的变化与底质对磷的吸附能力的变化有关。挺水植物可以通过根系直接从沉积物中吸收磷等营养物质，还可以通过影响微生物的代谢来影响营养物质的循环。挺水植物的吸收能增加水生态系统中磷向上覆水的分配，底泥对磷的吸附能力相对香蒲对水中磷分配的影响较小。在垂直分布中，湖滨湿地符合“表面富集”现象，表现出表层最高，随着深度向下层递减。.（4）挺水植物在不同钙胁迫下叶绿素含量变化显著，研究发现，挺水植物狭叶香蒲在高浓度钙胁迫情况下会启动自我防御机制，表现出较强耐受性，最明显范围在900~1200mg/kg，若超过某个阈值，植物生长被明显抑制，在岩溶湿地以及高钙环境中具有较大的推广和应用潜力。