人工铺地黍-消落带系统真菌反硝化作用的脱氮效应研究

The environmental pollution of river water level fluctuating zone is increasingly prominent. Aiming at the extreme alternate conditions of drought and waterlogging and the pollution problem of eutrophication, the Panicum repens (torpedograss) has reflected the potential and advantage in eco-restoration of polluted water level fluctuating zone because of strong drought resistance, submergence tolerance, and nitrogen removal ability. Fungi denitrification is important nitrogen removal process such as soil, water, and so on. In this research we will simulate Pearl River system’s natural conditions to construct torpedograss-water-level-fluctuating-zone artificial eutrophication, and in the present research, the fungal biomass, the vertical distribution, seasonal dynamics of fungal denitrification, mechanism and efficiency of fungal denitrification in this system will be studied. At the same time, the fungal community composition, the contribution of fungi denitrification to total of denitrification and total nitrogen purification for the constructed eco-system will be analyzed applying the technology of 18S rDNA-PCR-DGGE, DNA sequencing and BLAST. Thus, the seasonal response regularity between plant-environmental factors-fungi community during the eco-restoration process based on the eutrophication system of torpedograss and water-level-fluctuating-zone will be explored. The work will help people to broaden the understanding for the denitrification mechanisms of the system and to provide theoretical basis for ecological rehabilitation efficiently using torpedograss in water level fluctuating zone system.

河岸消落带的环境污染问题日益突出。针对消落带旱-涝交替的极端条件及系统富营养化等污染环境，铺地黍（Panicum repens）因其较强的抗旱、耐淹及氮去除能力已突显出其生态修复潜力与优势。而铺地黍-消落带系统的氮净化机制尚不明确。真菌反硝化是土壤、水体的重要脱氮过程，本项目将模拟珠江水系消落带自然条件，构建人工富营养化铺地黍-消落带系统，分析真菌生物量及其反硝化作用的垂直分布及季节动态，探究该系统真菌反硝化作用机制及脱氮效率；并基于18S rDNA-PCR-DGGE方法，结合DNA片段测序和BLAST比对技术，鉴定系统反硝化真菌群落组成，研究真菌反硝化作用对该系统总反硝化作用和总氮净化的贡献，揭示富营养化铺地黍-消落带系统生态重建过程中植被-环境因子-真菌群落三者间的动态响应规律。为拓宽人们对富营养化消落带系统脱氮机制的理解和认识，及构建高效脱氮的人工消落带系统提供一定理论基础。

项目以人工构建的铺地黍-消落带氮净化系统为研究基础，通过TN，NH4+-N，TP，DTP，C/N /P比率及溶解性有机碳等指标的动态监测，对系统运行过程中氮、磷的变化趋势及真菌反硝化作用重要性进行研究。揭示了系统运行过程中的反硝化真菌群落组成、生物量及其反硝化作用的发生规律，主要从真菌反硝化作用对总反硝化作用的相对贡献和真菌反硝化作用对总氮净化的相对贡献等两个方面进行研究。利用铺地黍的相对电导率、叶绿素、游离脯氨酸、可溶性蛋白、可溶性糖、丙二醛、酶活性等生理指标测定，从生理水平揭示了铺地黍在模拟污染消落带系统中的渗透调节规律与响应机制。通过水体有机碳、有机氮、硝态氮、氨态氮、碳/氮比率、pH、温度、枯水期土壤含水率、水体化学需氧量、生化需氧量等指标测定，揭示了铺地黍-消落带系统真菌反硝化作用对环境因子变化的响应规律。同时，项目延申了铺地黍转录组分析及相关基因功能研究，铺地黍在Cd、Pb胁迫下的亚细胞分布与化学结合态特征及铺地黍光合作用和叶绿素荧光特性等方面的研究，取得重要成果。总之，项目研究结果最终阐明了富营养化铺地黍-消落带系统生态重建过程中植被-环境因子-真菌群落三者间的动态响应规律。为拓宽人们对富营养化消落带系统脱氮机制的理解和认识，及构建高效脱氮的人工消落带系统提供一定理论参考。