植物多样性对人工湿地中硝化反硝化作用机理研究

Nitrogen removal in constructed wetlands is closely related to nitrification and denitrification process, and the plant is the indirect driver of nitrification-denitrification process. Therefore, the effect of plant diversity on the nitrification-denitrification and its mechanism are very important to improve nitrogen removal in constructed wetlands. In the study, more than 20 species of plants with high nitrogen removal capacity, which were selected from our preliminary study, and different NO3-/NH4+ proportion of nitrogen wastewater will be used to study nitrification- denitrification process in controlled constructed wetlands microcosms. We want to know how the different plants and NO3-/NH4+ proportion of nitrogen wastewater affect nitrification-denitrification process. And plant diversity experiment (species richness and functional group richness) will be performed. We want to use plant diversity to optimize the ecosystem structure, to improve the process of nitrification-denitrification and the nitrogen removal ability in constructed wetlands. The study of the effect of biodiversity on nitrification-denitrification process and its possible mechanism will extend relationships between biodiversity and ecosystem functioning (nitrification-denitrification process and the nitrogen removal rate) under high nitrogen condition. And also suitable species and species compositions for different NO3-/NH4+ proportion nitrogen wastewater treatment will be chosen for constructed wetlands, which is important to improve the nitrogen removal of constructed wetlands.

人工湿地氮去除与系统硝化-反硝化过程关系密切，而植物是硝化-反硝化的间接驱动者。因此，研究人工湿地植物多样性对系统硝化-反硝化的影响机理对提高系统氮去除具有重要意义。本研究以小型人工湿地为实验平台，以不同NO3-/NH4+比例的含氮废水为研究对象，利用前期获得的具有高氮去除能力的20余种植物为物种来源，研究不同植物单种系统的硝化-反硝化过程，以及不同NO3-/NH4+比对植物系统硝化-反硝化过程的影响；并开展植物多样性（物种多样性和功能群多样性）实验，尝试通过植物多样性来优化生态系统结构来提高系统的硝化-反硝化过程及氮去除能力。本项目通过植物多样性对系统硝化-反硝化过程影响及可能机理的探索，一方面在高氮下拓展植物多样性与生态系统功能（硝化-反硝化、氮去除率）的研究，另一方面为人工湿地选择适用于不同NO3-/NH4+含氮废水的高脱氮优良物种及物种组合，对提高人工湿地氮去除具有重要意义。

人工湿地氮去除与系统硝化-反硝化过程关系密切，而植物是硝化-反硝化的间接驱动者。本研究以小型可控人工湿地为实验平台，选取美人蕉（Canna indica）、常绿鸢尾（Iris tectorum）、梭鱼草（Pontederia cordata）、风车草（Cyperus alternifolius）、再力花（Thalia dealbata）、黄菖蒲（Iris pseudacorus）、菖蒲（Acorus calamus）与水葱（Scirpus validus Vahl）等常见湿地植物作为实验物种，通过不同植物物种组合在模拟不同硝铵比(NO3-/NH4+比例:100/0，75/25，50/50，25/75，0/100)废水情况下的氮去除实验, 研究不同植物单种系统的硝化-反硝化过程，以及不同NO3-/NH4+比对植物系统硝化-反硝化过程的影响；并开展植物多样性实验，通过植物多样性来优化生态系统结构来提高系统的硝化-反硝化过程及氮去除能力。研究表明：（1）不同硝铵比对单种、混种组合的硝化-反硝化过程具有重要影响。25/75的NO3-/NH4+比的废水可以显著提高8种植物混种组合的硝化-反硝化过程。（2）在不同硝铵比下，系统出水NH4+浓度在四种多样性物种配置中无明显差异。出水NO3-浓度在四种多样性物种配置中有较大差异，其中4个物种混种组合具有较高的硝氮和总氮去除能力。较优的组合为再力花+常绿鸢尾+梭鱼草+黄菖蒲、水葱+常绿鸢尾+风车草+菖蒲。（3）不同硝铵比下，物种多样性对植物生物量及氮积累有明显影响。8个物种混种的生物量和氮积累均高于其余3种多样性梯度，2个物种混种次之。（4）整体上，25/75NO3-/NH4+比例下，硝化与反硝化之和随着多样性的升高而升高，8个物种混种的硝化与反硝化之和显著高于其它组合；在75/25NO3-/NH4+比例下，4个物种混种的硝化与反硝化之和显著高于其它组合，而其余3种NO3-/NH4+比例下，物种多样性对人工湿地根区硝化-反硝化过程不存在显著影响。