康丽娟,许海,朱广伟,朱梦圆,赵锋.太湖主要环湖河道沉积物反硝化潜力及其控制因子[J].环境科学学报,2021,41(4):1393-1400
太湖主要环湖河道沉积物反硝化潜力及其控制因子
- Sediment denitrification potential and its influencing factors in the main rivers of Lake Taihu
- 基金项目：国家自然科学基金（No.41830757，41573076，41671494）
- 康丽娟
- 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2. 中国科学院大学, 北京 100049
- 许海
- 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2. 中国科学院大学, 北京 100049
- 朱广伟
- 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008
- 朱梦圆
- 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008
- 赵锋
- 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;3. 江南大学环境与土木工程学院, 无锡 214122
- 摘要：河流反硝化作用是水体氮素去除的重要途径，对流域氮负荷削减具有重要意义.为探究河网区河道的反硝化脱氮能力及其主要控制因子，本研究调查了太湖14条主要环湖河道的水质和沉积物特征，通过泥浆培养实验，利用氮氩比的方法和膜接口质谱仪分析技术，测定了14条环湖河道的沉积物反硝化潜力.结果表明，太湖环湖河道的反硝化潜力为-9.93~35.71 μmol·L-1·d-1，均值为（20.79±14.79） μmol·L-1·d-1，南部河道的反硝化潜力显著低于北部河道，负值代表沉积物的吸附或固氮行为.水柱中的硝态氮浓度、溶解氧、溶解性有机碳（DOC）和沉积物中的碳含量均会对沉积物反硝化潜力产生影响.相关分析结果表明，硝态氮浓度对河道反硝化作用的影响有限，反硝化作用对硝态氮底物的响应遵从米氏动力学模型（R2=0.77）的规律.而在太湖氮负荷严重的西部和北部河道区，水体中的DOC是反硝化潜力的主要限制因素.改善氮的去除环境对促进水体氮去除过程和区域氮管理具有重要意义，在氮负荷严重的流域河道，水体的DOC应该得到更多的关注.
- Abstract：River denitrification is an important mechanism for nitrogen removal from water bodies, and as such may be a significant way to reduce nitrogen load in river basins. In order to estimate the rates and determine factors controlling denitrification in the river channels connecting to the lake, we investigated water quality and sediment characteristics of the 14 dominant channels discharging to Taihu Lake, and calculated the denitrification potential of sediments in 14 channels by mud incubation experiments, using the N2:Ar ratio method and membrane inlet mass spectrometry (MIMS). The results show that the denitrification potential of sediments in 14 channels ranged from -9.93 to 35.71 μmol·L-1·d-1, with a mean value of (20.79±14.79) μmol·L-1·d-1. The denitrification potential of southern river channels was significantly lower than the counterpart of the northern river channel, and even yielded negative value, indicative of net nitrogen fixation. The concentrations of water column nitrate nitrogen and sediment dissolved oxygen, dissolved organic carbon, and carbon content in sediments all impacted denitrification potential of sediments. Correlation analysis results of denitrification potential and these environmental factors showed that not all river channel denitrification rates are controlled by nitrate concentration, which follows the law of Mie kinetic model (R2=0.77). In the western and northern river regions which showed high nitrogen loads, DOC in water column was the main limiting factor for denitrification potential. Improving denitrification potential is critical for promoting the nitrogen removal process of water bodies and regional nitrogen management. The results indicate that in water bodies showing high nitrogen loading, DOC content should receive close attention.
