季节与水文影响下鄱阳湖碟形湖湿地沉积物氮去除功能变化  

Changes in the Sediment Nitrogen Removal Function of Saucer-shaped Depressions in Lake Poyang under Different Seasons and Hydrological Scenarios

作　　者：王正文 姚晓龙 姜星宇 傅大放[1] 张路[2] WANG Zheng-wen;YAO Xiao-long;JINAG Xing-yu;FU Da-fang;ZHANG Lu(School of Civil Engineering,Southeast University,Nanjing 210096,China;Nanjing Institute of Geography&Limnology,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]东南大学土木工程学院,江苏南京210096 [2]中国科学院南京地理与湖泊研究所,江苏南京210008

出　　处：《长江流域资源与环境》2022年第3期673-684,共12页Resources and Environment in the Yangtze Basin

基　　金：国家自然科学基金项目(51839011,41771519)。

摘　　要：从水力学和生态学角度,碟形湖是鄱阳湖湿地中最具特点和最重要的生态功能区,不仅具有较高的生产力,而且具有重要的生态缓冲功能。受水位影响,碟形湖水力连通性具有明显的季节性变化特点,并直接影响氮去除过程,从而影响湿地沉积物对鄱阳湖氮负荷的去除贡献。采用沉积物柱样流动培养和稳定氮同位素配对技术,研究了鄱阳湖9个典型碟形湖丰水和枯水两种水文时段下湿地沉积物-水界面氮的迁移和去除速率,分析和讨论了季节与水文影响下鄱阳湖碟形湖湿地氮去除功能的变化。结果表明,丰水期碟形湖湿地与主湖区连通条件下,赣江西支周围碟形湖沉积物具有呼吸强、氮去除速率高的特征,修水河周围碟形湖沉积物氮去除速率相对较低,主要受到硝态氮(NO_(3)^(-))浓度水平的影响;而枯水期两个区域碟形湖沉积物表现出类似的氮迁移和去除规律,沉积物氮去除速率相比丰水期均显著降低。整体而言,丰水期各碟形湖沉积物氮去除速率均值为26.69±12.98μmol m^(-2) h^(-1),其中非耦合反硝化占总的氮去除的90%±11%,厌氧氨氧化仅贡献了约1%的氮去除,而枯水期沉积物氮去除速率较低,并且以耦合反硝化为主,其对氮去除的贡献达57%±17%,厌氧氨氧化对氮去除的贡献仍较小(4%)。通过对丰、枯水期沉积物氮去除特征的分析发现,丰水期碟形湖与高NO_(3)^(-)负荷的主湖区或入湖河流连通有助于充分发挥湿地的氮去除功能,从而提升碟形湖对入湖氮负荷的削减。研究结果表明保护鄱阳湖碟形湖湿地并保持其与主湖区的水力连通对降低鄱阳湖氮负荷具有重要意义。Saucer-shaped depressions are important areas that have high primary productivity and functions as ecological buffer zones.The hydrological connectivity of saucer-shaped depressions with the inflow rivers and open area of Lake Poyang shows obvious seasonal changes,which influences the nitrogen(N) removal process of the wetlands and thereby can change the volume contribution of wetland N removal to the total N load of Lake Poyang.In this study,N fluxes and removal rates across the sediment-water interface in 9 saucer-shaped depressions of Lake Poyang during the flood and dry period were investigated by conducting sediment core flow-through incubations and using the stable isotope pairing technique.Results showed that,during the flood period,the saucer-shaped depression sediments surrounding the west branch of Ganjiang River exhibited strong respiration and high N removal rates.In contrast,the saucer-shaped depression sediments surrounding Xiushui River showed relatively lower N removal rates,which might be mainly influenced by the level of nitrate(NO_(3)^(-)) concentrations.During the dry period,the saucer-shaped depression sediments in the two sub-areas showed similar patterns of N fluxes and removal rates,with N removal rates significantly lower than those during the flood period.Overall,the average sediment N removal rate during the flood period was 26.69 ± 12.98 μmol m^(-2) h^(-1),of which uncoupled denitrification accounted for 90% ± 11%,and anaerobic ammonium oxidation(anammox) only contributed about 1%.The average sediment N removal rate during the dry period were low,and coupled denitrification accounted for 57% ± 17% of the total sediment N removal.The contribution of anammox to the total sediment N removal during the dry period remained small(4%).The hydrological connectivity of saucer-shaped depressions to the open area and major inflow rivers of Lake Poyang,where higher NO_(3)^(-) loads were shown,can take better advantages of the sediment N removal function of the wetlands,thereby alleviating the

关 键 词：鄱阳湖 碟形湖湿地 沉积物-水界面 氮通量 反硝化 

分 类 号：X524[环境科学与工程—环境工程]