Spatial variability of nutrient fluxes associated with lacustrine groundwater discharge in a typical oxbow lake, Central China

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-04-22 DOI:10.1016/j.watres.2025.123701

Jiawen Xu , Yao Du , Xiaoliang Sun , Hao Tian , Shunjie Zhu , Yiqun Gan , Yanxin Wang

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Abstract

Lacustrine groundwater discharge (LGD) is increasingly being recognized as an important component in the water and nutrient budgets of lakes. Oxbow lakes, with specific hydrological or geological features, are widespread in floodplains worldwide and provide important ecological functions. Previous studies on LGD in oxbow lakes have focused on hydrological fluxes, but nutrient fluxes associated with LGD remain poorly understood. This study estimated the overall LGD-related nutrient fluxes and their spatial variability in Heiwawu oxbow lake along the middle reaches of the Yangtze River, using the radon (²²²Rn) mass balance model coupled with ancillary water chemistry. The LGD rates were found to range from 3.39 to 149.39 mm/d, with an average of 37.87 mm/d. The NH₄N, total dissolved nitrogen (TN), and total dissolved phosphorus (TP) fluxes with LGD ranged from 6.22 to 1168.96 mg/(m²d), 8.82 to 1076.04 mg/(m²d), and 1.81 to 100.00 mg/(m²d), with averages of 212.31, 218.92, and 27.87 mg/(m²d), respectively. LGD rates and associated nutrient fluxes were dominated by water depth. In the lake interior, where the water depth was high and the lakebed was directly connected to a porous confined aquifer, LGD rates and associated nutrient fluxes were higher. In shallow area, the LGD rates and associated nutrient fluxes were lower. The proportion of LGD and associated nutrient fluxes to the lake significantly influenced nutrient concentrations, highlighting the important role of LGD in regulating nutrient dynamics in the lake. Heiwawu oxbow lake is mainly nitrogen-limited, suggesting that high TN fluxes carried by LGD would exacerbate eutrophication. The average uncertainty percentages of LGD and associated nutrient fluxes (NH₄N, TN, and TP) were 36.94 %, 22.11 %, 26.47 %, and 23.47 %, respectively. This study highlighted the role of groundwater in the nutrient status of oxbow lakes in humid floodplains.

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中国中部典型牛首湖湖底地下水排放相关营养通量的空间变异性

湖泊地下水排放（LGD）越来越被认为是湖泊水和营养收支的重要组成部分。牛轭湖具有独特的水文或地质特征，广泛分布于全球洪泛平原，具有重要的生态功能。以往对牛轭湖LGD的研究主要集中在水文通量上，但与LGD相关的营养通量仍然知之甚少。采用氡（222Rn）质量平衡模型和辅助水化学模型，估算了长江中游黑瓦坞牛牛湖与lgd相关的总体养分通量及其空间变异。LGD速率范围为3.39 ~ 149.39 mm/d，平均为37.87 mm/d。NH4-N、总溶解氮（TN）和总溶解磷（TP）通量随LGD变化范围分别为6.22 ~ 1168.96 mg/(m2d)、8.82 ~ 1076.04 mg/(m2d)和1.81 ~ 100.00 mg/(m2d)，平均值分别为212.31、218.92和27.87 mg/(m2d)。LGD速率和相关的养分通量受水深的影响。在湖泊内部，水深较高，湖床直接与多孔承压含水层相连，LGD率和相关的养分通量较高。浅水区LGD速率和相关的养分通量较低。LGD的比例和相关的湖泊养分通量显著影响了营养物浓度，凸显了LGD在调节湖泊养分动态中的重要作用。黑瓦武牛轭湖以限氮为主，表明LGD携带的高TN通量会加剧富营养化。土壤LGD及其相关养分通量（NH4-N、TN和TP）的平均不确定率分别为36.94%、22.11%、26.47%和23.47%。本研究强调了地下水在湿润洪泛平原牛轭湖营养状况中的作用。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.