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Ren X, Yu R, Wang R, Kang J, Li X, Zhang P, Liu T. Tracing spatial patterns of lacustrine groundwater discharge in a closed inland lake using stable isotopes. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 354:120305. [PMID: 38359630 DOI: 10.1016/j.jenvman.2024.120305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
Tracing lacustrine groundwater discharge (LGD) is essential for understanding the hydrological cycle and water chemistry behaviour of lakes. LGD usually exhibits large spatial variability, but there are few reports on quantitatively revealing the spatial patterns of LGD at the whole lake scale. This study investigated the spatial patterns of LGD in Daihai Lake, a typical closed inland lake in northern China, based on the stable isotopes (δ2H and δ18O) of groundwater, surface water, and sediment pore water (SPW). The results showed that there were significant differences between the δ2H and δ18O values of different water bodies in the Daihai Lake Basin: groundwater < SPW < lake water. The LGD through SPW was found to be an important recharge pathway for the lake. Accordingly, stable isotopes of SPW showed that LGD in the northeastern and northwestern of Daihai Lake was significantly greater both horizontally and vertically than that in the other regions, and the proportions of groundwater in SPW in these two regions were 55.53% and 29.84%, respectively. Additionally, the proportion of groundwater in SPW showed a significant increase with profile depth, and the proportion reached 100% at 50 cm below the sediment surface in the northeastern of the lake where the LGD intensity was strongest. The total LGD to Daihai Lake was 1.47 × 107 m3/a, while the LGD in the northeastern and northwestern of the lake exceeded 1.9 × 106 m3/a. This study provides new insights into assessing the spatial patterns of LGD and water resource management in lakes.
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Affiliation(s)
- Xiaohui Ren
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China
| | - Ruihong Yu
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China; Key Laboratory of Mongolian Plateau Ecology and Resource Utilization, Ministry of Education, Hohhot, 010021, China; Autonomous Region Collaborative Innovation Center for Integrated Management of Water Resources and Water Environment in the Inner Mongolia Reaches of the Yellow River, Hohhot, 010018, China.
| | - Rui Wang
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China
| | - Jianfang Kang
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China
| | - Xiangwei Li
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China
| | - Pengxuan Zhang
- Inner Mongolia Key Laboratory of River and Lake Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, 010021, China
| | - Tingxi Liu
- Inner Mongolia Water Resource Protection and Utilization Key Laboratory, Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot, 010018, China
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Wang Y, Cao X, Yu H, Xu Y, Peng J, Qu J. Nitrate with enriched heavy oxygen isotope linked to changes in nitrogen source and transformation as groundwater table rises. JOURNAL OF HAZARDOUS MATERIALS 2023; 455:131527. [PMID: 37163892 DOI: 10.1016/j.jhazmat.2023.131527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/19/2023] [Accepted: 04/26/2023] [Indexed: 05/12/2023]
Abstract
Nitrate is a significant constituent of the total nitrogen pool in shallow aquifers and poses an escalating threat to groundwater resources, making it crucial to comprehend the source, conversion, and elimination of nitrogen using appropriate techniques. Although dual-isotope dynamics in nitrate have been widely used, uncertainties remain regarding the asynchronously temporal changes in δ18O-NO3- and δ15N-NO3- observed in hypoxic aquifers. This study aimed to investigate changes in nitrogen sources and transformations using temporal changes in field-based NO3- isotopic composition, hydro-chemical variables, and environmental DNA profiling, as the groundwater table varied. The results showed that the larger enrichment in δ18O-NO3- (+13‰) compared with δ15N-NO3- (-2‰) on average during groundwater table rise was due to a combination of factors, including high 18O-based atmospheric N deposition, canopies nitrification, and soil nitrification transported vertically by rainfalls, and 18O-enriched O2 produced through microbial and root respiration within denitrification. The strong association between functional gene abundance and nitrogen-related indicators suggests that anammox was actively processed with nitrification but in small bacterial population during groundwater table rise. Furthermore, bacterial species associated with nitrogen-associated gradients provided insight into subsurface nitrogen transformation, with Burkholderiaceae species and Pseudorhodobacter potentially serving as bioindicators of denitrification, while Candidatus Nitrotogn represents soil nitrification. Fluctuating groundwater tables can cause shifts in hydro-chemical and isotopic composition, which in turn can indicate changes in nitrogen sources and transformations. These changes can be used to improve input sources for mixture models and aid in microbial remediation of nitrate.
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Affiliation(s)
- Yajun Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, and State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xiaofeng Cao
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Hongwei Yu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yan Xu
- College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
| | - Jianfeng Peng
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jiuhui Qu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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