Lacustrine groundwater discharge as a key role for DOM dynamics during non-freezing and freezing seasons: Evidence from fluorescence and radon isotopic model.

Authors

Yuanzhen Zhao, Lijuan Hu, Shen Qu, Chuntao Zhao, Xu Yang, Heyang Sun, Zhongli Wang, Xiaomin Liu, Ruihong Yu

Published in

Journal of environmental management. Volume 415. Pages 130601. Jul 31, 2026. Epub Jul 31, 2026.

Abstract

The relationship between lacustrine groundwater discharge (LGD) and dissolved organic matter (DOM) dynamics remains insufficiently understood, particularly during the freezing season. In this study, the spatial and seasonal variability and controlling factors of DOM in surface water and groundwater were investigated in a representative ice-covered lake basin (Ulansuhai Lake, China). Specifically, the effects of LGD on DOM sources and transport during non-freezing and freezing seasons were examined using fluorescence excitation-emission matrix spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) and a ²²²Rn mass balance model (RMBM). During the non-freezing season, DOM was primarily composed of humic-like components (C1-C3), whereas during the freezing season, in addition to humic-like components (C1-C3), protein-like component (C4) was also identified. Quantitative source apportionment indicated that effluent (mean: 39%), soil (mean: 27%), fertilizers (mean: 20%), and plants (mean: 14%) were the dominant DOM sources. During the non-freezing season, LGD was relatively weak (mean LGD rate: 5.12 mm/d), and canal water served as the primary recharge source for both groundwater and lake water; consequently, allochthonous humic-like substances (components C1-C3) dominated the DOM pool. In contrast, during the freezing season, LGD intensified markedly (mean LGD rate: 17.49 mm/d), becoming the sole recharge source for the lake and amplifying the relative contribution of protein-like DOM (C4). Moreover, hydrological conditions and vegetation cover further regulated DOM dynamics by modulating LGD processes. Overall, this study highlights the crucial role of LGD in governing DOM dynamics and demonstrates the effectiveness of integrating optical techniques with isotopic mass balance modelling to elucidate biogeochemical processes under seasonally variable environmental conditions.

PMID:
42537254
Bibliographic data and abstract were imported from PubMed on 01 Aug 2026.

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