Empirical dynamic modeling helps deciphering the nonlinear feedback loops governing freshwater methane emissions
Methane (CH4) emissions from freshwater ecosystems represent a major and dynamic component of the global greenhouse gas budget, yet their regulation by interacting physical, chemical, and biological processes remains inadequately understood, particularly under nonlinear and lagged system responses....
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-08-01
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| Series: | Ecological Indicators |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S1470160X25007216 |
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| Summary: | Methane (CH4) emissions from freshwater ecosystems represent a major and dynamic component of the global greenhouse gas budget, yet their regulation by interacting physical, chemical, and biological processes remains inadequately understood, particularly under nonlinear and lagged system responses. Here, we introduce a data-driven modeling framework that integrates Non-negative Latent Factor (NLF) imputation and Empirical Dynamic Modeling (EDM) to disentangle the nonlinear mechanisms driving freshwater CH4 emissions. Using 12 years of in-situ observations from a hydrologically regulated reservoir system, our results reveal that diffusive CH4 emissions are jointly driven by allochthonous organic carbon inputs and phytoplankton community dynamics. Dissolved organic carbon (DOC) dominates CH4 emissions, contributing ∼ 40 % under extreme reservoir inflows (>30,000 m3·s−1), while phytoplankton biomass surpasses DOC’s influence when total phosphorus exceeds 0.14 mg·L−1, highlighting eutrophication’s role in amplifying methanogenic pathways. A time lag of 1 to 2 weeks exists in the air–water CH4 flux response to environmental changes, aligning with phytoplankton growth cycles and underscoring the complexity of the ecosystem-level regulation for CH4 emissions. Dynamic path analysis and scenario simulations based on interaction strength trajectories demonstrate that the dominant regulation pathways of CH4 emissions shift with seasonality and environmental thresholds. This study advances a transferable framework for modeling nonlinear emission dynamics and feedback regulation in freshwater systems, underscoring the necessity of integrating hydrological and ecological controls into CH4 mitigations and must be balanced with CO2 management at the ecosystem scale. |
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| ISSN: | 1470-160X |