Sediment amplifies organic matter cycling and nutrients feedback in eutrophic lake zones

Junfeng Xing; Yuping Zhou; Ding He; Fen Guo; Penghui Li; Yuan Zhang; Rui Lv; Runze Xue; Changqing Liu; Yihua Xiao

doi:10.1016/j.watres.2025.124164

Sediment amplifies organic matter cycling and nutrients feedback in eutrophic lake zones

Water Res. 2025 Jul 5:286:124164. doi: 10.1016/j.watres.2025.124164. Online ahead of print.

Authors

Junfeng Xing¹, Yuping Zhou², Ding He³, Fen Guo⁴, Penghui Li⁵, Yuan Zhang⁴, Rui Lv⁶, Runze Xue³, Changqing Liu¹, Yihua Xiao⁷

Affiliations

¹ National and Local & Joint Engineering Research Center for Urban Sewage Treatment and Resource Recycling, Qingdao University of Technology, Qingdao 266520, China; School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China.
² School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China.
³ Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology, Hong Kong.
⁴ Guangdong Basic Research Center of Excellence for Ecological Security and Green Development, Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, China.
⁵ School of Marine Sciences, Sun Yat-Sen University, Zhuhai 519082, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China.
⁶ National and Local & Joint Engineering Research Center for Urban Sewage Treatment and Resource Recycling, Qingdao University of Technology, Qingdao 266520, China.
⁷ National and Local & Joint Engineering Research Center for Urban Sewage Treatment and Resource Recycling, Qingdao University of Technology, Qingdao 266520, China; School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266520, China. Electronic address: yihuaxiao163@163.com.

PMID: 40651443
DOI: 10.1016/j.watres.2025.124164

Abstract

Eutrophication alters the composition of dissolved organic matter (DOM) in lakes, yet its impact on particulate (POM) and sedimentary organic matter (SOM) remains poorly explored, particularly in large shallow lake systems. Here, we investigated spatial variation in DOM, POM, and SOM across different eutrophic zones in a large shallow lake using optical spectroscopy and ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Compared to the light-eutrophic region, middle-eutrophic region exhibited elevated dissolved organic carbon, chromophoric DOM, and fluorescent DOM concentrations but lower molecular weights, with cyanobacteria abundance strongly correlated with SOM composition. While DOM molecular signatures were relatively consistent across different eutrophic zones, as eutrophication intensifies, SOM showed more pronounced changes, including higher proportions of aliphatic, lipid-like, and sulfur-containing (CHOS) compounds, and reduced levels of phosphorus-containing compounds (CHOP) and carboxyl-rich alicyclic molecules (CRAM). These compositional shifts, along with declining aromaticity and oxidation state, suggest enhanced accumulation of algal-derived labile organic matter and microbially-mediated release of phosphorus from sediments. Our findings reveal that SOM is more responsive to eutrophication than DOM and may act as both a sink and a source of nutrients, contributing to internal feedbacks that sustain algal blooms. This study provides new insights into organic matter dynamics in eutrophic lakes and supports more targeted management strategies for carbon and nutrient regulation.

Keywords: Algal bloom; Dissolved organic matter; Eutrophication; FT-ICR-MS; Sediment.