文献类型：期刊文献

英文题名：Tidal Dynamics Shaped the Dissolved Organic Carbon Fate and Exchange Flux Across Estuary-Coastal Water Continuum in Zhanjiang Bay, China

作者：Chen, Xiao-Ling[1];Zhang, Peng[1];He, Ying-Xian[1];Zhou, Lin[1];Zhang, Ji-Biao[1]

机构：[1]Guangdong Ocean Univ, Coll Chem & Environm Sci, Zhanjiang 524088, Peoples R China

年份：2026

卷号：14

期号：2

外文期刊名：JOURNAL OF MARINE SCIENCE AND ENGINEERING

收录：SCI-EXPANDED(收录号：WOS:001670662000001)、、EI(收录号：20260519984952)、Scopus(收录号：2-s2.0-105028611630)、WOS

基金：This research was funded by the Guangdong Basic and Applied Basic Research Foundation (2023A1515012769), Research and Development Projects in Key Areas of Guangdong Province (2020B1111020004), Guangdong Provincial Graduate Education Innovation Program Project in 2025 (2025JGXM_084), Graduate Education Innovation Program Project (202538) of Guangdong Ocean University for funding, Graduate Education Innovation Program Project (202523) of Guangdong Ocean University for funding.

语种：英文

外文关键词：dissolved organic matter; tidal dynamics; Zhanjiang Bay; DOC net exchange fluxes; biogeochemistry

外文摘要：Dissolved organic matter (DOM) is central to biogeochemical cycles in estuarine-coastal zones, with its source-sink dynamics linking regional ecological functions to global carbon budgets. As a typical semi-enclosed bay in southern China, Zhanjiang Bay (ZJB) features intense tidal mixing and significant seasonal runoff variations, making it a representative system for understanding DOM dynamics in complex land-sea interaction zones. The migration of dissolved organic carbon (DOC) is crucial for bay carbon budgets, yet its estimation is constrained by land-water interface dynamics and in situ observation limitations. To clarify the regulation of DOM's fate and exchange flux in ZJB, this study integrated in situ observations, ultraviolet spectroscopy, and three-dimensional fluorescence techniques to analyze DOM tidal dynamics and net DOC exchange flux. Results indicated terrestrial runoff dominated rainy-season DOC sources, resulting in slightly higher concentrations (1.86 +/- 0.46 mgL-1) compared to the dry season (1.82 +/- 0.20 mgL-1). Terrestrial inputs endowed rainy-season DOM with high molecular weight and aromaticity, with microbial humic substances (C2) accounting for 36%. Tidal fluctuations affected DOC via water exchange: ebb tides diluted concentrations with low-DOC open-ocean seawater, while flood tides increased them through high-DOC bay water discharge. Dry-season DOM relied on in situ biotransformation, characterized by low molecular weight and aromaticity, with the protein-like fraction (C4) accounting for 24.3%. Fluorescence index (FI = 1.77-1.79) confirmed DOM as a mixture of allochthonous and autochthonous sources, with significant in situ contributions and weak humification. Net DOC exchange flux, regulated by terrestrial runoff, was 3.6-4.6 times higher in the rainy season, decreasing from the estuary to the coast. In conclusion, the joint regulation of terrestrial runoff-driven seasonal dynamics and tidal water exchange governs ZJB's DOM dynamics, providing valuable insights for biogeochemical research in semi-enclosed bays.