Chen Xing, Zhang Zihan, Xie Fazhi
Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reus Energy, Anhui Jianzhu University, Hefei, 230601, China; Anhui Province Engineering Research Center for Mine Ecological Remediation, Anhui University, Hefei, 230601, China.
Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reus Energy, Anhui Jianzhu University, Hefei, 230601, China; Anhui Province Engineering Research Center for Mine Ecological Remediation, Anhui University, Hefei, 230601, China.
Environ Res. 2025 Aug 2;285(Pt 3):122491. doi: 10.1016/j.envres.2025.122491.
Large river basins integrate the three major ecosystems of atmosphere, land, and oceans, serving as crucial mediators in the global carbon cycle. Nevertheless, pronounced variations occur in geographic locations, climatic conditions, land-use patterns, and anthropogenic activities across sub-catchments of these large basins. As a result, systematic investigations into the spatial heterogeneity of dissolved organic matter (DOM) composition, abundance, and their driving factors are still lacking. In this study, we combined Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), Ultraviolet-Visible Spectroscopy (UV-vis), excitation-emission matrix spectroscopy (EEM), and water isotopes (δH-HO and δO-HO) to investigate DOM characteristics across sub-catchments of Asia's longest river (Yangtze River). The results demonstrated that dissolved organic carbon (DOC) concentration in the Yangtze River is relatively low (mean: 3.17 ± 0.95 mg L) compared with global major rivers. The predominance of humic-like and lignin-like components in DOM across all sub-catchments highlights the dominance of allochthonous DOM sources. Notably, chromophoric dissolved organic matter (CDOM) concentration peaked in the Poyang Lake (PYL) catchment. Meanwhile, the Yangtze River mainstem (YRM) catchment, featuring extensive spatial coverage and complex environmental dynamics, showed substantial variability in DOM optical and molecular characteristics. Among sub-catchments, the Jialing River (JLR) exhibited the highest proportion of humic-like compositions (C1+C3), suggesting DOM originating primarily from forest-derived macromolecules and soil organic matter. Conversely, the Taihu Lake Catchment (THL) catchment displayed elevated abundance of protein-like components (C2) and lipid/aminoglycan-related compounds, indicative of significant contributions from autochthonous organic matter associated with eutrophication driven by intensive anthropogenic activities. These findings underscore that terrestrial carbon inputs constitute a pivotal component of riverine carbon cycling.
大河流域整合了大气、陆地和海洋这三大生态系统，是全球碳循环的关键调节者。然而，这些大流域的子流域在地理位置、气候条件、土地利用模式和人类活动方面存在显著差异。因此，针对溶解有机物（DOM）组成、丰度及其驱动因素的空间异质性仍缺乏系统研究。在本研究中，我们结合傅里叶变换离子回旋共振质谱（FT-ICR MS）、紫外可见光谱（UV-vis）、激发发射矩阵光谱（EEM）和水同位素（δH-HO和δO-HO）来研究亚洲最长河流（长江）各子流域的DOM特征。结果表明，与全球主要河流相比，长江中的溶解有机碳（DOC）浓度相对较低（平均值：3.17±0.95毫克/升）。所有子流域中DOM里类腐殖质和类木质素成分占主导地位，突出了外源DOM来源的主导性。值得注意的是，发色溶解有机物（CDOM）浓度在鄱阳湖（PYL）流域达到峰值。同时，长江干流（YRM）流域具有广泛的空间覆盖范围和复杂的环境动态，其DOM光学和分子特征表现出显著变异性。在各子流域中，嘉陵江（JLR）类腐殖质成分（C1+C3）的比例最高，表明DOM主要源自森林大分子和土壤有机质。相反，太湖流域（THL）中类蛋白质成分（C2）以及脂质/氨基聚糖相关化合物的丰度较高，这表明密集人类活动导致的富营养化相关的本地有机质贡献显著。这些发现强调陆地碳输入是河流碳循环的关键组成部分。
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