He Jia, Jiao Lixin, Zhi Guoqiang, Wu Xue, Yang Yan, Ding Shuai, Zheng Jinlong, Shao Zhi, Xia Rui
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Kunming Institute of Eco-Environmental Sciences, Kunming 650032, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Institute of Water Environment Research, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
J Environ Manage. 2023 May 15;334:117420. doi: 10.1016/j.jenvman.2023.117420. Epub 2023 Feb 17.
Aquatic macrophytes and algae are the most important sources of autochthonous dissolved organic matter (DOM), and their transformation and reuse significantly affect aquatic ecosystem health. In this study, Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to identify the molecular features between submerged macrophyte-derived DOM (SMDOM) and algae-derived DOM (ADOM). The photochemical heterogeneity between SMDOM and ADOM by UV-irradiation and their molecular mechanism were also discussed. The results showed that the molecular abundance of SMDOM was dominated by lignin/CRAM-like structures, tannins, and concentrated aromatic structures (sum of 91.79%), while that of ADOM was dominated by lipids, proteins, and unsaturated hydrocarbons (sum of 60.30%). UV-radiation resulted in a net reduction of tyrosine-like, tryptophan-like and terrestrial humic-like, and conversely a net production of marine humic-like. The light decay rate constants obtained by the multiple exponential function model fitting revealed that both tyrosine-like and tryptophan-like components of SMDOM could be rapidly and directly photodegraded, while the photodegradation of tryptophan-like in ADOM depended on the production of photosensitizers. The photo-refractory fractions of both SMDOM and ADOM were as follows: humic-like > tyrosine-like > tryptophan-like. Our results provide new insights into the fate of autochthonous DOM in aquatic ecosystems where "grass-algae" coexist or evolve.
水生大型植物和藻类是本地溶解有机物（DOM）的最重要来源，它们的转化和再利用对水生生态系统健康有显著影响。在本研究中，利用傅里叶变换离子回旋共振质谱（FT-ICR-MS）来识别沉水大型植物衍生的DOM（SMDOM）和藻类衍生的DOM（ADOM）之间的分子特征。还讨论了UV照射下SMDOM和ADOM之间的光化学非均一性及其分子机制。结果表明，SMDOM的分子丰度以木质素/CRAM样结构、单宁和浓缩芳香结构为主（总和为91.79%），而ADOM的分子丰度以脂质、蛋白质和不饱和烃为主（总和为60.30%）。UV辐射导致类酪氨酸、类色氨酸和陆地腐殖质类物质净减少，相反，海洋腐殖质类物质净产生。通过多指数函数模型拟合得到的光衰减速率常数表明，SMDOM中的类酪氨酸和类色氨酸成分都可以快速直接光降解，而ADOM中类色氨酸的光降解取决于光敏剂的产生。SMDOM和ADOM的光难降解部分顺序如下：腐殖质类>类酪氨酸>类色氨酸。我们的结果为“草-藻”共存或演变的水生生态系统中本地DOM的归宿提供了新的见解。
