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我校在磷素生物地球化学循环过程方面取得新进展

核心提示:近日,我校资源与环境学院刘广龙教授团队在磷素生物地球化学循环过程方面取得新进展,相关成果以“New insights into the mechanism of phosphate release during particulate organic matter photodegradation based on optical and molecular signatures”为题发表在水环境期刊Water Research上。

图1 光照前(a)、光照后(b) POM和含磷分子的Van Krevelen图及其分子量分布情况(c)

图1 光照前(a)、光照后(b) POM和含磷分子的Van Krevelen图及其分子量分布情况(c)

南湖新闻网讯(通讯员 安珈奇)近日,我校资源与环境学院刘广龙教授团队在磷素生物地球化学循环过程方面取得新进展,相关成果以“New insights into the mechanism of phosphate release during particulate organic matter photodegradation based on optical and molecular signatures”为题发表在水环境期刊Water Research上。

水体富营养化导致的藻类水华频发对生态健康和饮用水安全构成重大威胁。磷是水体富营养化和水华爆发的关键元素。研究表明,在有效控制外源磷输入后,内源磷的快速转化已成为磷补偿的主要途径。作为内源磷的重要载体,颗粒有机物(POM)的迁移和转化极大地影响了水中生物可利用磷的含量。然而,现阶段对湖泊水体中POM驱动磷循环的过程和机制缺乏系统认知,致使客观描述水体富营养化和水华爆发过程缺失了重要环节和依据。

在水生生态系统中,颗粒有机物(POM)可通过生物矿化和化学分解释放营养盐从而参与磷循环。太阳辐射引起的POM的光化学转化可以改变其化学组成和分子大小,最终影响磷的生物地球化学循环过程。然而,由于POM复杂的组成结构使这一过程认知始终面临挑战。基于此,刘广龙团队创新性地结合激发-发射矩阵荧光光谱(EEM)和傅里叶变换离子回旋共振质谱(FT-ICR MS)技术揭示了POM光解驱动溶解无机磷酸盐(DIP)的释放过程。结果表明,悬浮液中的POM在光照下显著降解,同时产生和释放DIP。化学连续提取结果表明,POM中的有机磷参与了光化学反应。此外,FT-ICR MS分析显示,光照后POM中含磷分子的平均分子量从374.2 Da降至340.1 Da。低氧化程度和不饱和度的含磷分子优先被光降解,产生富氧和饱和的分子化合物,如类蛋白质和类碳水化合物,从而有利于有机物对磷的进一步利用。活性氧物种(ROS)在POM的光降解中起着重要作用,激发三重态发色溶解有机物(3CDOM*)是POM光降解的主要原因。这些结果为水生生态系统中磷的生物地球化学循环过程提供了新的见解。

我校资源与环境学院博士研究生郭敏丽为论文的第一作者,刘广龙教授为论文通讯作者,中国科学院南京地理与湖沼研究所张运林研究员、中国地质大学(武汉)付庆龙特任研究员和法国索邦大学Arnaud Huguet研究员等人参与了该研究。该研究得到了国家自然科学基金、中央高校基本科研业务费和广西省自然科学基金等项目的资助。

英文摘要:

Phosphate release from particulate organic matter (POM) dominates phosphorus (P) cycling in aquatic ecosystems. However, the mechanisms underlying P release from POM remain poorly understood because of complex fractionation and analytical challenges. In this study, the release of dissolved inorganic phosphate (DIP) during POM photodegradation was assessed using excitation–emission matrix (EEM) fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). POM in suspension was significantly photodegraded under light irradiation, concomitantly with the production and release of DIP in the aqueous solution. Chemical sequential extraction revealed that organic phosphorus (OP) in POM participated in photochemical reactions. Moreover, FT-ICR MS analysis revealed that the average molecular weight of P-containing formulas decreased from 374.2 to 340.1 Da. Formulas containing P with a lower oxidation degree and unsaturation were preferentially photodegraded, generating oxygen-enriched and saturated formula compounds, such as protein- and carbohydrate-like P-containing formulas, benefiting further utilization of P by organisms. Reactive oxygen species played an important role in the photodegradation of POM, and excited triplet state chromophoric dissolved organic matter (3CDOM*) was mainly responsible for POM photodegradation. These results provide new insights into the P biogeochemical cycle and POM photodegradation in aquatic ecosystems.

论文链接https://doi.org/10.1016/j.watres.2023.119954

审核人 刘广龙

责任编辑:晏华华 孟丹琼