Rapid photodegradation of terrestrial soil dissolved organic matter (DOM) with abundant humic-like substances under simu
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Rapid photodegradation of terrestrial soil dissolved organic matter (DOM) with abundant humic-like substances under simulated ultraviolet radiation Shuaidong Li & Xue Hou & Yu Shi & Tao Huang & Hao Yang & Changchun Huang
Received: 7 July 2019 / Accepted: 30 October 2019 # Springer Nature Switzerland AG 2020
Abstract Solar ultraviolet (UV) radiation exhibits a significant degradation for dissolved organic matter (DOM) in natural water ecosystems. However, research on photodegradation process of terrestrial components (e.g., humic-like substances) of DOM are limited due to drastic water dilution and rapid degradation. Here, photochemical degradation of terrestrial soil DOM with abundant humic-like substances from different land use were investigated by utilizing spectral technologies. Simulated UV radiation caused obvious losses on concentration, component structures, and fluorescence characteristic of soil DOM samples. The correlations between absorption specific parameters (a280, SUVA254, and SR) and dissolved organic carbon (DOC) were S. Li : X. Hou : Y. Shi : T. Huang : H. Yang : C. Huang (*) School of Geography Science, Nanjing Normal University, Nanjing 210023, People’s Republic of China e-mail: [email protected] T. Huang : H. Yang : C. Huang Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023, People’s Republic of China T. Huang : H. Yang : C. Huang Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, People’s Republic of China T. Huang : H. Yang : C. Huang State Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province), Nanjing 210023, People’s Republic of China
especially pronounced (p < 0.05), which could be used as valid indicators to determine changes in DOM composition and molecular size during photobleaching process. The decreases of DOM fluorescence intensity were corresponded to first-order kinetic and half-life reactions. The greatest reduction on fluorescence intensity (31.56–81.97%) belonged to peak C (i.e., humic-like substances). Overall, DOM from forest and grass soil ecosystems was more easily photochemical degraded than anthropogenic soil DOM. Enhancive contribution of fresh DOM formed by photodegradation increased autochthonous characteristic and bioavailable nutrition by increasing biological index (BIX) values and ammonia nitrogen (NH4+–N) concentration. The slight microbial decomposition effects on DOM happened in unsterilized dark condition. Our findings provided insights for understanding the rapid photodegradation processes of composition and structure of terrestrial DOM.
Keywords Dissolved organic matter . UV-vis absorption spectroscopy . Three-dimensional fluorescence spectroscopy . Photodegradation
Introduction Dissolved organic matter (DOM) is a mixture of organic substances with multiple functional groups and different molecular weights. Its components are mainly composed of h
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