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Contrasting effects of different light regimes on the photoreactivities of allochthonous and autochthonous chromophoric dissolved organic matter.
Zhu, Wen-Zhuo; Wang, Shu-Heng; Wang, De-Zhong; Feng, Wei-Hua; Li, Bo; Zhang, Hong-Hai.
Afiliação
  • Zhu WZ; College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, 316022, China.
  • Wang SH; College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, 316022, China.
  • Wang DZ; College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, 316022, China.
  • Feng WH; Key Laboratory of Engineering Oceanography, Second Institute of Oceanography, Ministry of Natural Resource of the People' s Republic of China, Hangzhou, 310012, China.
  • Li B; College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan, 316022, China; Donghai Laboratory, Zhoushan, 316021, China. Electronic address: acelibo@zjou.edu.cn.
  • Zhang HH; Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China. Electronic address: honghaizhang@ouc.edu.cn.
Chemosphere ; 332: 138823, 2023 Aug.
Article em En | MEDLINE | ID: mdl-37232197
Chromophoric dissolved organic matter (CDOM) plays an important role in ultraviolet (UV) light absorption in the ocean. CDOM is known to originate from either an allochthonous or autochthonous source and has varying compositions and levels of reactivity; however, the effects of individual radiation treatments and the combined effects of UVA and UVB on allochthonous and autochthonous CDOM remain poorly understood. Thus, here, we measured changes in the common optical properties of CDOM collected from China's marginal seas and the Northwest Pacific, using full-spectrum, UVA (315-400 nm), and UVB (280-315 nm) irradiation to induce photodegradation over the same time period (60 h). Excitation-emission matrices (EEMs) combined with parallel factor analysis (PARAFAC) identified four components: marine humic-like C1, terrestrial humic-like C2, soil fulvic-like C3, and tryptophan-like C4. Although the behaviours of these components during full-spectrum irradiation exhibited similar decreasing tendencies, three components (C1, C3, and C4) underwent direct photodegradation under UVB exposure, whereas C2 was more susceptible to UVA degradation. The diverse photoreactivities of the source-dependent components to different light treatments led to differing photochemical behaviours of other optical indices [aCDOM(355), aCDOM(254), SR, HIX, and BIX]. The results indicate that irradiation preferentially reduced the high humification degree or humic substance content of allochthonous DOM, and promoted the transformation from the allochthonous humic DOM components to recently produced components. Although values for the samples from different sources overlapped frequently, principal component analysis (PCA) indicated that the overall optical signatures could be linked to the original CDOM source features. The degradation of CDOM humification, aromaticity, molecular weight, and autochthonous fractions under exposure can drive the CDOM biogeochemical cycle in marine environments. These findings can aid in a better understanding of the effects of different combinations of light treatments and CDOM characteristics on CDOM photochemical processes.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Matéria Orgânica Dissolvida / Substâncias Húmicas Tipo de estudo: Prognostic_studies País/Região como assunto: Asia Idioma: En Revista: Chemosphere Ano de publicação: 2023 Tipo de documento: Article País de afiliação: China

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Matéria Orgânica Dissolvida / Substâncias Húmicas Tipo de estudo: Prognostic_studies País/Região como assunto: Asia Idioma: En Revista: Chemosphere Ano de publicação: 2023 Tipo de documento: Article País de afiliação: China