Photochemistry of dissolved organic matter in water from the Pearl river (China): Seasonal patterns and predictive modelling

Liao, Zhiyang; Wang, Yi; Xie, Kunting; Xie, Nangeng; Cai, Xixi; Zhou, Lihua; Yuan, Yong

doi:10.1016/j.watres.2021.117875

Cited by 27 publications

(2 citation statements)

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“…Dissolved organic matter (DOM) is de ned as complex organic material that can of passing through a 0.45µm lter membrane. It is widely distributed in the environment and primarily consists of protein-like substances (tryptophan-like, tyrosine-like) and humic substances (fulvic acid-like) (Zhou, 2020, Wei Zhang, 2019.DOM plays important roles in biogeochemical processes, including participation in nutrient transformation and carbon cycling in aquatic environments, microbial metabolism, and the formation and migration of heavy metals (Zhiyang et al, 2021, Leyva et al, 2022.The main sources of DOM include humic substances from soils; contributions from terrestrial input, such as aquatic plant and animal decomposition; and endogenous contributions from the metabolism of planktonic organisms. The content and composition of DOM vary temporally and spatially, serving as valuable indicators of aquatic environmental conditions (Yuhong et al, 2018, Liu et al, 2020.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Dissolved Organic Matter in the Huai River (Bengbu Section) during Wet and Dry Seasons

Song,

Kai,

Gao

et al. 2024

Preprint

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This study investigates the different characteristics of dissolved organic matter (DOM) in the Huai River in China (Bengbu section) during wet and dry seasons, using a combination of three-dimensional fluorescence spectroscopy (EEMs) with parallel factor analysis (PARAFAC) and self-organizing map (SOM). Results indicate that the degree levels of humification and the relative molecular weight of DOM in the Huai River are significantly higher during the wet season compared to the dry season (P<0.01). The PARAFAC model resolves three chemical components for both wet and dry seasons: C1 (UVC-like fulvic acid), C2 (humic acid-like), and C3 (tyrosine-like). Humic substances are the main fluorescent components of the Huai River water. During the dry season, the lower rate of water flow leads to an increase in protein-like components due to the slowing of biodegradation rates. The SOM model shows that representative neurons 1 (wet season) and 12 (dry season) are UV-like humic substances, influenced by exogenous inputs and agricultural activities. PCA results show the effects of seasonal variations on dissolved oxygen (DO) and the size of DOM molecules. Organic acids and alkaline functional groups in humic substances buffer the pH value of the water, slowing down its variation. Overall, these results demonstrate dynamic changes of DOM in the Huai River during wet and dry seasons, with terrestrial inputs increasing the level of humification, while also promoting the influence of autochthonous sources in the water.

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Section: Introductionmentioning

confidence: 99%

Characteristics of Dissolved Organic Matter in the Huai River (Bengbu Section) during Wet and Dry Seasons

Song,

Kai,

Gao

et al. 2024

Preprint

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“…Dissolved organic matter (DOM) is one of the largest reactive carbon pools on the earth, and its chemical composition and reactivity are closely associated with aquatic carbon and nutrient cycling, , trace-element transport, microbial metabolism, and reactions with environmental contaminants . Photochemical reactions (photoproduction and photodegradation) are essential components altering DOM chemistry, by directly mineralizing it to CO 2 or indirectly inducing its biogeochemical function changes for subsequent microbial mediation. − The state-of-the-art ultrahigh resolution mass spectrometry, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), can unprecedentedly provide thousands of molecular formulas (MFs) within one DOM sample and provide an opportunity to directly link the molecular chemical composition and photochemical reactivity. , Previous studies demonstrated significant DOM compositional conversions after photoirradiation, , and the MFs linked to photochemical processing are operationally classified as photoresistant, photolabile, and photoproduct types according to their occurrence before and after irradiation experiments. , …”

Section: Introductionmentioning

confidence: 99%

Exploring the Complexities of Dissolved Organic Matter Photochemistry from the Molecular Level by Using Machine Learning Approaches

Zhao

Chen

et al. 2023

Environ. Sci. Technol.

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Dissolved organic matter (DOM) sustains a substantial part of the organic matter transported seaward, where photochemical reactions significantly affect its transformation and fate. The irradiation experiments can provide valuable information on the photochemical reactivity (photolabile, photoresistant, and photoproduct) of molecules. However, the inconsistency of the fate of irradiated molecules among different experiments curtailed our understanding of the roles the photochemical reactions have played, which cannot be properly addressed by traditional approaches. Here, we conducted irradiation experiments for samples from two large estuaries in China. Molecules that occurred in irradiation experiments were characterized by the Fourier transform ion cyclotron resonance mass spectrometry and assigned probabilistic labels to define their photochemical reactivity. These molecules with probabilistic labels were used to construct a learning database for establishing a suitable machine learning (ML) model. We further applied our well-trained ML model to "unmatched" (i.e., not detected in our irradiation experiments) molecules from five estuaries worldwide, to predict their photochemical reactivity. Results showed that numerous molecules with strong photolability can be captured solely by the ML model. Moreover, comparing DOM photochemical reactivity in five estuaries revealed that the riverine DOM chemistry largely determines their subsequent photochemical transformation. We offer an expandable and renewable approach based on ML to compatibly integrate existing irradiation experiments and shed insight into DOM transformation and degradation processes.

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Spatiotemporal response of the optical characteristics of dissolved organic matter to seasonality and land use in tropical island rivers

Xiao,

Wei,

Wang

et al. 2024

Environ Geochem Health

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Photochemistry of dissolved organic matter in water from the Pearl river (China): Seasonal patterns and predictive modelling

Cited by 27 publications

References 50 publications

Characteristics of Dissolved Organic Matter in the Huai River (Bengbu Section) during Wet and Dry Seasons

Characteristics of Dissolved Organic Matter in the Huai River (Bengbu Section) during Wet and Dry Seasons

Exploring the Complexities of Dissolved Organic Matter Photochemistry from the Molecular Level by Using Machine Learning Approaches

Spatiotemporal response of the optical characteristics of dissolved organic matter to seasonality and land use in tropical island rivers

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