Evolution of dissolved organic nitrogen chemistry during transportation to the marginal sea: Insights from nitrogen isotope and molecular composition analyses

Yan, Zhenwei; Xin, Yu; Zhong, Xiaosong; Yi, Yuanbi; Li, Penghui; Wang, Yuntao; Zhou, Yuping; He, Yuhe; He, Chen; Shi, Quan; Xu, Wenqi; He, Ding

doi:10.1016/j.watres.2023.120942

Cited by 7 publications

(2 citation statements)

References 80 publications

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“…More N-containing formulas have been found in river water compared to seawater and drinking water. This is consistent with observations from other studies 58 where a decrease of CHON formulas was observed along a river-to-sea transect and associated with the increasing salinity. According to Yan et al, a gradual increase in the degree of saturation and aromaticity was also observed with the increasing number of nitrogen atoms per formula.…”

Section: Resultssupporting

confidence: 93%

Enhancing Molecular Characterization of Dissolved Organic Matter by Integrative Direct Infusion and Liquid Chromatography Nontargeted Workflows

Patrone,

Vila-Costa,

Dachs

et al. 2024

Environ. Sci. Technol.

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Dissolved organic matter (DOM) in aquatic systems is a highly heterogeneous mixture of water-soluble organic compounds, acting as a major carbon reservoir driving biogeochemical cycles. Understanding DOM molecular composition is thus of vital interest for the health assessment of aquatic ecosystems, yet its characterization poses challenges due to its complex and dynamic chemical profile. Here, we performed a comprehensive chemical analysis of DOM from highly urbanized river and seawater sources and compared it to drinking water. Extensive analyses by nontargeted direct infusion (DI) and liquid chromatography (LC) high-resolution mass spectrometry (HRMS) through Orbitrap were integrated with novel computational workflows to allow molecularand structural-level characterization of DOM. Across all water samples, over 7000 molecular formulas were calculated using both methods (∼4200 in DI and ∼3600 in LC). While the DI approach was limited to molecular formula calculation, the downstream data processing of MS2 spectral information combining library matching and in silico predictions enabled a comprehensive structural-level characterization of 16% of the molecular space detected by LC-HRMS across all water samples. Both analytical methods proved complementary, covering a broad chemical space that includes more highly polar compounds with DI and more less polar ones with LC. The innovative integration of diverse analytical techniques and computational workflow introduces a robust and largely available framework in the field, providing a widely applicable approach that significantly contributes to understanding the complex molecular composition of DOM.

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Section: Resultssupporting

confidence: 93%

Enhancing Molecular Characterization of Dissolved Organic Matter by Integrative Direct Infusion and Liquid Chromatography Nontargeted Workflows

Patrone,

Vila-Costa,

Dachs

et al. 2024

Environ. Sci. Technol.

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“…Among these exogenous DOM sources, the riverine input has been suggested to be large enough to sustain the steady-state age and carbon sequestration of the marine DOM pool. , Terrigenous DOM carried across the river plume, estuary, and adjacent seawater undergoes a variety of biogeochemical reactions in this geological continuum, including flocculation, photochemical transformation, biological degradation, among others, − before entering the oceanic DOM pool. Consequently, the fate of terrigenous DOM and the contribution of this DOM to long-time carbon storage in the ocean have attracted much attention. ,− A recent study has revealed that a fraction of terrigenous carboxyl-rich alicyclic molecules and aromatic molecules with biological and photochemical persistence probably contribute to the oceanic recalcitrant DOM pool . Yet, most studies have not included the unassigned mass peaks to evaluate the carbon sequestration effect of DDOM.…”

Section: Introductionmentioning

confidence: 99%

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

Cai,

Yao,

et al. 2024

Environ. Sci. Technol.

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Thousands of mass peaks emerge during molecular characterization of natural dissolved organic matter (DOM) using ultrahigh-resolution mass spectrometry. While mass peaks assigned to certain molecular formulas have been extensively studied, the uncharacterized mass peaks that represent a significant fraction of organic matter and convey biogenic elements and energy have been previously ignored. In this study, we introduce the term dark DOM (DDOM) for unassigned mass peaks and have explored its characteristics and environmental behaviors using a data set of 38 DOM extracts covering the Yangtze River-to-ocean continuum. We identified a total of 9141 DDOM molecules, which exhibited higher molecular weight and greater diversity than the DOM subset with assigned DOM formulas. Although DDOM contributed a smaller fraction of relative abundance, it significantly impacted the molecular weight and molecular composition of bulk DOM. A portion of DDOM with higher molecular weight was found to increase molecular abundance across the river-to-ocean continuum. These compounds could contain halogenated organic molecules and might have a high potential to contribute to the refractory organic carbon pool. With this study, we underline the contribution of dark matter to the total DOM pool and emphasize that more DDOM research is needed to understand its contribution to global biogeochemical cycles and carbon sequestration.

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Optical signatures as a diagnostic tool for tracking dynamics of sedimentary dissolved organic nitrogen, phosphorus, and sulfur in an anthropogenic bay

Zhang,

Zhao,

Chen

et al. 2025

Chemical Geology

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Evolution of dissolved organic nitrogen chemistry during transportation to the marginal sea: Insights from nitrogen isotope and molecular composition analyses

Cited by 7 publications

References 80 publications

Enhancing Molecular Characterization of Dissolved Organic Matter by Integrative Direct Infusion and Liquid Chromatography Nontargeted Workflows

Enhancing Molecular Characterization of Dissolved Organic Matter by Integrative Direct Infusion and Liquid Chromatography Nontargeted Workflows

The Hunt for Chemical Dark Matter across a River-to-Ocean Continuum

Optical signatures as a diagnostic tool for tracking dynamics of sedimentary dissolved organic nitrogen, phosphorus, and sulfur in an anthropogenic bay

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