Molecular composition of dissolved organic matter across diverse ecosystems: Preliminary implications for biogeochemical cycling

Yi, Yaolin; Cai, Ruanhong; Chen, Chunmao; Shi, Quan

doi:10.1016/j.jenvman.2023.118559

Cited by 8 publications

(3 citation statements)

References 66 publications

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“…N-Acetyl-D-glucosamine is the main component of bacterial peptidoglycan and lipopolysaccharides in the ocean (Riemann and Azam, 2002). The remaining four nitrogen-containing compounds comprise peptides and aromatic compounds, which are common constituents in aquatic DOM (He et al, 2023). The photoproduction of cyanate was examined during the irradiation of the nitrogen-containing compound amended and unamended seawater DOM sample to explore the potential sources of cyanate production in seawater.…”

Section: Photochemical Production Of Cyanate From Natural Seawater Do...mentioning

confidence: 99%

Unraveling sources of cyanate in the marine environment: insights from cyanate distributions and production during the photochemical degradation of dissolved organic matter

Wang,

Liu,

et al. 2024

Front. Mar. Sci.

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Cyanate is a nitrogen and energy source for diverse marine microorganisms, playing important roles in the nitrogen cycle. Despite the extensive research on cyanate utilization, the sources of this nitrogen compound remain largely enigmatic. To unravel the sources of cyanate, distributions and production of cyanate during photochemical degradation of natural dissolved organic matter (DOM) were investigated across various environments, including freshwater, estuarine, coastal areas in Florida, and the continental and slope regions of the North American mid-Atlantic Ocean (NATL). Cyanate production was also examined during the photochemical degradation of exudates from a typical strain of Synechococcus, an important phytoplankton component. To deepen our understanding of the sources and production mechanisms of cyanate, its production was assessed during the photochemical degradation of a natural seawater DOM supplemented with five nitrogen–containing compounds with distinguishing structures and functional groups. Generally, cyanate exhibited higher concentrations in the Florida coastal, estuarine, and freshwater environments than the NATL. However, cyanate distribution did not consistently align with its production rates. Despite significantly low concentrations in the NATL, DOM from this region exhibited cyanate production rates comparable to estuarine and Florida coastal environments. Although relatively high cyanate concentrations were observed in the freshwaters, DOM in this environment exhibited very low cyanate production rates. A highly significant correlation was observed between cyanate and chlorophyll a (Chl a) concentrations in these areas. Moreover, in most estuarine and NATL stations, cyanate concentration and production rate in the Chl a maximum layer were significantly higher than in other layers. Cyanate was produced during the photochemical degradation of the Synechococcus exudates. The cyanate production was significantly enhanced when the natural seawater DOM was supplemented with GlycylGlycine, 4-(methylamino) benzoic acid, 4-[ethyl(methyl)amino] benzaldehyde or methyl 2-aminobenzoate. Our study implies that photochemical degradation of marine DOM, especially phytoplankton-derived DOM, is a substantial source of cyanate in the ocean. Additionally, cyanate may form during the degradation of peptides and small aromatic compounds in DOM, providing novel insights into the nitrogen cycle.

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Section: Photochemical Production Of Cyanate From Natural Seawater Do...mentioning

confidence: 99%

Unraveling sources of cyanate in the marine environment: insights from cyanate distributions and production during the photochemical degradation of dissolved organic matter

Wang,

Liu,

et al. 2024

Front. Mar. Sci.

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“…Carboxylate-rich alicyclic molecules (CRAM) are a class of compounds hypothesized to be present within DOM (Figure a, 1 , 2 ). ,, Originally proposed to explain signature regions in the NMR and MS data of DOM, CRAM was at first speculated to comprise up to 8% of the Earth’s total DOM pool, but this number is as of yet poorly constrained. Since their proposal, CRAM formulas have been detected in complex environmental samples from all types of ecosystem and are prominent in both freshwater and marine environments, , indicating that they may have diverse biogeochemical sources. If these conceptual CRAM molecules do in fact represent such a large quantity of material within DOM, then they must also be responsible for a sizable portion of the properties of DOM.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Simple Bicyclic Carboxylate-Rich Alicyclic Molecules for the Investigation of Dissolved Organic Matter

Craig,

Moodie,

Hawkes

2024

Environ. Sci. Technol.

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Dissolved organic matter (DOM) is a vast and complex chemical mixture that plays a key role in the mediation of the global carbon cycle. Fundamental understanding of the source and fate of oceanic organic matter is obscured due to poor definition of the key molecular contributors to DOM, which limits accurate sample analysis and prediction of the Earth's carbon cycle. Previous work has attempted to define the components of the DOM through a variety of chromatographic and spectral techniques. However, modern preparative and analytical methods have not isolated or unambiguously identified molecules from DOM. Therefore, previously proposed structures are based solely on the mixture's aggregate properties and do not accurately describe any true individual molecular component. In addition to this, there is a lack of appropriate analogues of the individual chemical classes within DOM, limiting the scope of experiments that probe the physical, chemical, and biological contributions from each class. To address these problems, we synthesized a series of analogues of carboxylate-rich alicyclic molecules (CRAM), a molecular class hypothesized to exist as a major contributor to DOM. Key analytical features of the synthetic CRAMs were consistent with marine DOM, supporting their suitability as chemical substitutes for CRAM. This new approach provides access to a molecular toolkit that will enable previously inaccessible experiments to test many unproven hypotheses surrounding the everenigmatic DOM.

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“…A latest study recommends several state-of-the-art techniques for characterizing plastic-leached DOM (Zhu et al, 2023), among them, the Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with soft electrospray ionization (ESI) is a promising approach, since thousands of molecular formulas can be assigned to present high accuracy of DOM formulas and comprehensive understandings on DOM fingerprints via the FT-ICR MS (Kim et al, 2020). Although ESI-FT-ICR MS has been successfully applied on characterization of DOM in diverse ecosystems (Shi et al, 2021;He et al, 2022;He et al, 2023), limited studies have applied such state-of-the-art technique to provide high-resolution molecular composition on the plastics-leached DOM. Here, two popular microplastics, lowdensity polyethylene (LDPE) and polystyrene (PS), were selected for solar radiation degradation experiments, which aimed at revealing the effect of solar radiation on the molecular composition and bioavailability of microplastic-derived DOM in seawater.…”

Section: Introductionmentioning

confidence: 99%

Solar radiation stimulates release of semi-labile dissolved organic matter from microplastics

Wang,

Cai

2023

Front. Mar. Sci.

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Microplastics can release dissolved organic matter (DOM) into seawater under solar radiation exposure. However, the molecular composition and bioavailability of this DOM remain to be investigated. Here, two popular microplastics, low-density polyethylene (LDPE) and polystyrene (PS), were exposed to solar radiation in an artificial seawater for 10 days. The solar-induced LDPE-DOM and PS-DOM were molecularly characterized using ultra-high-resolution mass spectrometry, and were further incubated in a coastal microbial assemblage to examine their bioavailability. Results showed that solar radiation stimulated release of DOM from the microplastics. Dissolved organic carbon concentration analysis indicated that approximately 19.03 µg C L–1 and 3.85 µg C L–1 were released from each gram of LDPE and PS per day, respectively. Molecular composition analysis showed that both the LDPE-DOM and PS-DOM comprised a proportion of nitrogen- and sulfur-bearing molecules, and that the LDPE-DOM molecules were associated with lower molecular abundance and values of double-equivalent-bond and aromatic-index, but higher average hydrogen-to-carbon ratio than that in the PS-DOM. In addition, a proportion of the assigned formulas in LDPE-DOM (22.3%) and PS-DOM (55.8%) could be found in a coastal-DOM sample, suggesting their potential contribution to coastal DOM pool. The further incubation experiment showed that nearly 18.7% of LDPE-DOM and 9.5% of PS-DOM were utilized or transformed within 30 days. Still, a fraction of the solar-induced LDPE-DOM and PS-DOM resisted rapid microbial utilization, remained as semi-labile DOM. These results underlined unaccounted consequences of microplastic-derived DOM in coastal DOM pool.

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Molecular composition of dissolved organic matter across diverse ecosystems: Preliminary implications for biogeochemical cycling

Cited by 8 publications

References 66 publications

Unraveling sources of cyanate in the marine environment: insights from cyanate distributions and production during the photochemical degradation of dissolved organic matter

Unraveling sources of cyanate in the marine environment: insights from cyanate distributions and production during the photochemical degradation of dissolved organic matter

Preparation of Simple Bicyclic Carboxylate-Rich Alicyclic Molecules for the Investigation of Dissolved Organic Matter

Solar radiation stimulates release of semi-labile dissolved organic matter from microplastics

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