Emerging patterns in the global distribution of dissolved organic matter fluorescence

Wünsch, Urban; Bro, Rasmus; Stedmon, Colin A.; Wenig, Philip; Murphy, Kathleen R.

doi:10.1039/c8ay02422g

Cited by 60 publications

(45 citation statements)

References 23 publications

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“…In fluorescence applications, PARAFAC is often able to account for more than 99% of the raw data and is thus able to reduce hundreds of fluorescence matrices to typically less than six components. 23 Besides information on fluorescence spectra, the component abundances are commonly used to distinguish water masses or elucidate the biogeochemistry of DOM. 24,25 The PARAFAC model assumes rigidly aligned data and linear detector responses and is capable of distinguishing between highly similar analyte spectra.…”

Section: Introductionmentioning

confidence: 99%

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

Wünsch

Hawkes

2020

Analyst

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Section: Introductionmentioning

confidence: 99%

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

Wünsch

Hawkes

2020

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“…However, contrary to our expectations, there was no relationship between concentrations or proportions of MeHg with either the concentrations or composition of DOC, as determined by its optical properties. We quantified patterns in DOC composition using PARAFAC modeling of fluorescence scans, which identified five components (Figure S2) corresponding to commonly identified humic or fulvic material with a dominant terrestrial origin (C1, C2, and C4) and to microbial‐derived or protein‐like material associated to recent production on land or in the water (C3 and C5) (Lapierre & del Giorgio, 2014; Wünsch et al, 2019). We found that THg covaried more strongly with humic‐like C2 and C4, as well as with bulk DOC.…”

Section: Resultsmentioning

confidence: 99%

Mobilization and Transformation of Mercury Across a Dammed Boreal River Are Linked to Carbon Processing and Hydrology

Bonville

Amyot

Giorgio

et al. 2020

Water Resources Research

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Reservoirs are known to accelerate the mobilization and cycling of mercury and carbon as a result of flooding of terrestrial organic matter, which can lead to environmental concerns at local and broader spatial scales. We explored the covariation of mercury (Hg) and carbon (C) functional pools in natural and recently dammed portions of the aquatic network of the Romaine River watershed in Northern Quebec, Canada, to understand how the fate of these elements varies across systems with contrasting hydrology and environmental conditions. We found that total Hg (THg) concentrations in surface waters were relatively constant along the network, whereas both the concentrations and proportions of MeHg tended to increase in reservoirs compared to surrounding nonflooded systems, and along the cascade of reservoirs. Whereas THg was related to total and terrestrial pools of dissolved organic carbon (DOC), MeHg was weakly related to DOC but strongly linked to surface concentrations of CO 2 , as well as to concentrations of iron and manganese. The latter are proxies of cumulative organic matter processing within the network, presumably in anoxic portions of shallow bays, deep reservoir waters, and river sediments, as well as in prior seasons (e.g., under ice). Our results suggest that these deep boreal reservoirs acted more as transformation sites for Hg that was already present than as mobilizers of new Hg, and that under ice metabolism plays a role in MeHg production in these systems as we found strong dichotomies in MeHg patterns between spring and summer.

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“…In this study, we showed that labile DOC (BDOC L ), the fraction of DOC consumed within 31 days, represents an unexpectedly stable proportion of the total DOC pool across a wide range of aquatic ecosystems at 6.1% on average. One possible explanation for this is that its origin is tightly coupled to primary production (Wünsch et al, ; Yamashita & Tanoue, ) when conditions are in steady state (non‐blooming), where production is on par with consumption and DOC does not accumulate. This is in part supported by the threefold higher proportion of BDOC L in ecosystems where rates of primary production are very high (upwellings and bloom conditions), where the rapid production of BDOC L by excessive phytoplankton growth apparently overrides the metabolic capacity of prokaryotes to consume it, thus enabling DOC to accumulate.…”

Section: Discussionmentioning

confidence: 99%

Contrasting Patterns of Labile and Semilabile Dissolved Organic Carbon From Continental Waters to the Open Ocean

2020

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Marine and freshwater prokaryotes feed primarily on bioavailable labile dissolved organic carbon (BDOCL), as well as the bioavailable fraction of the semilabile DOC (BDOCSL) pool. These fractions are operationally defined here as the DOC consumed within a month and greater than a month to a year and a half, respectively. Organic matter from these different pools comes from various autochthonous and allochthonous sources, but their relative bioavailability is unknown across aquatic ecosystems. To fill this gap, we compiled literature information that included 653 batch culture DOC biodegradation experiments across eight aquatic ecosystem types over the past 20 years. We show that the proportion of BDOCL across all aquatic ecosystems was surprisingly consistent (6.1%) despite a 2 order of magnitude variation in initial DOC concentrations, suggesting an overall tight balance between carbon supply and consumption. A higher proportion of BDOCL, 16.3% on average, was observed in high productivity ecosystems. BDOCSL, on the other hand, gradually decreased from 16.0% in lakes to 7.2% in estuaries to undetectable in the open ocean, suggesting that terrestrial connectivity regulates BDOCSL across the continuum. Our results support that recent primary production fuels short‐term prokaryotic DOC needs with an increasing reliance on the abundant BDOCSL pool as ecosystems approach the land‐water interface. Batch culture experiments show that BDOCSL is metabolizable in freshwater and coastal environments but not in the open ocean. We estimate that BDOCSL can sustain 62% of total prokaryotic biomass in inland waters and coasts and an estimated total of 16.7% across aquatic biomes.

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Emerging patterns in the global distribution of dissolved organic matter fluorescence

Cited by 60 publications

References 23 publications

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

Mobilization and Transformation of Mercury Across a Dammed Boreal River Are Linked to Carbon Processing and Hydrology

Contrasting Patterns of Labile and Semilabile Dissolved Organic Carbon From Continental Waters to the Open Ocean

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