Trace metal stoichiometry of dissolved organic matter in the Amazon plume

Gledhill, Martha; Hollister, Adrienne Patricia; Seidel, Michael; Zhu, Kechen; Achterberg, Eric P.; Dittmar, Thorsten; Koschinsky, Andrea

doi:10.1126/sciadv.abm2249

Cited by 16 publications

(13 citation statements)

References 89 publications

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“…Dissolved organic matter (DOM) contains more carbon than the global marine and terrestrial biomass combined . Production and consumption processes of this vast pool of DOM are critical in aquatic biogeochemical cycles and food webs because DOM contains not only carbon but also other elements essential for life . The molecular composition of DOM is thought to play a major role in its long-term persistence in aquatic systems.…”

Section: Introductionmentioning

confidence: 99%

“… 1 Production and consumption processes of this vast pool of DOM are critical in aquatic biogeochemical cycles and food webs because DOM contains not only carbon but also other elements essential for life. 2 The molecular composition of DOM is thought to play a major role in its long-term persistence in aquatic systems. Therefore, factors influencing aquatic DOM composition have been the focus of study in recent years, revealing that environmental variables such as hydrological processes and climatic factors are often the primary drivers.…”

Section: Introductionmentioning

confidence: 99%

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Determinants of Microbial-Derived Dissolved Organic Matter Diversity in Antarctic Lakes

Kida

Merder

Fujitake

et al. 2023

Environ. Sci. Technol.

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Identifying drivers of the molecular composition of dissolved organic matter (DOM) is essential to understand the global carbon cycle, but an unambiguous interpretation of observed patterns is challenging due to the presence of confounding factors that affect the DOM composition. Here, we show, by combining ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, that the DOM molecular composition varies considerably among 43 lakes in East Antarctica that are isolated from terrestrial inputs and human influence. The DOM composition in these lakes is primarily driven by differences in the degree of photodegradation, sulfurization, and pH. Remarkable molecular beta-diversity of DOM was found that rivals the dissimilarity between DOM of rivers and the deep ocean, which was driven by environmental dissimilarity rather than the spatial distance. Our results emphasize that the extensive molecular diversity of DOM can arise even in one of the most pristine and organic matter source-limited environments on Earth, but at the same time the DOM composition is predictable by environmental variables and the lakes' ecological history.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determinants of Microbial-Derived Dissolved Organic Matter Diversity in Antarctic Lakes

Kida

Merder

Fujitake

et al. 2023

Environ. Sci. Technol.

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“…However, the precipitation mechanisms of soil HS by Fe 3+ by forming a π-d electron bonding system between the HS functional groups and d-orbitals of Fe remain unclear. Secondly, Fe 3+ shows to sink HS in aquatic environments which typically occurs by trapping terrestrially derived DOM by Fe 3+20 , flocculation and coprecipitation [19][20][21][22]41 . Similarly, Fe 3+ can form complexes with protein of extracellular polymeric substances (EPS) and siderophores of prokaryotes [23][24][25][26]42 , and may act as a key factor for their subsequent sinking in aquatic environments.…”

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confidence: 99%

Isolation of dissolved organic matter from aqueous solution by precipitation with FeCl3: mechanisms and significance in environmental perspectives

Zhang

Mostofa

Yang

et al. 2023

Sci Rep

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Ferric ions can bind strongly with dissolved organic matter (DOM), including humic acids (HA), fulvic acids (FA), and protein-like substances, whereas isolation of Fe-DOM precipitates (Fe-DOMP) and their biochemical characteristics remain unclear. In this work FeCl3 was used to isolate DOM components from various sources, including river, lake, soil, cow dung, and standard tryptophan and tyrosine, through precipitation at pH 7.5–8.5. The Fe-DOMP contribute to total DOM by approximately 38.6–93.8% of FA, 76.2% of HA and 25.0–30.4% of tryptophan and tyrosine, whilst fluorescence spectra allowed to monitor/discriminate the various DOM fractions in the samples. The relative intensity of the main infrared peaks such as 3406‒3383 cm−1 (aromatic OH), 1689‒1635 cm−1 (‒COOH), 1523–1504 cm−1 (amide) and 1176–1033 cm−1 (‒S=O) show either to decline or disappear in Fe‒DOMP. These results suggest the occurrence of Fe bonds with various functional groups of DOM, indicating the formation of π–d electron bonding systems of different strengths in Fe‒DOMP. The novel method used for isolation of Fe-DOMP shows promising in opening a new frontier both at laboratory and industrial purposes. Furthermore, results obtained may provide a better understanding of metal–organic complexes involved in the regulation of the long-term stabilization/sequestration of DOM in soils and waters.

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“…Selected equilibrium constants in critical compilations usually refer to the reference temperature T = 298.15 K (or 25°C) and to the standard state, that is, a pressure of 0.1 MPa (or 1 bar) and, for aqueous species, infinite dilution (ionic strength I = 0). Application of stoichiometric constants to solutions at the ionic strength of seawater results in systematic bias of the order of 10%–30%, dependent on the charge of the ion under consideration, since the extended Davies equation used to make the calculations is not valid above ionic strengths of 0.5 M (Gledhill et al., 2022; Turner et al., 2016). Constants for the formation of Fe hydroxide species are taken from Liu and Millero (1999).…”

Section: Methodsmentioning

confidence: 99%

Influence of Changes in pH and Temperature on the Distribution of Apparent Iron Solubility in the Oceans

Zhu

Achterberg

Bates

et al. 2023

Global Biogeochemical Cycles

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An insufficient supply of the micronutrient iron (Fe) limits phytoplankton growth across large parts of the ocean. Ambient Fe speciation and solubility are largely dependent on seawater physico‐chemical properties. We calculated the apparent Fe solubility (SFe(III)app) at equilibrium for ambient conditions, where SFe(III)app is defined as the sum of aqueous inorganic Fe(III) species and Fe(III) bound to organic matter formed at a free Fe3+ concentration equal to the solubility of Fe hydroxide. We compared the SFe(III)app to measured dissolved Fe (dFe) in the Atlantic and Pacific Oceans. The SFe(III)app was overall ∼2–4‐fold higher than observed dFe at depths less than 1,000 m, ∼2‐fold higher than the dFe between 1,000 and 4,000 m and ∼3‐fold higher than dFe below 4,000 m. Within the range of used parameters, our results showed that there was a similar trend in the vertical distributions of horizontally averaged SFe(III)app and dFe. Our results suggest that vertical dFe distributions are underpinned by changes in SFe(III)app, which are driven by relative changes in ambient pH and temperature. Since both pH and temperature are essential parameters controlling ambient Fe speciation, these should be accounted for in investigations of changing Fe dynamics, particularly in the context of ocean acidification and warming.

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Trace metal stoichiometry of dissolved organic matter in the Amazon plume

Cited by 16 publications

References 89 publications

Determinants of Microbial-Derived Dissolved Organic Matter Diversity in Antarctic Lakes

Determinants of Microbial-Derived Dissolved Organic Matter Diversity in Antarctic Lakes

Isolation of dissolved organic matter from aqueous solution by precipitation with FeCl3: mechanisms and significance in environmental perspectives

Influence of Changes in pH and Temperature on the Distribution of Apparent Iron Solubility in the Oceans

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