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Hassler CS, Simó R, Fawcett SE, Ellwood MJ, Jaccard SL. Marine biogenic humic substances control iron biogeochemistry across the Southern Ocean. Nat Commun 2025; 16:2662. [PMID: 40102391 PMCID: PMC11920038 DOI: 10.1038/s41467-025-57491-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Accepted: 02/24/2025] [Indexed: 03/20/2025] Open
Abstract
Iron, which is an essential element for marine photosynthesis, is sparingly soluble in seawater. In consequence, iron bioavailability controls primary productivity in up to 40% of the world's ocean, including most of the Southern Ocean. Organic ligands are critical to maintaining iron in solution, but their nature is largely unknown. Here, we use a comprehensive dataset of electroactive humics and iron-binding ligands in contrasting regions across the Southern Ocean to show that humic substances are an important part of the iron binding ligand pool, as has been found elsewhere. However, we demonstrate that humics are mostly produced in situ and composed of exopolymeric substances from phytoplankton and bacteria, in contrast to other regions where terrestrially-derived humics are suggested to play a major role. While phytoplankton humics control the biogeochemistry, bioavailability and cycling of iron in surface waters, humics produced or reprocessed by bacteria affect iron cycling and residence time at the scale of the global ocean. Our findings indicate that autochthonous, freshly released organic matter plays a critical role in controlling primary productivity and ocean-climate feedbacks in iron-limited oceanic regions.
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Affiliation(s)
- C S Hassler
- Department F.-A. Forel for Environmental and Aquatic Sciences, University of Geneva, Geneva, Switzerland.
- School of Architecture, Civil, and Environmental Engineering, Smart Environmental Sensing in Extreme Environements, ALPOLE, Ecole Polytechnique Fédérale de Lausanne, Sion, Switzerland.
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland.
| | - R Simó
- Institut de Ciències del Mar, ICM-CSIC, Barcelona, Catalonia, Spain
| | - S E Fawcett
- Department of Oceanography, University of Cape Town, Rondebosch, South Africa
- Marine and Antarctic Research Centre for Innovation and Sustainability, University of Cape Town, Rondebosch, South Africa
| | - M J Ellwood
- Research School of Earth Sciences, Australian National University, Canberra, Australia
- Australian Centre for Excellence in Antarctic Science (ACEAS), Australian National University, Canberra, Australia
| | - S L Jaccard
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
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Puente‐Sánchez F, Macías‐Pérez LA, Campbell KL, Royo‐Llonch M, Balagué V, Sánchez P, Tamames J, Mundy CJ, Pedrós‐Alió C. Bacterioplankton taxa compete for iron along the early spring-summer transition in the Arctic Ocean. Ecol Evol 2024; 14:e11546. [PMID: 38895568 PMCID: PMC11183961 DOI: 10.1002/ece3.11546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 05/21/2024] [Accepted: 05/26/2024] [Indexed: 06/21/2024] Open
Abstract
Microbial assemblages under the sea ice of the Dease Strait, Canadian Arctic, were sequenced for metagenomes of a small size fraction (0.2-3 μm). The community from early March was typical for this season, with Alpha- and Gammaproteobacteria as the dominant taxa, followed by Thaumarchaeota and Bacteroidetes. Toward summer, Bacteroidetes, and particularly the genus Polaribacter, became increasingly dominant, followed by the Gammaproteobacteria. Analysis of genes responsible for microbial acquisition of iron showed an abundance of ABC transporters for divalent cations and ferrous iron. The most abundant transporters, however, were the outer membrane TonB-dependent transporters of iron-siderophore complexes. The abundance of iron acquisition genes suggested this element was essential for the microbial assemblage. Interestingly, Gammaproteobacteria were responsible for most of the siderophore synthesis genes. On the contrary, Bacteroidetes did not synthesize siderophores but accounted for most of the transporters, suggesting a role as cheaters in the competition for siderophores as public goods. This cheating ability of the Bacteroidetes may have contributed to their dominance in the summer.
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Affiliation(s)
- Fernando Puente‐Sánchez
- Department of Systems BiologyCentro Nacional de Biotecnología, CSICMadridSpain
- Microbial Ecology Division, Department of Aquatic Sciences and AssessmentSwedish University of Agricultural SciencesUppsalaSweden
- Present address:
Department of Aquatic Sciences and AssessmentSwedish University for Agricultural Sciences (SLU)UppsalaSweden
| | - Luis Alberto Macías‐Pérez
- Department of Systems BiologyCentro Nacional de Biotecnología, CSICMadridSpain
- Present address:
Department of Evolutionary and Integrative EcologyLeibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)BerlinGermany
| | - Karley L. Campbell
- UiT The Arctic University of NorwayTromsøNorway
- Centre for Earth Observation Science, University of ManitobaWinnipegManitobaCanada
- Present address:
UiT The Arctic University of NorwayTromsøNorway
| | - Marta Royo‐Llonch
- Department of Marine Biology and OceanographyInstitut de Ciències del Mar, CSICBarcelonaSpain
| | - Vanessa Balagué
- Department of Marine Biology and OceanographyInstitut de Ciències del Mar, CSICBarcelonaSpain
| | - Pablo Sánchez
- Department of Marine Biology and OceanographyInstitut de Ciències del Mar, CSICBarcelonaSpain
| | - Javier Tamames
- Department of Systems BiologyCentro Nacional de Biotecnología, CSICMadridSpain
| | | | - Carlos Pedrós‐Alió
- Department of Systems BiologyCentro Nacional de Biotecnología, CSICMadridSpain
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Cui D, He H, Xie W, Yang S, Guo Z, Liao Z, Liu F, Lai C, Ren X, Huang B, Pan X. Occurrence and cycle of dissolved iron mediated by humic acids resulting in continuous natural photodegradation of 17α-ethinylestradiol. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133155. [PMID: 38091802 DOI: 10.1016/j.jhazmat.2023.133155] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/16/2023] [Accepted: 11/29/2023] [Indexed: 02/08/2024]
Abstract
17α-ethinylestradiol (EE2), a synthetic endocrine-disrupting chemical, can degrade in natural waters where humic acids (HA) and dissolved iron (DFe) are present. The iron is mostly bound in Fe(III)-HA complexes, the formation process of Fe(III)-HA complexes and their effect on EE2 degradation were explored in laboratory experiments. The mechanism of ferrihydrite facilitated by HA was explored with results indicating that HA facilitated the dissolution of ferrihydrite and the generation of Fe(III)-HA complexes with the stable chemical bonds such as C-O, CO in neutral, alkaline media with a suitable Fe/C ratio. 1O2, •OH, and 3HA* were all found to be important in the photodegradation of EE2 mediated by Fe(III)-HA complexes. Fe(III)-HA complexes could produce Fe(II) and hydrogen peroxide (H2O2) to create conditions suitable for photo-Fenton reactions at neutral pH. HA helped to maintain higher dissolved iron concentrations and alter the Fe(III)/Fe(II) cycling. The natural EE2 photodegradation pathway elucidated here provides a theoretical foundation for investigating the natural transformation of other trace organic contaminants in aquatic environments.
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Affiliation(s)
- Danni Cui
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Huan He
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
| | - Wenxiao Xie
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Shanshan Yang
- School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Ziwei Guo
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Zhicheng Liao
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; Southwest United Graduate School, Kunming 650092, China
| | - Feng Liu
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Chaochao Lai
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Xiaomin Ren
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Bin Huang
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China
| | - Xuejun Pan
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; Southwest United Graduate School, Kunming 650092, China
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Arnone V, Santana-Casiano JM, González-Dávila M, Sarthou G, Krisch S, Lodeiro P, Achterberg EP, González AG. Distribution of copper-binding ligands in Fram Strait and influences from the Greenland Shelf (GEOTRACES GN05). THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 909:168162. [PMID: 37952666 DOI: 10.1016/j.scitotenv.2023.168162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 09/11/2023] [Accepted: 10/25/2023] [Indexed: 11/14/2023]
Abstract
The Fram Strait represents the major gateway of Arctic Ocean waters towards the Nordic Seas and North Atlantic Ocean and is a key region to study the impact of climate change on biogeochemical cycles. In the region, information about trace metal speciation, such as copper, is scarce. This manuscript presents the concentrations and conditional stability constants of copper-binding ligands (LCu and log KcondCu2+L) in the water column of Fram Strait and the Greenland shelf (GEOTRACES cruise GN05). Cu-binding ligands were analysed by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using salicylaldoxime (SA) as competitive ligand. Based on water masses and the hydrodynamic influences, three provinces were considered (coast, shelf, and Fram Strait) and differences were observed between regions and water masses. The strongest variability was observed in surface waters, with increasing LCu concentrations (mean values: Fram Strait = 2.6 ± 1.0 nM; shelf = 5.2 ± 1.3 nM; coast = 6.4 ± 0.8 nM) and decreasing log KcondCu2+L values (mean values: Fram Strait = 15.7 ± 0.3; shelf = 15.2 ± 0.3; coast = 14.8 ± 0.3) towards the west. The surface LCu concentrations obtained above the Greenland shelf indicate a supply from the coastal environment to the Polar Surface Water (PSW) which is an addition to the ligand exported from the central Arctic to Fram Strait. The significant differences (in terms of LCu and log KcondCu2+L) between shelf and coastal samples were explained considering the processes which modify ligand concentrations and binding strengths, such as biological activity in sea-ice, phytoplankton bloom in surface waters, bacterial degradation, and meltwater discharge from 79NG glacier terminus. Overall, the ligand concentration exceeded those of dissolved Cu (dCu) and kept the free copper (Cu2+) concentrations at femtomolar levels (0.13-21.13 fM). This indicates that Cu2+ toxicity limits were not reached and dCu levels were stabilized in surface waters by organic complexes, which favoured its transport to the Nordic Seas and North Atlantic Ocean and the development of microorganism.
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Affiliation(s)
- Veronica Arnone
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain
| | | | - Melchor González-Dávila
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain
| | | | - Stephan Krisch
- GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany
| | - Pablo Lodeiro
- Department of Chemistry, Physics, Environmental and Soil sciences, University of Lleida-AGROTECNIO-CERCA Center, Rovira Roure 191, 25198, Lleida, Spain
| | - Eric P Achterberg
- GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany
| | - Aridane G González
- Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, Spain.
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Muller FLL, Tankéré-Muller SPC, Tang CH. Terrigenous humic substances regulate the concentrations of dissolved Fe and Cu (but not Al, Mn, Ni or Zn) in the Gaoping River plume. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167374. [PMID: 37758148 DOI: 10.1016/j.scitotenv.2023.167374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/17/2023] [Accepted: 09/24/2023] [Indexed: 10/03/2023]
Abstract
The small mountainous rivers of Oceania discharge a large fraction of their dissolved and particulate load of materials within a very small percentage of the time. As a result, the yearly inputs and physicochemical forms of dissolved metals exported to the ocean by these rivers are poorly quantified. We investigated the wet-season distribution patterns of metals and fluorescent organic substances in the surface waters of the Gaoping River plume, SW Taiwan, under both moderate (Sep 2020) and strong flow conditions (Aug 2021). The mixing behaviour of both soluble (<5 kDa) and colloidal (>5 kDa) metals and fluorescent components was examined over the salinity range 3.0-32.2 in 2020 and 5.8-31.1 in 2021. We detected two humic-like and one protein-like fluorescent components, the same on both surveys. The humic-like components, C1 and C3, originated from the Gaoping River and correlated strongly with Cu and Fe, respectively. Component C3 showed a greater enrichment relative to C1 in the colloidal (C3/C1 > 0.8) than in the soluble phase (C3/C1 = 0.4). The protein-like component, C2, came from both terrestrial and marine sources and displayed a more complex mixing behaviour than the other two. One striking result was that the effective zero-salinity concentrations of Fe (∼300 nM) and Cu (∼23 nM) did not change significantly in response to a 10-fold increase in river discharge between Sep 2020 and Aug 2021. Similarly to Fe and Cu, the distribution patterns of Components C1 and C3 did not change significantly between the moderate and the strong plume, and C3 and C1 correlated strongly with Fe and Cu, respectively. We conclude that subtropical mountainous rivers can provide soil-derived humic substances which facilitate and regulate the delivery of Fe and Cu to the ocean, provided mountain forests are preserved.
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Affiliation(s)
- François L L Muller
- Department of Oceanography, National Sun Yat-sen University, 70 Lienhai Road, Kaohsiung 80424, Taiwan.
| | | | - Chuan-Ho Tang
- National Museum of Marine Biology and Aquarium, 2 Houwan Road, Checheng, Pingtung 94450, Taiwan
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Iriarte-Mesa C, Pretzler M, von Baeckmann C, Kählig H, Krachler R, Rompel A, Kleitz F. Immobilization of Agaricus bisporus Polyphenol Oxidase 4 on mesoporous silica: Towards mimicking key enzymatic processes in peat soils. J Colloid Interface Sci 2023; 646:413-425. [PMID: 37207423 DOI: 10.1016/j.jcis.2023.04.158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/24/2023] [Accepted: 04/28/2023] [Indexed: 05/21/2023]
Abstract
HYPOTHESIS The use of immobilized enzyme-type biocatalysts to mimic specific processes in soil can be considered one of the most promising alternatives to overcome the difficulties behind the structural elucidation of riverine humic-derived iron-complexes. Herein, we propose that the immobilization of the functional mushroom tyrosinase, Agaricus bisporus Polyphenol Oxidase 4 (AbPPO4) on mesoporous SBA-15-type silica could contribute to the study of small aquatic humic ligands such as phenols. EXPERIMENTS The silica support was functionalized with amino-groups in order to investigate the impact of surface charge on the tyrosinase loading efficiency as well as on the catalytic performance of adsorbed AbPPO4. The oxidation of various phenols was catalyzed by the AbPPO4-loaded bioconjugates, yielding high levels of conversion and confirming the retention of enzyme activity after immobilization. The structures of the oxidized products were elucidated by integrating chromatographic and spectroscopic techniques. We also evaluated the stability of the immobilized enzyme over a wide range of pH values, temperatures, storage-times and sequential catalytic cycles. FINDINGS This is the first report where the latent AbPPO4 is confined within silica mesopores. The improved catalytic performance of the adsorbed AbPPO4 shows the potential use of these silica-based mesoporous biocatalysts for the preparation of a column-type bioreactor for in situ identification of soil samples.
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Affiliation(s)
- Claudia Iriarte-Mesa
- Department of Inorganic Chemistry - Functional Materials, Faculty of Chemistry, University of Vienna, Währinger Str. 42, 1090 Vienna, Austria; Vienna Doctoral School in Chemistry (DoSChem), University of Vienna, Währinger Str. 42, 1090 Vienna, Austria
| | - Matthias Pretzler
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Josef-Holaubek-Platz 2, 1090 Vienna, Austria; www.bpc.univie.ac.at
| | - Cornelia von Baeckmann
- Department of Inorganic Chemistry - Functional Materials, Faculty of Chemistry, University of Vienna, Währinger Str. 42, 1090 Vienna, Austria; Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Hanspeter Kählig
- Department of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria
| | - Regina Krachler
- Department of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 42, 1090 Vienna, Austria
| | - Annette Rompel
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Josef-Holaubek-Platz 2, 1090 Vienna, Austria; www.bpc.univie.ac.at.
| | - Freddy Kleitz
- Department of Inorganic Chemistry - Functional Materials, Faculty of Chemistry, University of Vienna, Währinger Str. 42, 1090 Vienna, Austria.
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Zhang J, Mostofa KMG, Yang X, Mohinuzzaman M, Liu CQ, Senesi N, Senesi GS, Sparks DL, Teng HH, Li L, Yuan J, Li SL. Isolation of dissolved organic matter from aqueous solution by precipitation with FeCl 3: mechanisms and significance in environmental perspectives. Sci Rep 2023; 13:4531. [PMID: 36941375 PMCID: PMC10027667 DOI: 10.1038/s41598-023-31831-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 03/17/2023] [Indexed: 03/23/2023] Open
Abstract
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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Affiliation(s)
- Jie Zhang
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
- Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Khan M G Mostofa
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
- Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
| | - Xuemei Yang
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
- Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Mohammad Mohinuzzaman
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
- Department of Environmental Science and Disaster Management, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Cong-Qiang Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
- Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Nicola Senesi
- Dip.to di Scienze del Suolo, della Pianta e degli Alimenti, Università Degli Studi Di Bari "Aldo Moro", Via G. Amendola 165/A, 70126, Bari, Italy
| | - Giorgio S Senesi
- CNR - Istituto per la Scienza e Tecnologia dei Plasmi (ISTP) - Sede Di Bari Via Amendola, 122/D, 70126, Bari, Italy
| | - Donald L Sparks
- Department of Plant and Soil Sciences, Delaware Environmental Institute, University of Delaware, Newark, DE, 19716-7310, USA
| | - H Henry Teng
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
- Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Longlong Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China
| | - Jie Yuan
- College of Resources and Environment, Xingtai University, Quanbei East Road 88, Qiaodong District, Xingtai City, Hebei Province, China
| | - Si-Liang Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
- Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, 92 Weijin Road, Tianjin, 300072, China.
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin, 300192, China.
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Luo J, Huang Z, Li S, Zheng F, Liu F, Huang Q, Huang X, Xie H. Photodegradation Kinetics and Deep Learning-Based Intelligent Colorimetric Method for Bioavailability-Based Dissolved Iron Speciation. Anal Chem 2022; 94:14801-14809. [PMID: 36239120 DOI: 10.1021/acs.analchem.2c04014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Via the photodegradation of dissolved iron (dFe) complexes in the euphotic zone, released free Fe(III) is the most important source of bioavailable iron for eukaryotic phytoplankton. There is an urgent need to establish bioavailability-based dissolved iron speciation (BDIS) methods. Herein, an intelligent system with dFe pretreatment and a colorimetric sensor is developed for real-time monitoring of newly generated Fe(III) ions. According to the photodegradation kinetics of dFe, including kinetic constant and photogenerated time of free Fe(III) ions, 3 sources, 6 kinds, and 12 species of dFe are determined by our photocatalytic-assisted colorimetric sensor and deep learning model within 20.0 min. The algal dFe-uptake for 4 days can be predicted by BDIS with correlation coefficient 0.85, which could be explained by the hard and soft acids and bases theory (HSAB) and density functional theory (DFT). These results successfully demonstrate the proof-of-concept for photodegradation kinetics-based speciation and bioavailability assessments of dissolved metals.
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Affiliation(s)
- Jiayi Luo
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Zhaojing Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Shunxing Li
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Fengying Zheng
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Fengjiao Liu
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Qianyan Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Xuguang Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Haijiao Xie
- Hangzhou Yanqu Information Technology Company of Limited Liability, Hangzhou 310003, China
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9
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Heerah KM, Reader HE. Towards the identification of humic ligands associated with iron transport through a salinity gradient. Sci Rep 2022; 12:15545. [PMID: 36109552 PMCID: PMC9477803 DOI: 10.1038/s41598-022-19618-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Humic ligands from boreal rivers have been identified as important sources of iron-binding ligands to the coastal marine environment but remain poorly characterized. A novel method using Fourier transformed infrared spectroscopy (FTIR) was used to identify and quantify iron-binding ligands present in a boreal river in Newfoundland, Canada. 20 to 35% of the total iron load was carried through an artificial salinity gradient, and remained in solution at 35 salinity. Using FTIR combined with linear regression and 2D correlation analysis, we identified two pools of organic ligands, with different behaviour with regards to iron across the salinity gradient. The weaker ligand pool consisted of alkenes, ethers, and esters, and was found to release iron to flocculation at low salinities, and not contribute to iron transport into the marine environment. The stronger ligand group contained carboxylic acids and aliphatic functional groups. This group appears to contain two subgroups, one which was able to retain iron in the dissolved phase at 35 salinity, and another that flocculated out with iron across the salinity gradient. The strong ligands that retain iron in solution through the salinity gradient provide a much-needed source of the micronutrient to the coastal and marine environment, while the other subgroup sequesters iron and carbon in estuarine sediments. The balance between these two subgroups appears to be controlled by the hydrographic and weather conditions at the time of sampling, suggesting a dynamic ligand-iron relationship throughout the year, impacting the biogeochemical cycles of both iron and carbon in contrasting ways.
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10
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Krachler R, Krachler RF. Northern High-Latitude Organic Soils As a Vital Source of River-Borne Dissolved Iron to the Ocean. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9672-9690. [PMID: 34251212 DOI: 10.1021/acs.est.1c01439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Organic soils in the Arctic-boreal region produce small aquatic humic ligands (SAHLs), a category of naturally occurring complexing agents for iron. Every year, large amounts of SAHLs-loaded with iron mobilized in river basins-reach the oceans via river runoff. Recent studies have shown that a fraction of SAHLs belong to the group of strong iron-binding ligands in the ocean. That means, their Fe(III) complexes withstand dissociation even under the conditions of extremely high dilution in the open ocean. Fe(III)-loaded SAHLs are prone to UV-photoinduced ligand-to-metal charge-transfer which leads to disintegration of the complex and, as a consequence, to enhanced concentrations of bioavailable dissolved Fe(II) in sunlit upper water layers. On the other hand, in water depths below the penetration depth of UV, the Fe(III)-loaded SAHLs are fairly resistant to degradation which makes them ideally suited as long-lived molecular transport vehicles for river-derived iron in ocean currents. At locations where SAHLs are present in excess, they can bind to iron originating from various sources. For example, SAHLs were proposed to contribute substantially to the stabilization of hydrothermal iron in deep North Atlantic waters. Recent discoveries have shown that SAHLs, supplied by the Arctic Great Rivers, greatly improve dissolved iron concentrations in the Arctic Ocean and the North Atlantic Ocean. In these regions, SAHLs play a critical role in relieving iron limitation of phytoplankton, thereby supporting the oceanic sink for anthropogenic CO2. The present Critical Review describes the most recent findings and highlights future research directions.
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Affiliation(s)
- Regina Krachler
- Institute of Inorganic Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria; http://anorg-chemie.univie.ac.at
| | - Rudolf F Krachler
- Institute of Inorganic Chemistry, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria; http://anorg-chemie.univie.ac.at
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Grunert BK, Tzortziou M, Neale P, Menendez A, Hernes P. DOM degradation by light and microbes along the Yukon River-coastal ocean continuum. Sci Rep 2021; 11:10236. [PMID: 33986333 PMCID: PMC8119953 DOI: 10.1038/s41598-021-89327-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/20/2021] [Indexed: 11/30/2022] Open
Abstract
The Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.
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Affiliation(s)
- Brice K Grunert
- Department of Earth and Atmospheric Sciences, The City College of New York, The City University of New York, 160 Convent Avenue, New York, NY, 10031, USA.
| | - Maria Tzortziou
- Department of Earth and Atmospheric Sciences, The City College of New York, The City University of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Patrick Neale
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD, 21037, USA
| | - Alana Menendez
- Department of Earth and Atmospheric Sciences, The City College of New York, The City University of New York, 160 Convent Avenue, New York, NY, 10031, USA
| | - Peter Hernes
- Department of Land, Air and Water Resources, University of California, Davis, CA, 95616, USA
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