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Wu Y, Su H, Cheng L, Qin S, Zou K, Liu Y, Zhou J, Liu P, Zhang L. Exploring hydrological controls on dissolved organic carbon export dynamics in a typical flash flood catchment using a process-based model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:171139. [PMID: 38402981 DOI: 10.1016/j.scitotenv.2024.171139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/17/2024] [Accepted: 02/19/2024] [Indexed: 02/27/2024]
Abstract
The dynamics of dissolved organic carbon (DOC) export from headwater catchments are of critical importance for the global carbon balance and are driven by complex runoff processes. Most previous studies have used statistical relationships between runoff and DOC concentration to estimate DOC export dynamics. Thus, the coupling mechanisms between runoff generation and DOC export dynamics at the process level were obscured in the fitting parameters and have rarely been addressed. In this study, high-frequency (hourly) discharge and DOC export from a typical flash flood experimental headwater catchment with an area of 1.8 km2 were simulated using a process-based model (INCA-C). The results showed that the INCA-C model successfully captured the hourly dynamics of both discharge and DOC concentrations with a Nash-Sutcliffe efficiency (NSE) of 0.47-0.81 and 0.28-0.70 among moderate events and 0.81-0.85 and 0.19-0.90 among extreme events, respectively. The DOC was exported with distinct concentration dynamics, fluxes, and contributions from the four flow pathways under different storm intensities. At higher intensities, the DOC fluxes were exported by subsurface flows, particularly from shallow organic soil, with greater peaks and shorter time-to-peaks. Exported DOC is primarily sourced from subsurface runoff from the mineral layer (73 %-77 %) during moderate events, whereas it is primarily sourced from subsurface runoff from the organic layer (61 %-79 %) during extreme events. The two contrasting contributions suggest that hydrological pathway controls and DOC dynamic patterns can shift owing to runoff generation influenced by storm intensity. The distinct and variable controls of different flow pathways on DOC export highlight the need to explain the role of hydrology in regulating DOC storm exports through process-based modelling.
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Affiliation(s)
- Yue Wu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Hang Su
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Lei Cheng
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China.
| | - Shujing Qin
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Kaijie Zou
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Yanghe Liu
- China Yangtze Power Co., Ltd., Yichang 443133, China; Hubei Key Laboratory of Intelligent Yangtze and Hydroelectric Science, Yichang 443133, China
| | - Jingzhe Zhou
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Pan Liu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
| | - Lu Zhang
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Hubei Provincial Collaborative Innovation Centre for Water Resources Security, Wuhan 430072, China
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2
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Freeman EC, Emilson EJS, Dittmar T, Braga LPP, Emilson CE, Goldhammer T, Martineau C, Singer G, Tanentzap AJ. Universal microbial reworking of dissolved organic matter along environmental gradients. Nat Commun 2024; 15:187. [PMID: 38168076 PMCID: PMC10762207 DOI: 10.1038/s41467-023-44431-4] [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: 11/25/2022] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
Soils are losing increasing amounts of carbon annually to freshwaters as dissolved organic matter (DOM), which, if degraded, can offset their carbon sink capacity. However, the processes underlying DOM degradation across environments are poorly understood. Here we show DOM changes similarly along soil-aquatic gradients irrespective of environmental differences. Using ultrahigh-resolution mass spectrometry, we track DOM along soil depths and hillslope positions in forest catchments and relate its composition to soil microbiomes and physico-chemical conditions. Along depths and hillslopes, we find carbohydrate-like and unsaturated hydrocarbon-like compounds increase in abundance-weighted mass, and the expression of genes essential for degrading plant-derived carbohydrates explains >50% of the variation in abundance of these compounds. These results suggest that microbes transform plant-derived compounds, leaving DOM to become increasingly dominated by the same (i.e., universal), difficult-to-degrade compounds as degradation proceeds. By synthesising data from the land-to-ocean continuum, we suggest these processes generalise across ecosystems and spatiotemporal scales. Such general degradation patterns can help predict DOM composition and reactivity along environmental gradients to inform management of soil-to-stream carbon losses.
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Affiliation(s)
- Erika C Freeman
- Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK.
| | - Erik J S Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. E., Sault Ste, Marie, ON, P6A 2E5, Canada
- Ecosystems and Global Change Group, School of the Environment, Trent University, Peterborough, ON, K9L 0G2, Canada
| | - Thorsten Dittmar
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, 26129, Oldenburg, Germany
- Helmholtz Institute for Functional Marine Biodiversity, University of Oldenburg, 26129, Oldenburg, Germany
| | - Lucas P P Braga
- Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Caroline E Emilson
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. E., Sault Ste, Marie, ON, P6A 2E5, Canada
| | - Tobias Goldhammer
- Department of Ecohydrology and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Mueggelseedamm, 301, Berlin, Germany
| | - Christine Martineau
- Natural Resources Canada, Laurentian Forestry Centre, 1055 Du P.E.P.S. Street, P.O. Box 10380, Québec, G1V 4C7, Canada
| | - Gabriel Singer
- Department of Ecology, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria
| | - Andrew J Tanentzap
- Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
- Ecosystems and Global Change Group, School of the Environment, Trent University, Peterborough, ON, K9L 0G2, Canada
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3
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Nissan A, Alcolombri U, Peleg N, Galili N, Jimenez-Martinez J, Molnar P, Holzner M. Global warming accelerates soil heterotrophic respiration. Nat Commun 2023; 14:3452. [PMID: 37301858 PMCID: PMC10257684 DOI: 10.1038/s41467-023-38981-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 05/22/2023] [Indexed: 06/12/2023] Open
Abstract
Carbon efflux from soils is the largest terrestrial carbon source to the atmosphere, yet it is still one of the most uncertain fluxes in the Earth's carbon budget. A dominant component of this flux is heterotrophic respiration, influenced by several environmental factors, most notably soil temperature and moisture. Here, we develop a mechanistic model from micro to global scale to explore how changes in soil water content and temperature affect soil heterotrophic respiration. Simulations, laboratory measurements, and field observations validate the new approach. Estimates from the model show that heterotrophic respiration has been increasing since the 1980s at a rate of about 2% per decade globally. Using future projections of surface temperature and soil moisture, the model predicts a global increase of about 40% in heterotrophic respiration by the end of the century under the worst-case emission scenario, where the Arctic region is expected to experience a more than two-fold increase, driven primarily by declining soil moisture rather than temperature increase.
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Affiliation(s)
- Alon Nissan
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zürich, 8093, Switzerland.
| | - Uria Alcolombri
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zürich, 8093, Switzerland
| | - Nadav Peleg
- Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, 1015, Switzerland
| | - Nir Galili
- Geological Institute, Department of Earth Sciences, ETH Zürich, Zürich, 8092, Switzerland
| | - Joaquin Jimenez-Martinez
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zürich, 8093, Switzerland
- Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology, EAWAG, Dübendorf, 8600, Switzerland
| | - Peter Molnar
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zürich, 8093, Switzerland
| | - Markus Holzner
- Department of Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology, EAWAG, Dübendorf, 8600, Switzerland
- Biodiversity and Conservation Biology, Swiss Federal Institute for Forest Snow and Landscape Research, WSL, Birmensdorf, 8903, Switzerland
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4
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Dewey C, Kaplan DI, Fendorf S, Boiteau RM. Quantitative Separation of Unknown Organic-Metal Complexes by Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry. Anal Chem 2023; 95:7960-7967. [PMID: 37163723 DOI: 10.1021/acs.analchem.3c00696] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Dissolved organic matter (DOM) is widely recognized to control the solubility and reactivity of trace metals in the environment. However, the mechanisms that govern metal-DOM complexation remain elusive, primarily due to the analytical challenge of fractionating and quantifying metal-organic species within the complex mixture of organic compounds that comprise DOM. Here, we describe a quantitative method for fractionation and element-specific detection of organic-metal complexes using liquid chromatography with online inductively coupled plasma mass spectrometry (LC-ICP-MS). The method implements a post-column compensation gradient to stabilize ICP-MS elemental response across the LC solvent gradient, thereby overcoming a major barrier to achieving quantitative accuracy with LC-ICP-MS. With external calibration and internal standard correction, the method yields concentrations of organic-metal complexes that were consistently within 6% of their true values, regardless of the complex's elution time. We used the method to evaluate the effects of four stationary phases (C18, phenyl, amide, and pentafluoroylphenyl propyl) on the recovery and separation of environmentally relevant trace metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in Suwannee River Fulvic Acid and Suwannee River Natural Organic Matter. The C18, amide, and phenyl phases generally yielded optimal metal recoveries (>75% for all metals except Pb), with the phenyl phase separating polar species to a greater extent than C18 or amide. We also fractionated organic-bound Fe, Cu, and Ni in oxidized and reduced soils, revealing divergent metal-DOM speciation across soil redox environments. By enabling quantitative fractionation of DOM-bound metals, our method offers a means for advancing a mechanistic understanding of metal-organic complexation throughout the environment.
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Affiliation(s)
- Christian Dewey
- College of Earth, Ocean, & Atmospheric Sciences, Oregon State University, Corvallis, Oregon, 97331, United States
- Department of Earth System Science, Stanford University, Stanford, California, 94305, United States
| | - Daniel I Kaplan
- Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, 29802, United States
| | - Scott Fendorf
- Department of Earth System Science, Stanford University, Stanford, California, 94305, United States
| | - Rene M Boiteau
- College of Earth, Ocean, & Atmospheric Sciences, Oregon State University, Corvallis, Oregon, 97331, United States
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5
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Borges AV, Deirmendjian L, Bouillon S, Okello W, Lambert T, Roland FAE, Razanamahandry VF, Voarintsoa NRG, Darchambeau F, Kimirei IA, Descy JP, Allen GH, Morana C. Greenhouse gas emissions from African lakes are no longer a blind spot. SCIENCE ADVANCES 2022; 8:eabi8716. [PMID: 35749499 PMCID: PMC9232103 DOI: 10.1126/sciadv.abi8716] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Natural lakes are thought to be globally important sources of greenhouse gases (CO2, CH4, and N2O) to the atmosphere although nearly no data have been previously reported from Africa. We collected CO2, CH4, and N2O data in 24 African lakes that accounted for 49% of total lacustrine surface area of the African continent and covered a wide range of morphology and productivity. The surface water concentrations of dissolved CO2 were much lower than values attributed in current literature to tropical lakes and lower than in boreal systems because of a higher productivity. In contrast, surface water-dissolved CH4 concentrations were generally higher than in boreal systems. The lowest CO2 and the highest CH4 concentrations were observed in the more shallow and productive lakes. Emissions of CO2 may likely have been substantially overestimated by a factor between 9 and 18 in African lakes and between 6 and 26 in pan-tropical lakes.
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Affiliation(s)
| | | | - Steven Bouillon
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
| | - William Okello
- Department of Limnology, National Fisheries Resource Research Institute, Jinja, Uganda
| | | | | | | | | | | | | | | | - George H. Allen
- Department of Geography, Texas A&M University, College Station, TX, USA
| | - Cédric Morana
- Chemical Oceanography Unit, University of Liège, Liège, Belgium
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
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6
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de Raad M, Li YV, Kuehl JV, Andeer PF, Kosina SM, Hendrickson A, Saichek NR, Golini AN, Han LZ, Wang Y, Bowen BP, Deutschbauer AM, Arkin AP, Chakraborty R, Northen TR. A Defined Medium for Cultivation and Exometabolite Profiling of Soil Bacteria. Front Microbiol 2022; 13:855331. [PMID: 35694313 PMCID: PMC9174792 DOI: 10.3389/fmicb.2022.855331] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
Exometabolomics is an approach to assess how microorganisms alter, or react to their environments through the depletion and production of metabolites. It allows the examination of how soil microbes transform the small molecule metabolites within their environment, which can be used to study resource competition and cross-feeding. This approach is most powerful when used with defined media that enable tracking of all metabolites. However, microbial growth media have traditionally been developed for the isolation and growth of microorganisms but not metabolite utilization profiling through Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). Here, we describe the construction of a defined medium, the Northen Lab Defined Medium (NLDM), that not only supports the growth of diverse soil bacteria but also is defined and therefore suited for exometabolomic experiments. Metabolites included in NLDM were selected based on their presence in R2A medium and soil, elemental stoichiometry requirements, as well as knowledge of metabolite usage by different bacteria. We found that NLDM supported the growth of 108 of the 110 phylogenetically diverse (spanning 36 different families) soil bacterial isolates tested and all of its metabolites were trackable through LC–MS/MS analysis. These results demonstrate the viability and utility of the constructed NLDM medium for growing and characterizing diverse microbial isolates and communities.
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Affiliation(s)
- Markus de Raad
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Yifan V. Li
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Jennifer V. Kuehl
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Peter F. Andeer
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Suzanne M. Kosina
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Andrew Hendrickson
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Nicholas R. Saichek
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Amber N. Golini
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - La Zhen Han
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Ying Wang
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Benjamin P. Bowen
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Adam M. Deutschbauer
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
| | - Adam P. Arkin
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, United States
| | - Romy Chakraborty
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Trent R. Northen
- Lawrence Berkeley National Laboratory, Environmental Genomics and Systems Biology Division, Berkeley, CA, United States
- Lawrence Berkeley National Laboratory, Joint Genome Institute, Berkeley, CA, United States
- *Correspondence: Trent R. Northen,
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7
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Tipping E, Elias JL, Keenan PO, Helliwell RC, Pedentchouk N, Cooper RJ, Buckingham S, Gjessing E, Ascough P, Bryant CL, Garnett MH. Relationships between riverine and terrestrial dissolved organic carbon: Concentration, radiocarbon signature, specific UV absorbance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 817:153000. [PMID: 35031358 DOI: 10.1016/j.scitotenv.2022.153000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
The transfer of dissolved organic carbon (DOC) from land to watercourses plays a major role in the carbon cycle, and in the transport and fate of associated organic and inorganic contaminants. We investigated, at global scale, how the concentrations and properties of riverine DOC depend upon combinations of terrestrial source solutions. For topsoil, subsoil, groundwater and river solutions in different Köppen-Geiger climatic zones, we compiled published and new values of DOC concentration ([DOC]), radiocarbon signature (DO14C), and specific UV absorbance (SUVA). The average value of each DOC variable decreased significantly in magnitude from topsoil to subsoil to groundwater, permitting the terrestrial sources to be distinguished. We used the terrestrial data to simulate the riverine distributions of each variable, and also relationships between pairs of variables. To achieve good matches between observed and simulated data, it was necessary to optimise the distributions of water fractions contributed by each of the three terrestrial sources, and also to reduce the mean input terrestrial [DOC] values, to about 60% of the measured ones. One possible explanation for the required lowering of the modelled terrestrial [DOC] values might be unrepresentative sampling of terrestrial DOC, including dilution effects; another is the loss of DOC during riverine transport. High variations in simulated riverine DOC variables, which match observed data, are due predominantly to variations in source solution values, with a lesser contribution from the different combinations of source waters. On average, most DOC in rivers draining catchments with forest and/or grass-shrub land cover comes in similar amounts from topsoil and subsoil, with about 10% from groundwater. In rivers draining croplands, subsoil and groundwater solutions are the likely dominant DOC sources, while in wetland rivers most DOC is from topsoil.
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Affiliation(s)
- Edward Tipping
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK.
| | - Jessica L Elias
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK
| | - Patrick O Keenan
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK
| | - Rachel C Helliwell
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK
| | - Nikolai Pedentchouk
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK; Skolkovo Institute of Science and Technology, 30 Bld. 1 Bolshoy Boulevard, Moscow 121205, Russian Federation
| | - Richard J Cooper
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Sarah Buckingham
- Carbon Crop and Soils Group, Scotland's Rural College, Edinburgh EH9 3JG, UK
| | - Egil Gjessing
- Faculty of Mathematics and Natural Sciences, University of Oslo, NO-0316 Oslo, Norway
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8
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Kaal J, Pérez-Rodríguez M, Biester H. Molecular Probing of DOM Indicates a Key Role of Spruce-Derived Lignin in the DOM and Metal Cycles of a Headwater Catchment: Can Spruce Forest Dieback Exacerbate Future Trends in the Browning of Central European Surface Waters? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:2747-2759. [PMID: 35104105 DOI: 10.1021/acs.est.1c04719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Peatlands of the Northern Hemisphere and Central European coniferous forests experience significant environmental change. The resultant browning of surface waters, that is, elevated concentrations of dissolved organic matter (DOM) and metals, is of interest in the context of the global C cycle, peatland and forest management, and water treatment. In an attempt to identify the causes of this process in the Harz Mountains (Central Germany), we studied the spatiotemporal variations in DOM molecular composition (thermally assisted hydrolysis and methylation combined with GC-MS) and metal concentrations in headwater stream samples. We found strong relationships between DOM and metals and seasonal variations in the DOM quality and tentatively DOM-metal binding mode: during summer base flow, DOM and metal concentrations are low, and all elements other than the alkali and alkaline earth metals (Ca, Mg, Sr, K, and Na) are positively correlated to DOM, whereas during spring and autumn (high discharge), only metals with strong affinity for DOM (Fe, As, Cu, Cr, Pb, and Ti), but not weakly binding ones (Al, Cd, La, Mn, Ni, Zn, and Zr), are correlated to DOM, indicative of selectivity in DOM-metal interactions. The products of polyphenols are the key ingredients of the DOM-metal complexes. We argue the importance of spruce lignin-derived vanillic acid moieties, which are involved in weak (all seasons) and strong, multidentate and/or colloidal, binding (spring and autumn) of metals. Considering the ongoing spruce forest dieback and climate change acceleration, it is tempting to conclude that spruce necromass and forest soils may release vast amounts of lignin-derived DOM and associated metals to headwater streams. This would have significant implications for forest soil C stocks and the management of connected drinking water reservoirs.
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Affiliation(s)
- Joeri Kaal
- Institut für Geoökologie, Abteilung Umweltgeochemie, Technische Universität Braunschweig, Langer Kamp 19C, Braunschweig 38106, Germany
| | - Marta Pérez-Rodríguez
- Institut für Geoökologie, Abteilung Umweltgeochemie, Technische Universität Braunschweig, Langer Kamp 19C, Braunschweig 38106, Germany
| | - Harald Biester
- Institut für Geoökologie, Abteilung Umweltgeochemie, Technische Universität Braunschweig, Langer Kamp 19C, Braunschweig 38106, Germany
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