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Button ES, Marsden KA, Nightingale PD, Dixon ER, Chadwick DR, Jones DL, Cárdenas LM. Separating N 2O production and consumption in intact agricultural soil cores at different moisture contents and depths. Eur J Soil Sci 2023; 74:e13363. [PMID: 38529015 PMCID: PMC10962597 DOI: 10.1111/ejss.13363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 03/29/2023] [Accepted: 04/01/2023] [Indexed: 03/27/2024]
Abstract
Agricultural soils are a major source of the potent greenhouse gas and ozone depleting substance, N2O. To implement management practices that minimize microbial N2O production and maximize its consumption (i.e., complete denitrification), we must understand the interplay between simultaneously occurring biological and physical processes, especially how this changes with soil depth. Meaningfully disentangling of these processes is challenging and typical N2O flux measurement techniques provide little insight into subsurface mechanisms. In addition, denitrification studies are often conducted on sieved soil in altered O2 environments which relate poorly to in situ field conditions. Here, we developed a novel incubation system with headspaces both above and below the soil cores and field-relevant O2 concentrations to better represent in situ conditions. We incubated intact sandy clay loam textured agricultural topsoil (0-10 cm) and subsoil (50-60 cm) cores for 3-4 days at 50% and 70% water-filled pore space, respectively. 15N-N2O pool dilution and an SF6 tracer were injected below the cores to determine the relative diffusivity and the net N2O emission and gross N2O emission and consumption fluxes. The relationship between calculated fluxes from the below and above soil core headspaces confirmed that the system performed well. Relative diffusivity did not vary with depth, likely due to the preservation of preferential flow pathways in the intact cores. Gross N2O emission and uptake also did not differ with depth but were higher in the drier cores, contrary to expectation. We speculate this was due to aerobic denitrification being the primary N2O consuming process and simultaneously occurring denitrification and nitrification both producing N2O in the drier cores. We provide further evidence of substantial N2O consumption in drier soil but without net negative N2O emissions. The results from this study are important for the future application of the 15N-N2O pool dilution method and N budgeting and modelling, as required for improving management to minimize N2O losses.
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Affiliation(s)
- Erik S. Button
- School of Natural SciencesBangor UniversityBangorGwyneddUK
| | | | - Philip D. Nightingale
- Plymouth Marine Laboratory, Prospect Pl, Marine Biogeochemical ObservationsPlymouthDevonUK
| | - Elizabeth R. Dixon
- Rothamsted Research North Wyke, Net Zero and Resilient FarmingOkehamptonDevonUK
| | | | - David L. Jones
- School of Natural SciencesBangor UniversityBangorGwyneddUK
- Centre for Sustainable Farming Systems, Food Futures InstituteMurdochWestern AustraliaAustralia
| | - Laura M. Cárdenas
- Rothamsted Research North Wyke, Net Zero and Resilient FarmingOkehamptonDevonUK
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Kitidis V, Shutler JD, Ashton I, Warren M, Brown I, Findlay H, Hartman SE, Sanders R, Humphreys M, Kivimäe C, Greenwood N, Hull T, Pearce D, McGrath T, Stewart BM, Walsham P, McGovern E, Bozec Y, Gac JP, van Heuven SMAC, Hoppema M, Schuster U, Johannessen T, Omar A, Lauvset SK, Skjelvan I, Olsen A, Steinhoff T, Körtzinger A, Becker M, Lefevre N, Diverrès D, Gkritzalis T, Cattrijsse A, Petersen W, Voynova YG, Chapron B, Grouazel A, Land PE, Sharples J, Nightingale PD. Winter weather controls net influx of atmospheric CO 2 on the north-west European shelf. Sci Rep 2019; 9:20153. [PMID: 31882779 PMCID: PMC6934492 DOI: 10.1038/s41598-019-56363-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 12/06/2019] [Indexed: 11/08/2022] Open
Abstract
Shelf seas play an important role in the global carbon cycle, absorbing atmospheric carbon dioxide (CO2) and exporting carbon (C) to the open ocean and sediments. The magnitude of these processes is poorly constrained, because observations are typically interpolated over multiple years. Here, we used 298500 observations of CO2 fugacity (fCO2) from a single year (2015), to estimate the net influx of atmospheric CO2 as 26.2 ± 4.7 Tg C yr-1 over the open NW European shelf. CO2 influx from the atmosphere was dominated by influx during winter as a consequence of high winds, despite a smaller, thermally-driven, air-sea fCO2 gradient compared to the larger, biologically-driven summer gradient. In order to understand this climate regulation service, we constructed a carbon-budget supplemented by data from the literature, where the NW European shelf is treated as a box with carbon entering and leaving the box. This budget showed that net C-burial was a small sink of 1.3 ± 3.1 Tg C yr-1, while CO2 efflux from estuaries to the atmosphere, removed the majority of river C-inputs. In contrast, the input from the Baltic Sea likely contributes to net export via the continental shelf pump and advection (34.4 ± 6.0 Tg C yr-1).
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Affiliation(s)
| | - Jamie D Shutler
- University of Exeter, College of Life and Environmental Sciences, Exeter, UK
| | - Ian Ashton
- University of Exeter, College of Life and Environmental Sciences, Exeter, UK
| | | | - Ian Brown
- Plymouth Marine Laboratory, Plymouth, UK
| | | | | | | | - Matthew Humphreys
- Ocean and Earth Science, University of Southampton, Southampton, UK
- School of Environmental Sciences, University of East Anglia, Norwich, UK
| | | | - Naomi Greenwood
- Centre for Environment Fisheries and Aquaculture Science (Cefas), Lowestoft, UK
| | - Tom Hull
- Centre for Environment Fisheries and Aquaculture Science (Cefas), Lowestoft, UK
| | - David Pearce
- Centre for Environment Fisheries and Aquaculture Science (Cefas), Lowestoft, UK
| | | | | | | | | | - Yann Bozec
- Station Biologique de Roscoff, UMR CNRS - UPMC 7144 - Equipe Chimie Marine, Roscoff, France
| | - Jean-Philippe Gac
- Station Biologique de Roscoff, UMR CNRS - UPMC 7144 - Equipe Chimie Marine, Roscoff, France
| | | | - Mario Hoppema
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Ute Schuster
- University of Exeter, College of Life and Environmental Sciences, Exeter, UK
| | - Truls Johannessen
- Geophysical Institute, University of Bergen and Bjerknes Center for Climate Research, Bergen, Norway
| | - Abdirahman Omar
- NORCE Norwegian Research Centre, Bjerknes Center for Climate Research, Bergen, Norway
| | - Siv K Lauvset
- NORCE Norwegian Research Centre, Bjerknes Center for Climate Research, Bergen, Norway
| | - Ingunn Skjelvan
- NORCE Norwegian Research Centre, Bjerknes Center for Climate Research, Bergen, Norway
| | - Are Olsen
- Geophysical Institute, University of Bergen and Bjerknes Center for Climate Research, Bergen, Norway
| | | | - Arne Körtzinger
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Meike Becker
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
- Geophysical Institute, University of Bergen and Bjerknes Center for Climate Research, Bergen, Norway
| | - Nathalie Lefevre
- Sorbonne Universités (UPMC, Univ Paris 06)-IRD-CNRS-MNHN, LOCEAN, Paris, France
| | - Denis Diverrès
- Institut de Recherche pour le Développement (IRD), centre de Bretagne, Plouzané, France
| | | | | | - Wilhelm Petersen
- Helmholtz Zentrum Geesthacht, Centre for Materials and Coastal Research, Geesthacht, Germany
| | - Yoana G Voynova
- Helmholtz Zentrum Geesthacht, Centre for Materials and Coastal Research, Geesthacht, Germany
| | - Bertrand Chapron
- Institut Francais Recherche Pour ĹExploitation de la Mer, Pointe du Diable, 29280, Plouzané, France
| | - Antoine Grouazel
- Institut Francais Recherche Pour ĹExploitation de la Mer, Pointe du Diable, 29280, Plouzané, France
| | | | - Jonathan Sharples
- University of Liverpool, School of Environmental Sciences, Liverpool, UK
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Abstract
Acetone is an important oxygenated volatile organic compound (OVOC) in the troposphere where it influences the oxidizing capacity of the atmosphere. However, the air-sea flux is not well quantified, in part due to a lack of knowledge regarding which processes control oceanic concentrations, and, specifically whether microbial oxidation to CO2 represents a significant loss process. We demonstrate that (14)C labeled acetone can be used to determine microbial oxidation to (14)CO2. Linear microbial rates of acetone oxidation to CO2 were observed for between 0.75-3.5 h at a seasonally eutrophic coastal station located in the western English Channel (L4). A kinetic experiment in summer at station L4 gave a V max of 4.1 pmol L(-1) h(-1), with a K m constant of 54 pM. We then used this technique to obtain microbial acetone loss rates ranging between 1.2 and 42 pmol L(-1) h(-1.)(monthly averages) over an annual cycle at L4, with maximum rates observed during winter months. The biological turnover time of acetone (in situ concentration divided by microbial oxidation rate) in surface waters varied from ~3 days in February 2011, when in situ concentrations were 3 ± 1 nM, to >240 days in June 2011, when concentrations were more than twofold higher at 7.5 ± 0.7 nM. These relatively low marine microbial acetone oxidation rates, when normalized to in situ concentrations, suggest that marine microbes preferentially utilize other OVOCs such as methanol and acetaldehyde.
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Abstract
In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air-sea methanol transfer along a ∼10,000-km north-south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air-sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface-an important term for improving air-sea gas exchange models.
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Affiliation(s)
- Mingxi Yang
- Plymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom
| | | | - Rachael Beale
- Plymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom
| | - Peter S. Liss
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
- Department of Oceanography, Texas A & M University, College Station, TX 77843
| | - Byron Blomquist
- Department of Oceanography, University of Hawaii, Honolulu, HI 96822; and
| | - Christopher Fairall
- Physical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO 80305
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Read KA, Carpenter LJ, Arnold SR, Beale R, Nightingale PD, Hopkins JR, Lewis AC, Lee JD, Mendes L, Pickering SJ. Multiannual observations of acetone, methanol, and acetaldehyde in remote tropical atlantic air: implications for atmospheric OVOC budgets and oxidative capacity. Environ Sci Technol 2012; 46:11028-39. [PMID: 22963451 DOI: 10.1021/es302082p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Oxygenated volatile organic compounds (OVOCs) in the atmosphere are precursors to peroxy acetyl nitrate (PAN), affect the tropospheric ozone budget, and in the remote marine environment represent a significant sink of the hydroxyl radical (OH). The sparse observational database for these compounds, particularly in the tropics, contributes to a high uncertainty in their emissions and atmospheric significance. Here, we show measurements of acetone, methanol, and acetaldehyde in the tropical remote marine boundary layer made between October 2006 and September 2011 at the Cape Verde Atmospheric Observatory (CVAO) (16.85° N, 24.87° W). Mean mixing ratios of acetone, methanol, and acetaldehyde were 546 ± 295 pptv, 742 ± 419 pptv, and 428 ± 190 pptv, respectively, averaged from approximately hourly values over this five-year period. The CAM-Chem global chemical transport model reproduced annual average acetone concentrations well (21% overestimation) but underestimated levels by a factor of 2 in autumn and overestimated concentrations in winter. Annual average concentrations of acetaldehyde were underestimated by a factor of 10, rising to a factor of 40 in summer, and methanol was underestimated on average by a factor of 2, peaking to over a factor of 4 in spring. The model predicted summer minima in acetaldehyde and acetone, which were not apparent in the observations. CAM-Chem was adapted to include a two-way sea-air flux parametrization based on seawater measurements made in the Atlantic Ocean, and the resultant fluxes suggest that the tropical Atlantic region is a net sink for acetone but a net source for methanol and acetaldehyde. Inclusion of the ocean fluxes resulted in good model simulations of monthly averaged methanol levels although still with a 3-fold underestimation in acetaldehyde. Wintertime acetone levels were better simulated, but the observed autumn levels were more severely underestimated than in the standard model. We suggest that the latter may be caused by underestimated terrestrial biogenic African primary and/or secondary OVOC sources by the model. The model underestimation of acetaldehyde concentrations all year round implies a consistent significant missing source, potentially from secondary chemistry of higher alkanes produced biogenically from plants or from the ocean. We estimate that low model bias in OVOC abundances in the remote tropical marine atmosphere may result in up to 8% underestimation of the global methane lifetime due to missing model OH reactivity. Underestimation of acetaldehyde concentrations is responsible for the bulk (∼70%) of this missing reactivity.
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Affiliation(s)
- K A Read
- National Centre for Atmospheric Science, University of York, York, YO10 5DD, U.K
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Abstract
Methanol is the predominant oxygenated volatile organic compound in the troposphere, where it can significantly influence the oxidising capacity of the atmosphere. However, we do not understand which processes control oceanic concentrations, and hence, whether the oceans are a source or a sink to the atmosphere. We report the first methanol loss rates in seawater by demonstrating that (14)C-labelled methanol can be used to determine microbial uptake into particulate biomass, and oxidation to (14)CO(2). We have found that methanol is used predominantly as a microbial energy source, but also demonstrated its use as a carbon source. We report biological methanol oxidation rates between 2.1 and 8.4 nmol l(-1) day(-1) in surface seawater of the northeast Atlantic. Kinetic experiments predict a V(max) of up to 29 nmol l(-1) day(-1), with a high affinity K(m) constant of 9.3 nM in more productive coastal waters. We report surface concentrations of methanol in the western English channel of 97±8 nM (n=4) between May and June 2010, and for the wider temperate North Atlantic waters of 70±13 nM (n=6). The biological turnover time of methanol has been estimated between 7 and 33 days, although kinetic experiments suggest a 7-day turnover in more productive shelf waters. Methanol uptake rates into microbial particles significantly correlated with bacterial and phytoplankton parameters, suggesting that it could be used as a carbon source by some bacteria and possibly some mixotrophic eukaryotes. Our results provide the first methanol loss rates from seawater, which will improve the understanding of the global methanol budget.
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Affiliation(s)
- Joanna L Dixon
- Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth, Devon, UK.
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Abstract
The principal volatile sulphur species found in seawater are dimethyl sulphide (DMS), carbonyl sulphide (COS) and carbon disulphide (CS
2
. Of these, DMS is the most abundant and widespread in its distribution. The predominant oceanic source of DMS is dimethylsulphonioproprionate (DMSP), a compatible solute synthesized by phytoplankton for osmoregulation and/or cryoprotection. Not all species have the same ability to form DMSP; for example, diatoms generally produce little, whereas prymnesiophytes and some dinoflagellates make significantly larger amounts. Much of the release of DMSP and DMS to the water occurs on death or through predation of the plankton. Our recent field data strongly suggest that oxidation of DMS to dimethyl sulphoxide (DMSO) is an important process in the water column, and it is clear that considerable internal cycling in the DMSP/DMS/DMSO system occurs in the euphotic zone. A fraction of the DMS crosses the sea surface and enters the atmosphere where it is oxidized by radicals such OH and NO
3
to form products such as methanesulphonate (MSA), DMSO and non-sea salt sulphate (NSSS) particles. These particles are the main source of cloud condensation nuclei (CCN) over oceanic areas remote from land.
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Affiliation(s)
- Peter S. Liss
- School of Environmental Sciences, University of East AngliaNorWich NR4 7TJUK
| | - Angela D. Hatton
- School of Environmental Sciences, University of East AngliaNorWich NR4 7TJUK
| | - Gill Malin
- School of Environmental Sciences, University of East AngliaNorWich NR4 7TJUK
| | | | - Suzanne M. Turner
- School of Environmental Sciences, University of East AngliaNorWich NR4 7TJUK
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