Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru
<p>The fate of the organic matter (OM) produced by marine life controls the major biogeochemical cycles of the Earth's system. The OM produced through photosynthesis is either preserved, exported towards sediments or degraded through remineralisation in the water column. The productive...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-08-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/5093/2018/bg-15-5093-2018.pdf |
| _version_ | 1818316018855968768 |
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| author | M. Bretagnon M. Bretagnon A. Paulmier V. Garçon B. Dewitte B. Dewitte B. Dewitte B. Dewitte S. Illig S. Illig N. Leblond L. Coppola F. Campos F. Campos F. Campos F. Velazco C. Panagiotopoulos A. Oschlies J. M. Hernandez-Ayon H. Maske O. Vergara I. Montes P. Martinez E. Carrasco J. Grelet O. Desprez-De-Gesincourt C. Maes C. Maes L. Scouarnec |
| author_facet | M. Bretagnon M. Bretagnon A. Paulmier V. Garçon B. Dewitte B. Dewitte B. Dewitte B. Dewitte S. Illig S. Illig N. Leblond L. Coppola F. Campos F. Campos F. Campos F. Velazco C. Panagiotopoulos A. Oschlies J. M. Hernandez-Ayon H. Maske O. Vergara I. Montes P. Martinez E. Carrasco J. Grelet O. Desprez-De-Gesincourt C. Maes C. Maes L. Scouarnec |
| author_sort | M. Bretagnon |
| collection | DOAJ |
| description | <p>The fate of the organic matter (OM) produced by marine life controls the
major biogeochemical cycles of the Earth's system. The OM produced through
photosynthesis is either preserved, exported towards sediments or degraded
through remineralisation in the water column. The productive eastern
boundary upwelling systems (EBUSs) associated with oxygen minimum zones
(OMZs) would be expected to foster OM preservation due to low O<sub>2</sub>
conditions. But their intense and diverse microbial activity should enhance
OM degradation. To investigate this contradiction, sediment traps were
deployed near the oxycline and in the OMZ core on an instrumented moored
line off Peru. Data provided high-temporal-resolution O<sub>2</sub> series
characterising two seasonal steady states at the upper trap: suboxic
([O<sub>2</sub>] < 25 µmol kg<sup>−1</sup>) and hypoxic–oxic (15 < [O<sub>2</sub>] < 160 µmol kg<sup>−1</sup>) in austral summer and
winter–spring, respectively. The OMZ vertical transfer efficiency of
particulate organic carbon (POC) between traps (<i>T</i><sub>eff</sub>) can be classified
into three main ranges (high, intermediate, low). These different <i>T</i><sub>eff</sub>
ranges suggest that both predominant preservation (high <i>T</i><sub>eff</sub> > 50 %) and remineralisation (intermediate <i>T</i><sub>eff</sub>
20  <  50 % or low <i>T</i><sub>eff</sub> < 6 %) configurations can occur. An efficient OMZ vertical transfer
(<i>T</i><sub>eff</sub> > 50 %) has been reported in summer and winter associated with extreme
limitation in O<sub>2</sub> concentrations or OM quantity for OM degradation.
However, higher levels of O<sub>2</sub> or OM, or less refractory OM, at the
oxycline, even in a co-limitation context, can decrease the OMZ transfer
efficiency to below 50 %. This is especially true in summer during
intraseasonal wind-driven oxygenation events. In late winter and early
spring, high oxygenation conditions together with high fluxes of sinking
particles trigger a shutdown of the OMZ transfer (<i>T</i><sub>eff</sub> < 6 %). Transfer efficiency of chemical elements composing the majority of
the flux (nitrogen, phosphorus, silica, calcium carbonate) follows the same
trend as for carbon, with the lowest transfer level being in late winter and
early spring. Regarding particulate isotopes, vertical transfer of
<i>δ</i><sup>15</sup>N suggests a complex pattern of <sup>15</sup>N
impoverishment or enrichment according to <i>T</i><sub>eff</sub> modulation. This
sensitivity of OM to O<sub>2</sub> fluctuations and particle concentration calls
for further investigation into OM and O<sub>2</sub>-driven remineralisation
processes. This should include consideration of the intermittent behaviour of
OMZ towards OM demonstrated in past studies and climate projections.</p> |
| first_indexed | 2024-12-13T09:14:46Z |
| format | Article |
| id | doaj.art-83eb8899b27d446292971bb12944ac63 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-13T09:14:46Z |
| publishDate | 2018-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-83eb8899b27d446292971bb12944ac632022-12-21T23:52:52ZengCopernicus PublicationsBiogeosciences1726-41701726-41892018-08-01155093511110.5194/bg-15-5093-2018Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off PeruM. Bretagnon0M. Bretagnon1A. Paulmier2V. Garçon3B. Dewitte4B. Dewitte5B. Dewitte6B. Dewitte7S. Illig8S. Illig9N. Leblond10L. Coppola11F. Campos12F. Campos13F. Campos14F. Velazco15C. Panagiotopoulos16A. Oschlies17J. M. Hernandez-Ayon18H. Maske19O. Vergara20I. Montes21P. Martinez22E. Carrasco23J. Grelet24O. Desprez-De-Gesincourt25C. Maes26C. Maes27L. Scouarnec28Laboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceACRI, Sophia Antipolis, FranceLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceCentro de Estudios Avanzado en Zonas Áridas (CEAZA), Coquimbo, ChileDepartamento de Biología, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, ChileMillennium Nucleus for Ecology and Sustainable Management of Oceanic Islands (ESMOI), Coquimbo, ChileLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceDepartment of Oceanography, MARE Institute, LMI ICEMASA, University of Cape Town, Cape Town, Rondebosch, South AfricaSorbonne Université, CNRS, Laboratoire d'Océanographie de Villefanche, LOV, Villefranche-sur-Mer, FranceSorbonne Université, CNRS, Laboratoire d'Océanographie de Villefanche, LOV, Villefranche-sur-Mer, FranceUNAC, Lima, PeruIGP, Lima, PeruCICESE, Ensenada, MexicoIMARPE, Callao, PeruAix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO), UM 110, Marseille, FranceGEOMAR/SFB754, Kiel, GermanyUABC, Ensenada, MexicoCICESE, Ensenada, MexicoLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceIGP, Lima, PeruEPOC, Bordeaux, FranceIMARPE, Callao, PeruUS IMAGO/IRD, Brest, FranceINSU/CNRS, DT, Brest, FranceLaboratorie d'Etude en Géophysique et Océanographie Spatiales (UPS/CNRS/IRD/CNES), Toulouse, FranceLOPS, Brest, FranceINSU/CNRS, DT, Brest, France<p>The fate of the organic matter (OM) produced by marine life controls the major biogeochemical cycles of the Earth's system. The OM produced through photosynthesis is either preserved, exported towards sediments or degraded through remineralisation in the water column. The productive eastern boundary upwelling systems (EBUSs) associated with oxygen minimum zones (OMZs) would be expected to foster OM preservation due to low O<sub>2</sub> conditions. But their intense and diverse microbial activity should enhance OM degradation. To investigate this contradiction, sediment traps were deployed near the oxycline and in the OMZ core on an instrumented moored line off Peru. Data provided high-temporal-resolution O<sub>2</sub> series characterising two seasonal steady states at the upper trap: suboxic ([O<sub>2</sub>] < 25 µmol kg<sup>−1</sup>) and hypoxic–oxic (15 < [O<sub>2</sub>] < 160 µmol kg<sup>−1</sup>) in austral summer and winter–spring, respectively. The OMZ vertical transfer efficiency of particulate organic carbon (POC) between traps (<i>T</i><sub>eff</sub>) can be classified into three main ranges (high, intermediate, low). These different <i>T</i><sub>eff</sub> ranges suggest that both predominant preservation (high <i>T</i><sub>eff</sub> > 50 %) and remineralisation (intermediate <i>T</i><sub>eff</sub> 20  <  50 % or low <i>T</i><sub>eff</sub> < 6 %) configurations can occur. An efficient OMZ vertical transfer (<i>T</i><sub>eff</sub> > 50 %) has been reported in summer and winter associated with extreme limitation in O<sub>2</sub> concentrations or OM quantity for OM degradation. However, higher levels of O<sub>2</sub> or OM, or less refractory OM, at the oxycline, even in a co-limitation context, can decrease the OMZ transfer efficiency to below 50 %. This is especially true in summer during intraseasonal wind-driven oxygenation events. In late winter and early spring, high oxygenation conditions together with high fluxes of sinking particles trigger a shutdown of the OMZ transfer (<i>T</i><sub>eff</sub> < 6 %). Transfer efficiency of chemical elements composing the majority of the flux (nitrogen, phosphorus, silica, calcium carbonate) follows the same trend as for carbon, with the lowest transfer level being in late winter and early spring. Regarding particulate isotopes, vertical transfer of <i>δ</i><sup>15</sup>N suggests a complex pattern of <sup>15</sup>N impoverishment or enrichment according to <i>T</i><sub>eff</sub> modulation. This sensitivity of OM to O<sub>2</sub> fluctuations and particle concentration calls for further investigation into OM and O<sub>2</sub>-driven remineralisation processes. This should include consideration of the intermittent behaviour of OMZ towards OM demonstrated in past studies and climate projections.</p>https://www.biogeosciences.net/15/5093/2018/bg-15-5093-2018.pdf |
| spellingShingle | M. Bretagnon M. Bretagnon A. Paulmier V. Garçon B. Dewitte B. Dewitte B. Dewitte B. Dewitte S. Illig S. Illig N. Leblond L. Coppola F. Campos F. Campos F. Campos F. Velazco C. Panagiotopoulos A. Oschlies J. M. Hernandez-Ayon H. Maske O. Vergara I. Montes P. Martinez E. Carrasco J. Grelet O. Desprez-De-Gesincourt C. Maes C. Maes L. Scouarnec Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru Biogeosciences |
| title | Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru |
| title_full | Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru |
| title_fullStr | Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru |
| title_full_unstemmed | Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru |
| title_short | Modulation of the vertical particle transfer efficiency in the oxygen minimum zone off Peru |
| title_sort | modulation of the vertical particle transfer efficiency in the oxygen minimum zone off peru |
| url | https://www.biogeosciences.net/15/5093/2018/bg-15-5093-2018.pdf |
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