Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea
<p>Coastal systems can act as filters for anthropogenic nutrient input into marine environments. Here, we assess the processes controlling the removal of phosphorus (P) and nitrogen (N) for four sites in the eutrophic Stockholm archipelago. Bottom water concentrations of oxygen (<span class...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-05-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/17/2745/2020/bg-17-2745-2020.pdf |
| _version_ | 1818896961579778048 |
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| author | N. A. G. M. van Helmond N. A. G. M. van Helmond N. A. G. M. van Helmond E. K. Robertson E. K. Robertson D. J. Conley M. Hermans C. Humborg L. J. Kubeneck L. J. Kubeneck W. K. Lenstra C. P. Slomp |
| author_facet | N. A. G. M. van Helmond N. A. G. M. van Helmond N. A. G. M. van Helmond E. K. Robertson E. K. Robertson D. J. Conley M. Hermans C. Humborg L. J. Kubeneck L. J. Kubeneck W. K. Lenstra C. P. Slomp |
| author_sort | N. A. G. M. van Helmond |
| collection | DOAJ |
| description | <p>Coastal systems can act as filters for anthropogenic
nutrient input into marine environments. Here, we assess the processes
controlling the removal of phosphorus (P) and nitrogen (N) for four sites in
the eutrophic Stockholm archipelago. Bottom water concentrations of oxygen
(<span class="inline-formula">O<sub>2</sub></span>) and P are inversely correlated. This is attributed to the seasonal
release of P from iron-oxide-bound (Fe-oxide-bound) P in surface sediments and from
degrading organic matter. The abundant presence of sulfide in the pore water
and its high upward flux towards the sediment surface (<span class="inline-formula">∼4</span> to
8 mmol m<span class="inline-formula"><sup>−2</sup></span> d<span class="inline-formula"><sup>−1</sup></span>), linked to prior deposition of organic-rich
sediments in a low-<span class="inline-formula">O<sub>2</sub></span> setting (“legacy of hypoxia”), hinder the
formation of a larger Fe-oxide-bound P pool in winter. This is most
pronounced at sites where water column mixing is naturally relatively low
and where low bottom water <span class="inline-formula">O<sub>2</sub></span> concentrations prevail in summer. Burial rates
of P are high at all sites (0.03–0.3 mol m<span class="inline-formula"><sup>−2</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>), a combined
result of high sedimentation rates (0.5 to 3.5 cm yr<span class="inline-formula"><sup>−1</sup></span>) and high
sedimentary P at depth (<span class="inline-formula">∼30</span> to 50 <span class="inline-formula">µ</span>mol g<span class="inline-formula"><sup>−1</sup></span>).
Sedimentary P is dominated by Fe-bound P and organic P at the sediment
surface and by organic P, authigenic Ca-P and detrital P at depth. Apart
from one site in the inner archipelago, where a vivianite-type Fe(II)-P
mineral is likely present at depth, there is little evidence for
sink switching of organic or Fe-oxide-bound P to authigenic P minerals.
Denitrification is the major benthic nitrate-reducing process at all sites
(0.09 to 1.7 mmol m<span class="inline-formula"><sup>−2</sup></span> d<span class="inline-formula"><sup>−1</sup></span>) with rates decreasing seaward from the
inner to outer archipelago. Our results explain how sediments in this
eutrophic coastal system can remove P through burial at a relatively high
rate, regardless of whether the bottom waters are oxic or (frequently)
hypoxic. Our results suggest that benthic N processes undergo annual cycles
of removal and recycling in response to hypoxic conditions. Further nutrient
load reductions are expected to contribute to the recovery of the eutrophic
Stockholm archipelago from hypoxia. Based on the dominant pathways of P and
N removal identified in this study, it is expected that the sediments will
continue to remove part of the P and N loads.</p> |
| first_indexed | 2024-12-19T19:08:36Z |
| format | Article |
| id | doaj.art-40be78bf35174b0dbaac386adf2ad8d2 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-19T19:08:36Z |
| publishDate | 2020-05-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-40be78bf35174b0dbaac386adf2ad8d22022-12-21T20:09:22ZengCopernicus PublicationsBiogeosciences1726-41701726-41892020-05-01172745276610.5194/bg-17-2745-2020Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic SeaN. A. G. M. van Helmond0N. A. G. M. van Helmond1N. A. G. M. van Helmond2E. K. Robertson3E. K. Robertson4D. J. Conley5M. Hermans6C. Humborg7L. J. Kubeneck8L. J. Kubeneck9W. K. Lenstra10C. P. Slomp11Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, the NetherlandsDepartment of Geology, Lund University, Sölvegatan 12, 223 62 Lund, SwedenDepartment of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the NetherlandsDepartment of Geology, Lund University, Sölvegatan 12, 223 62 Lund, SwedenDepartment of Marine Sciences, University of Gothenburg, Box 461, 40530 Gothenburg, SwedenDepartment of Geology, Lund University, Sölvegatan 12, 223 62 Lund, SwedenDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, the NetherlandsBaltic Sea Centre, Stockholm University, 106 91 Stockholm, SwedenDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlandsnow at: Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, 8092 Zürich, SwitzerlandDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, the NetherlandsDepartment of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands<p>Coastal systems can act as filters for anthropogenic nutrient input into marine environments. Here, we assess the processes controlling the removal of phosphorus (P) and nitrogen (N) for four sites in the eutrophic Stockholm archipelago. Bottom water concentrations of oxygen (<span class="inline-formula">O<sub>2</sub></span>) and P are inversely correlated. This is attributed to the seasonal release of P from iron-oxide-bound (Fe-oxide-bound) P in surface sediments and from degrading organic matter. The abundant presence of sulfide in the pore water and its high upward flux towards the sediment surface (<span class="inline-formula">∼4</span> to 8 mmol m<span class="inline-formula"><sup>−2</sup></span> d<span class="inline-formula"><sup>−1</sup></span>), linked to prior deposition of organic-rich sediments in a low-<span class="inline-formula">O<sub>2</sub></span> setting (“legacy of hypoxia”), hinder the formation of a larger Fe-oxide-bound P pool in winter. This is most pronounced at sites where water column mixing is naturally relatively low and where low bottom water <span class="inline-formula">O<sub>2</sub></span> concentrations prevail in summer. Burial rates of P are high at all sites (0.03–0.3 mol m<span class="inline-formula"><sup>−2</sup></span> yr<span class="inline-formula"><sup>−1</sup></span>), a combined result of high sedimentation rates (0.5 to 3.5 cm yr<span class="inline-formula"><sup>−1</sup></span>) and high sedimentary P at depth (<span class="inline-formula">∼30</span> to 50 <span class="inline-formula">µ</span>mol g<span class="inline-formula"><sup>−1</sup></span>). Sedimentary P is dominated by Fe-bound P and organic P at the sediment surface and by organic P, authigenic Ca-P and detrital P at depth. Apart from one site in the inner archipelago, where a vivianite-type Fe(II)-P mineral is likely present at depth, there is little evidence for sink switching of organic or Fe-oxide-bound P to authigenic P minerals. Denitrification is the major benthic nitrate-reducing process at all sites (0.09 to 1.7 mmol m<span class="inline-formula"><sup>−2</sup></span> d<span class="inline-formula"><sup>−1</sup></span>) with rates decreasing seaward from the inner to outer archipelago. Our results explain how sediments in this eutrophic coastal system can remove P through burial at a relatively high rate, regardless of whether the bottom waters are oxic or (frequently) hypoxic. Our results suggest that benthic N processes undergo annual cycles of removal and recycling in response to hypoxic conditions. Further nutrient load reductions are expected to contribute to the recovery of the eutrophic Stockholm archipelago from hypoxia. Based on the dominant pathways of P and N removal identified in this study, it is expected that the sediments will continue to remove part of the P and N loads.</p>https://www.biogeosciences.net/17/2745/2020/bg-17-2745-2020.pdf |
| spellingShingle | N. A. G. M. van Helmond N. A. G. M. van Helmond N. A. G. M. van Helmond E. K. Robertson E. K. Robertson D. J. Conley M. Hermans C. Humborg L. J. Kubeneck L. J. Kubeneck W. K. Lenstra C. P. Slomp Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea Biogeosciences |
| title | Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea |
| title_full | Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea |
| title_fullStr | Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea |
| title_full_unstemmed | Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea |
| title_short | Removal of phosphorus and nitrogen in sediments of the eutrophic Stockholm archipelago, Baltic Sea |
| title_sort | removal of phosphorus and nitrogen in sediments of the eutrophic stockholm archipelago baltic sea |
| url | https://www.biogeosciences.net/17/2745/2020/bg-17-2745-2020.pdf |
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