Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study
In open-ocean regions, as is the Eastern Tropical North Atlantic (ETNA), pelagic production is the main source of dissolved organic matter (DOM) and is affected by dissolved inorganic nitrogen (DIN) and phosphorus (DIP) concentrations. Changes in pelagic production under nutrient amendments were sho...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-12-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/6897/2015/bg-12-6897-2015.pdf |
| _version_ | 1819094164681261056 |
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| author | A. N. Loginova C. Borchard J. Meyer H. Hauss R. Kiko A. Engel |
| author_facet | A. N. Loginova C. Borchard J. Meyer H. Hauss R. Kiko A. Engel |
| author_sort | A. N. Loginova |
| collection | DOAJ |
| description | In open-ocean regions, as is the Eastern Tropical North Atlantic (ETNA),
pelagic production is the main source of dissolved organic matter (DOM) and
is affected by dissolved inorganic nitrogen (DIN) and phosphorus (DIP)
concentrations. Changes in pelagic production under nutrient amendments were
shown to also modify DOM quantity and quality. However, little information
is available about the effects of nutrient variability on chromophoric
(CDOM) and fluorescent (FDOM) DOM dynamics. Here we present results from two
mesocosm experiments ("Varied P" and "Varied N") conducted with a
natural plankton community from the ETNA, where the effects of DIP and DIN
supply on DOM optical properties were studied. CDOM accumulated
proportionally to phytoplankton biomass during the experiments. Spectral
slope (<i>S</i>) decreased over time indicating accumulation of high molecular
weight DOM. In Varied N, an additional CDOM portion, as a result of
bacterial DOM reworking, was determined. It increased the CDOM fraction in
DOC proportionally to the supplied DIN. The humic-like FDOM component
(Comp.1) was produced by bacteria proportionally to DIN supply. The
protein-like FDOM component (Comp.2) was released irrespectively to
phytoplankton or bacterial biomass, but depended on DIP and DIN
concentrations. Under high DIN supply, Comp.2 was removed by bacterial
reworking, leading to an accumulation of humic-like Comp.1. No influence of
nutrient availability on amino acid-like FDOM component in peptide form
(Comp.3) was observed. Comp.3 potentially acted as an intermediate product
during formation or degradation of Comp.2. Our findings suggest that changes in
nutrient concentrations may lead to substantial responses in the quantity
and quality of optically active DOM and, therefore, might bias results of
the applied in situ optical techniques for an estimation of DOC
concentrations in open-ocean regions. |
| first_indexed | 2024-12-21T23:23:03Z |
| format | Article |
| id | doaj.art-80dbe422e00a4d198f10f364fa35491d |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-21T23:23:03Z |
| publishDate | 2015-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-80dbe422e00a4d198f10f364fa35491d2022-12-21T18:46:45ZengCopernicus PublicationsBiogeosciences1726-41701726-41892015-12-0112236897691410.5194/bg-12-6897-2015Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm studyA. N. Loginova0C. Borchard1J. Meyer2H. Hauss3R. Kiko4A. Engel5GEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyGEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyGEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyGEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyGEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyGEOMAR Helmholtz-Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, GermanyIn open-ocean regions, as is the Eastern Tropical North Atlantic (ETNA), pelagic production is the main source of dissolved organic matter (DOM) and is affected by dissolved inorganic nitrogen (DIN) and phosphorus (DIP) concentrations. Changes in pelagic production under nutrient amendments were shown to also modify DOM quantity and quality. However, little information is available about the effects of nutrient variability on chromophoric (CDOM) and fluorescent (FDOM) DOM dynamics. Here we present results from two mesocosm experiments ("Varied P" and "Varied N") conducted with a natural plankton community from the ETNA, where the effects of DIP and DIN supply on DOM optical properties were studied. CDOM accumulated proportionally to phytoplankton biomass during the experiments. Spectral slope (<i>S</i>) decreased over time indicating accumulation of high molecular weight DOM. In Varied N, an additional CDOM portion, as a result of bacterial DOM reworking, was determined. It increased the CDOM fraction in DOC proportionally to the supplied DIN. The humic-like FDOM component (Comp.1) was produced by bacteria proportionally to DIN supply. The protein-like FDOM component (Comp.2) was released irrespectively to phytoplankton or bacterial biomass, but depended on DIP and DIN concentrations. Under high DIN supply, Comp.2 was removed by bacterial reworking, leading to an accumulation of humic-like Comp.1. No influence of nutrient availability on amino acid-like FDOM component in peptide form (Comp.3) was observed. Comp.3 potentially acted as an intermediate product during formation or degradation of Comp.2. Our findings suggest that changes in nutrient concentrations may lead to substantial responses in the quantity and quality of optically active DOM and, therefore, might bias results of the applied in situ optical techniques for an estimation of DOC concentrations in open-ocean regions.http://www.biogeosciences.net/12/6897/2015/bg-12-6897-2015.pdf |
| spellingShingle | A. N. Loginova C. Borchard J. Meyer H. Hauss R. Kiko A. Engel Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study Biogeosciences |
| title | Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study |
| title_full | Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study |
| title_fullStr | Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study |
| title_full_unstemmed | Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study |
| title_short | Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study |
| title_sort | effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the eastern tropical north atlantic a mesocosm study |
| url | http://www.biogeosciences.net/12/6897/2015/bg-12-6897-2015.pdf |
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