Seasonal dynamics and bioavailability of dissolved organic matter in two contrasting temperate estuaries

Helle Knudsen-Leerbeck, Mustafa Mantikci, Mikkel Bentzon-Tilia, Sachia Jo Traving, Lasse Riemann, Jørgen L.S. Hansen, Stig Markager

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Abstract

Production and bioavailability of dissolved organic matter (DOM) were followed during a year in the nutrient-rich estuary, Roskilde Fjord (RF), and the more oligotrophic strait, Great Belt (GB), in Denmark. Bioavailability of dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP) was determined during incubations over six months. Overall, RF had three to five times larger pools of total nitrogen (TN) and total phosphorous (TP) and five to eight times higher concentrations of inorganic nutrients compared to GB. However, the allocation of carbon, nitrogen, and phosphorous into different pools were remarkably similar between the two systems. DON and DOP contributed with about equal relative fractions in the two systems: 72 ± 13% of total nitrogen and 21 ± 12% of total phosphorous. The average bioavailability of DOM was 25 ± 15, 17 ± 5.5, and 49 ± 29% for carbon, nitrogen, and phosphorous, respectively. The observed release of DIN from degradation of DON amounted to between 0.1 (RF winter) and 14 times (GB summer) the loadings from land and contributed with half of the total input of bioavailable nitrogen during summer. Hence, this study shows that nitrogen in DOM is important for the nitrogen cycling, especially during summer. The sum of inorganic nutrients, particulate organic matter, and bioavailable DOM (the dynamic pools of nutrients) accounted for 42 and 92% of nitrogen, and phosphorous, respectively, and was remarkably similar between the two systems compared to the difference in nutrient richness. It is hypothesized that the pelagic metabolism of nutrients in marine systems dictates a rather uniform distribution of the different fractions of nitrogen and phosphorous containing compounds regardless of eutrophication level.
Original languageEnglish
JournalBiogeochemistry
Number of pages20
ISSN0168-2563
DOIs
Publication statusAccepted/In press - 2017
Externally publishedYes

Keywords

  • Bioavailability
  • Eutrophication
  • Nitrogen budget
  • DOC
  • DON
  • DOP

Cite this

Knudsen-Leerbeck, H., Mantikci, M., Bentzon-Tilia, M., Traving, S. J., Riemann, L., Hansen, J. L. S., & Markager, S. (Accepted/In press). Seasonal dynamics and bioavailability of dissolved organic matter in two contrasting temperate estuaries. Biogeochemistry. https://doi.org/10.1007/s10533-017-0357-2
Knudsen-Leerbeck, Helle ; Mantikci, Mustafa ; Bentzon-Tilia, Mikkel ; Traving, Sachia Jo ; Riemann, Lasse ; Hansen, Jørgen L.S. ; Markager, Stig. / Seasonal dynamics and bioavailability of dissolved organic matter in two contrasting temperate estuaries. In: Biogeochemistry. 2017.
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abstract = "Production and bioavailability of dissolved organic matter (DOM) were followed during a year in the nutrient-rich estuary, Roskilde Fjord (RF), and the more oligotrophic strait, Great Belt (GB), in Denmark. Bioavailability of dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP) was determined during incubations over six months. Overall, RF had three to five times larger pools of total nitrogen (TN) and total phosphorous (TP) and five to eight times higher concentrations of inorganic nutrients compared to GB. However, the allocation of carbon, nitrogen, and phosphorous into different pools were remarkably similar between the two systems. DON and DOP contributed with about equal relative fractions in the two systems: 72 ± 13{\%} of total nitrogen and 21 ± 12{\%} of total phosphorous. The average bioavailability of DOM was 25 ± 15, 17 ± 5.5, and 49 ± 29{\%} for carbon, nitrogen, and phosphorous, respectively. The observed release of DIN from degradation of DON amounted to between 0.1 (RF winter) and 14 times (GB summer) the loadings from land and contributed with half of the total input of bioavailable nitrogen during summer. Hence, this study shows that nitrogen in DOM is important for the nitrogen cycling, especially during summer. The sum of inorganic nutrients, particulate organic matter, and bioavailable DOM (the dynamic pools of nutrients) accounted for 42 and 92{\%} of nitrogen, and phosphorous, respectively, and was remarkably similar between the two systems compared to the difference in nutrient richness. It is hypothesized that the pelagic metabolism of nutrients in marine systems dictates a rather uniform distribution of the different fractions of nitrogen and phosphorous containing compounds regardless of eutrophication level.",
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Seasonal dynamics and bioavailability of dissolved organic matter in two contrasting temperate estuaries. / Knudsen-Leerbeck, Helle; Mantikci, Mustafa; Bentzon-Tilia, Mikkel; Traving, Sachia Jo; Riemann, Lasse; Hansen, Jørgen L.S.; Markager, Stig.

In: Biogeochemistry, 2017.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Seasonal dynamics and bioavailability of dissolved organic matter in two contrasting temperate estuaries

AU - Knudsen-Leerbeck, Helle

AU - Mantikci, Mustafa

AU - Bentzon-Tilia, Mikkel

AU - Traving, Sachia Jo

AU - Riemann, Lasse

AU - Hansen, Jørgen L.S.

AU - Markager, Stig

PY - 2017

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N2 - Production and bioavailability of dissolved organic matter (DOM) were followed during a year in the nutrient-rich estuary, Roskilde Fjord (RF), and the more oligotrophic strait, Great Belt (GB), in Denmark. Bioavailability of dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP) was determined during incubations over six months. Overall, RF had three to five times larger pools of total nitrogen (TN) and total phosphorous (TP) and five to eight times higher concentrations of inorganic nutrients compared to GB. However, the allocation of carbon, nitrogen, and phosphorous into different pools were remarkably similar between the two systems. DON and DOP contributed with about equal relative fractions in the two systems: 72 ± 13% of total nitrogen and 21 ± 12% of total phosphorous. The average bioavailability of DOM was 25 ± 15, 17 ± 5.5, and 49 ± 29% for carbon, nitrogen, and phosphorous, respectively. The observed release of DIN from degradation of DON amounted to between 0.1 (RF winter) and 14 times (GB summer) the loadings from land and contributed with half of the total input of bioavailable nitrogen during summer. Hence, this study shows that nitrogen in DOM is important for the nitrogen cycling, especially during summer. The sum of inorganic nutrients, particulate organic matter, and bioavailable DOM (the dynamic pools of nutrients) accounted for 42 and 92% of nitrogen, and phosphorous, respectively, and was remarkably similar between the two systems compared to the difference in nutrient richness. It is hypothesized that the pelagic metabolism of nutrients in marine systems dictates a rather uniform distribution of the different fractions of nitrogen and phosphorous containing compounds regardless of eutrophication level.

AB - Production and bioavailability of dissolved organic matter (DOM) were followed during a year in the nutrient-rich estuary, Roskilde Fjord (RF), and the more oligotrophic strait, Great Belt (GB), in Denmark. Bioavailability of dissolved organic carbon (DOC), nitrogen (DON), and phosphorous (DOP) was determined during incubations over six months. Overall, RF had three to five times larger pools of total nitrogen (TN) and total phosphorous (TP) and five to eight times higher concentrations of inorganic nutrients compared to GB. However, the allocation of carbon, nitrogen, and phosphorous into different pools were remarkably similar between the two systems. DON and DOP contributed with about equal relative fractions in the two systems: 72 ± 13% of total nitrogen and 21 ± 12% of total phosphorous. The average bioavailability of DOM was 25 ± 15, 17 ± 5.5, and 49 ± 29% for carbon, nitrogen, and phosphorous, respectively. The observed release of DIN from degradation of DON amounted to between 0.1 (RF winter) and 14 times (GB summer) the loadings from land and contributed with half of the total input of bioavailable nitrogen during summer. Hence, this study shows that nitrogen in DOM is important for the nitrogen cycling, especially during summer. The sum of inorganic nutrients, particulate organic matter, and bioavailable DOM (the dynamic pools of nutrients) accounted for 42 and 92% of nitrogen, and phosphorous, respectively, and was remarkably similar between the two systems compared to the difference in nutrient richness. It is hypothesized that the pelagic metabolism of nutrients in marine systems dictates a rather uniform distribution of the different fractions of nitrogen and phosphorous containing compounds regardless of eutrophication level.

KW - Bioavailability

KW - Eutrophication

KW - Nitrogen budget

KW - DOC

KW - DON

KW - DOP

U2 - 10.1007/s10533-017-0357-2

DO - 10.1007/s10533-017-0357-2

M3 - Journal article

JO - Biogeochemistry

JF - Biogeochemistry

SN - 0168-2563

ER -