Nitrogen retention in coastal marine sediments: a field study of the relative importance of biological and physical removal in a Danish estuary

Publikation: Bidrag til tidsskriftTidsskriftartikel

Resumé

The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic sediment particles but not participating in any biological processes, and 15N–NO3 −, taken up by the MPB and turned over as part of the MPB nitrogen pool. Retention, down-mixing, and export of 15N were due to both biological and physical processes, so that by comparing retention of the two isotopes, we were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring/early summer, the system was characterized by tight N cycling and high N retention: any remineralized N was immediately taken up and retained in the MPB biomass. In late summer and autumn, the system was still physically stable, but high biological mediated N losses were observed. In early winter, the system was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally.
The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic sediment particles but not participating in any biological processes, and 15N–NO3 −, taken up by the MPB and turned over as part of the MPB nitrogen pool. Retention, down-mixing, and export of 15N were due to both biological and physical processes, so that by comparing retention of the two isotopes, we were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring/early summer, the system was characterized by tight N cycling and high N retention: any remineralized N was immediately taken up and retained in the MPB biomass. In late summer and autumn, the system was still physically stable, but high biological mediated N losses were observed. In early winter, the system was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally.
SprogEngelsk
TidsskriftEstuaries and Coasts
Vol/bind40
Udgave nummer5
Sider1276-1287
Antal sider13
ISSN1559-2723
DOI
StatusUdgivet - 25 jul. 2017

Emneord

  • Benthic chlorophyll
  • Microphytobenthos
  • Nitrogen dynamics
  • Nutrient cycling
  • Sediment processes

Citer dette

@article{174468c6090743879a2726c03e130875,
title = "Nitrogen retention in coastal marine sediments: a field study of the relative importance of biological and physical removal in a Danish estuary",
abstract = "The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic sediment particles but not participating in any biological processes, and 15N–NO3 −, taken up by the MPB and turned over as part of the MPB nitrogen pool. Retention, down-mixing, and export of 15N were due to both biological and physical processes, so that by comparing retention of the two isotopes, we were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring/early summer, the system was characterized by tight N cycling and high N retention: any remineralized N was immediately taken up and retained in the MPB biomass. In late summer and autumn, the system was still physically stable, but high biological mediated N losses were observed. In early winter, the system was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally.",
keywords = "Benthic chlorophyll, Microphytobenthos , Nitrogen dynamics, Nutrient cycling , Sediment processes , Benthic chlorophyll, Microphytobenthos , Nitrogen dynamics, Nutrient cycling , Sediment processes",
author = "Nielsen, {S\{o}ren Laurentius} and Nils Risgaard-Petersen and Banta, {Gary Thomas}",
year = "2017",
month = "7",
day = "25",
doi = "10.1007/s12237-017-0216-3",
language = "English",
volume = "40",
pages = "1276--1287",
journal = "Estuaries and Coasts",
issn = "1559-2723",
publisher = "Springer New York LLC",
number = "5",

}

TY - JOUR

T1 - Nitrogen retention in coastal marine sediments

T2 - Estuaries and Coasts

AU - Nielsen,Søren Laurentius

AU - Risgaard-Petersen,Nils

AU - Banta,Gary Thomas

PY - 2017/7/25

Y1 - 2017/7/25

N2 - The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic sediment particles but not participating in any biological processes, and 15N–NO3 −, taken up by the MPB and turned over as part of the MPB nitrogen pool. Retention, down-mixing, and export of 15N were due to both biological and physical processes, so that by comparing retention of the two isotopes, we were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring/early summer, the system was characterized by tight N cycling and high N retention: any remineralized N was immediately taken up and retained in the MPB biomass. In late summer and autumn, the system was still physically stable, but high biological mediated N losses were observed. In early winter, the system was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally.

AB - The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic sediment particles but not participating in any biological processes, and 15N–NO3 −, taken up by the MPB and turned over as part of the MPB nitrogen pool. Retention, down-mixing, and export of 15N were due to both biological and physical processes, so that by comparing retention of the two isotopes, we were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring/early summer, the system was characterized by tight N cycling and high N retention: any remineralized N was immediately taken up and retained in the MPB biomass. In late summer and autumn, the system was still physically stable, but high biological mediated N losses were observed. In early winter, the system was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally.

KW - Benthic chlorophyll

KW - Microphytobenthos

KW - Nitrogen dynamics

KW - Nutrient cycling

KW - Sediment processes

KW - Benthic chlorophyll

KW - Microphytobenthos

KW - Nitrogen dynamics

KW - Nutrient cycling

KW - Sediment processes

U2 - 10.1007/s12237-017-0216-3

DO - 10.1007/s12237-017-0216-3

M3 - Journal article

VL - 40

SP - 1276

EP - 1287

JO - Estuaries and Coasts

JF - Estuaries and Coasts

SN - 1559-2723

IS - 5

ER -