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Remineralization rate of terrestrial DOC as inferred from CO2 supersaturated coastal waters.

Authors :
Fransner, Filippa
Fransson, Agneta
Humborg, Christoph
Gustafsson, Erik
Tedesco, Letizia
Hordoir, Robinson
Nycander, Jonas
Source :
Biogeosciences; Feb2019, Vol. 16 Issue 4, p863-879, 17p, 4 Charts, 10 Graphs
Publication Year :
2019

Abstract

Coastal seas receive large amounts of terrestrially derived organic carbon (OC). The fate of this carbon, and its impact on the marine environment, is however poorly understood. Here we combine underway CO2 partial pressure (pCO2) measurements with coupled 3-D hydrodynamical–biogeochemical modelling to investigate whether remineralization of terrestrial dissolved organic carbon (tDOC) can explain CO2 supersaturated surface waters in the Gulf of Bothnia, a subarctic estuary. We find that a substantial remineralization of tDOC and a strong tDOC-induced light attenuation dampening the primary production are required to reproduce the observed CO2 supersaturated waters in the nearshore areas. A removal rate of tDOC of the order of 1 year, estimated in a previous modelling study in the same area, gives a good agreement between modelled and observed pCO2. The remineralization rate is on the same order as bacterial degradation rates calculated from published incubation experiments, suggesting that bacteria has the potential to cause this degradation. Furthermore, the observed high pCO2 values during the ice-covered season argue against photochemical degradation as the main removal mechanism. All of the remineralized tDOC is outgassed to the atmosphere in the model, turning the northernmost part of the Gulf of Bothnia into a source of CO2 to the atmosphere. [ABSTRACT FROM AUTHOR]

Subjects

Subjects :
TERRITORIAL waters
GOLD ores

Details

Language :
English
ISSN :
17264170
Volume :
16
Issue :
4
Database :
Complementary Index
Journal :
Biogeosciences
Publication Type :
Academic Journal
Accession number :
135430819
Full Text :
https://doi.org/10.5194/bg-16-863-2019