Vernal sedimentation trends in north Norwegian fjords:temporary anomaly in Th-234 particulate fluxes related to Phaeocystis pouchetii proliferation

We report data of a naturally occurring radionuclide, Th-234, an in situ tracer, to investigate vertical export of biogenic matter during a vernal bloom of Phaeocystis pouchetii in the fjords of northern Norway. To optimise sampling of different stages of the bloom, three fjords with increasing ocea...

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Bibliographic Details
Published in:Biogeochemistry
Main Authors: Schmidt, Sabine, Belviso, Sauveur, Wassmann, Paul, Thouzeau, Gerard, Stefels, Jacqueline
Format: Article in Journal/Newspaper
Language:English
Published: 2007
Subjects:
fjord
Northern Norwegian shelf waters
particle flux
Phaeocystis
sediment trap
Th-234
MEDITERRANEAN SURFACE WATERS
ORGANIC-CARBON
VERTICAL FLUX
PARTICLE DYNAMICS
SPRING BLOOM
EXPORT
OCEAN
MATTER
SEA
DISEQUILIBRIA
Balsfjord
Malangen
Norway
Northern Norway
Online Access:https://hdl.handle.net/11370/1c802e43-5b2d-4968-bb19-39502371505d
https://research.rug.nl/en/publications/1c802e43-5b2d-4968-bb19-39502371505d
https://doi.org/10.1007/s10533-007-9094-2
Description
Summary:We report data of a naturally occurring radionuclide, Th-234, an in situ tracer, to investigate vertical export of biogenic matter during a vernal bloom of Phaeocystis pouchetii in the fjords of northern Norway. To optimise sampling of different stages of the bloom, three fjords with increasing oceanic influence (Balsfjord, Malangen fjord and Ullsfjord, respectively) were investigated in April 1997. Contrasting situations were encountered between the three fjords: the proliferation of P. pouchetii in Ullsfjord surface waters coincided with a drastic reduction of particulate Th-234 fluxes in traps, although particulate organic carbon (POC) and dimethylsulphoniopropionate (DMSP) were exported and Th-234 was available in surface waters. When large colonies make up a significant fraction of the vertical flux, as observed in Ullsfjord in April 1997, there may be a large and rapid change in the POC/Th-234 ratio, further complicating the use of Th-234 as a tracer for POC export. The results suggest that the proliferation of Phaeocystis pouchetii during vernal bloom could temporary increase OC/Th-234 ratio of particles and delay the particulate export of Th-234, and probably of other particle-reactive species, from surface waters.

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