Project
presentation - Phase IV
An
integrated approach to assess carbon dynamics in the Southern
Ocean
Coordinator
Dr Frank DEHAIRS
Vrije Universiteit Brussel
Laboratorium voor Analytische Scheikunde (ANCH)
Pleinlaan, 2
B-1050 BRUSSELS
Phone: +32 (0)2 629 32 60
Fax: +32 (0)2 629 32 74
E-mail: fdehairs@vub.ac.be
www.vub.ac.be/infovoor/onderzoekers/research/team.php?team_code=ANCH
Promotors
Dr Christiane LANCELOT
Université Libre de Bruxelles - C.P. 221
Microbiologie des Milieux Aquatiques
Campus de la Plaine
Bd. du Triomphe
B-1050 BRUSSELS
Phone:+32 (0)2 650 59 88
Fax: +32 (0)2 650 59 93
E-mail: lancelot@ulb.ac.be
www.ulb.ac.be/rech/inventaire/unites/ULB115.html
Prof.
Luc ANDRÉ
Royal Museum for Central Africa
Dept of Geology and Mineralogy
Steenweg op Leuven, 13
B-3080 TERVUREN
Phone: +32 (0)2 769 54 59
Fax: +32 (0)2 769 54 32
E-mail: landre@africamuseum.be
www.africamuseum.be/research/geology/research/geology/mineralogy
Dr Michel FRANKIGNOULLE (Université de
Liège)
Université de Liège
Unité d'Océanographie chimique
Sart Tilman - Physique B5
B-4000 LIEGE
Phone: +32 (0)4 366 33 26
Fax: +32 (0)4 366 23 55
E-mail: michel.frankignoulle@ulg.ac.be
www.ulg.ac.be/oceanbio/co2/
Dr Eric DELEERSNIJDER
Université Catholique de Louvain
Institut d'Astronomie et de Géophysique G. Lemaître
Chemin du Cyclotron, 2
B-1348 LOUVAIN-LA-NEUVE
Phone: +32 (0)10 47 26 76
Fax: +32 (0)10 47 47 22
E-mail: ericd@astr.ucl.ac.be
www.astr.ucl.ac.be/index.php?page=ResearchModels
Topics
This research attempts to determine the role - CO2 source
or sink - of the Southern Ocean on a regional and seasonal
scale by implementing an integrated multidisciplinary approach
which combines in situ measurements, studies of process in
laboratory controlled conditions and numerical computation.
It approaches the whole of the processes which govern the cycle
of carbon in the Southern Ocean, from exchanges of CO2 at
the air/sea interface until to accumulation of carbon in the
sediments. It is based on a mechanistic scientific approach
which aims at improving comprehension of the production process
and of mineralisation of carbonated biomass in surface water
as well as export towards the deep ocean. In particular, the
roles of light and the availability in nutrients (major
and minor) in the determination of the dominant phytoplanktonic
community, and thus of the dynamics of the associated food
chain and the carbon exportation, will be studied in areas
dominated by various phytoplanktonic communities, namely the
diatoms, the colonies of Phaeocystis and the nanophytoplankton.
The role of aggregates as carbon conveyors, from surface to
the deep water and the sediments, will be investigated with
special attention to the following processes : the bacterial
mineralisation of aggregates and the production and fate of
the barite proxy.
The use of the barite as tracer of the exported
carbon flux will be evaluated in order to improve the existing
transfer functions. Acquired knowledge will then be integrated
in a 1D physical and biogeochemical model able to simulate
the cycle of carbon as well associated biogenic elements (N,
Si, Fe, Mn, Ba) in the whole water column of the Southern
Ocean over a seasonal cycle. All together, this study will
contribute to establish a diagnostic and predictive model
which will be used to evaluate the role of the Southern Ocean
in a global perspective.
Goals
This integrated study has as overall objective to determine
the role of the Southern Ocean - CO2 source or sink
- on a seasonal and regional scale. It more specifically aims
at bringing an answer to the following questions :
- Which are
the CO2 source and sink areas in the
Southern Ocean system, and which is the net flux of CO2 between
the ocean and the atmosphere?
- Which are the biological
and physicochemical mechanisms controlling the distribution
of CO2 partial pressure
(pCO2)?
- Which are the mechanisms governing the
production and the mineralisation of organic carbon in
surface waters?
- By which mechanisms do light, inorganic
nutrients (nitrate,
ammonium, silica) and trace elements (Fe,
Mn) control the photosynthesis and the growth
of the three key-component of the phytoplankton of the
Southern Ocean (diatoms, Phaeocystis,
nanophytoplankton)?
- Which are the mechanisms which
determine the fate of organic carbon in surface water
and in particular the factors controlling the formation
of aggregates derived from the controlling the formation
of aggregates derived from the phytoplankton and their
mineralisation by the micro-organisms which adhere
to it?
- Which are the mechanisms of transformation
of organic carbon during its transfer from surface to the
sediment, in particular those implied in the degradation
and the mineralisation of the aggregates in the first 500
meters of the water column?
- Up to what point are the geochemical
tracers such as Ba-barite valid "proxies" of the
export production?
- Up to what point the mechanistic
model CLIO-1D/SWAMCO whose numeric code results from the
assets of the project, allows the evaluation of the role
- sink or source of CO2 -
of the Southern Ocean at seasonal and regional scale?
The
project combines the specific expertise of different research
groups in Belgium. The expertise of the Royal Museum for Central
Africa-Section of Mineralogy and Petrography (Luc André)
is situated within the research of Barite geochemistry. Specific
research items include:
- Kinetics of the uptake of tracers (Sr, Nd, Ce,
Th, Pb) by suspended matter and aggregates by means of isotopic
dilution techniques.
- Kinetics of the uptake of tracers by aggregates by means
of in vitro incubation experiments.
- Geochemical composition and vertical distribution of barite.
- Barium-barite geochemical and isotopic fractionation between
particulate phase (sediment and suspended matter) and sea
water.
- Morphology and geochemical composition of sedimentary
barite.
Specific
expertise
Dr F. DEHAIRS : New and export production
- Space and time differentiation of phytoplankton functionality.
- Phytoplankton nitrogen uptake regime.
- Role of aggregates in the formation of barite.
- Kinetics of the uptake of Ba and other tracers (Sr,
Nd, Ce, Th, Pb) by suspended matter and aggregates
by means of isotopic dilution techniques (on
board experiments).
- Dynamics of Ba uptake and remineralization in the water
column.
- Space variability of BaSO4 saturation rate.
- Ba-based transfer functions for estimating export production.
- Overall synthesis of results of the integrated project.
Dr Ch. LANCELOT : Study and modellisation
of the planktonic system
- Physiological parameters characteristic of carbon metabolism
in diatom- and Phaeocystis-dominated communities by means
of an innovative protocol combining 14C labelling and biochemistry.
- Diatom silica uptake (32Si radio-tracer
method).
- Assimilation and adsorption of Fe and Mn by the phytoplankton.
- Diatom/Phaeocystis-derived aggregate formation and microbial
transformation.
- Sedimentation of diatom/Phaeocystis-derived material.
- Extension and upgrading of the mechanistic biogeochemical
model SWAMCO.
Prof. L. ANDRÉ : Barite geochemistry
- Kinetics of the uptake of tracers (Sr,
Nd, Ce, Th, Pb) by suspended matter and aggregates
by means of isotopic dilution techniques.
- Kinetics of the uptake of tracers by aggregates by means
of in vitro incubation experiments.
- Geochemical composition and vertical distribution of barite.
- Barium-barite geochemical and isotopic fractionation between
particulate phase (sediment and suspended
matter) and sea water.
- Morphology and geochemical composition of sedimentary barite.
Dr M. FRANKIGNOULLE : Air/sea exchanges
- Methodology for the assessment of pCO2, pH and O2 in the
polar environment.
- CO2 fluxes through the ocean/atmosphere interface.
- Vertical distribution of carbon and oxygen in relation
to organic matter production and mineralization.
Dr E. DELEERSNIJDER : 1-D modelling
of the sea-ice and water column
- One-dimensional adaptation of the CLIO-1 model and validation.
- On-line coupling of the SWAMCO and CLIO-1D models and calibration.
Complementary resources about this scientific
project:
www.co2.ulg.ac.be/belcanto
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