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Biogeochemistry of phaeocystis colonies and their derived aggregates

Objective

The general objective is to develop a predictive mathematical model of trace element (Fe/Mn) transfer and accumulation in the Phaeocystis-dominated ecosystem of the continental coastal zone of the North Sea focussing on the role of Phaeocystis colonies and their derived aggregates as vector for metal transport.


The biogeochemical model will be developed on the basis of the existing predictive mathematical model MIRO, established in the scope of the EC Phaeocystis project (1988-1993) and describing the response of the Phaeocystis-dominated ecosystem of the continental coastal zone of the North Sea to the cumulative nutrient discharges by the major NW European rivers.

The project methodology will combine field observations, field and laboratory process-oriented studies and modelling development in an attempt to build up a biogeochemical model representing, as accurately as possible, the kinetics and control of the physiological and geochemical processes involved in the functioning of the Phaeocystis-dominated North Sea ecosystem and trace element transfer and accumulation. Modelling work will include the improvement of the formulation of the biological module of the MIRO model through the addition of aggregates as explicite state variable; and its coupling with a chemical module of precipitation and dissolving of Fe/Mn hydroxides. Experimentally it implies :

1. Field study, during a Phaeocystis bloom in the continental coastal zone of the North Sea, of (i) particle aggregation/disaggregation and sedimentation; and (ii) Fe/Mn dissolved and particulate concentrations with special attention to Fe/Mn oxyhydroxide deposits in Phaeocystis colonies and bioaccumulation by phytoplankton cells.

2. Field and laboratory study of (i) the physiological and chemical processes controlling Fe/Mn sequestration by Phaeocystis colonies and their redissolving; and (ii) the physical and biological mechanisms governing Phaeocystis-derived aggregation/disaggregation.

Application of the biogeochemical model in the coastal zone of the North Sea will allow to evaluate the role of Phaeocystis colonies and their derived aggregates in the biogeochemical cycle of trace-metals.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITE LIBRE DE BRUXELLES
Address
221,Boulevard Du Triomphe 221
1050 Bruxelles
Belgium

Participants (2)

ALFRED WEGENER INSTITUTE FOR POLAR AND MARINE RESEARCH
Germany
Address
Columbusstrasse
27568 Bremerhaven
Netherlands Institute for Sea Research
Netherlands
Address

1790 AB Texel, Den Burg