Résultats exploitables
The developments of the Multi Physical-Chemical Profiler (MPCP) and its adaptation to an improved Buoy profiler system have been successfully achieved. It allows simultaneous in situ, autonomous monitoring of three specific fractions of Cu(II), Pb(II), Cd(II), i.e.: free ions, dynamic and total extractable concentrations, which play important role in term of toxicity, transport properties and residence time, as well as master variables (pressure, temperature, pH, oxygen, conductivity, salinity, redox E and chlorophyll a) down to 150 meters. The MPCP probe is based on the VIP System. The heart of the VIP probe is a gel integrated microelectrode (GIME) which allows the specific measurement of the dynamic fraction of trace metals, defined as the sum of the free metal ions and the small labile complexes with size of few nanometres. The probe is comprised of distinct specific modules: an electronic housing, three pressure-compensated flow-through voltammetric cells and sampling submersible peristaltic pumps, integrated standard physical, chemical and optical sensors. A user friendly. Windows management software allows the user to control and set up the MPCP probe operating parameters and functions, such as: fluidic and electrochemical parameters; data acquisition, transfer and display; calibration, and maintenance operations.
Remote control of the MPCP has been achieved by coupling it to an improved Buoy Controller Module (BCM). The BCM, via a stack of communication protocols and remote management software, supervises the monitoring activities, collects and stores data from the MPCP measuring probe at pre-set time intervals, forwarding them, via a wireless connection using GSM network, to the control node land based station. Intercalibration exercises, involving all IMTEC partners, undertaken during fieldworks in Sweden, Italy and UK have allowed co-ordination, integration and standardisation of sampling and common in situ and laboratory measurement methodologies resulting in accurate/precise measurements of specific metal fractions and biophysicochemical parameters by several European laboratories. They have also allowed evaluation of the suite of the MPCP speciation-sensitive measurement techniques which showed a good agreement with our present knowledge of trace metal speciation and field characterisation/ validation of the new analytical and technical developments.
The capability of the MPCP for reliable in situ monitoring of the temporal as well as spatial variations of trace metal speciation and master variables and its potentiality for:
- More efficient environmental monitoring and rigorous interpretation of trace metal cycles and their ecotoxicological impact in aquatic system, and
- Pollution control were demonstrated by the results obtained during field campaigns in various coastal ecosystems. The potentiality of the buoy supported MPCP with land station control as remote monitoring and early warning system was also demonstrated.
Results of biogeochemical studies and pollution monitoring in the various aquatic ecosystems have lead to important findings. They demonstrated that physical and geochemical processes may readily influence the biologically available fraction of metal, for which total metal concentrations are poor indicator. A clear link between the concentrations of bioavailable metals and the production of chelating agents in phytoplankton has been demonstrated which provided an important first link between in situ measurements of specific metal fractions and their ecotoxicological effects. These findings demonstrated the need and the usefulness of the MPCP as tool for the member state institutions for more efficient water quality evaluation, trace metal ecotoxicological assessment and legislation development.
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