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THE ROLE OF SURFACES IN THE TRANSPORT OF RADIONUCLIDES IN THE MARINE ENVIRONMENT

Objective

THE RESEARCH CONSISTS OF TWO COMPONENTS:
- TO PROVIDE AN EXPLANATION OF THE PROCESSES WHICH CONTROL THE PARTITIONING OF RADIONUCLIDES, AND THEIR STABLE ELEMENT ANALOGUES, BETWEEN CONSERVATIVE AND NON-CONSERVATIVE MATERIALS IN THE MARINE ENVIRONMENT.
- TO IDENTIFY WHETHER OR NOT, FOR PURPOSES OF RADIOLOGICAL PROTECTION, THE PARTITIONING OF RADIONUCLIDES ( I.E. KD VALUES) CAN BE EXPLAINED BY A SIMPLE MODEL.
The following studies have been carried out in order to determine the role of surfaces in the transport of radionuclides in the marine environment:
investigation of the origins and properties of organoliths in order to evaluate their associations with radionuclides, especially alpha particle emitters;
examination of the composition of surface deposits on sediment grains by various microchemical methods;
evaluation of 320 Atlantic ocean samples in order to determine transfer of radionuclides from the ocean to nearshore waters and estuaries of the United Kingdom;
determination of the way in which radionuclides are transferred from surface waters to the deep ocean, (ie the role of faecal debris and surfaces of detritus);
continuation of Chernobyl studies.

The origins and properties of organoliths have been investigated in order to evaluate their associations with radionuclides, especially alpha particle emitters.
The composition of surface deposits to sediment grains has been examined by various microchemical methods.
Atlantic Ocean samples have been processed in order to evaluate transfer of radionuclides from the ocean to nearshore waters and estuaries of the United Kingdom.
The process whereby radionuclides are transferred from surface waters to the deep ocean has been investigated (ie the role of faecal debris and the surfaces of detritus).
Chernobyl studies have been continued.
THE RESEARCH WILL ATTEMPT TO IDENTIFY WHETHER OR NOT THE CHARACTERISTIC PHYSICAL PROPERTIES OF DEFINED SURFACES (E.G. BULK SEDIMENTS, CONSTITUENT MINERALS, BIOTA) CONTROL THE UPTAKE AND LOSS OF RADIONUCLIDES BY VIRTUE OF THEIR CHEMICAL AND PHYSICAL FORM, OR WHETHER AN INTERMEDIATE PHASE SUCH AS THE PRESENCE OF AN ORGANIC COATING IS THE PRIME SURFACE FOR EXCHANGE. ATTENTION WILL BE DIRECTED TOWARDS THE CHARACTERISATION OF PARTICULATE DEBRIS IN ESTUARIES AND NEAR SHORE MARINE ENVIRONMENTS IN TERMS OF BULK AND SURFACE COMPOSITIONS. THIS WILL BE ATTEMPTED BY USING THE ALPHA BACK SCATTER APPROACH AS ONE WHICH IS ECONOMIC AND CAN PROVIDE THE ESSENTIAL INFORMATION. PARALLEL INVESTIGATIONS WILL BE UNDERTAKEN TO DETERMINE THE EXCHANGE BEHAVIOUR OF TRITIUM AND C-14 WITH SURFACES IN AN ATTEMPT TO IDENTIFY THE SIGNIFICANCE OF THE AVAILABILITY OF HYDROXYL BINDING SITES AND THOSE ASSOCIATED WITH ORGANIC COMPOUNDS. THE TRACERS TO BE USED (IN LABORATORY EXPERIMENTS AND VALIDATED IN THE FIELD) WILL BE SELECTED ACCORDING TO THE REQUIREMENTS OF THE RESEARCH. IN CONJUNCTION WITH THESE INVESTIGATIONS, AND IF REQUIRED, THE STABILITY OF ANY SIGNIFICANT BINDING LIGANDS WILL BE DETERMINED.
ANALYTICAL TECHNIQUES WHICH WILL BE USED ARE AS FOLLOWS:
- ALPHA BACK SCATTER ANALYSER. THIS INSTRUMENT HAS BEEN CONSTRUCTED AND A SUITABLE CM-242 SOURCE HAS NOW BEEN OBTAINED.
- GAMMA PHOTON MEASUREMENTS WILL BE MADE FOR THE TIME BEING USING OUR COAXIAL GE (LI) DETECTOR WHICH WAS USED IN THE PREVIOUS 5Y CEC CONTRACT B10-E-438-81UK, BUT BECAUSE OF A DEGRADATION IN ENERGY RESOLUTION IT HAS NOW BEEN REPLACED WITH A HIGH RESOLUTION INTRINSIC GE DETECTOR.
- ALPHA PARTICLE MEASUREMENTS WILL BE MADE BY SURFACE BARRIER AND CR-39 DETECTORS.
- STABLE ELEMENTS WILL BE DETERMINED BY X-RAYS FLUORESCENCE ANALYSIS, NEUTRON ACTIVATION ANALYSIS AND ATOMIC ABSORPTION SPECTOMETRY.
WHEN REQUIRED A DIRECT ESTIMATION OF DEFINED ELEMENTS AND COMPOUNDS ON SURFACES WILL BE DETERMINED BY MICROHISTOLOGICAL STAINING TECHNIQUES, (E.G. IRON COMPOUNDS). PARTICLE SIZE ANALYSIS IN ASSOCIATION WITH SURFACE AREA ANALYSIS WILL BE USED WHEN REQUIRED AS BOTH PARAMETERS ARE INVOLVED IN THE PARTITIONING OF ELEMENTS ON SURFACES. THE FIRST HALF OF THE CONTRACT WILL CONCENTRATE UPON GEOCHEMICAL ASPECTS TO BE FOLLOWED BY A CONSIDERATION OF ELEMENT AND RADIONUCLIDE PARTITIONING FOR BIOLOGICAL MATRIXES; BECAUSE OF THE INTER-RELATED NATURE OF THE TECHNIQUES TO BE USED, THE VALIDATION OF THE ANALYTICAL TECHNIQUES WILL BE A FIRST PRIORITY.
THE INSTITUTE IS WELL EQUIPPED FOR MOST OF OUR ANALYTICAL NEEDS AND ONCE THE VARIOUS DETECTION SYSTEMS HAVE BEEN REFURBISHED WE DO NOT ANTICIPATE THAT ADDITIONAL INSTRUMENTATION WILL BE REQUIRED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NERC Institute of Oceanographic Sciences
Address
Deacon Laboratory Brook Road Wormley
GU8 5UB Godalming
United Kingdom