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EXPERIMENTAL PROGRAMME TO SUPPORT THE DEVELOPMENT OF DYNAMIC MODELS DESCRIBING CARBON-14 (AND OTHER B-EMITTERS) IN SOIL- PLANT-ANIMAL SYSTEMS

Objective


Methods have been developed in which carbon-14 added as a bicarbonate to enclosed systems can be traced from solution to roots, roots to shoots and shoots to the atmosphere. Experimental studies with solution cultures and soil systems in both laboratory and glasshouse conditions provide categorical evidence that small quantities of carbon-14 can be absorbed by plant roots and translocated to shoots.
Preliminary field sampling around an operating nuclear installation has indicated that specific activities in native plant species are not constant, possibly as a result of differential uptake from soils.
A.DEVELOPMENT OF TECHNIQUES
IN ORDER TO PROVIDE THE MECHANISM FOR THE SPECIFIC STUDIES OUTLINED IN ITEMS B TO D (BELOW), THE FOLLOWING INVESTIGATIONS WILL BE CONDUCTED IN ORDER TO DEVELOP, TEST AND VALIDATE APPROPRIATE TECHNIQUES AND FACILITIES:
1. THE IMPROVEMENT OF CHEMICAL EXTRACTION TECHNIQUES TO REMOVE C-14 AND H-3 FROM LABELLED PLANT AND SOIL MATERIALS AND THE DEVELOPMENT OF SPECIFIC INORGANIC AND ORGANIC C-14 AND H-3 LABELLED FRACTIONS.
2. THE DEVELOPMENT OF CHEMICAL AND ANALYTICAL TECHNIQUES FOR ASSAY OF C-14 IN SOIL AND VEGETATION SAMPLES REPRESENTATIVE OF SITES CLOSE TO MAJOR SOURCES.
3. THE DEVELOPMENT OF TECHNIQUES APPROPRIATE FOR THE STUDY OF C-14 TRANSFERS BETWEEN VEGETATION, SOIL AND ATMOSPHERE DURING DECOMPOSITION IN SEMI-FIELD (LYSIMETER) AND FIELD CONDITIONS.
B. CONTROLLED ENVIRONMENT STUDIES
THE FOLLOWING STUDIES WILL BE UNDERTAKEN IN CONTROLLED-ENVIRONMENT CONDITIONS FOR THE PURPOSE OF INTERPRETING MEASUREMENTS MADE IN NON-CONTROLLED CONDITIONS AND FOR THE DERIVATION OF VALUES APPROPRIATE TO TIME-DEPENDENT PHYSIOLOGICAL MODELS.
1. AN INVESTIGATION OF THE SHORT-TERM (HOURS TO DAYS) DYNAMICS INVOLVED IN UPTAKE OF C-14 BY PASTURE SPECIES VIA ROOTS AND OF THE FATE OF ABSORBED C-14 IN RESPECT OF FIXATION IN INORGANIC AND ORGANIC FRACTIONS AND/OR SUBSEQUENT LOSSES VIA RESPIRATION.
2. INVESTIGATIONS ON THE DYNAMICS AND FATE OF C-14 FOLLOWING ATMOSPHERIC AND ASPERSION CONTAMINATION INCLUDING DOWNWARDS TRANSLOCATION, FIXATION AND LOSSES.
C. INVESTIGATIONS IN GREENHOUSE CONDITIONS
EFFECTS OF ENVIRONMENTAL VARIABLES SUCH AS SOIL TYPE, PLANT SPECIES AND FORM, AND MODE OF ADMINISTRATION WILL BE INVESTIGATED IN MULTIVARIATE, REPLICATED, EXPERIMENTS, USING THE TECHNIQUES DEVELOPED UNDER ITEM A (ABOVE). THESE STUDIES WILL INCLUDE:
1. AN INVESTIGATION OF THE EFFECT OF SOIL TYPE ON THE UPTAKE OF C-14 BY LOLIUM PERENNE FOLLOWING THE SPIKE AMENDMENT OF SOIL IN VARIOUS MANNERS WITH A RANGE OF COMPOUNDS AT THE START OF THE GROWING SEASON.
2. AN INVESTIGATION OF THE UPTAKE AND DISTRIBUTION OF C-14 FROM SOIL BY A RANGE OF PASTURE SPECIES FOLLOWING AMENDMENT OF SOIL WITH A RANGE OF CHEMICAL FORMS AT DIFFERENT STAGES OF PLANT DEVELOPMENT, INCLUDING STUDIES OF THE FIXATION OF C-14 IN VARIOUS FRACTIONS OF THE PLANTS.
D. INVESTIGATIONS IN SEMI-FIELD CONDITIONS
THESE STUDIES WILL BE UNDERTAKEN USING EXTERNAL LYSIMETER FACILITIES ALREADY AVAILABLE AND USING TECHNIQUES DEVELOPED UNDER ITEM A (ABOVE). THE OBJECTIVE WILL BE TO DERIVE DATA APPROPRIATE TO THE FURTHER DEVELOPMENT AND VALIDATION OF EXISTING MATHEMATICAL MODELS RELATING TO TRANSFERS OF C-14 OCCURRING DURING THE DECOMPOSITION OF LABELLED PLANT MATERIAL ON AND IN SOIL PROFILES. DUAL-LABELLING TECHNIQUES (USING BOTH C-14 AND H-3) WILL BE USED TO EVALUATE TRANSFERS OCCURRING AS A RESULT OF THE RESPIRATION OF C-14 LABELLED MATERIALS AND AS A RESULT OF CHANGES IN SOIL MOISTURE CONDITIONS.
E. FIELD INVESTIGATIONS
SOIL AND VEGETATION SAMPLES REPRESENTATIVE OF A NUMBER OF LOCALITIES LIKELY TO BE AFFECTED BY

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Associated Nuclear Services Ltd
Address
123 High Street
KT19 8EB Epsom
United Kingdom