DETERMINATION OF NATURAL P-32 AND P-33 IN RAINWATER, MARINE PARTICLESAND PLANKTON BY LOW-LEVEL BETA-COUNTING

Methods were developed for determining the natural levels of P-32 and P-33 in samples of rainwater, marine particulate matter and plankton. Preconcentration from rainwater consists of the extraction of radiopho sphorus on alumina. Filtration of large volumes of seawater is require d to obtain sufficient quantities of suspended particulate matter. The radiochemical scheme, which consists of a series of precipitations an d a column separation, results in a pure source containing the two bet a emitters. The activities of P-32 and P-33 in the source are determin ed separately by an external absorber method on low-level beta counter s. The yields are monitored by the addition of stable phosphate in rai nwater samples and by the natural levels of stable phosphate in marine particulate matter and plankton. The methods allow the specific activ ities and the activity ratio to be determined with a 10% precision.