CADMIUM LOSSES ON WET AND DRY ASHING OF PLANT MATERIALS

Cadmium lasses on wet and dry ashing were studied using tomato leaves with metabolized Cd-109 radiotracer. The most appreciable Cd losses (u p to 35%) occured when sulphuric acid was used on wet ashing due to Cd retention in the CaSO4 precipitate formed. Only trace amounts of Cd w ere retained in a silicaceous precipitate resulting from wet ashing in the absence of sulphuric and hydrofluoric acids in the decomposition mixtures employed. Small Cd losses (up to 7%) were observed on dry ash ing in the air in open systems at temperatures not exceeding 500 degre es C. Cd losses increased, however, to 30% when the final ashing tempe rature was raised to 900 degrees C. Incorporation of the Cd-109 radiot racer into various parts of tomato plants and its distribution between soil and the plants are also briefly reported.