VARIATIONS OF CADMIUM CONTENT IN PLANTS AFTER SEWAGE-SLUDGE APPLICATION

The effect of sewage sludge on cadmium (Cd) content in plants was exam ined in vegetation pot trials. Two types of sludge with average Cd con tent were used. Experiments were conducted in three soils (Chernozem, Orthic Luvisol, Fluvisol) and on four crops (poppy, barley, corn, oats ). Direct and subsequent effects of sewage sludge were studied. A Vari an SpectrAA-40 apparatus were used for Cd determination. A trend of el evated Cd content in plants was observed at the dose used (16.65 g dry matter/5 kg soil). The highest contents were determined in barley str aw and poppy seed, the lowest in barley grain. Cd content in the soil was also determined after the use of various extraction agents (2M HNO 3, 0.1M CaCl2, 0.01M CaCl2). An average Cd proportion in 2M HNO3 was 6 0.2% out of Cd-tot in soils. When 0.1M CaCl2 was used, 3.9 to 19.9% of the total Cd quantity in soils were released in dependence on the soi l. 0.01M CaCl2 extracted less than 1% of Cd-tot (except Prerov n/L soi l). The closest relation between Cd content in plants and extractable Cd quantity from soil was determined for 0.1M CaCl2 extraction.