Sr-90, Cs-137 and Ce-144 in commercial tea from several areas in China

18 kinds of tea, most of which are famous products, were collected in 1985 from 10 provinces of China. More than 1 kg of manufactured tea was collected from each sampling location and ashed in a stainless steel pan by a rapid ashing apparatus made in China Institute for Radiation Protection. A 10 g aliquot of the ashed sample was subjected to radiochemical analysis for 90Sr. 117Cs and 144Ce. Strontium, Cesium and Cerium carriers were added to the samples. The chemical yield of Sr, Cs and Ce were determined by weighting. After the radiochemical separation the mounted precipitates were counted for activity using a thin window methane gas-flow proportional counter normally for 100 min. Statistical error due to counting in generally was < 20%. Experimental results show that the mean values with standard deviation (as dry tea) of single measurement are 17 +- 9 Bq/kg for 90Sr, 2.2 +- 0.9 Bq/kg for 137Cs and 0.8 +- 0.2 Bq/kg for 144Ce. Among these data, the content of 144Ce in each tea sample is the lowest for its shorter lift. Higher values of 90Sr concentration occurred in each tea sample than that of 137Cs. This seems to be due to the fact that 137Cs is tightly bound by soil than 90Sr and the extent to which 90Sr is absorbed from the soil by plants is greater than 137Cs. (2 figs., 1 tab.)