Root Uptake of ¹³⁷Cs from Sedimentation Sludge-Amended Soils by Komatsuna (Brassica rapa var. perviridis)

Abstract

Root uptake of ¹³⁷Cs from sedimentation sludge-amended soils by Komatsuna (Brassica rapa var. perviridis) was studied. The sludge was mixed to an initial soil mixture of Akadamatsuchi, Kurotsuchi and muck to produce three kinds of soils:0S soil(sludge:initial soil mixture=0L:5L), 0.5S soil(0.5L:4.5L), and 1.5S soil(1.5L:3.5L). Komatsuna was grown for 33 days on those soil mixtures. Plant height above ground was similar during cultivation period among three kinds of soils. Fresh weights of Komatsuna at harvest increased in order of the0S, the 1.5S, and the 0.5S soil sample. These results mean no growth suppression effect of the sludge on Komatsuna under our experimental conditions. Activities of ¹³⁷Cs in Komatsuna at harvest were 1.89Bq/kg-dry for the 0S sample, 153Bq/kg-dry for the 0.5S sample, and 400Bq/kg-dry for the 1.5S sample. The activities of radiocaesium(¹³⁴Cs+¹³⁷Cs) per unit wet weight for all the samples were below 100Bq/kg, which is the new standard limit for general foods by Japanese guidelines. The soil-plant transfer factor of ¹³⁷Cs was 0.1 for both the 0.5S and the 1.5S soil samples when the transfer parameters were given for dry weight. Similarly, the transfer factor was 0.007 on a wet weight basis. The transfer factor value for the sludge was within the range of the values reported in the previous report for leafy vegetable, which were investigated before the Fukushima Daiihci Nuclear Power Plant accident.