Forest (re)vegetation impact on <226>Ra cycling in U-mining area
In revegetated contaminated area such as former U- mining sites, the long-term vegetation impact on the radioactivity dissemination is still few documented. Ca is required in large amounts by trees with possible effect on <226>Ra uptake. In this study, we compared the Ca and <226>Ra redistribution by 37- years Scots pine developped on an afforested U-mining heap and we quantified the recycling dynamics of both elements in terms of annual fluxes. Both elements mainly accumulated in ligneous organs (stem + branches) but our results provided further evidence of a preferential retention of <226>Ra in stemwood on exchange sites of xylem tissues. The net root uptake of <226>Ra amounted to 24 kBq·ha<-1>·y<-1>, i. e. less than 0.002％ of the NH<,4>-exchangeable <226>Ra pool in the soil (0-30cm). The efficiency of <226>Ra uptake by trees was shown to be 400 times less than that of Ca and could be ascribed to the high level of available Ca in the mining debris and the resultant competitive interaction for uptake. The rate of <226>Ra redistribution through vegetation was low and largely ruled by soil properties involving a high Ca availability for root uptake which dominates over discrimination effects in favor of <226>Ra retention in stemwood.
calcium cycling mining sites pine phytostabilization radium
Y. Thiry M. Van Hees
Biosphere Impact Studies, SCK CEN, Belgian Nuclear Research Center,2400 Mol, Belgium
国际会议
第九届痕量元素生物地球化学国际会议(9th International Conference on the Biogeochemistry of Trace Elements)
北京
英文
449-450
2007-07-15（万方平台首次上网日期，不代表论文的发表时间）