Faculty of Agriculture, Utsunomiya University, Utsunomiya, 321-8505, Japan,
J Plant Res. 2014;127(1):73-8. doi: 10.1007/s10265-013-0614-y. Epub 2013 Dec 15.
The radioactive cesium ((134,137)Cs) concentration in brown rice is correlated with that in the straw/husk. The distribution of (134,137)Cs, resembles that of potassium (K), a homologous element of Cs, in the rice plant body. The relative isotopic abundance of (40)K is 0.0117 %; thus, 1 g K contains 30.4 Bq ⁴⁰K, and the mass of 4,000 Bq (40)K is 0.0154 g, indicating that the K concentration can be calculated from (40)K concentration. We examined if the radioactive Cs concentration in brown rice can be estimated from (40)K concentrations in straw, and especially might be predicted from the (40)K:(134,137)Cs ratio in straw. We determined the concentrations of (40)K and radioactive Cs in straw and brown rice, and found a strong correlated-equation (y = 72.922 x(-0.759); r = 0.907) between the radioactive Cs concentration in brown rice and the ⁴⁰K:(134,137)Cs ratio in straw. The estimated-radioactive Cs concentration in brown rice can be as much as double, depending on the K nutritional status changing the ⁴⁰K:(134,137)Cs ratio in straw. We herein propose a nutritional diagnosis that radioactive Cs concentrations in brown rice can be predicted from the ⁴⁰K:(134,137)Cs ratio in shoots.
糙米中的放射性铯(¹³⁴、¹³⁷Cs)浓度与稻草/外壳中的浓度相关。Cs 的同系元素钾(K)在水稻植株体内的分布与 Cs 相似。⁴⁰K 的相对同位素丰度为 0.0117%;因此,1g K 中含有 30.4Bq ⁴⁰K,4000Bq (⁴⁰)K 的质量为 0.0154g,表明可以根据 (⁴⁰)K 浓度计算出 K 浓度。我们检验了是否可以根据稻草中的 (⁴⁰)K 浓度估算糙米中的放射性 Cs 浓度,尤其是是否可以根据稻草中 (⁴⁰)K 与 (¹³⁴、¹³⁷)Cs 的比值来预测。我们测定了稻草和糙米中 (⁴⁰)K 和放射性 Cs 的浓度,发现糙米中放射性 Cs 浓度与稻草中 ⁴⁰K 与 (¹³⁴、¹³⁷)Cs 的比值之间存在很强的相关方程(y=72.922x(-0.759);r=0.907)。取决于 K 营养状况改变稻草中 ⁴⁰K 与 (¹³⁴、¹³⁷)Cs 的比值,糙米中估算的放射性 Cs 浓度可能高达两倍。我们在此提出一种营养诊断方法,即可以根据茎叶中 ⁴⁰K 与 (¹³⁴、¹³⁷)Cs 的比值来预测糙米中的放射性 Cs 浓度。