Smith B S, Child D P, Fierro D, Harrison J J, Heijnis H, Hotchkis M A C, Johansen M P, Marx S, Payne T E, Zawadzki A
GeoQuEST, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia.
Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia.
J Environ Radioact. 2016 Jan;151 Pt 3:579-86. doi: 10.1016/j.jenvrad.2015.06.015. Epub 2015 Sep 4.
Soil and sediment samples from the Sydney basin were measured to ascertain fallout radionuclide activity concentrations and atom ratios. Caesium-137 ((137)Cs) was measured using gamma spectroscopy, and plutonium isotopes ((239)Pu and (240)Pu) were quantified using accelerator mass spectrometry (AMS). Fallout radionuclide activity concentrations were variable ranging from 0.6 to 26.1 Bq/kg for (137)Cs and 0.02-0.52 Bq/kg for (239+240)Pu. Radionuclides in creek sediment samples were an order of magnitude lower than in soils. (137)Cs and (239+240)Pu activity concentration in soils were well correlated (r(2) = 0.80) although some deviation was observed in samples collected at higher elevations. Soil ratios of (137)Cs/(239+240)Pu (decay corrected to 1/1/2014) ranged from 11.5 to 52.1 (average = 37.0 ± 12.4) and showed more variability than previous studies. (240)Pu/(239)Pu atom ratios ranged from 0.117 to 0.165 with an average of 0.146 (±0.013) and an error weighted mean of 0.138 (±0.001). These ratios are lower than a previously reported ratio for Sydney, and lower than the global average. However, these ratios are similar to those reported for other sites within Australia that are located away from former weapons testing sites and indicate that atom ratio measurements from other parts of the world are unlikely to be applicable to the Australian context.
对悉尼盆地的土壤和沉积物样本进行了测量，以确定沉降放射性核素的活度浓度和原子比。使用伽马能谱法测量铯 - 137（¹³⁷Cs），并使用加速器质谱法（AMS）对钚同位素（²³⁹Pu和²⁴⁰Pu）进行定量。沉降放射性核素的活度浓度变化较大，¹³⁷Cs为0.6至26.1 Bq/kg，²³⁹⁺²⁴⁰Pu为0.02 - 0.52 Bq/kg。小溪沉积物样本中的放射性核素比土壤中的低一个数量级。尽管在较高海拔处采集的样本中观察到一些偏差，但土壤中¹³⁷Cs和²³⁹⁺²⁴⁰Pu的活度浓度具有良好的相关性（r² = 0.80）。土壤中¹³⁷Cs/²³⁹⁺²⁴⁰Pu（衰变校正至2014年1月1日）的比值范围为11.5至52.1（平均值 = 37.0 ± 12.4），且比先前的研究显示出更大的变异性。²⁴⁰Pu/²³⁹Pu原子比范围为0.117至0.165，平均值为0.146（±0.013），误差加权平均值为0.138（±0.001）。这些比值低于先前报道的悉尼比值，也低于全球平均值。然而，这些比值与澳大利亚其他远离前武器试验场的地点所报道的比值相似，表明世界其他地区的原子比测量结果不太可能适用于澳大利亚的情况。
