Payne Timothy E, Harrison Jennifer J, Hughes Catherine E, Johansen Mathew P, Thiruvoth Sangeeth, Wilsher Kerry L, Cendón Dioni I, Hankin Stuart I, Rowling Brett, Zawadzki Atun
Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, Sydney, New South Wales 2232, Australia.
Environ Sci Technol. 2013;47(23):13284-93. doi: 10.1021/es403278r. Epub 2013 Nov 20.
Radioactive waste containing a few grams of plutonium (Pu) was disposed between 1960 and 1968 in trenches at the Little Forest Burial Ground (LFBG), near Sydney, Australia. A water sampling point installed in a former trench has enabled the radionuclide content of trench water and the response of the water level to rainfall to be studied. The trench water contains readily measurable Pu activity (~12 Bq/L of (239+240)Pu in 0.45 μm-filtered water), and there is an associated contamination of Pu in surface soils. The highest (239+240)Pu soil activity was 829 Bq/kg in a shallow sample (0-1 cm depth) near the trench sampling point. Away from the trenches, the elevated concentrations of Pu in surface soils extend for tens of meters down-slope. The broader contamination may be partly attributable to dispersion events in the first decade after disposal, after which a layer of soil was added above the trenched area. Since this time, further Pu contamination has occurred near the trench-sampler within this added layer. The water level in the trench-sampler responds quickly to rainfall and intermittently reaches the surface, hence the Pu dispersion is attributed to saturation and overflow of the trenches during extreme rainfall events, referred to as the 'bathtub' effect.
1960年至1968年期间，含有几克钚（Pu）的放射性废物被倾倒在澳大利亚悉尼附近小森林墓地（LFBG）的壕沟中。在一条旧壕沟中安装的一个水采样点，使得能够对壕沟水的放射性核素含量以及水位对降雨的响应进行研究。壕沟水中含有易于测量的钚活度（在经0.45μm过滤的水中，（239+240）Pu约为12 Bq/L），并且表层土壤中存在相关的钚污染。在壕沟采样点附近的一个浅层样本（0-1厘米深度）中，土壤中（239+240）Pu的最高活度为829 Bq/kg。在远离壕沟的地方，表层土壤中钚浓度升高的区域向下坡延伸数十米。更广泛的污染可能部分归因于处置后的头十年中的扩散事件，之后在壕沟区域上方添加了一层土壤。自那时以来，在这一添加层内靠近壕沟采样器的地方又发生了进一步的钚污染。壕沟采样器中的水位对降雨反应迅速，并且间歇性地达到地表，因此钚的扩散归因于极端降雨事件期间壕沟的饱和与溢流，即所谓的“浴缸”效应。
