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为研究不同示踪源层材料对水份运移和核素迁移的影响 ,开展了以石英砂和黄土分别为示踪源层载体时 Sr、Nd、Ce在包气带中迁移的对比试验。试验历时 4 70 d,在两种源层条件下各取土芯样 4次。试验结果表明 :在喷淋强度为 5 mm/h、3h/d条件下 ,Nd和 Ce无论在石英砂示踪源层还是黄土示踪源层中浓度峰位均没有明显向下迁移 ;对于 Sr,在黄土示踪源层中 ,4 70 d后其峰位向下迁移约 15 cm(按质心计算为 10 cm左右 ) ,而从石英砂示踪源层中向下迁移不明显 (按质心计算 ,迁移约 2 .7cm) ,只是峰位有些展宽。上述结果表明 ,极薄 (7mm)的细石英砂层也能对非饱和入渗水产生明显屏流作用 ,使得核素从石英砂示踪源层中向下迁移速度减慢。
In order to study the influence of source material of different tracers on water migration and nuclide migration, a comparative experiment on the migration of Sr, Nd, Ce in the gas-bearing zone with quartz sand and loess as the carrier of the tracer source was carried out. The test lasted 4 70 d, taking earth core sample 4 times under the condition of two kinds of source layers. The experimental results show that there is no obvious downward migration of Nd and Ce peaks in the source layer of quartz sand or loess source layer under the conditions of 5 mm / h and 3 h / d, , The peak position of loess tracer migrates about 15 cm (about 10 cm according to the centroid) after 4 70 days and does not migrate downward from the quartz sand tracer source layer (calculated by the center of mass , Migrate about 2 .7cm), but some peak broadening. The above results show that the ultrathin (7mm) fine quartz sand layer can also have a significant screen flow to unsaturated infiltration water, causing the downward migration of nuclides from the quartz sand tracer source layer.