Many mineral P fertilizers contain toxic uranium (U) in high concentrations. When the fertilizers are applied to agricultural sites, U can either accumulate in the soil or leach to ground and surface waters. We analyzed the U fluxes at three arable and three grassland agricultural sites on the Swiss plateau for 1 year. We calculated all inputs and outputs to the soils, modeled the speciation of U in the soil solution and investigated the possible leaching of U along preferential flow paths. We found that all sites showed positive U budgets (+0.9–6.6 g ha–1 y–1), indicating an accumulation of U. However, the accumulation of U was low and a doubling of U concentration in the surface soil would need 850–2,660 years assuming today’s U fluxes. Mineral P fertilizers were the quantitatively most important input, followed by manure application and mineral weathering (only important in the soils developed on limestone). While at sites with slightly acidic pH only little U (<0.01 μg L–1) was leached, the U leaching increased at neutral pH values, because of the formation of carbonato-U complexes. In all soil solutions, the U concentrations (≤0.8 μg L–1) were below legal threshold values and comparable to local drinking and surface waters. We found no indication for enhanced U leaching along preferential flow paths.

中文翻译：

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瑞士农业系统中的铀预算和浸出

许多矿物磷肥都含有高浓度的有毒铀 (U)。当肥料施用于农业场地时，U 可能会在土壤中积累或浸出到地下水和地表水中。我们分析了瑞士高原 3 个耕地和 3 个草地农业点 1 年的 U 通量。我们计算了土壤的所有输入和输出，模拟了土壤溶液中 U 的形态，并研究了 U 沿着优先流动路径的可能浸出。我们发现所有地点都显示出正的 U 收支（+0.9-6.6 g ha-1 y-1），表明 U 的积累。然而，U 的积累很低，表层土壤中 U 浓度增加一倍需要 850 –2,660 年假设今天的 U 通量。矿物磷肥是数量上最重要的投入，其次是施肥和矿物风化（仅在石灰石上发育的土壤中很重要）。虽然在弱酸性 pH 值的地点，只有很少的 U (<0.01 μg L-1) 被浸出，但在中性 pH 值下，U 浸出量增加，因为形成了碳酸-U 复合物。在所有土壤溶液中，U 浓度（≤0.8 μg L-1）均低于法定阈值，与当地饮用水和地表水相当。我们没有发现沿优先流动路径增强 U 浸出的迹象。8 μg L-1) 低于法定阈值，与当地饮用水和地表水相当。我们没有发现沿优先流动路径增强 U 浸出的迹象。8 μg L-1) 低于法定阈值，与当地饮用水和地表水相当。我们没有发现沿优先流动路径增强 U 浸出的迹象。