Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden.
Department of Soil and Environment, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden; Swedish Geotechnical Institute, Kornhamnstorg 61, SE-111 27 Stockholm, Sweden.
Chemosphere. 2019 May;222:453-460. doi: 10.1016/j.chemosphere.2019.01.148. Epub 2019 Jan 28.
Laboratory-based leaching tests are frequently used for in situ risk assessments of contaminant leaching to groundwater and surface waters. This study evaluated the ability of three standardised leaching tests to assess leaching of lead (Pb), zinc (Zn), arsenic (As) and antimony (Sb) from four intact soil profiles, by considering particulate (0.45-8 μm; percolation test), colloidal (10 kDa-0.45 μm) and truly dissolved (<10 kDa) fractions of these elements. Deionised water was used as the percolation test leachant, while either deionised water or 1 mM CaCl was used in batch tests. Data from an irrigation experiment were used as reference. The results indicated that in percolation tests, leachate should be collected at a liquid:solid ratio (L/S) range of 2-10, instead of 0-0.5 or 0.5-2. Even at L/S = 2-10, the percolation test overestimated total Pb concentration, mainly because of greater mobilisation of particle-bound Pb, but appeared suitable for categorising soils into high/low risk with respect to mobilisation of particulate and colloidal contaminants. The batch test performed better with CaCl than with deionised water when standard membrane filtration (0.45 μm) was used, as the high Ca concentration reduced colloidal mobilisation, avoiding overestimation of concentrations of elements such as Pb. However, the higher Ca concentration and lower pH could result in overestimated concentrations of weakly sorbed elements, e.g. Zn.
实验室浸出试验常用于原位评估污染物对地下水和地表水的浸出风险。本研究通过考虑这些元素的颗粒（0.45-8 μm；渗滤试验）、胶体（10 kDa-0.45 μm）和真正溶解（<10 kDa）分数，评估了三种标准化浸出试验评估从四个完整土壤剖面中浸出铅（Pb）、锌（Zn）、砷（As）和锑（Sb）的能力。渗滤试验的淋洗剂采用去离子水，而批量试验则采用去离子水或 1 mM CaCl。灌溉试验的数据用作参考。结果表明，在渗滤试验中，淋出液应在液体：固体比（L/S）范围为 2-10 时收集，而不是在 0-0.5 或 0.5-2 时收集。即使在 L/S=2-10 时，渗滤试验也高估了总 Pb 浓度，主要是因为颗粒结合态 Pb 的迁移率更大，但似乎适合根据颗粒和胶体污染物的迁移能力将土壤归类为高/低风险。当使用标准膜过滤（0.45 μm）时，与去离子水相比，CaCl 的批量试验性能更好，因为高 Ca 浓度降低了胶体的迁移率，避免了对 Pb 等元素浓度的高估。然而，较高的 Ca 浓度和较低的 pH 值可能导致对弱吸附元素（如 Zn）的浓度高估。
