Knight B P, Chaudri A M, McGrath S P, Giller K E
Soil Science Department, IACR-Rothamsted, Harpenden, Herts, AL5 2JQ, UK.
Environ Pollut. 1998;99(3):293-8. doi: 10.1016/s0269-7491(98)00021-9.
A rapid method for extracting soil solutions using porous plastic soil-moisture samplers was combined with a cation resin equilibration based speciation technique to look at the chemical availability of metals in soil. Industrially polluted, metal sulphate amended and sewage sludge treated soils were used in our study. Cadmium sulphate amended and industrially contaminated soils all had > 65% of the total soil solution Cd present as free Cd2+. However, increasing total soil Cd concentrations by adding CdSO4 resulted in smaller total soil solution Cd. Consequently, the free Cd2+ concentrations in soil solutions extracted from these soils were smaller than in the same soil contaminated by sewage sludge addition. Amendment with ZnSO4 gave much greater concentrations of free Zn2+ in soil solutions compared with the same soil after long-term Zn contamination via sewage sludge additions. Our results demonstrate the difficulty in comparing total soil solution and free metal ion concentrations for soils from different areas with different physiochemical properties and sources of contamination. However, when comparing the same Woburn soil, Cd was much less available as Cd2+ in soil solution from the CdSO4 amended soils compared with soil contaminated by about 36 years of sewage sludge additions. In contrast, much more Zn was available in soil solution as free Zn2+ in the ZnSO4 amended soils compared with the sewage sludge treated soils.
一种使用多孔塑料土壤水分采样器提取土壤溶液的快速方法与基于阳离子树脂平衡的形态分析技术相结合，以研究土壤中金属的化学有效性。我们的研究使用了工业污染土壤、添加金属硫酸盐的土壤和经过污水污泥处理的土壤。添加硫酸镉的土壤和受工业污染的土壤中，土壤溶液中总镉的65%以上以游离Cd2+的形式存在。然而，通过添加硫酸镉增加土壤总镉浓度会导致土壤溶液中总镉含量降低。因此，从这些土壤中提取的土壤溶液中游离Cd2+的浓度低于添加污水污泥的相同土壤。与通过添加污水污泥长期受锌污染的相同土壤相比，添加硫酸锌后土壤溶液中游离Zn2+的浓度要高得多。我们的结果表明，比较来自不同地区、具有不同理化性质和污染源的土壤的土壤溶液总量和游离金属离子浓度存在困难。然而，在比较同一沃本土壤时，与添加了约36年污水污泥的污染土壤相比，添加硫酸镉的土壤溶液中Cd2+的有效性要低得多。相比之下，与经过污水污泥处理的土壤相比，添加硫酸锌的土壤溶液中游离Zn2+的有效性要高得多。
