石灰和磷酸盐结合稳定石灰性重金属污染土壤的研究

Immobilization of heavy metals in calcareous polluted soils with lime and phosphate

为了探讨磷酸盐和石灰对重金属污染土壤的稳定效果,采用铅冶炼污染石灰性土壤(镉、铜、铅和锌全量分别为4.12、81.0、455和115 mg·kg^(-1))、设置磷酸盐和3个不同石灰用量及磷酸盐和石灰同时施用及间隔15 d施用的处理,培养后测定土壤性质。结果表明,两种添加剂间隔15 d施用且石灰用量为250和500 mg·kg^(-1)时,土壤pH和磷有效性均高于同时施用处理。两种添加剂间隔15 d施用时,土壤镉有效性显著低于二者同时施用时(P<0.05,低6.63%~11.82%)、土壤锌有效性显著高于同时加入的处理(P<0.05,高17.64%~28.39%)。两种添加剂的不同施用方式对土壤铅和铜的有效性影响较小。石灰用量为1000 mg·kg^(-1)且两种添加剂间隔15 d施用时,土壤镉和铅有效性最低。以上说明,对于石灰性镉污染土壤,磷酸盐和石灰的施用方式对土壤镉的稳定效果存在重要影响。

To investigate the effect of lime and phosphate on the immobilization of heavy metals in lead-smelting polluted soils.A lead-smelting polluted soil(total concentrations of cadmium,copper,lead and zinc were 4.12,81.0,455 and 115 mg·kg^(-1),respectively)was amended with phosphate and lime(250,500 and 1000 mg·kg^(-1))and the lime was added simultaneously or with a 15 d interval with phosphate amendment.After incubation,the soil was analyzed.The results indicated that,when lime was added at 250 and 500 mg·kg^(-1) and with a 15 d interval with phosphate amendment,soil pH and Olsen-P concentrations were greater than those when they were added simultaneously;when the two additives were added with a 15 d interval,the DTPA-Cd concentrations were significantly less(6.63%~11.82%)than that when they were added simultaneously(P<0.05),however,the DTPA-Zn concentrations of soils amended with a 15 d interval were 17.64%~28.39%greater than that without the interval(P<0.05).The DTPA-Pb and DTPA-Cu concentrations were not affected by the way the additives added.Judged by the variation of soil Cd and Pb availabilities,amendment of the soil with phosphate and 1000 mg·kg^(-1) lime with a 15 d interval is the optimal immobilization method for the soil studied.The results of this work suggest that,the methodology by which the phosphate and lime are added into soil is crucial for the cadmium immobilization in polluted calcareous soils.