The effects on the physical and chemical properties of two kinds of improved methods,topsoil mixed and sludge covering,were studied using dewatered sludge as saline-alkali soil ameliorant.The results of field improvement experiment for two years show that with the dewatered sludge usage of 10 kg · m-2,the mixed treatment was much better than the covering treatment; the soil bulk density was effectively reduced by ca 25％ ; the soil exchange sodium percentage was reduced more than 10％ ; the soil organic matter content doubled; the nitrogen and phosphorus content in the soil increased.Heavy metal concentrations in soil were below the Soil Environmental Quality Standard (GB15618-1995) (Dry land soil pH ＞ 7.5,secondary standard) and existed in residual form.Except the As activity became stronger,the other heavy metals tended to be more stable.%以脱水污泥为盐碱土改良剂,研究污泥与表土翻混及污泥表面平涂两种改良方式对盐碱化土壤理化性质的改良效果.为期2年的田间改良实验结果表明,以10 kg·m-2的量施加脱水污泥改良盐碱化土壤,翻混的效果明显好于平涂,可有效降低土壤容重25％左右,降低土壤碱化度10％以上,同时使土壤有机质含量提高了1倍左右,并明显增加了土壤中的氮磷含量.改良后土壤中重金属含量低于土壤环境质量标准(GB15618-1995)(旱地土壤pH ＞7.5,二级标准)最高允许浓度指标值,且多以稳定的残渣态存在,除As有活性变强的趋势外,其余重金属均趋于向更稳定的形态转化.
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