施加石灰降低不同母质土壤中镉毒性机理研究

The Mechanism of Detoxification of Cadmium After Liming in Soils

研究了土壤施加石灰后对镉的形态转化和迁移的影响。结果表明，水溶态镉随石灰用量的增加而急剧减少，ｐＨ＞７．５时９４％以上的水溶态镉进入土壤中；交换态镉在ｐＨ＜５．５时随石灰用量的增加而增加，ｐＨ＞５．５时随石灰用量增加而急剧减少；有机结合态镉在ｐＨ＜５．５时随石灰用量的增加而增加，ｐＨ＞５．５时随石灰用量增加而急剧减少；粘土矿物和氧化物结合态镉随石灰用量的增加而增加；残留态镉随石灰用量的增加而增加。ｐＨ＞７．５时镉主要以粘土矿物和氧化物结合态及残留态形式存在，ｐＨ７．５时粘土矿物和氧化物结合态及残留态的含量在旱地黄筋泥、水田黄筋泥、旱地红砂土、水田红砂土中分别高达９４％，８５％，７７％，５９％，其是导致镉毒性降低的主要原因。

Effects of liming on the transformation and distribution of cadmium formations in soils were studied. The soluble cadmium decreased sharply with the increase in lime application. More than 94% of the soluble cadmium was adsorbedby soils at pH>7.5. The amount of exchangeable and organic cadmium increased at pH<5.5 and decreased sharply at pH>5.5. The cadmium bound to clays and oxides as well as residual cadmium increased with the increase of lime application. When the soil pH value was at 7.5, the bound and residual cadmium took 94%, 85%, 77% and 59% of the total soil cadmium in red clayey upland soil, red clayey paddy soil, red sandy upland soil and red sandy paddy soil,respectivity, which was the cause of detoxification of cadmium in soils.