添加碳酸钙对土壤中镉形态转化与玉米叶片镉组分的影响

EFFECTS OF CALCIUM CARBONATE ADDITION ON TRANSFORMATION OF CADMIUM SPECIES IN SOIL AND CADMIUM FORMS IN LEAVES OF MAIZE

采用土壤培养、盆栽试验及连续提取测定等方法研究添加碳酸钙对外源镉在棕壤中的转化与玉米叶片镉组分的影响。与不加碳酸钙处理比较，添加碳酸钙处理土壤交换态镉含量显著下降，专性吸附态镉、铁锰氧化物结合态镉和残余态镉含量显著增加；添加碳酸钙处理可显著增加土壤ｐＨ、土壤饱和浸提液［Ｃａ２十］及［Ｃａ２十］／［Ｃｄ２十］，并显著降低饱和浸提液［Ｃｄ２＋］碳酸钙处理玉米根、茎、叶干重和全钙量显著增加，全镉含量及叶片Ｈ２Ｏ提取镉、２ｍｏｌ Ｌ－１ ＮａＮＯ３提取镉、１０％ＨＯＡｃ提取镉、２ｍｏｌ Ｌ－１ ＨＣＩ提取镉和残余镉含量均明显减少。上述结果显示，添加碳酸钙可降低土壤─植物体系的镉毒害。

Pot experiment, laboratory culture and the sequential extraction procedures for the speciation of Cd in soil and plant were used to study the effects of calcium carbonate (CaCO3) addition on transformation of cadmium (Cd) species in a brown soil added with Cd and change of Cd forms in leaves of maize. Compared to no CaCO3 addition, CaCO3 addition could lower content of exchangeable Cd, but increase the specifically adsorbed Cd, Cd bound to iron and manganese oxides, and residual Cd in the soil significantly. In presence of CaCO3, soil pH, and [Ca2+] and [Ca2+] / [Cd2+] in saturation extracts increased, while [Cd2+] decreased, significantly. It was also found that dry weight and total Ca content of roots, stems and leaves of maize significantly increased, While the contents of total Cd, extractable Cd (H2O, 2mol L-1 NaNo3, 10% HOAc and 2mol L-1 HCI) and residual Cd obviously decreased with adding CaCO3. It was concluded that Cd toxicity in soil-plant system could be alleviated by CaCO3 addition.