典型土壤中有效态镉CaCl_2提取条件优化研究

Optimization of CaCl_2 Extraction of Available Cadmium in Typical Soils

为了研究CaCl2提取不同类型土壤中有效态镉的优化条件,以中国南方酸性水稻土和西北中偏碱性灰钙土为研究对象,探讨不同浓度CaCl2提取剂和不同提取时间对2种土壤中镉提取量的影响。结果表明,CaCl2提取的镉主要为土壤中的水溶态镉与部分交换态镉;0.01mol/LCaCl2浸提下,酸性水稻土在3h达到平衡,提取量占土壤中水溶态与交换态镉含量之和的4.68%～54.90%,灰钙土仅需1h就达到平衡,但提取量占土壤中水溶态与交换态镉含量之和的3.60%～3.89%;0.1mol/LCaCl2浸提下,水稻土需12h才达到平衡,提取量占土壤中水溶态与交换态镉含量之和的83.28%～90.32%,灰钙土3h达到平衡,提取量占土壤中水溶态与交换态镉含量之和的44.21%～45.26%;提取剂CaCl2浓度越高,镉提取量就越大,达到平衡所需要的时间也越长;0.1mol/LCaCl2比0.01mol/LCaCl2更适宜酸性水稻土和中偏碱性灰钙土有效态镉的提取,水稻土和灰钙土所需的提取时间分别为12h和3h。

In order to study the optimal conditions for extracting available cadmium from different types of soil with CaCl2, different concentrations of CaCl2 were used to extract available cadmium from sierozem and paddy soil with different extraction times. The results showed that： the extracted cadmium by CaCl2 was water-soluble and exchangeable cadmium, and the extracted contents increased with the time prolonged. The extracted cadmium by 0.01 mol/L CaCl2 from paddy soil reached equilibrium after 3 h and accounted for 4.68%-54.90% of the sum of water-soluble cadmium and exchangeable cadmium; the extracted cadmium by 0.01 mol/L CaCl2 from sierozem reached equilibrium after 3 h and accounted for 3.60%-3.89% of the sum of water-soluble cadmium and exchangeable cadmium; the extracted cadmium by 0.1 mol/L CaCl2 from paddy soil reached equilibrium after three hours and accounted for 83.28%-90.32% of the sum of water-soluble cadmium and exchangeable cadmium; the extracted cadmium by 0.01 mol/L CaCl2 from paddy soil reached equilibrium after 3 h and accounted for 44.21%-45.26% of the sum of water-soluble cadmium and exchangeable cadmium. It indicated that 0.1 mol/L CaCl2 was more suitable than 0.01 mol/L CaCl2 in available cadmium extracting for paddy soil and sierozem , and their equilibrium time was 12 h and 3 h, respectively.