外源铅在土壤中的形态、分布及其对土壤养分的影响

Form and Distribution of Exogenous Pb in Soil and Its Effect on Soil Nutrition

通过对加入外源铅的砂姜黑土、黄褐土、红壤进行培养处理,测定土壤中各形态铅及水溶态NH4+,K+和速效态磷的含量,研究外源铅在各类土壤中的形态分布特点及对土壤养分的影响。结果表明:交换态和残渣态的铅为红壤>黄褐土>砂姜黑土,碳酸盐态铅为砂姜黑土>黄褐土>红壤,铁锰氧化态铅为红壤>砂姜黑土>黄褐土,有机结合态铅为黄褐土>砂姜黑土>红壤;交换态和残渣态所占比例随着外源铅的浓度增大而提高,有机结合态的比例随着外源铅浓度增大降低,碳酸盐结合态铅在砂姜黑土、铁锰氧化态铅在红壤上则呈现外源铅小于500 m g/kg时比例增高,大于500 m g/kg时比例开始下降的状况;加入外源铅的土壤中,水溶态的NH4+和K+的浓度增大,使其流失的风险性增加;水溶态磷和铅离子生成难溶性磷酸铅盐被固结,使速效磷的浓度减少,降低了水溶性磷肥的功效。

The content of lead of all forms and water-soluble NH^＋ ,K^＋ as well as rapidly available phosphorus was determined through the cultivation of Sajiang black soil, yellow cinnamon soil and red earth with added lead. The feature of form and distribution of added lead and the effect it made to soil nutrient was studied. The result showed： the contents of lead of exchangeable form and residual form were red earth〉yellow cinnamon soil〉 Sajiang black, the contents of carbonate lead were red earth〉 Sajiang black soil〉 yellow cinnamon soil, the contents of Fe-Mn oxide-bound lead were red earth〉 Sajiang black soil〉 yellow cinnamon soil, and the contents of organic combined lead were red earth〉 Sajiang black soil〉 yellow cinnamon soil; the proportion of lead of exchangeable form and residual form rose as the added lead increased, while that of organic combined form lead reduced, the proportion of carbonate combined form lead in Sajiang black soil and that of Fe-Mn oxide-bound form lead in red earth, however, rose as the lead increased when the added lead is less than 500 mg/kg, and reduced when the added lead was more than 500 mg/kg. In the soil where extra lead was added, the concentration of water-soluble NH^＋, K^＋ rose which increase the risk of efflux. Water-soluble phosphorus and lead ion was consolidated into undissolved lead phosphate, that reduce the concentration of rapidly available phosphorus, decrease the effect of water-soluble phosphorus.