外源铅在红壤中的迁移和形态转化

Transportation and Form Transformation of Water-Soluble Pb in Red Soil

[目的]为污染土壤的控制和修复治理提供科学依据。[方法]采用实验室土柱法,研究外源铅在红壤中的迁移和形态转化。[结果]在水分不饱和条件下,外源水溶性铅进入红壤90 d后并未向15～30 cm土层迁移,而是集中在0～15 cm层次;外源水溶性铅进入红壤(0～15 cm)30 d后水溶态迅速向其他形态转化,其形态分布主要以交换态为主,其次为铁锰氧化物态、残渣态、碳酸盐结合态、有机结合态(未检出)。[结论]外源铅进入红壤90 d后绝大部分还未转化为相对稳定的形态,对土壤—植物系统的污染存在着潜在的危害。红壤(0～15 cm)对外源铅的吸附主要通过离子交换和络合(或螯合)作用。

[Objective]The research aimed to provide scientific basis for the control and remediation of soil pollution.[Method]Transportation and form transformation of water-soluble Pb in red soil were simulated by laboratory soil column tests.[Result]Exotic Pb entered soil concentrated mostly on the stratum in depth 0-15 cm and hadn＇t migrated on the stratum at unsaturated condition in depth 15-30 cm after ninety days.Water-soluble Pb added to soil were rapidly transformed to other forms,exotic Pb mainly existed in exchangeable fraction,secondly existed in Fe/Mn oxide bounded fraction,residual fraction,carbonate fraction,organic bound fractionin depth 0-15 cm after thirty days.[Conclusion] Exotic Pb hadn＇t changed into more stable fractions after ninety days which had potential harm for soil-plant system.The absorption mechanism on Pb of red soil mainly existed in ion exchange and complexation（chelation）.