Objective  The experiments were carried out to explore the passivation effect of passivators including CaCO₃, CaO and CaSiO₃ on mercury (Hg) contaminated soil and Hg contents in peppers.

  Method  A pot experiment was conducted to study the effects of three passivators on the pH, Hg and the biological availability of Hg in soil which was collected from Wanshan Mercury Mine in Guizhou Province. Besides, the Hg contents and Hg transport coefficient in pepper plants driven by exogenous passivators were investigated.

  Result  The applications of CaCO₃, CaO and CaSiO₃ could increase respectively pH of soil by 0.74-2.28, 2.11-5.36 and 1.79-2.62. The three passivators could decrease the contents of active state and biological Hg availability and increase the contents of residual form Hg in soil. The application of calcium oxide has the best effect on reducing the effective Hg in soil, and its proper amount was 0.1%. The application of three passivators reduced the effective Hg contents in pepper root, stem and fruit. The Hg content of pepper root, stem and fruit decreased with the application of passivators, the pepper leaf was opposite. The effects of the three passivators on Hg transport in pepper tissues were varied. The three passivators promoted the transport of Hg from capsicum root to stem, and they also promoted the transport of Hg from capsicum root to leaf, but inhibited the transport of Hg from capsicum root to fruit.

  Conclusion  All of the three passivators can be used as passivation materials for the remediation of Hg-contaminated soil. In general, the remediation effect of CaO is the best, and its proper amount is 0.1%, which is worth popularizing and applying.