Abstract: Soil acidification is a critical factor influencing the activity and chemical form distribution of heavy metals. Acid rain is one of the main causes of soil acidification. To comprehensively summarize the effects of acid rain on the remediation effectiveness (stability and form changes) of amendments for soils contaminated by heavy metals, a meta-analysis was conducted with 59 published studies. The results showed that adding amendments under the influence of acid rain could significantly reduce the total leaching of heavy metals from soil by an average of 66.40%. The exchangeable and carbonate-bound forms of heavy metals  reduced by 43.02% and 11.17%, respectively, while the iron-manganese oxide-bound, organic matter-bound, and residual forms was increased by 12.33%, 14.20%, and 27.71%, respectively.  The composite material-type amendments exhibited superior remediation effects compared with single-component ones. The fixation and stabilization of soil heavy metals through amendments were influenced by both soil environmental conditions and its intrinsic properties. The optimal stabilizing effect of amendments on soil heavy metals was observed when soil pH is maintained between 5.5 and 6.5, with a CEC value below 15.4 cmol·kg^-1, organic matter content ranging from 30 to 40 g·kg^-1, clay content exceeding 35%, amendment pH between 6 and 8, and amendment concentration within the range of 20 to 30 g·kg^-1. These findings provide valuable insights for more effectively remediating heavy metalcontaminated soils affected by acid rain based on specific local conditions.

Key words: amendment, heavy metal pollution, acid rain, soil