Abstract: To scientifically evaluate the solidification/ stabilization efficacy for lead (Pb) and nickel (Ni) co-contaminated
soil at a construction site in Yunnan,this study investigated the performance of lime,sulfate-reducing bacteria (SRB),and
their combined application through laboratory solidification experiments,chemical analysis,and in vivo tests. The remediation
effectiveness was comprehensively assessed using available content,relative bioavailability (RBA),and non-carcinogenic risk
quotient (HQ). The results showed that after 30 days of remediation with 11% lime,the reduction rates of Pb and Ni bioavailability
in low,medium,and high-level contaminated soils were 91% & 90%,86% & 87%,and 81% & 79%,respectively. Subsequent
inoculation with 10% (by valume) SRB for another 30 days further enhanced the reduction rates to 93. 57% &
92. 34% and 89. 77% & 89. 79% for the medium and high-level contaminated soils,respectively. In vivo tests revealed that
compared to the original highly contaminated soil (RBA:64. 82% for Pb,67. 47% for Ni),the RBA of Pb and Ni decreased to
32. 72% and 37. 63% after lime treatment,and further declined to 21. 44% and 25. 84% after the combined lime-SRB treat
ment. The non-carcinogenic risk assessment indicated that after combined remediation,the HQCS values of Pb for adults and
children were 0. 77 and 0. 86 (acceptable level),respectively,while those for Ni were 0. 95 (adults) and 1. 07 (children),
indicating an unacceptable health risk for children from residual Ni. This study confirms that the combined lime-SRB technology
effectively immobilizes Pb and Ni in soil and reduces their bioavailability. However,the potential health risk of Ni to children
after remediation requires attention. The integrated evaluation system combining bioavailability and health risk provides a
more scientific basis for assessing the remediation effectiveness of contaminated soils in construction sites.