钙镁硅调理剂对镉污染稻田细菌和T4噬菌体群落的影响及镉钝化效果OA

Addressing key scientific issues regarding the unclear temporal effects,insufficient stability,and poorly understood mechanisms of soil Cd immobilization by conditioners on soil ecological health,this study employed a continuous seven-year field trial applying the Ca-Mg-Si conditioner(CMC).Utilizing a two-year cessation period followed by continuous monitoring,the trial used the rice variety Xiushui 14 as an indicator crop.Treatments included a control group(CK),low-dose treatment group(1 500 kg/hm2 CMC,denoted as L),and high-dose treatment group(3 000 kg/hm2 CMC,denoted as H).This study systematically analyzed the response processes of soil physicochemical properties,Cd speciation transformation,and the bacteria-T4 bacteriophage ecological network to CMC application.The results showed that two years after discontinuing CMC application,the soil pH in two treatment groups was significantly higher than those in the control group(P＜0.05).Cd speciation underwent directed transformation:the exchangeable Cd(Exc-Cd)decreased by 18.92%in the L group,while carbonate-bound Cd(CB-Cd)increased by 3.64%.In the H group,Exc-Cd decreased by 10.81%,and Fe-Mn oxide-bound Cd(IMOX-Cd)increased by 18.75%,achieving effective transformation of Cd from highly reactive to less reactive forms.CMC treatment significantly reshaped soil bacterial community structure.Group L exhibited highly differentiated characteristics at the phylum level(P＜0.001),specifically,the relative abundances of Proteobacteria and Planctomycetota were significantly lower than that in the control group.Within the T4 bacteriophage community,the relative abundance of Uroviricota was significantly lower in the two treatment groups than in the control group(P＜0.001),while Artverviricota in Group L and Negarnaviricota in Group H exhibited specific enrichment patterns,with Negarnaviricota in Group H being significantly higher than that in the control group(P＜0.01).The Mantel test revealed that both bacteria and T4 bacteriophages exhibited significant responses to total soil Cd,water-soluble Cd(WS-Cd),Exc-Cd,CB-Cd,and IMOX-Cd in the soil environment(P＜0.01);network analysis revealed that bacteria and T4 bacteriophages formed complex interaction networks(161 negative connections and 45 positive connections),where Actinobacteriota,Acido-bacteriota,and Chloroflexi formed a high-density connection module(56.1%)with the bacteriophage community,primarily concentrated in Uroviricota,constituting the core ecological network responding to Cd pollution.Metabolic pathway reconstruction using the PICRUSt2 functional prediction platform revealed a significant positive correlation between histidine kinase activity and IMOX-Cd content(P＜0.05),highlighting the pivotal role of enzymatic catalysis in Cd speciation.Quantitative assessment using random forest algorithm and soil quality index area(SQI-area)method indicated that low-dose CMC treatment achieved the optimal balance between soil Cd immobilization and ecological health.This provides a scientific basis and practical guidance for establishing a precision remediation technology system for Cd-contaminated soils based on viral ecology.