## 3 Results and Discussion
### Mechanism Involved in the Transmission of ARGs  
#### 3.2.1 Microbial Community  
As illustrated in Figure 4, Pb concentrations of 2.5 g/kg, 5 g/kg, and 10 g/kg significantly influenced soil microbial communities. Specifically, these Pb levels enhanced the relative abundance of dominant soil genera while suppressing _Gp6_ and _Gp4_. Compared to PS2.5, Imvite treatment resulted in a slight increase in the relative abundances of Acidobacteria and Bacteroidetes, but a reduction of 18.68% in Actinobacteria. Conversely, MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) treatment led to a 20.39% increase in Firmicutes. [PERSON] et al. [30] noted that genus of potential ARG host bacteria, including _Bacillus_, _Acinetobacter_, _Mycobacterium_, and _Staphylococcus_, are often found among Bacteroides, Chloroflexi, and Firmicutes, all of which were identified as potential ARG hosts. Given that many pathogenic bacteria are classified within Firmicutes, the application of MgO and Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) may substantially enhance ARGs proliferation in Pb-contaminated soils, thereby elevating potential risks to human health. In the Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) system, the relative abundance of Proteobacteria increased by 19.07%. However, in the BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) system, Proteobacteria abundance significantly decreased compared to Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) (Figure 4a). Acidobacteria abundance also declined in BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) relative to BES. Previous studies suggested that Proteobacteria and Acidobacteria were key hosts of ARGs [31], and the reduction in their relative abundances in BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) likely contributed to the observed decrease in ARGs. Overall, the synergistic remediation involving composite agents and BES primarily inhibited Proteobacteria and Acidobacteria. In contrast, while dominant genera declined in Imvite, their relative abundances increased in MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) and Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) systems. For instance, the abundances of _Sphingomonas_, _Arthobacter_, _Nocardioides_, _Gp4_, and _Blastococcus_ decreased significantly in Imvite (Figure 4b), whereas Truepera, Hydrogenphaga, and Fontibacter increased by 4-5% in MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\). [PERSON] et al. [32] also identified _Bacillus_ as Pb-resistant. In the Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) system, _Alishewanella_, _Pseudomonas_, _Hyphomonas_, and _Hydrogenophaga_ increased by 6-10%, suggesting that the added remediation agents substantially influenced the distribution of resistance genes by affecting genera like _Sphingomonas_, _Arthobacter_, and _Gp6_. The BES5-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) system exhibited higher abundances of Actinobacteria, Proteobacteria, and Bacteroides compared to BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) and BES10-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) (Figure 4a), indicating that composite remediation combined with BES had a more pronounced impact on these bacterial phyla. Additionally, _Tenericutes_ reached its highest relative abundance in BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\), signifying a shift in dominant bacterial taxa after remediation. The relative abundance of _Alishewanella_ increased by 10.88% in BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) compared to Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\), while _Hydrogenophaga_ and _Pseudomonas_ significantly decreased. Moreover, _Alishewanella_ and _Truepera_ increased by 18.77% and 9.11% in BES-Imvite-MgO-Ca(H\({}_{2}\)PO\({}_{4}\))\({}_{2}\) compared to BES, whereas _Gp16_ and _Mycobacterium_ declined by approximately 10%. These changes suggested that synergistic remediation enhanced beneficial genera, such as _Alishewanella_ and _Truepera_, while inhibiting pathogenic bacteria, including _Pseudomonas_ and _Mycobacterium_.