## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Catalase** & **Urease** & **Sucarse** & **Phosphatase** \\ \hline TF-Cd & 0.254 & \(-\)0.174 & \(-\)0.632 & 0.371 \\ TF-Cr & 0.169 & \(-\)0.340 & \(-\)0.583 & 0.321 \\ TF-Cu & \(-\)0.139 & \(-\)0.738 & \(-\)0.297 & \(-\)0.005 \\ TF-Pb & \(-\)0.644 & \(-\)0.283 & 0.679 & \(-\)0.900 * \\ TF-Zn & \(-\)0.775 & \(-\)0.905 * & 0.614 & \(-\)0.636 \\ \hline \hline \end{tabular}  
* Correlation is significant at the 0.05 level (2-tailed).  
\end{table} 
Table 4: The Pearson correlations among soil enzyme activities and transfer factors of different heavy metals of soil. Physicochemical factors of soil, such as heavy metals, pH, N, and S were the key factors that affected the structure of soil bacterial community, for example, Sphingomonadaceae showed certain tolerance to heavy metals [50]. The structure and diversity of the soil microbial community varied in conjunction with the various ecological environmental factors [51], such as pH [52], heavy metals [53], salinity [54], and the C/N [55]. The relationships between microbial communities and habitats can be indicative of specific microbiological groups, which can reflect the response mechanisms of microbial communities to environmental change [6]. This relationship showed that microbial biomass differed in soil that was subjected to heavy metal pollution [56], and different concentrations and types of heavy metals had different effects on soil microbial biomass. We determined that soil physicochemical factors also had an effect on heavy metals; for instance, we found a significant negative correlation between soil NO\({}_{3}\)+-N and As, while soil N and Zn were significantly positively correlated. We also found a significantly positively correlation between S and Cd in soil (Figure 4). The abundance of bacterial genes in non-rhizosphere soil was higher than that in rhizosphere soil, but the abundance of fungi genes in rhizosphere soil was significantly higher than that in non-rhizosphere soil (Figure 6). These findings indicated that different rhizosphere regions also had different effects on soil bacteria and fungi. These results could be explained by the differences in environmental heterogeneity and microbial interactions [57]. We found that rhizosphere fungi diversity was significantly correlated to phosphatase, and non-rhizosphere fungi diversity was significantly correlated to sucrose enzymes. The reason for this could potentially be that plants have a stronger influence on microbial habitats in the soil [58]. Studies have shown that the composition of root exudates, which mainly serve as C and energy sources for soil microorganisms (especially rhizosphere microbes), strongly influence the structural and functional diversity of microbial communities [59; 60]. Under heavy metal stress, microbes can actively change the state of heavy metals in the environment by means of their own metabolic activities, which could improve the soil aggregate structure and properties, while affecting the process of plant root secretion, indirectly influencing heavy metal speciation [61]. According to [PERSON] et al. [62], high concentrations of heavy metals lead to a significant decrease in soil microbial biomass, while low concentrations of heavy metals can stimulate microbial growth and increase the overall microbial C biomass. Soil properties have a certain effect on microbial diversity. We found that soil S and Cd were significantly positively correlated to the Shannon-Wiener index and Simpson's Diversity index. Moreover, we also found that soil S, soil bacteria species richness, and Margalef's richness index were significantly positively correlated (Table S2). Ammonium nitrogen, total nitrogen, and Zn were positively correlated to non-rhizosphere soil fungi diversity, but the C/N was significantly negatively correlated to its diversity.