## 4 Results and Discussion
### Comparative Analysis of Three Risk Assessment Methods  
The results of the above three risk evaluation methods can be seen that there is a certain degree of variability between the results obtained by different evaluation methods. For instance, this study demonstrates that the Hg and Cd geo-accumulation index methods indicate a moderate to high pollution status, while the potential ecological risk index  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Item** & **Cr** & **Ni** & **Cu** & **Zn** & **As** & **Cd** & **Pb** & **Hg** \\ \hline Minimum & 0.02\% & 0.22\% & 0.69\% & 4.14\% & 0.06\% & 0.06\% & 0.34\% & 0.00\% \\ Maximum & 0.24\% & 3.09\% & 6.11\% & 21.95\% & 3.74\% & 28.75\% & 3.76\% & 5.71\% \\ Average & 0.15\% & 1.64\% & 2.84\% & 10.46\% & 0.85\% & 6.08\% & 1.49\% & 0.32\% \\ contamination degree & None & Slight & Slight & Mediate & None & Slight & Slight & None \\ \hline \hline \end{tabular}
\end{table}
Table 9: The evaluation results of the risk assessment code method of heavy metals in the study area.  
Figure 6: Evaluation results of the potential ecological risk index method.  
Figure 7: Evaluation results of the risk assessment code method.  
methods suggest an extremely high ecological risk level and a very high ecological risk level, respectively. Conversely, the risk assessment code method suggests a pollution-free fraction and a slightly polluted fraction.  
The geo-accumulation index method reflects the regional enrichment characteristics of heavy metals and mainly considers the impact of the total amount of heavy metal elements on the environment but lacks the consideration of the bio-effectiveness of heavy metal elements The evaluation method of the potential ecological risk index combines the total amount of heavy metals, spatial heterogeneity of soil background value, and ecotoxicity to provide more reasonable evaluation results. However, this method places emphasis on the potential ecological harm caused by heavy metals to the environment, resulting in a higher level of ecological risk for heavy metals with higher toxicity coefficients [44]. The risk assessment code method evaluates the risk of heavy metals in soil from the perspective of the accumulation form of heavy metal elements and pays more attention to the relative content of the bio-directly available fraction of heavy metal elements, the mild acid-soluble fraction and water-soluble fraction, but the bio-toxicity of the elements does not depend entirely on the bio-efficacy [45]. For example, in this study, Zn had the highest percentage of the mild acid-soluble fraction and water-soluble fraction, but the toxicity coefficients of Zn were low and it was not easy to cause ecological risks.  
When evaluating the risk of pollution by heavy metals in soil, the use of one evaluation method is prone to one-sidedness and deficiency; multiple evaluation methods should be selected, and based on the evaluation results of multiple evaluation methods, the influence of natural, anthropogenic, the nature of heavy metals, the characteristics of the distribution of heavy metals and other factors on the evaluation results should be comprehensively analyzed, in order to evaluate the pollution of the environment by heavy metals in soil in Pingshui Village, Zhaoping County, Hezhou, and the potential risk situation in the environment in a more objective manner.