## 4 Conclusions  
(1) The study concludes that the mean concentrations of heavy metals in the farmland soil around Dachang mining area are in the decreasing order of Zn (2422.0 mg/kg)? Pb (730.0 mg/kg)? As (307.1 mg/kg)? Cu (86.5 mg/kg)? Cr (66.9 mg/kg)? Ni (42.7 mg/kg)? Cd (16.4 mg/kg). The soil is generally acidic, in a reduced state, with low organic matter content. Cd, As, and Pb even exceed the risk intervention values, indicating that Cd, As, and Pb are significantly enriched and that they are the main pollution elements of soil.  
(2) Speciation analysis of heavy metals shows that Cd in soil is mainly in ion-exchange form, Cu is mainly in residual form and humic acid combined form, and the other elements are mainly in residual form. Among the seven heavy metal elements, Cd has the strongest mobility and biological toxicity, followed by As, Ni, and Zn; Cr, Cu, and Pb have poor biological activity and mobility.  
(3) The assessment results show that the overall pollution level of the study area is heavy, which means a very strong ecological risk level. The main pollutants are Pb, As, and Cd; Cd is the most serious pollution. CA and PCA showed that the pollution sources of Cu, Pb, Zn, Cd, and As are mainly affected by tailings accumulation, mining and transportation, while Cr and Ni sources are controlled by soil-forming parent materials.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Elements**} & \multicolumn{3}{c}{**Principal Components Factor Load**} & \multicolumn{3}{c}{**Rotated Principal Components Factor Load**} \\ \cline{2-7}  & **PC1** & **PC2** & **PC3** & **PC1** & **PC2** & **PC3** \\ \hline Cr & 0.184 & 0.488 & 0.852 & 0.065 & 0.063 & 0.994 \\ Ni & 0.132 & 0.866 & \(-\)0.396 & \(-\)0.039 & 0.959 & 0.052 \\ Cu & 0.750 & 0.365 & \(-\)0.199 & 0.664 & 0.538 & 0.069 \\ Zn & 0.953 & \(-\)0.044 & 0.039 & 0.941 & 0.107 & 0.119 \\ Cd & 0.963 & \(-\)0.039 & 0.014 & 0.951 & 0.125 & 0.100 \\ Pb & 0.843 & \(-\)0.255 & \(-\)0.016 & 0.877 & \(-\)0.070 & \(-\)0.036 \\ As & 0.884 & \(-\)0.208 & 0.009 & 0.908 & \(-\)0.034 & 0.012 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Composition matrix of heavy metals.  
(4) According to the actual situation of the farmland around the mining area, it is proposed to clean up the pollution source by using stabilization remediation technology, such as using calcium dihydrogen phosphate to reduce the bioavailability of the most polluted elements, Pb and Cd, in the soil. In the industrial and mining wasteland and some unused land, _Typha orientalis_ Presl can be used for repair in order to achieve the goal of green governance and beautification of the environment.  
Writing--original draft preparation, J.Z., S.H. and P.L.; Writing--review and editing, M.W. and Y.L.; Collecting the samples, Y.L. and S.H.; Software and data processing, C.Z. and P.L.; Funding acquisition, P.L. and M.W. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Natural Science Foundation of China (42203067) and the Natural Science Foundation of Guangxi (2022 CXNSFBA035548 and 2021 JJA150037). This work was supported by the Basic Ability Enhancement Program for Young and Middle-aged Teachers of Guangxi (2022 KY0261).  
Not applicable.  
The authors declare no conflict of interest.