## 3 Results and Discussion  
### Results of Poted Experiments on Remediation Plants  
As shown in Figure 2, the contaminated soil of the Zhongshan Huilong Arsenic Smellting Plant in Guangxi was used as the planting soil for pot experiments. After 60 days of greenhouse cultivation, _Cynodon dactylon, Bidens pilosa_, and _Boelmeria nivea_ exhibited robust growth and substantial biomass. The results of the greenhouse pot experiment demonstrated that these three test plants were equipped with good adaptability towards the contaminated soil, and they exhibited strong tolerance to As and Cd pollution. Samples of the three plant species and the soil after remediation were collected and subjected to analysis. The results are presented in Tables 2-4. Figure 2: Growth status of Cynodon dactylon **(A)**, Bidens pilosa **(B)**, and Boehmeria nivea **(C)**. In the study, as presented in Table 2, the adaptability of three plant species in polluted soil environments was assessed, revealing significant insights into their potential for phytoremediation. _Cynodon dactylon_ exhibited robust growth, with an average root length of 9.1 cm and an average plant height of 9.6 cm. Both indicators of growth were favorable, suggesting healthy vegetative development under stress conditions. Additionally, the moisture content of _Cynodon dactylon_ was recorded at 68.1%, which fell within the normal physiological range of 65%-80%, indicating efficient water uptake and retention capabilities. _Bidens pilosa_ also demonstrated commendable growth characteristics, with a root length of 9.7 cm and a plant height of 8.5 cm. Although shorter in stature compared to Cynodon dactylon, the slightly greater root length of _Bidens pilosa_ might indicated a superior capacity for nutrient uptake in contaminated soils. Furthermore, the moisture content for _Bidens pilosa_ was measured at 71.5%, which was well within the optimal range for maintaining metabolic activities in stressful environments. Among the species studied, _Boehmeria nivea_ showed the most impressive growth parameters, with an average root length of 11.7 cm and a plant height of 12.7 cm, surpassing the other two species. Additionally, Boehmeria nivea maintained a moisture content of 75.5%, suggesting it possesses enhanced adaptability traits, potentially enabling it to thrive in contaminated soils more effectively than the other species tested. This higher moisture content also supported its ability to efficiently manage water stress under adverse conditions. Suitable plants used in the remediation project should exhibit strong tolerance to heavy metals in soil [50]. The bioconcentration factor was a crucial indicator for measuring the tolerance and accumulation capacity of a certain plant towards heavy metals [51]. Therefore, the bioconcentration factor was a critical factor in selecting remediation plants. According to Table 3, _Cynodon dactylon_, _Bidens pilosa_, and _Boehmeria nivea_ had bioconcentration factors of 0.43, 0.33, and 0.07 for arsenic, and 0.13, 0.62, and 0.08 for Cd, respectively. The bioconcentration factors of _Bidens pilosa_ for both As and Cd were greater than 0.3, indicating \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Plants**} & \multicolumn{2}{c}{**Reduction Rate of**} & \multicolumn{2}{c}{**Reduction Rate of**} \\  & **Bioavailable As (\%)** & **Bioavailable Cd (\%)** \\ \hline _Cynodon dactylon_ & 22.1 & 16.3 \\ _Bidens pilosa_ & 33.8 & 35.4 \\ _Boehmeria nivea_ & 29.4 & 24.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Reduction rate of bioavailable heavy metals in soil after plant remediation.