# Analysis of Heavy Metal Sources in Xutuan Mining Area Based on APCS-MLR and PMF Model
## 4 Conclusions  
In this study, the total amount of six heavy metals in water and the occurrence forms and ecological risks of six heavy metals in sediments in the Xutuan mining area were determined. A correlation analysis, APCS-MLR, and PMF models were used to quantify the heavy metal pollution sources in the sediment. The main conclusions of this study are as follows: 1. The average Cu, Pb, Zn, Cd, As, and Cr concentrations in the collapsed water bodies of the mining area were 6.28, 2.29, 26.15, 0.41, 32.86, and 37.26 \(\upmu\)g\(\cdot\)L\({}^{-1}\), respectively. Cr and the remaining heavy metal elements were in line with the national Class I and Class II water quality standards, respectively. The average pH value of the mining water was 7.19, and the whole water was weakly alkaline. 2. The average Cu, Cr, Cd, Zn, Pb, and As contents in the collapsed sediments of the mining area were 16.44, 51.89, 1.98, 37.29, 16.42, and 31.49 mg/kg, respectively. In fact, Cd and As exhibited higher contents than the corresponding background values of the Xutuan mining area, showing certain enrichment degrees. F5 was the most dominant form of Cu, Cr, Zn, and As, accounting for 49.39, 65.78,  
Figure 6: Sources of the heavy metal elements and their PMF-based factor contribution rates.  
52.56, and 50.94%, respectively. On the other hand, the non-residual forms of Cd and Pb accounted for 75.11 and 79.06%, respectively, of which the F4 form was the most dominant. 3. Igeo indicated that Cd and As were in the polluted forms, while the remaining heavy metal elements were in the unpolluted forms. On the other hand, the RAC evaluation results indicated moderate ecological risks associated with Cu, Zn, Cd, and Pb. These elements can be easily released from sediments into the water bodies, causing secondary pollution. 4. APCS-MLR identified two types of pollution sources, natural and industrial, with contribution rates of 72.5% and 27.5%, respectively. The PMF model results revealed four heavy metal pollution sources, namely natural, coal mining, agricultural, and traffic sources, with relative contribution values of 25.1%, 26.4%, 21.44%, and 27.05%, respectively.  
This study quantifies the pollution sources of heavy metals in mine sediment, determines the pollution sources that should be controlled first, and provides a future direction for the prevention and control of sediment pollution. However, the prevention and control of heavy metal pollution sources in mining environments should be combined with the overall research of mining soil. In addition, GIS statistical analysis should be combined with the approaches presented in this study to prove the accuracy of the models' analysis of heavy metal pollution sources.  
Writing--original draft, J.X.; writing--review and editing, L.G.; data curation, J.Y. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Anhui Provincial Key Research and Development Project, grant number 20200407020012.  
Not applicable.  
Data Availability Statement: Data will be made available on request to the authors. The data that support the findings of this study are available from the corresponding author upon reasonable request.  
Author [PERSON] was employed by the company Anhui Lida Earth and Environment Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.