# Risk Assessment and Source Apportionment of Heavy Metals in Soils from Handan City
## 4 Conclusions  
Except for Mn, the average contents of other heavy metals exceeded the background values. The average content of Cd was the highest, at about 10 times the background value. Figure 8: Spatial distribution diagrams of factor profiles. (**a**). factor 1, (**b**). factor 2, (**c**). factor 3. According to the results of the pollution assessment and ecological risk assessment, Cd pollution was the most serious. In terms of health risk, Cr has the highest non-carcinogenic risk, followed by Mn, Pb, Ni, Cd, Cu and Zn. Cd, Cr and Ni had an acceptable or tolerable carcinogenic risk for children and adults, while Pb had no significant carcinogenic risk. For non-carcinogenic risk and carcinogenic risk, the ingestion risk was far greater than other pathways. The non-carcinogenic risk of children far exceeds that of adults. The distribution of heavy metals showed that the distribution of Cr and Ni was highly similar, and the high-content regions were in the middle and northeast of the research region. The distribution trends of Mn, Zn and Cd were consistent, and the high contents were concentrated near the industrial area. The contents of Cu and Pb were very high on the main roads, with a high vehicle density. Combined with correlation analysis, cluster analysis and PCA, three pollution sources were identified, which were traffic sources with Cu, Pb and Cd as main loads, industrial sources with Mn, Cd and Zn as main loads, and natural sources with Cr and Ni as main loads. According to the source apportionment by PMF model, there were three factors for heavy metal accumulation in the study area: traffic source (17.61%), natural source (28.62%) and industrial source (53.77%). The source categories and main load elements were consistently obtained from the PCA and PMF models. This study can not only help to better understand the spatial distribution of heavy metals, but also offer suggestions for heavy metal contamination control in the study area. However, there were certain limitations in this study. Firstly, for the human-health risk assessment, some exposure and toxicological parameters were based on US EPA, which might not be fully applicable, given the location of this study area in China. Secondly, the ecotoxicities of heavy metal had limited bioavailability. The total concentration of heavy metals was used to assess their health risk, which might cause an overestimation of the actual carcinogenic risk. The following are available online at [[https://www.mdpi.com/article/10.3390/app11209615/s1](https://www.mdpi.com/article/10.3390/app11209615/s1)]([https://www.mdpi.com/article/10.3390/app11209615/s1](https://www.mdpi.com/article/10.3390/app11209615/s1)), Figure S1: Scatter plots of predicted and observed concentrations of species using the PMF model, Table S1: Classification standard of PI, Igeo, NIPI, PLI and PERI, Table S2: Abbbreviation and reference values for health risk assessment parameters, Table S3: Reference dose (RfD) and slope factor (SF) of each heavy metal. Conceptualization, H.Z. and Y.M. ; methodology, H.Z., L.W. and A.C.; formal analysis, X.W. ([PERSON]) and X.W. ([PERSON]); writing--original draft preparation, X.W. ([PERSON]); writing--review and editing, H.Z. and A.C.; supervision, H.Z. and Y.M. ; project administration, L.W. and Q.W. ; funding acquisition, H.Z., and A.C.; A.C. and H.Z. had equal contribution in this study. All authors have read and agreed to the published version of the manuscript. This research was funded by Hebei Provincial Department of Science and Technology, grant number 17273712D and Hebei Provincial innovation funding project for postgraduate students, grant number CXZZSS2021086. Not applicable. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to participants not having consented to the data being shared. We would like to express our sincere gratitude to the editors and reviewers who have put considerable time and effort into their comments on this paper.