## 4 Conclusions  
The SWRC is a critical soil hydraulic property for studying unsaturated soil mechanics, contaminant transport simulation in the aerated zone of the soil, irrigation and drainage scheduling, predicting nutrients leaching, and other soil conservation activities. The results obtained in this study showed that [PERSON] model adequately represented the SWRC and HCF of the natural soil. However, when the model was applied to the contaminated soil, an increase in the equivalent soil's particle diameter was observed, suggesting a change in the soil's structure. This resulted in the modification of the hydraulic properties of the contaminated soil because it is related to the porous system of the soil (i.e., geometry and size).  
The values of the parameter \(n\) increased when using the simulation for either the contaminated or natural conditions and modified the slope of the SWRCs. In the wetting path and for \(s_{r}<45\%\), the suction values of the arsenic-contaminated soils obtained by [PERSON] model were higher than those obtained by the filter paper method. Even if fractal analyses were used (geometrical pore, neutral pore, and larger pore), the estimated SWRC did not represent the hydraulic and mechanical behavior of the arsenic-contaminated soils, especially at low saturation degrees. Hence, the use of this model to estimate the SWRC of contaminated soil from the unsaturated soil mechanics perspective must be considered carefully because the results highlight the necessity to use a soil stabilization  
Figure 3: Hydraulic conductivity function of the 0 mg/kg (natural soil) and the 25 mg/kg and 50 mg/kg arsenic-contaminated soils by the van Genuchten method.  
method to control the soil's volume variations. Although [PERSON] model provides an initial and fast approximation for the SWRC, compared to the filter paper method, additional analyses should be performed to ensure this model adequately represents the contaminated soil behavior.  
[PERSON] model does not consider the soil-contaminant interaction, which is essential to evaluate the distribution and accumulation of heavy metals in soil. Knowing how the contaminant modifies the SWRC should allow a better parametrization of the Richards equation. Consequently, a better prediction of solute transport in the aerated zone of the soil can be obtained. Since the [PERSON] model provided higher hydraulic conductivity values for the contaminated soil, it can result in the misinterpretation of contaminant transport in soil. Therefore, the time and costs associated with soil remediation can vary significantly. Moreover, the results obtained using this model may suggest the development of a soil erosion process, which has important repercussions on civil works and soil mechanical and hydraulic behavior.  
Conceptualization, C.E.H.-M.; Data curation, I.V.-N.; Formal analysis, I.V.-N., C.E.H.-M., A.I.C.-R. and E.R.-G.; Funding acquisition, C.E.H.-M.; Investigation, I.V.-N. and C.E.H.-M.; Methodology, I.V.-N.; Project administration, C.E.H.-M.; Supervision, C.E.H.-M. and E.R.-G.; Visualization, I.V.-N. and A.I.C.-R.; Writing--original draft, I.V.-N. and C.E.H.-M.; Writing--review and editing, A.I.C.-R. and E.R.-G. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Consejo Nacional de Ciencia y Tecnologia (CONACYT), grant number CONACYT 270161.  
Not applicable.  
Data Availability Statement: Data presented are contained within the article.  
[PERSON] acknowledges the scholarship provided by CONACYT for his Ph.D. studies.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.