## 4 Conclusions  
A variety of assessment tools, methods, and indices were used to evaluate lead contamination in soils and sediments in Aguascalientes, Mexico. The results of this study indicate that soils and sediments are contaminated with Pb. Soils and sediments nearest to mining activity presented the highest geo accumulation index and metal enrichment factors. Tessier's sequential extraction scheme confirmed high potential Pb mobility, exceeding 26% for soil and 28% for sediment, suggesting an anthropogenic origin and representing a significant risk to the ecosystem. The predominant fraction was Fe/Mn oxide bound, both for soil and for sediment samples. The Tessier method was useful in determining that the possible bioavailability of Pb is related to its chemical forms rather than its pseudo-total concentration. The results (concentrations and environmental indicators) suggested that the study zone should be given priority for effective waste management purposes to sustain the ecological integrity.  
The information generated in this study is useful for establishing Pb reference levels for soil and sediment in the state of Aguascalientes, Mexico. The obtained information will help the regional and federal authorities cope with the current environmental regulations and may be useful in planning remediation activities.  
Future studies are needed to assess the pollution at the affected sites fully. These studies should include an increased number of sample points, multivariate analyses, and spatial distribution mapping for a more comprehensive contamination assessment. Additional chemical analyses should include the discrimination of metals associated with amorphous and crystalline Fe and Mn oxides to provide a clearer picture of the metal-substrate stability.  
Conceptualization, R.M., M.S.R. and M.G.F.; Formal analysis, R.M.; Funding acquisition, F.J.A.; Investigation, R.M.; Methodology, R.M. and M.S.R.; Project administration, R.M. and F.J.A.; Resources, M.S.R. and F.J.A.; Supervision, M.S.R., A.L.G. and F.J.A.; Validation, R.M. and M.G.F.; Visualization, R.M., M.G.F., K.M. and F.J.A.; Writing--Original Draft, R.M. and M.G.F.; Writing--Review and Editing, A.L.G., K.M. and F.J.A. All authors have read and agreed to the published version of the manuscript.  
Figure 3: Enrichment Factor for soils and sediments during dry and rainy seasons. Class: 1 (Deficiency to minimal enrichment), 2 (Moderate enrichment), 3 (Significant enrichment), 4 (Very high enrichment), 5 (Extremely high enrichment).  
**Funding:** This research received no external funding and was conducted on the financial means of the doctoral program of Universidad Autonoma de Aguascalientes.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** We gratefully acknowledge the support of the National Council of Science and Technology (Consejo Nacional de Ciencia y Tecnologia), Mexico by means of the research scholarship # 651043 used for this study. The authors thank [PERSON] from the Universidad Autonoma de Aguascalientes for technical assistance and [PERSON] for his suggestions that led to an improved manuscript.  
**Conflicts of Interest:** The authors declare no conflict of interest.