**6. Conclusions**

Soils and stream sediments of the PB are strongly influenced by the geological environment of the region. The geochemical maps revealed substantial differences between the NPB and the SPB regions. At the regional scale, the local anomalies are mostly influenced by the bedrock lithologies rather than by any anthropogenic impact. Significant evidence has shown that the metavolcanosedimentary rocks of the CB and, particularly, the mineralizations along the northern and southern Cu belts in the NPB are the main source for several anomalous concentrations of PTE in both sampling media. Considering the elements under investigation in the PB area, the geochemical compositions of soils and, especially, stream sediments of the BD and CB are statistically similar. The soils and stream sediments are strongly to moderately correlated for many elements (Fe, As, Bi, Cr, Cu, Hg, Mo, Ni, Sb, Sn, U, and V), which sugges<sup>t</sup> the same rock source or, in some cases, the soils themselves as the primary source for the constitution of stream sediments, driven by erosion processes and intensified by the deforestation in the area. The comparison between new statistically derived threshold values of the NPB and SPB regions with the threshold values of the whole PB and to quality guidelines proposed by Brazilian environmental agencies demonstrates that a uniform value of quality guideline is not adequate, because it does not consider the natural geological/geochemical variation of the area. For this reason, geochemical compartments, instead of political boundaries, should be considered prior to defining new guideline values. The integrated assessment used here is easily replicated and remarkably useful for territorial and watershed management, important for the Sustainable Development Goals.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2571-878 9/5/1/21/s1, Figure S1 Geochemical maps for Ag, B, Cd, Sb, and Se; Figure S2: Geochemical maps for Ba, Bi, Pb, Sn, and U; Figure S3: Boxplots for 8 potentially toxic elements (PTE; Ag, B, Cd, Mo, Sb, Sn, Pb, and U); Figure S4: Scatter plot comparing the concentrations of the studied elements in surface soil and stream sediment samples; Table S1: Descriptive statistics for 10 potentially toxic elements (PTE; Ag, B, Ba, Bi, Cd, Pb, Sb, Se, Sn, and U) in surface soils and stream sediments; Table S2. Geochemical threshold values for 10 potentially toxic elements (PTE; Ag, B, Ba, Bi, Cd, Pb, Sb, Se, Sn, and U) in surface soils and stream sediments.

**Author Contributions:** Conceptualization, D.S.; Data curation, G.N.S.; Formal analysis, G.N.S.; Funding acquisition, R.D.; Investigation, D.d.L.F.; Methodology, G.N.S.; Supervision, R.D.; Validation, P.K.S.; Writing—original draft, G.N.S. and D.d.L.F.; Writing—review & editing, P.K.S., R.D. and D.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was financed mostly with resources of the ITV (Instituto Tecnológico Vale) and Gerência Ambiental de Ferrosos Norte (Vale S.A). This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil (CAPES)—Finance Code 001. This work was partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq (306108/2014-3 and 304648/2019-1 to RD; 443247/2015-3 and 402727/2018-5 projects coordinated by RD).

**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. The data are not publicly available due to privacy restrictions.

**Acknowledgments:** The Instituto Tecnológico Vale provided the geochemical dataset of the Itacaiúnas Geochemical Mapping and Background Project. The authors acknowledge Pedro Walfir Martins e Souza Filho, Wilson da Rocha Nascimento Junior and Jair da Silva Ferreira Júnior for the project conceptualization and sampling design; Marcio Sousa da Silva and Carlos Augusto de Medeiros Filho for the managemen<sup>t</sup> of the field work and sampling. Marlene F. da Costa (Vale S.A.) for the financial support to the project development.

**Conflicts of Interest:** The authors declare no conflict of interest.
