An integrated framework toward soil geochemical background determination in the case of Lori region, Armenia

Separation of anomalies from background distribution is critical for geochemical studies and ensures the establishment of soil geochemical background (SGB) values. This study aims to expand the methodological framework of SGB determination via the incorporation of existing methods into a single algorithm embedded with spatial zoning and its application to establish background values of mining related elements in a heterogeneous area. Multifractal modeling was employed to distinguish anomalous from background distributions of the studied elements and geospatial zoning was applied. After, zone-specific determination of the SGB values using iterative 2-sigma and Median ± 2 MAD methods was done. The results revealed that high background and anomaly values of the studied elements were spatially located in areas characterized by the presence of univariate and multivariate outliers and extreme values, potentially conditioned by natural mineralization and active mining. By combining background maps derived from multifractal modeling of Cu, Zn, Pb, and As distributions, a map of three spatial zones within the study area was obtained. One zone was characterized by natural mineralization and significantly impacted by mining activities, supporting the determination of a geochemical baseline for this site. In the other zones, site-specific SGB values were calculated, with median values of the studied elements selected and justified as representative SGB values. The established baseline and background values of Cu, Zn, Pb, and As can serve as reliable estimators of contamination, while the combined approach used in this study is promising and has the potential to be applied in other high-background areas to determine robust SGB values.