Soil niobium (Nb) contents and potential origins in a mining province of Lori, Armenia

Niobium (Nb) is a critical metal characterized by high global demand and important high-tech applications. Therefore, studying Nb geochemical patterns in the soil environment is essential. This study provides the first geochemical insight into Nb in Lori soils (Armenia) - a province having a centuries-long mining history. The aim of this study is to investigate the background distribution patterns of Nb in Lori soils, reveal its relationship with some major elements, identify its potential origin, and establish a local geochemical background. For the determination of Nb, Fe, Mn, Ti, Zr, Al, Si, and Ca, X-ray fluorescence spectroscopy was used. The mean Nb concentration was 11.6 mg/kg which was equal to the world soil average. The absence of outliers and the normal distribution of Nb indicated the dominant role of natural processes conditioning its distribution. The local variability of Nb among different soil types showed the absence of statistically significant differences suggesting its homogenous distribution across the province. Active mining sites in the province were characterized by relatively low soil Nb concentrations, suggesting the absence of mining-related Nb enrichment in these areas. The results of the correlation analyses and detailed inspection of Nb vs. major elements scatterplots indicated that Nb distribution is predominantly associated with Ti- and Zr-bearing minerals, reflecting a strong lithogenic influence. The multivariate regression results explained 59.3% of Nb variance, highlighting the predominant role of weathering resistant minerals in Nb accumulation in soils. The background range (3.55–19.5 mg/kg) and single background value (11.5 mg/kg) of Nb were established.