Assessment of residential soil contamination with arsenic and lead in mining and smelting towns of northern Armenia

Environmental characterization was conducted in one mining and one smelting community in Armenia, Akhtala and Alaverdi, respectively. The aim of the study was to quantify the levels and possible origins of arsenic and lead in the residential soil of these communities, and measure the relationship between those levels in the soil, and its proximity to the industrial source. In total, 459 soil samples were tested in the communities using an X-Ray Fluorescence (XRF) spectrometer. The study team followed standard protocols during the process of soil collection, processing, testing and quality assurance procedures. We compared arsenic and lead concentrations with the Maximum Allowable Concentrations (MAC), Clean up Level (CL) and Highest Background Level (HBL). We, also calculated the Geoaccumulation index (Igeo) and Enrichment Factor (EF). To identify the possible origin of contamination we performed linear regression, principal component analysis (PCA) and interpolation using the distance of each sampling point from the smelter smokestacks, sampling point elevation and measured content of arsenic and lead for Alaverdi. The results showed that in the smelting town of Alaverdi, 75.6% of soil samples exceeded Clean up Level for arsenic and 24.0% for lead. In the mining town of Akhtala, 3.2% of all soil samples exceeded Clean up Level for arsenic and 27.1% for lead. Pollution levels in the towns studied were classified as moderate to strongly polluted. In Alaverdi, both distance and elevation were statistically significant predictors for elevated arsenic and lead levels in residential soil. In Alaverdi, the PCA resulted in three components, one of which consisted of As, Pb, Mn, Cu and Zn, suggesting influence of copper-smelter emission on contamination. In Akhtala, the PCA resulted in four components. Anthropogenic influence was found in two components. One was related to the operation of a smelter during the Armenian Bagratid dynasty in the 10th century (the component consists of Pb, Cu, Zn and Ba) and the other, to later industrial activities (the component consists of As, Cr, Ti, Fe and Co). This study contributes to the evidence on levels of environmental contamination in mining and smelting communities worldwide.