The impact of toxic elements on the quality of surface soil in Albania

Due to the toxicity and persistence of trace chemical elements, soil contamination has become a crucial issue for its sensitive impact on biodiversity and human health. It is of interest to assess and understand the distribution and sources of potentially toxic elements in the soil, particularly in regions with high topographical and geological diversity. This research represents the first attempt to create a consistent spatial database of the topsoil quality across Albania. Seventy-five topsoil samples were collected at a density of one site every 380 km² and analyzed for 13 chemical elements. The content of potentially toxic elements has been assessed and compared with the neighboring and European regions, as well as the recommended threshold and guideline values. Concentration and geochemically normalized data were used to distinguish between the natural and anthropogenic origins of elements, determine their background levels, and map out the contaminated areas. The content of elements from natural sources remained essentially constant and revealed small variation, while those of anthropogenic and geogenic origins exhibited relatively high variability. Elevated content and significant variation were observed for Cr, Ni, and Co, with an increasing trend, particularly in the eastern part. The geochemical normalization of the data yielded significant insights into the natural and anthropogenic sources and the baseline levels of trace elements in this study area. Factor analysis indicated notable differences between the structure of the concentration and normalized data and identified the same outliers, primarily linked to geological and human-related sources.