Rapid assessment of soil and contaminant variability via portable x-ray fluorescence spectroscopy: Copşa Mică, Romania

Abstract

Many rural villages in Eastern Europe are severely impacted by aeolian smelter dust/deposits. Commonly, elemental studies in Romania have suffered from limited sampling numbers (n=5–10) and/or incomplete digestion offering only semi-total quantification of elements using traditional, laboratory-based techniques. These approaches are simply inadequate for evaluating potentially hazardous soils and their spatial extent, particularly at urban/rural interfaces of variable land use. Portable x-ray fluorescence (PXRF) spectroscopy can accurately quantify contamination rapidly, in-situ with a wide dynamic range and little to no sample preparation for analysis of regulated elements (e.g., As, Cd, Cu, Mn, Pb, V, Zn) and other common soil elements such as Ca, Fe, K, Rb, Sr, Ti, and Zr. A contemporary PXRF spectrometer was used to scan 61 soil samples across multiple land use types in urban/rural interfaces on-site. Each site was georeferenced with elemental data inputted into a geographic information system for high resolution kriging interpolation. These models were superimposed over modern aerial imagery to evaluate the extent of pollution for each government-regulated element with simultaneous consideration and quantification of spatial variability in naturally occurring soil elements. Pb exceeded governmental action limits across 100% of the area, while V, Mn, Cu, and Zn were exceeded in 2.2, 2.1, 39.6, and 9.8% of the area. Furthermore, many regulated elements were closely correlated to natural soil elements. In short, georeferenced PXRF data proved a powerful new tool for on-site assessment of contaminated soils; one which has rarely been utilized in Eastern Europe to date.