Soil contamination by heavy metals

X-ray fluorescence is the simplest and least expensive method for studying the heavy metals in soils. But niobium is the last element reliably identified by conventional X-ray fluorescence analysis. A radically different situation is observed when the X-ray radiometric modification of energy dispersive X-ray fluorescence method is used in which the sample is excited by a high-energy radioisotope source Am-241 rather then by X-ray tube radiation. An advantage of this method is that the K-lines of heavy metals are actively excited and are not overlapped by the lines of macro-elements.