Pixe analysis of trace amounts in environmental materials

The characteristic features of the multielemental analysis by the quantitative identification of the Particle Induced X-Ray Emission are outlined. As an illustration with thin samples, tens of micograms of such elements as S, Ti, Fe ... are found per liter of water from the Guadalquivir river, filtered through a Millipore membrane, or the ratio of 16 different elements to Fe found in the air of Seville in a given day is reported as well as the time evolution of the concentration of some elements in the air. Thick samples offer specific difficulties: the technique of sample preparation is described and ways of gaining sensitivity by diminishing the bremsstrahlung background or enhancement of certain energy regions by means of filters are shown with the occasion or sediment samples. (author)