Elemental analysis of urban stormwater particulate matter by PIXE

Particle Induced X-ray Emission (PIXE) has been used to determine the average elemental concentrations of various size fractions in the particulate phase of urban stormwater derived from areas with different land-use characteristics. Water samples were filtered through Nucleopore polycarbonate filter papers to separate particulate in the 0.4–60 μm and 60–250 μm fractions and the dry weights determined. Elements such as Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Ag, Cd and Pb are measured with concentrations ranging from 10 ppm to a few percent in both water sample fractions. For the elements P, S, Cl, Ca and Mn, there was no apparent relationship with land-use in the 0.4–60 μm fraction water particulate. However, in the 60–250 μm fraction particulate, higher concentrations were determined at sampling location number 6 which had the largest percentage of industrial use. Significant increased heavy metal concentrations were measured in samples collected from industrial and commercial land-use areas. Our preliminary study reveals that PIXE can be used to measure the elemental concentrations in different particulate size fractions from water samples.