New methods for metal contaminant source attribution

Conventional methods used in monitoring systems to assess concentrations of metals and metalloids, particularly at trace levels, are generally based on instruments such as X-ray fluorescence spectrometry (XRF) or inductively coupled plasma mass spectrometry (ICP-MS), following a preliminary digestion step. These techniques provide highly accurate measurements of the concentration of elements present in airborne particles. However, they are limited to an average analysis of the overall composition of the particles collected, offering little information on the elemental distribution according to particle size, or on the specific chemical nature of individual particles. Recently, instrumental advances in ICP-MS have made it possible to achieve extremely high analysis frequencies (~1 million points per minute), opening up the possibility of examining each particle individually (SP-ICP-MS). The ability to determine the elemental and isotopic composition of each particle (SP-TOF-ICPMS) is a particularly powerful methodology for identifying the origin of particles, especially when studying atmospheric samples containing a complex mixture from various sources. This new approach will be used to gain a deeper understanding of the particulate emission sources associated with the Horne Smelter.