High resolution X-ray fluorescence micro-tomography on single sediment particles

This work focuses on the investigation of the distribution of contaminants in individual sediment particles from the New York/New Jersey Harbor. Knowledge of the spatial distribution of the contaminants within the particles is needed to enable (1) more sophisticated approaches to the understanding of the fate and transport of the contaminants in the environment and (2) more refined methods for cleaning the sediments. The size of the investigated particles ranges from 30-80 microns. Due to the low concentration of the elements of interest and the microscopic size of the environmental particles in these measurements, the small size and high intensity of the analyzing X-ray beam was critical. The high photon flux at the ESRF Microfocus beam line (ID13) was used as the basis for fluorescence tomography to investigate whether the inorganic compounds are taken upon the surface organic coating or whether they are distributed through the volume of the grains being analyzed. The experiments were done using a 13 keV monochromatic beam of approximately 2 μm in size having an intensity of 10¹⁰ ph/s, allowing absolute detection limits on the 0.04-1 fg level for Ti, Cr, Mn, Fe, Ni, and Zn.