Effects of Water Absorption on Mercury Contamination in Fiberbank Sediments using X-ray Fluorescence Spectrometer

A large amount of contaminated cellulose and wood fibers were emitted directly onto the seabed by the pulp and paper industry before the year of 1970. This fiber-rich sediment contains concentrations of hazardous substances that cause environmental problems. Mercury (Hg) in the fiber sediment is a worldwide threat because it can bioaccumulate in the aquatic ecosystem and eventually affect human health. X-ray fluorescence (XRF) analysis is anelemental analysis method for earth materials, which is rapid and requires minimal sample preparation. However, for in-situ XRF analyses, constraints in the measurement conditions will strongly affect the measurement sensitivity and accuracy, such as the scattered background and the water content surrounding the sample. In this work, we showed that applying an X-ray beam filter foil, optimized by using the material absorption edge, can improve the sensitivity of the XRF spectrometer system for Hg determination. Furthermore, the influence of water content in XRF measurement for Hg contamination analysis was investigated. The attenuation coefficient in water was determined by simulation of water layer with varying thickness using a Monte Carlo simulation code. The measured intensity for Hg was decreased exponentially asthe water thickness increase, as expected. We propose a method to correct the attenuation in water with XRF analysis and we expect that these findings can contribute to an accurate in-situ Hg detection experiment.