Magnetic Screening for Heavy Metal Contamination of the Woody Earthquake Rubble

Abstract

Recycling the large amount of rubble ejected during earthquakes reduces the large cost and amount of land required for its disposal. Furthermore, the use of earthquake rubble consisting of wood as a fuel for heating and power generation results in a reduction of greenhouse gases. We used magnetic screening to quickly examine heavy metal contamination in large amounts of rubble. Six specimens of earthquake disaster rubble were obtained from Ishinomaki and Shiogama each. The heavy metal content, saturated isothermal remanent magnetization (SIRM), and magnetic susceptibility (χ) of wood chip specimens processed from the obtained specimens were measured. We detected 14 metals in the specimens. None of the measured values exceeded the European Standard EN 14961-2. However, the content of certain metals (Zn, Cd) exceeded one-half of the value specified by this standard for some specimens obtained from Ishinomaki. None of the measured values exceeded one-tenth of the value specified by the standard for specimens obtained from Shiogama. Magnetic screening using SIRM and χ is shown to be valid to some extent for the assessment of heavy metal contamination of a concentration of up to one half of the value specified by the standard.