Magnetic Screening for Heavy Metal Pollution in the Wood Biomass Obtained from the Roadside Trees

Magnetic screening as a cost-effective and non-time-consuming approach has been successfully applied to wood biomass (wood chip and/or wood pellet) obtained from the trimming of the branches of roadside trees in Hiroshima Prefecture, Japan. It appears to be a suitable method for the contamination assessment of wood biomass. The heavy metal contents, magnetic susceptibility and saturation isothermal remanent magnetism (SIRM) of wood biomass specimens for 15 roadside sites and 1 forest site were measured. We measured 15 metals. Generally, the obtained content values were less than the European Standard EN 14961-2. However, the content values of some metals (Cu, Zn, Cd) slightly exceeded this standard for some samples. A simple correlation analysis revealed the existence of relationships and high correlations between magnetic parameters and metals such as Fe, Zn, Pb, Al, K and Cr. The specimens whose SIRMs are approximately 90 mA/m or more do not meet the specified Europe Standard. Specimens that have significantly positive values of magnetic susceptibility also do not meet the standard. It was shown that a simple inspection of heavy metal contamination in wood biomass can be performed by measuring its SIRM or magnetic susceptibility.