Using magnetic and chemical measurements to detect atmospherically-derived metal pollution in artificial soils and metal uptake in plants

Quantification of potential effects of ambient atmospheric pollution on magnetic and chemical properties of soils and plants requires precise experimental studies. A controlled growth experiment assessing magnetic and chemical parameters was conducted within (controls) and outside (exposed) a greenhouse setting. Magnetic susceptibility (MS) measurements showed that while initial MS values were similar for the sample sets, the overall MS value of exposed soil was significantly greater than in controls, suggesting an additional input of Fe-containing particles. Scanning electron microscope images of the exposed soils revealed numerous angular magnetic particles and magnetic spherules typical of vehicular exhaust and combustion processes, respectively. Similarly, chemical analysis of plant roots showed that plants grown in the exposed soil had higher concentrations of Fe and heavy (toxic) metals than controls. This evidence suggests that atmospheric deposition contributed to the MS increase in exposed soils and increased metal uptake by plants grown in this soil.

► Magnetic susceptibility (MS) values increased in exposed soils during the growth.
► MS values in control soils decreased from their initial values during the growth.
► Decrease in MS values due to downwards migration of Fe particles, magnetic mineral transformations and Fe uptake by plants.
► Higher metal uptake in plants grown in exposed soils than those grown in controls.
► Atmospheric particulate deposition isolated as main contributor to these effects.