A research team from the University of Castilla-La Mancha (UCLM) has analysed the presence of heavy metals in 12 species of mushroom collected from non-contaminated natural areas, and has found that the levels vary depending on the type of mushroom. The results of the study, which appears this month in the journal Biometals, show that the largest quantities of lead and neodymium are found in chanterelles. "The aim was to find out if there is a connection between the concentrations of specific heavy metals detected in the mushrooms, based on three factors: the type of substrate, the study area and the species of mushroom. The third was the determining factor", explains Juan Antonio Campos, principal author of the study and researcher at the Department of Crop Production and Agricultural Technology at UCLM. The researchers have analysed the presence of lead (Pb), neodymium (Nd), thorium (Th) and uranium (U) in a hundred samples of 12 different species of common mushroom, both edible and non-edible, collected from non-contaminated zones in the Ciudad Real province. They were collected from wooded areas comprising Holm oak, Kermes oak, Pyrenean oak, Pine and Cistus. The results of the study, published this month in the journal Biometals, reveal that there are 'considerable' quantities of the four metals in all the species examined, as well as significant differences in the capacity for accumulation of these elements depending on the species. The analysis of these heavy metals – which can be toxic to humans – was carried out using X-ray fluorescence spectometry, a technique that enables a sample's composition to be detected and quantified using X-rays. The highest levels of neodymium (7.1 micrograms/gram) and lead (4.86 µg/g) were found in the chanterelle (Cantharellus cibarius), a mushroom widely used in European cuisine. This mushroom grows in the shadow of Holm oaks, Cork oaks and oaks, and is ectomycorrhizal (it clings to the external roots of plants to exchange nutrients), thereby it has direct contact with the mineral particles of the soil.
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