Element distribution in Lactarius rufus in comparison to the underlying substrate along a transect in southern Norway

Lactarius rufus, the rufous milkcap, is one of the most widespread fungi in northern Europe. 40 samples of Lactarius rufus were collected along a 100 km transect in an almost pristine area of southern Norway. Along the transect two mineral deposits occur (a) the Nordli porphyry molybdenum deposit and (b) the Snertingdal Pb occurrence. 53 chemical elements were analysed in Lactarius rufus and its substrate, the soil O and C horizon. Of these, 32 elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, Tl, V and Zn) returned values above the respective detection limits for the majority of samples. Compared to the soil C-horizon Lactarius rufus is strongly enriched (factor> 2 to 72) in K, Rb, Ag, P, S, Na, Cd, Hg, Cu, Zn and Cs. Compared to the soil O horizon Rb, K, P, Cs, Cu, S and Na are the most enriched (factor>2 to 50) elements in Lactarius rufus. Compared to the median of in total 15 plant materials collected along the same transect Lactarius rufus is most strongly enriched in Ag (195 times), more than 10 times in Cs, Rb, Na, Cd and 10 to 2 times in K, Hg, P, Cu, Ti, As, S and Zn. Compared to other plants the uptake of Ba, Ca, Mn, Sr, Al and Mo by Lactarius rufus is very low. Element correlations between Lactarius rufus and the substrate are generally poor. Within Lactarius rufus only the major nutrients (K, P, S, Mg) correlate well. Part of the study was to investigate Lactarius rufus suitability for biogeochemical exploration; although this mushroom species enriches many elements, it does not provide a good indication of the presence of the mineral occurrences.