Abstract:

In this study, a high-purity germanium γ spectrometer was employed to determine the activities of artificial
radionuclide 137Cs and natural radionuclides 40K, 226Ra, 214Bi and 214Pb in fruiting bodies of cultivated and wild Macrocybe
gigantea collected in Yunnan, China. The results showed that for the samples collected in 2011, the maximum concentrations
of 137Cs, 40K, 226Ra, 214Bi and 214Pb were < 6.1, 821, < 66, 140 and 145 Bq/kg dry weight (dw) in caps, and 6.7, 926, < 50, 16
and 27 Bq/kg in stipes, respectively. For the samples collected in 2012, the values of 137Cs, 40K, 226Ra, 214Bi and 214Pb were 13,
3 323, 79, 82 and 85 Bq/kg in caps, and 6.6, 1 194, 127, 31 and 39 Bq/kg in stipes, respectively. For the samples collected in
2013, the values of 137Cs, 40K, 226Ra, 214Bi and 214Pb were 11, 1 417, 92, 14 and 32 Bq/kg in caps, and 7.9, 1 139, < 58, 19 and
27 Bq/kg dw in stipes, respectively. The concentrations of 137Cs in M. gigantea were much lower than the maximal allowable
concentrations of radionuclides in foods as well as the concentrations in fungi collected from contaminated areas in some
European countries and Japan. The concentrations of natural radionuclides in M. gigantea were at the normal levels. It is
concluded that M. gigantea collected from Yunnan is not contaminated by radiocesium and therefore could be consumed
safely without any risk of radiation exposure.

Key words: edible mushroom, high-purity germanium &gamma, spectrometer, radioactivity, ¹³⁷Cs