Artificial 137Cs and natural 40K in mushrooms from the subalpine region of the Minya Konka summit and Yunnan Province in China

A study on 137Cs pollution and activity concentrations of 40K in mushrooms of the genera Cortinarius, Leccinum, Russula, Tricholoma, Tylopilus, and Xerocomus from two neighboring regions in southwest China in 2010-2013 revealed different patterns of pollution with 137Cs, which seemed to be highly dependent on climate conditions. Tricholoma matsutake was collected in Yunnan before and after the Fukushima Dai-ichi nuclear accident and showed similar contamination with 137Cs. Mushrooms from the elevation of 2800-3480 m above sea level on the east slope of Minya Konka and forest topsoil showed higher contamination with 137Cs than mushrooms from the highlands of Yunnan. In detail, the activity concentration of 137Cs in caps of mushrooms from Minya Konka were in the range 62 ± 6-280 ± 150 Bq kg-1 dry biomass and from Yunnan at < 4.4-83 ± 3 Bq kg-1 dry biomass. The climate in the region of the Minya Konka is much colder than in Yunnan, which seems to favor deposition of 137Cs at higher altitudes from global atmospheric circulation. The activity concentration of 40K in mushrooms and soils highly exceeded that of 137Cs. The assessed annual effective doses for 137Cs in 1 kg of consumed mushrooms of the genera Leccinum and Xerocomus in Yunnan were low, i.e., in the range < 0.0043-0.049 ± 0.004 μSv, while those for 40K were 0.26 ± 0.02-0.81 ± 0.09 μSv.