Activity concentrations and bioconcentration factors (BCFs) of natural radionuclides (40 K, 226Ra, and 232Th) from cultivated substrates to mushrooms

Abstract

This study examined 42 mushroom samples and corresponding cultivated substrates. The radionuclide activity concentrations and bioconcentration factor (BCF) from substrate-to-mushroom were determined. The substrate activity concentrations were 59.1-727.5, 4.5-37.6, and 4.0-53.0 Bq/kg dw (dry weight) for ⁴⁰ K, ²²⁶Ra, and ²³²Th, respectively. The average ⁴⁰ K concentrations were 1546.5, 1115.7, and 749.3 Bq/kg dw; the BCFs were 2.49, 3.56, and 5.58 for A. bisporus, F. velutipes, and L. edodes, respectively. The ⁴⁰ K concentrations were insignificantly correlated with each species' corresponding substrate concentration. The ⁴⁰ K BCFs had a significantly negative correlation with the substrate concentration for each species. Each mushroom species' ⁴⁰ K concentration was almost stable, suggesting that ⁴⁰ K has a regulated homeostasis for a given species. The average ²²⁶Ra concentrations were 5.5, 5.4, and 3.4 Bq/kg dw; the BCFs were 0.58, 0.17, and 0.50 for L. edodes, A. bisporus, and F. velutipes, respectively. The average ²³²Th concentrations were 4.7, 4.7, and 3.0 Bq/kg dw; the BCFs were 0.50, 0.11, and 0.53 for L. edodes, A. bisporus, and F. velutipes, respectively. The ²²⁶Ra and ²³²Th concentrations in mushrooms had a weak to moderate correlation with the cultivated substrate concentrations. The absorption of the ²²⁶Ra and ²³²Th from substrate-to-mushroom was similar to the hypothesis of the linear model that mushroom concentration yields a positive correlation with substrate concentration.

Keywords: Bioconcentration factor; Cultivated substrates; Linear absorption; Mushroom; Natural radionuclides.