An evaluation of the occurrence and trends in 137Cs and 40K radioactivity in King Bolete Boletus edulis mushrooms in Poland during 1995–2019

B. edulis, collected from 33 forested or woodland sites across Poland over 25 years since 1995, were analysed for radiocaesium. The results ( 137Cs activity range: 25 to 10,000 Bq kg -1 dry weight) provide a good indication of artificial radioactivity in this food material. The relatively higher levels detected in the earlier years, mostly in easterly location, is consistent with depositions from the projected Chernobyl incident (1986) fallout plumes. Nevertheless, the 137Cs concentrations during 1995–2010 were, on average, higher than those reported by other studies for Polish B. edulis over the period 1986–1994. The data concurs with the general hypothesis and observations that deposited 137Cs permeates slowly over time to deeper soil horizons which host the mycelial networks. This delay in availability shows that (apart from hotspots) higher contamination of fruiting bodies occurred around 10 to 20 years after the incident. Local consumers and recreational mushroomers were undoubtedly exposed, although reported 137Cs concentrations suggest that serious breaches of regulated levels were uncommon

Radiocaesium in Tricholoma spp. from the Northern Hemisphere in 1971–2016

A considerable amount of data has been published on the accumulation of radiocaesium ( 134Cs and particularly, 137Cs) in wild fungi since the first anthropogenically influenced releases into the environment due to nuclear weapon testing, usage and subsequently from major accidents at nuclear power plants in Chernobyl (1986) and Fukushima (2011). Wild fungi are particularly susceptible to accumulation of radiocaesium and contamination persists for decades after pollution events. Macromycetes (fruiting bodies, popularly called mushrooms) of the edible fungal species are an important part of the human and forest animal food-webs in many global locations. This review discusses published occurrences of 134Cs and 137Cs in twenty four species of Tricholoma mushrooms sourced from the Northern Hemisphere over the last five decades, but also includes some recent data from Italy and Poland. Tricholoma are an ectomycorrhizal species and the interval for contamination to permeate to lower soils layers which host their mycelial networks, results in a delayed manifestation of radioactivity. Available data from Poland, over similar periods, may suggest species selective differences in accumulation, with some fruiting bodies, e.g. T. portentosum, showing lower activity levels relative to others, e.g. T. equestre. Species like T. album, T. sulphurescens and T. terreum also show higher accumulation of radiocaesium, but reported observations are few. The uneven spatial distribution of the data combined with a limited number of observations make it difficult to decipher any temporal contamination patterns from the observations in Polish regions. When data from other European sites is included, a similar variability of 137Cs activity is apparent but the more recent Ukrainian data appears to show relatively lower activities. 40K activity in mushrooms which is associated with essential potassium, remains relatively constant. Further monitoring of 137Cs activity in wild mushrooms would help to consolidate these observations

137Cs and 40K in Cortinarius caperatus mushrooms (1996–2016) in Poland - Bioconcentration and estimated intake: 137Cs in Cortinarius spp. from the Northern Hemisphere from 1974 to 2016

Cortinarius caperatus grows in the northern regions of Europe, North America and Asia and is widely collected by mushroom foragers across Europe. This study shows that in the last three decades since the Chernobyl nuclear accident, C. caperatus collected across much of Northern Poland exhibited high activity concentrations of radiocaesium (137Cs) - a long-lived radionuclide. The mushroom appears to efficiently bioconcentrate 137Cs from contaminated soil substrata followed by sequestration into its morphological parts such as the cap and stipe which are used as food. The gradual leaching of 137Cs into the lower strata of surface soils in exposed areas are likely to facilitate higher bioavailability to the mycelia of this species which penetrate to relatively greater depths and may account for the continuing high activity levels noticed in Polish samples (e.g. activity within caps in some locations was still at 11,000 Bq kg−1 dw in 2008 relative to a peak of 18,000 in 2002). The associated dietary intake levels of 137Cs have often exceeded the tolerance limits set by the European Union (370 and 600 Bq kg−1 ww for children and adults respectively) during the years 1996–2010. Human dietary exposure to 137Cs is influenced by the method of food preparation and may be mitigated by blanching followed by disposal of the water, rather than direct consumption after stir-frying or stewing. It may be prudent to provide precautionary advice and monitor activity levels, as this mushroom continues to be foraged by casual as well as experienced mushroom hunters

Bioaccumulation of gamma emitting radionuclides in red algae from the Baltic Sea under laboratory conditions

The bioaccumulation ability of radionuclides ⁵¹Cr, ⁵⁴Mn, ⁵⁷Co, ⁶⁰Co, ^65Zn, ⁸⁵Sr, ¹⁰⁹Cd, ¹¹⁰mAg, ¹¹³Sn, <sup>137Cs and ²⁴¹Am in two red algae species from the southern Baltic Sea - <i>Polysiphonia fucoides</i> and <i>Furcellaria lumbricalis</i> - was determined under laboratory conditions. <i>P. fucoides</i> demonstrated better bioaccumulative properties towards most of the investigated radionuclides. As a result, <i>P. fucoides</i> can be recommended as a good bioindicator of radioactive environmental pollution. The bioaccumulation of radionuclides in <i>F. lumbricalis</i> was studied during an extended laboratory experiment. The initial extensive uptake of radioisotopes was followed by the rapid removal of cations; in general, concentrations tended to decrease with time. ¹³⁷Cs displayed a different behaviour, its concentration in the algae increasing over time mainly due to its large ion radius; this is a factor that could be responsible for the stronger mechanical and chemical bonding of Cs⁺ and that could hamper the movement of ions in both directions