Introduction

Following the Chernobyl nuclear reactor accident in 1986, there has been much scientific effort to establish the extent of radiocaesium contamination of the terrestrial environment, and to determine the propensity for radiocaesium to transfer to plants and through the food chain to man. In upland ecosystems (grassland and forest) fungi play a major role in controlling cycling of nutrients in soil and, through mycorrhizal associations, the uptake of nutrients into plants. Little attention, however, has been directed at understanding the role of fungi in the movement and availability of Cs in soil.

It has been shown that radiocaesium may be accumulated in the basidiomes of basidiomycete fungi (Haselwandter, 1978; Eckl, Hofmann & Turk, 1986; Elstner et al., 1987; Byrne, 1988; Dighton & Horrill, 1988; Haselwandter, Berreck & Brunner, 1988; Oolberkkink & Kuyper, 1989; Watling et al., 1993). Post-Chernobyl levels of radiocaesium in fruiting structures range from background to 15 000 Bq kg-1 dry wt depending on author, fungal species and locality. Ectomycorrhizal basidiomycete species investigated by Byrne (1988) contained a range from background to 117 Bq kg-1 dry wt of total radiocaesium; Dighton and Horrill (1988) recorded a range of 3890–15 820 Bq kg-1 dry wt for the basidiomes of the ectomycorrhizal species Lactarius rufus and Inocybe longicystis. The more recent study of Watling et al. (1993) showed 137Cs contents of fruiting structures from a range of fungal species from different habitats in the UK.