Occurrence and Detection Profiles of Technology-Critical Elements (Ga, Ge, Nb, Ta and W) in Wild Mushrooms from Leicester and Leicestershire, UK

Technology-critical elements are increasingly used in electronics, renewable-energy systems, high-performance alloys and other strategic technologies, yet their occurrence in wild fungi remains poorly characterised. This study evaluated gallium (Ga), germanium (Ge), niobium (Nb), tantalum (Ta) and tungsten (W) in wild mushrooms collected from Leicester and Leicestershire, UK. The dataset was reconstructed at fruiting-body level to avoid pseudo-replication from paired cap and stem records, yielding 121 analytical units. Results were corrected using digestion-date acid blanks, interpreted against analytical-portion-specific working limits of detection and classified as fully quantified (FQ), partially censored (PC) or fully censored (FC). Ga was FQ in 106/121 units and was the only element with sufficient quantitative coverage for continuous distributional estimation; its regression-on-order-statistics median was 475.48 ng g−1 dw (IQR: 278.70–941.63). The corresponding FQ counts were 16 for Ge, 33 for Nb, 10 for Ta and 24 for W, with 7, 4 and 4 additional PC observations for Nb, Ta and W, respectively. In 22 paired Agaricus bitorquis fruiting bodies, Ga concentrations were higher in stems than caps (Wilcoxon p = 5.25 × 10−5; BH-FDR = 1.05 × 10−4). Composite topsoils from 26 monitored sites provided park-scale geochemical context only and were not used to infer bioaccumulation or direct soil-to-fungus transfer. These findings establish a blank-corrected and censoring-aware occurrence baseline and suggest exploratory, site-specific potential for wild mushrooms as complementary biomonitoring matrices for selected technology-critical elements, while demonstrating that their usefulness is element-, taxon- and design-dependent.