This study measured acid-recoverable zirconium, hafnium and tellurium in 121 wild mushroom fruiting bodies collected in urban and peri-urban green spaces in Leicester and Leicestershire, England, in autumn 2019, alongside 26 composite topsoils. Zirconium was detected in every mushroom and soil sample. Concentrations varied by taxon and site, but the soil data could not show whether mushrooms take up zirconium from soil.
Key numbers
- Zirconium in mushrooms, all 121 units: median 170 ng/g dry weight (IQR 61 to 380), range 28 to 3200, mean 320, geometric mean 170, 95th percentile 1100, 97.5th percentile 1500 ng/g dry weight; detected in 121/121 (Table 1, p. 11).
- Working limit of detection for zirconium in mushrooms 0.294 ng/g dry weight; instrumental limit 0.007 µg/L (Section 2.8, p. 7).
- Taxon-site medians for zirconium: Panaeolina foenisecii 390 ng/g (n 28, range 32 to 3200); Mycena citrinomarginata 390 ng/g (n 22, range 120 to 2000); Coprinopsis atramentaria 260 ng/g (n 8); Agaricus bitorquis 56 ng/g (n 22, range 38 to 140); unidentified group 89 ng/g (n 17), all dry weight (Table 2, p. 13).
- Zirconium in contextual topsoils: median 11.0 mg/kg dry weight (IQR 9.68 to 12.7), range 6.65 to 17.7 mg/kg, n 26 composites; working limit of detection 0.0131 mg/kg (Table 3, p. 15).
- Park-level medians of zirconium, hafnium and tellurium were strongly correlated (Spearman rho 0.819 to 0.885, 13 parks); the first principal component explained 93.4% of variance (Abstract).
- Independent aqueous check standard recovery for zirconium about 102% (RSD 3.27%) in the mushroom run (Section 2.8, p. 8).
Methods (brief)
Opportunistic collection of fruiting bodies (September to November 2019), cleaning with tap, deionized and ultrapure water, oven drying at 50 °C, cryogenic homogenization, closed-vessel nitric acid and hydrogen peroxide digestion, filtration, and ICP-MS (helium mode for zirconium-90, indium-115 internal standard). Cap and stipe results were averaged to one value per fruiting body. Topsoil composites (0 to 5 cm) were digested with reverse aqua regia.
Evidence fitness
Supports occurrence of acid-recoverable zirconium in wild mushroom fruiting bodies and urban topsoil in one English city. It does not support dietary exposure estimates: the paper does not address which taxa are eaten, gives no consumption data, and does not assess health risk. It does not support soil-to-mushroom transfer claims.
Limitations
Opportunistic sampling with taxon and site confounded; most taxa came from a single park. Values are acid-recoverable, not total, because refractory minerals may not dissolve and surface particles may remain. No certified reference materials, matrix spikes, procedural blanks or replicate digestions were available; no blank subtraction was applied. Topsoils were contextual composites, not paired with individual fruiting bodies.
Related evidence
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