Nickel, Cu, Fe, Zn, and Se Accumulation, and the Antioxidant Status of Mushrooms Grown in the Arctic Under Ni/Cu Pollution and in Unpolluted Areas

Mushrooms play an important role in ecosystem sustainability and are highly valued in medicine and human nutrition. Using AAS and biochemical methods of analysis, the antioxidant status and mineral composition of seven mushroom species (Armillaria mellea, Xeromocus illudens, Leccinum aurantiacum, Leccinum scrabum, Lactarium pubescens, Rusula vesca, and Lycoperpon molle Pers.) gathered near the Pechenganikel smelting plant in the Pasvik Nature Reserve of the Murmansk region were evaluated. The concentrations of Ni and Cu in the fruiting bodies of mushrooms were in the ranges of 0.43–39.7 and 7.9–45.9 mg kg−1 d.w., respectively. An unusually high biological concentration factor (BCF) for Ni, Cu, and Zn levels in mushrooms grown in soils with a low amount of these elements indicates the low suitability of the mentioned parameter for mushroom characteristics in territories with an uneven distribution of elements in soil. On the other hand, selenium (Se) showed high BCF levels, exceeding 1, for all mushrooms tested, with the highest values associated with L. saccatum (5.17) and the lowest values with A. mellea (1.36). A significant excess (3.4) of the Recommended Daily Allowance (RDA) level per 30 g of dry mushrooms was recorded for Ni in Russula vesca gathered 6 km from the Ni/Cu smelting plant, and 1.3 excess of the RDA was recorded in L. scrabum grown in the vicinity of the Shuonyoka waterfall. No RDA excess was revealed for Cu. Positive correlations between Se, polyphenol content, and total antioxidant activity (AOA) (r = 0.915–0.926; p < 0.001) and a negative correlation between Cu–Se and Cu–AOA in Leccinum species indicate the important role of antioxidant defense and Se, particularly in Arctic mushroom growth and survival, providing a specific protection of mushrooms against Cu toxicity.