Stable Carbon and Nitrogen Isotopes in Woody Plants and Herbs near the Large Copper Smelting Plant

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Abstract—Variations of stable carbon (¹³С and ¹²С) and nitrogen (¹⁵N and ¹⁴N) isotopic composition are analyzed in forest plants subjected to the emissions of large copper smelting plant. The studies were carried out in pine forests at ten test plots near the Karabash copper smelting plant and in the Ilmen State Reserve at South Urals. The ¹³С/¹²С and ¹⁵N/¹⁴N isotopic ratios were analyzed in leaves of plants of different functional groups (with ecto-, ericoid, or arbuscular mycorrhiza; with nitrogen-fixing symbiosis, and non-mycorrhizal). The ¹³С/¹²С ratio did not change under technogenic pollution. The low isotopic ¹⁵N/¹⁴N ratio was established in ectomycorrhizal trees, while the high ratio was found in herbs with arbuscular mycorrhiza, nitrogen-fixing symbiosis, and non-mycorrhizal groups. As compared to nonpolluted habitats, the ¹⁵N content in leaves near the copper smelting plant increases by 2.7‰ in the ectomycorrhizal trees and by 3.4‰ in undershrubs with ericoid mycorrhiza, and by 2.2‰ in herbs with arbuscular mycorrhiza. This indicates a significant change in conditions of mineral feeding of plants under heavy metal pollution of natural ecosystems.