Accumulation of heavy metals and arsenic in great nettle (Urtica dioica L.) leaf tissues

The aim of the paper was to study the heavy metal contamination of medical herbs in the Voronezh region. The authors analyzed leaf tissues of Urtica Dioica L. collected in urban and agroecosystems and exposed to various anthropogenic effects. Materials and Methods. Heavy metal (including lead, mercury, cadmium, nickel, copper, zinc, cobalt, chromium) and arsenic concentrations were studied in 51 samples of Urtica Dioica L. leaf tissues. The research was conducted by atomic absorption spectrometry, using MGA-915MD atomic absorption spectrometer in accordance with a pharmacopoeia method. Results. All samples met the regulatory requirements on standardized heavy metal (lead, cadmium, mercury) and arsenic concentrations. Comparing the data on the heavy metal concentrations in Urtica Dioica L. leaf tissues and in the upper soil layers collected in the Voronezh region, the authors state that there are significant physiological barriers that prevent ecotoxicant accumulation in the generative plant tissues. It is especially evident for such elements as lead, mercury, arsenic, cadmium, cobalt and chrome. Urtica Dioica L. is able to selectively accumulate some heavy metals constituting the enzyme active sites (e.g., copper and zinc), if their environmental concentrations are below a certain vital level. The plant can also block the delivery of these elements into leaf tissues if their environmental concentrations in the soil are too high. It can be assumed that under anthropogenic load manifested in technogenic environmental pollution a peculiar edaphic type is being formed for Urtica Dioica L. as a result of selection and adaptation to such conditions. Conclusion. Urtica Dioica L. leaf tissues accumulate toxic elements from soils, which is important when planning the places for procuring medicinal plant material and assessing its quality.