Arsenic and cadmium accumulated in lavender flowers grown in contaminated bottom sediment from the Baltic Sea (Malmfjärden)

Lavender (Lavandula angustifolia Mill.) is an ornamental and medicinal plant, used for human consumption. In this preliminary study the lavender plants were grown in a mixture of soil and contaminated bottom sediment. The objective of the study was to test if lavender plants grown in contaminated soil contain higher concentrations of heavy metals than permitted by WHO. The levels of heavy metals in lavender flowers were compared to inflorescence from plants grown in ordinary untreated soil. The levels of manganese, zinc, cobalt, nickel, lead, arsenic, chromium, cadmium and mercury were determined. High levels of lead, arsenic, cobalt and cadmium were accumulated in the lavender inflorescence of plants growing in contaminated soil. Cadmium and arsenic are harmful elements of great concern and have a negative impact on human health. The concentration of arsenic was 0.16 mg/kg dry weight of lavender flowers growing in contaminated sediment. No arsenic was detected in the control flower. In addition, the levels of cadmium were higher in the flowers of lavender grown in contaminated soil in comparison with the inflorescences from plants grown in the untreated soil. A higher concentration of cadmium was detected in the flowers from plants that had grown in the contaminated mixture of soil than in the control, the concentration was 0,7 mg/kg dry weight and 0,01 mg/kg dry weight, respectively. Mercury was not detected in any of the tested inflorescence. The results from this preliminary study suggested that lavender accumulates heavy metals from contaminated soil and may be used in the restoration of contaminated land by taking up toxic heavy metals. Further studies are needed to evaluate the efficiency of lavender as a phytoremediation plant.