ACCUMULATION OF FLUORIDE IN HORSE -CHESTNUT (AESCULUS HIPPOCASTANUM L.) LEAVES COLLECTED FROM WEST POMERANIAN DISTRICT OF POLAND

Since the finding that fluoride is a bioelement, research on its biological role, its applicability in practice, and its toxicity has intensified. Fluoride is characterized by a narrow safety margin. The entire ecosystems located within the range of fluoride emitters are highly susceptible, especially plants, to fluoride toxicity. The West Pomeranian District in Poland is an area with chemical plants that emit significant amounts of fluoride into the atmosphere. Literature regarding the use of various plant species as bioindicators of fluoride in air is currently available. However, to the best of our knowledge, there is no information regarding the accumulation of fluorides in horse chestnut leaves. Therefore, in this study, we aimed to assess the fluoride content in horse chestnut leaves according to the distance from the emitter and the year of collection of leaves. Horse chestnut leaves were collected in the first week of July from 2013 to 2016 from the 12 measurement points located in the West Pomeranian District, Poland. The fluoride content was determined potentiometrically. According to the results, fluoride content in horse chestnut leaves ranged from 6.89 mg/kg DW to 22.88 mg/kg DW. The median value of fluoride content decreased as the distance from the emission source increased. However, the year of sampling did not significantly affect the fluoride content in horse chestnut leaves. Thus, these results indicate the potential application of horse chestnut leaves as a bioindicator of air pollution with fluorides.