Biomonitoring and assessment of airborne fluoride using Lolium perenne near a phosphate fertilizer production facility.

Airborne fluoride emission is an environmental concern. There is a lack of knowledge in determining factors influencing internal fluoride accumulation in plant tissue. The aim of this study was to improve understanding of how temporal, spatial and physiological factors influence internal fluoride accumulation. Lolium perenne L. (perennial rye grass) was used as a bioindicator and exposed in 52 sites in 2015 and 11 sites in 2016 surrounding the emission source. Biomass was harvested for fluoride analysis. A biomonitoring system was developed to standardize greenhouse cultivation, field exposure, and plant harvest. Results show that relatively cooler weather may promote internal fluoride accumulation of perennial rye grass over time. Distance from the source and exposure time significantly influenced internal fluoride accumulation. Internal fluoride concentrations decreased exponentially with distance from the source, with a sharp drop within 500 m. Generally, fluoride accumulation increased with days of exposure. It peaked after 81 days of exposure in 2015 and 110 days in 2016. Plant age had no significant impact on fluoride accumulation. Biomonitoring can be a cost effective approach for detecting long term environmental impacts of airborne pollution. The method in this research can be applied in various point source air pollution scenarios to assess emission impacts on biota and to aid in land use management.