Environmental monitoring of fluoride emissions using precipitation, dust, plant and soil samples.

A pollution gradient was observed in precipitation, plants and soils sampled at different locations around a fluoride producing chemical plant in Germany. In all samples the influence of emissions was discernible up to a distance of 500 m from the plant. However, fluoride concentrations in plant bioindicators (leaves of birch and black berry) and in bulk precipitation showed a more pronounced relationship with the distance from the source than fluoride concentrations in soil. Vegetables sampled in the vicinity of the plant also had elevated concentrations of fluoride, but only the consumption of larger quantities of this material would lead to exceedances of recommended daily F-intake. The present study did not indicate the existence of low phytotoxicity thresholds for fluoride in the plant species used in the study. Even at very high fluoride concentrations in leaf tissue (963 ppm) plants did not show injury due to HF. Dust sampling downwind of the chemical plant confirmed that particulate fluoride was of minor importance in the study area.