I recommend you to make contact him. He is old member of International Society for Fluoride Research and friend of both Albert Burgstahler and I . Unfortunately, I do not know his phone number. Have a good weekend. Not only gases like HF are important in this respect but also the dust-like fluoride compounds.
Fluorides accumulate in the soil.
One of the indirectly toxic effects observed is the leaching of organic matter as well as aluminum and iron from soil samples by fluoride. In experiments they cacrried out with soil samples, the amount of those substances dissolved was proportional to the fluoride content of the solutions used. Another variable should be mentioned. Both sources of nitrogen are converted in the plant to amino acids and proteins, containing the -NH2 group. They sell a special piece that ties into the actual gutter that redirects the water into the drum through a simple filter.