THE INFLUENCE OF ORGANIC MATTER ON THE GEOCHEMISTRY OF FLUORINE IN BROWN SOILS OF TRANSCARPATHIEN (SVIDOVETS MASSIF)

The content of water-soluble fluorine and humic components was determined: humus content in the upper horizon (С org), the content of humic acids (Сga), the content of fulvic acids (Сfa) in brown soils (Svidovets Massif of the Carpathian Bio- sphere Reserve) of various natural taxa — spruce, beech, beech-spruce forest. Research methods: the quantitative content of organic matter in soils was obtained by dry ashing; humic and fulvic acids by alkaline extraction; water-soluble forms of fluorine by potentiometric method. It was established that in all soils the humus type is humic-fulvic — Cga:Cfa 0.65—0.95. The following zonality was recorded for the Cga:Cfa values: 0.65—0.75 (soils under spruce forests), 0.75—0.85 (soils under beech-spruce forests), 0.85—0.95 (soils under beech forests). Reverse zoning is characteristic of the content of water-soluble forms of fluorine in soils, mg/kg: under spruce forests — 1.4—1.8; under beech-spruce forests — 1—1.4; under beech forests — 0.6—0.9. This dependence means that the more fulvic acids in humus, the higher the content of water-soluble fluorine in soils. It has been found that fulvic acids actively destroy soil minerals, which facilitates the release of ions, including fluorine, from mineral forms. The higher cation exchange capacity of fulvic acids (compared to humic acids) also contributes to their ability to mobilize and transport ions in soil solution.