Features of formation of natural and technogenic diffuse sources of pollution of water bodies in their catchments
Dispersed (diffuse) sources of heavy metals in catchments play an important role in the pollution of water bodies. The main depositing medium for elements entering the catchment area are soils. They form lithochemical halos of elevated concentrations of heavy metals. Therefore, it is important to study the features of the formation of anomalous zones of scattering of heavy metals of natural and technogenic genesis and the mechanisms of their interaction with soil components. It is important to consider the formation of mobile forms of elements that are able to transform into aqueous solutions and create a potential and real threat to water and soil ecosystems. The article shows that natural and technogenic lithochemical haloes of heavy metals differ fundamentally from each other by sources of their entry, formation mechanisms, peculiarities of localization of elements and their forms in the solid phase of soils, mineralogical composition. A method that allows to quantify the potential hazard of lithochemical haloes is proposed. Significant differences in the assessment of the toxicity of individual elements for soil and aquatic biota have been identified, which should be taken into account when assigning water protection measures in river basins. The presented method allows to rank diffuse lithochemical haloes according to their degree of danger for biota.