Dynamics of migration property of some heavy metals in soils in Kharkiv region under the influence of the pyrogenic factor

Abstract

In soils after fires trace metals sharply change their migration ability and can form poorly-soluble hydroxides which are hazardous chemical formations, the nature of which has not been fully explored until now. In addition, in interstitial water, there is a probability of the formation by metals of hydroxocomplexes with different amounts of hydroxide ions. We studied the range of dynamics of migration capacity of sedimentation of hydroxides and the region of predominance of soluble hydroxocomplexes by developing logarithmic concentration diagrams (LCD). We developed logarithmic concentration diagrams, the equation of formation of prevailing forms, using which it is possible to clearly determine the regions of maximum sedimentation (accumulation) of hydroxides and hydroxocomplexes of heavy metals after the influence of the pyrogenic factor. The obtained calculations of the results of the predictive modeling of the dynamics of migration capacity and postpyrogenic migration geochemical processes in ecogeosystems have been organized and systematized. The determined patterns can be useful for the analysis of possible geochemical migration (accumulation) of heavy metals in ecological systems in the study of technogenic and ecological situation after fires. Based on the calculations made, mathematical models of heavy metals` behaviour are developed, which are useful for drawing up a forecast estimation of the dynamics of their geochemical migration and accumulation in ecological systems as a result of the influence of the technogenic loading of the pyrogenic factor. The conditions of concentration and migration of compounds of heavy metals were determined, and the equation for calculating the concentration of mobile forms of trace metal compounds has been developed. The developed map of the activity of geochemical migration of heavy metals under the influence of the technogenic loading of pyrogenic factor will make it possible to elaborate the migratory capacity of trace metals and provide a forecast of their behaviour in ecological systems after fires. This will allow preventive measures to be taken to ensure environmental safety and prevent adverse effects on human health and the condition of the components of the environment. The creation of similar cartographic material may be extrapolated to other regions of Ukraine, affected by technogenic loading of pyrogenic factor. The development of logarithmic concentration diagrams allows us to predict the capacity of compounds of lead, nickel, chromium,and copper for migration or accumulation of heavy metals due to changes in the acidity of soils under the influence of the pyrogenic factor. Having used the map of the soils of the Kharkiv region, we analyzed and provided a forecast of the migration ability of lead compounds in cases of fire in different types and subtypes of different environmental conditions.