Abstract. The study of geochemical aspects of the transformation of migration properties of heavy metals under the influence of anthropogenic loading of pyrogenic origin has been given insufficient attention. We studied the concentration of heavy metals in soils by atomic absorption analysis. The results indicate the transformation of their migration properties. The diversity and versatility of behaviour of chemical elements in environmental components after fire was noted. In different ecological conditions, it is possible to observe a wide range of quantitative values of geochemical migration or accumulation of any particular chemical element. The analytical results show that the contents of migrant elements, pH values, areas of disasters which are approximately in the same conditions, but passed by the grass or upper fire differ quite tangibly. Heavy metals that hit the environment can form difficult soluble hydroxides. In addition, in the soil solution, there is a probability of the formation of hydroxocomplexes with different amounts of hydroxide ions by metals. The range of precipitation of hydroxides and the region of predominance of soluble hydroxocomplexes have been studied by constructing concentration-logarithmic diagrams. On the basis of the calculations it can be argued that the influence of technogenic loading of pyrogenic origin influences the geochemical migration of heavy metals . Compounds Fe 3+ at the pH = 4.5-14, Cu 2+ at pH = 7-14, Cr 2+ at pH = 7-9, Zn 2+ at pH= 8-11, Ni 2+ at pH = 8-14 have the lowest migration potential. Compounds Pb 2+ at pH = 9-12, Fe 2+ -pH = 9.5-14 have the lowest migration potential also. In a more acidic environment, soluble substances are formed, but at a pH increase of only 0.5-1, they can decrease their mobility by an order of magnitude which contributes to their concentration in the soils after the fire. In a neutral soil reaction, most of the heavy metals (Al, Cr, Zn, Cu, Fe (II), Ni) are in a slightly soluble form (in the form of hydroxides), with insignificant, migration capacity which leads to the accumulation of these chemical elements in the soil. It is necessary to allocate heavy metals moving in a neutral environment (Fe (II), Cd, Co, Mg, Mn) into a separate group. Any increase in pH values contributes to their fixation. The obtained calculations can be used to predict the geochemical migration of heavy metals in soils which result from anthropogenic disasters of a pyrogenic origin. України, Харків, Україна, e-mail: asotskiy@nuczu.edu.ua 3 Харківський національний автомобільно-дорожній університет, Харків, Україна, e-mail: alenauvarova@ukr.net 4 Національний університет цивільного захисту України, Харків, Україна, e-mail: prv1984@ukr.net Aнотація. Дослідженням геохімічних аспектів трансформації міграційних властивостей важких металів за впливу техноген-ного навантаження пірогенного походження приділено недостатньо уваги. Проведено дослідження концентрації важких ме-талів у ґрунтах методом атомно-абсорбційного аналізу. Результати вказують на...
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.
This article presents the analysis of results of experimental data of postpyrogenic change of soils of ecological systems of pine forests.Ground fires transform the surface organogenic horizons of soils. The negative influence of low-intensity fires of different intensity on the change of humus stock, qualitative fractional composition of organogenic soil horizons and their chemical composition is shown.Post-pyrogenic transformations of physical and chemical soil characteristics are found, which are not simply their corresponding reaction to the pyrogenic effect, but a clear signal reflecting the state of the soil immediately after the fire, taking into account its strength and intensity, and after a certain period of time. There is a certain dependence of the degree of pyrogenicity on the duration of the effect of fire on the soil. The recent influence of a medium intensity fire on the soil is marked by a clear reaction of the complex of its properties.Physical and chemical properties of soils after fires deteriorate: humus burns, the content of nitrate nitrogen decreases.Forest fires sharply change the morphological state of the upper part of the soil profile. The nature of the surface horizons of soils changes, a new pyrogenic horizon is formed, which differs from natural analogues in terms of physical and chemical properties and the content of ash elements. Under the influence of fire there are changes in such properties as: pH, content of exchange cations, gross and moving forms of nitrogen, etc.The heavy metal concentration in surface horizons increases several times and exceeds the background values due to the mineralization of forest litter and herbaceous vegetation from the combustion and subsequent migration of chemical elements , which presents an environmental hazard.The change in the chemical composition of soils can create conditions for the impossibility of the existence of a root ecosystem, its death, and development, after a certain time, of another modified ecogeosystem.
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