Soils Of Different Genesis Research Articles

Forecasting the levels of trace elements and heavy metals content in soils of different genesis for the assessment of their environmental and productional functions

Grounded the method for predicting of trace elements (TE) and heavy metals (HM) content in the soil system of different genesis were examined on the example of soils in different natural-climatic zones of Ukraine, contaminated soils in Kharkiv, Donetsk and Lugansk regions, and intensive fertilizer (organo-mineral, organic and mineral system of fertilizers) of soils in Kiev, Kharkiv, Poltava and Lviv region. In the developed methodical approach by using the parameters indicators of the energy state of the soil (calorific value of humus, the reserves of energy in the soil layer of 0–20 cm) using mathematical models and the spread of the algorithm of the method on other soil types of a particular natural-climatic zone in the conditions of technogenic pollution and technological load is predicted the TE and/or HM content in soils of different types, which ensures the rapidity of the assessment and improve the accuracy of the trace element status prediction, energy and humus state of soils of different genesis with the identification of soils ecological differences to predict their quality by assessment of ecological functions for the ranking of energy intensity indicators of the soil. Scientific elaboration of a method for predicting levels of chemical elements in soils of different types on the natural environment, the effects of man-made pollution and technological load, should be used in the environmental regulation of the TE content and normalization of loads (technogenic, technological) on the soil system, agroecology on issues of organic farming, bioenergy and energy of soil formation; diagnosis, estimation, prediction of humus quality and the of TE status and the danger of excessive accumulation of HM in the soil for indicators of the energy state; the effective environmental management of soils as in natural conditions, and the influence of various anthropogenic factors, taking into account their ecological functions; in research practice – for system research of natural components of the biosphere, the assessment of carbon sequestration in soils and assess of their quality. Distinctive features and advantages of the proposed elaboration in comparison with known methods and approaches are: greater predictability of energy and trace element status, humus and ecological state of the soil as a whole to prevent the degradation of soil organic matter and reduction of risks of influence of HM technogenic pollution; rapidity of obtaining and improving the accuracy of the predictions of the HM and TE content in the soil; universality way to suitability of the method for all soil types in different climatic zones; stimulating further research in the field of energy of soil formation and solution of practical tasks of conservation and restoration of soils functions, identification optimal energy cost and taking into account the ecological functions of soil certain type.

Determination of oil and oil products total content in soils for monitoring of contamination and effectiveness of remediation

The method of determining the content of oil and petroleum products in the soils is substantiated through the use established by thermogravimetric curves optimum temperatures and time intervals thermal sample of contaminated soil, determination of total losses its weight on the appropriate formula which ensures the quantitative determination of total content level of hydrocarbons of oil and oil products in the soil with increased accuracy and quick testing of the method. In the methodical approach by combining individual components of the known methods thermogravimetry and gas chromatography, the distribution regularities of changes in the sample mass under the influence of thermal effects on a new class of objects with simultaneous production of a rapid method for determination of total content of petroleum hydrocarbons in soils, provided simplification soil samples algorithm analyzing for pollution monitoring and the remediation effectiveness of obtaining the economic use of resources. The invention belongs to the field of environmental protection, soil quality, namely to the ways of determine the content of oil and petroleum products (diesel, kerosene, fuel oil, etc.) in contaminated soils while of soils lands plot monitoring. The method can be used in the field of conservancy in the oil industrial complex in determining the degree of contamination of soil for rapid analysis of soil samples; in agroecology, soil ecological management for environmental monitoring of technologically contaminated soils of lands plots for various purposes and their using; in research practice - to investigate the thermal processes and properties of soils; elaboration of scientific and methodical bases of contaminated soils monitoring (diagnosis, assessment, forecast ecological state), environmental regulation of organic nature contaminants in soils; regulation of the using and soil remediation processes to improve quality. Based on the analysis of the scientific literature data and results of long-term experiments it was determined the optimal temperature range of 280–500 ○C with different temperature ranges of thermal evaporation the fractions of petroleum hydrocarbons. Series conducted modeling experiments with varying temperature, time, sample the soils and the changing quantitative and qualitative composition of hydrocarbons in contaminated soils, the total petroleum hydrocarbons thermogravimetric method has been found that the thermal degradation of contaminated soils samples formed various fractions of hydrocarbons, which leads to increased losses mass Dm contaminated soil sample to obtain thermogravimetric curves. By the method of gas chromatography, in the range of 100–200 ○C it is set the selective extraction of lighter fractions of petroleum and petroleum products in the soil; in the range of 280–350 ○C – it is noted a sharp increase in the rate of decomposition of oil saturated hydrocarbons (C10–C40) with intensive gas evolution, the formation of a mixture of reaction products is a significant amount of unsaturated hydrocarbons. Thus, the use of established ranges of determining the optimum temperature desorption fractions of petroleum hydrocarbons and their thermal degradation of soil samples for thermolysis with simultaneous identification of the total content of oil and petroleum products in the soil, it is possible to determine the total amount of oil hydrocarbons fractions in soil as the amount of oil hydrocarbons. The proposed algorithm method is suitable for the soils of different genesis. It is determined that the consistent increase in temperature is a necessary procedure for the identification of pollution if soil sample analysis of the expected low concentrations of oil and petroleum products and water content in soils of different types and different size distribution of more than 5 % of oil production zones. By evaluating the flow of thermal processes in the surveyed contaminated and uncontaminated soil samples the temperature ranges degradation of petroleum hydrocarbons is determined. Their using, as an indicator, significantly reduced the timing of selection of optimal technological parameters of thermal oils in the soils for determining the total content of oil and petroleum products in the soils, pollution monitoring and remediation efficiency control.

Physically based mathematical models of the water vapor sorption by soils

Models for the quantitative description of the water vapor sorption isotherms in soils were developed on the basis of fundamental equations of equilibrium thermodynamics and the molecular-kinetic theory of gases. The derivation of the corresponding equations, their analytical study, and real data for some isotherms of the water vapor sorption by soils of different genesis and degree of dispersion were described. The models adequately described typical S-shaped sorption isotherms in the entire range of the relative water pressure with high determination coefficients (0.98 ≤ R2 ≤ 1) and statistically reliable parameters of the nonlinear regression. Along with the variable relative water content (pressure) of the water vapor in the atmosphere and the content of water in the soil, the parameters of the solid phase (specific surface), soil solution (concentration, electrolyte charges), and temperature were used as the base parameters of the models, which theoretically enable the prediction of changes in the sorption isotherms under the effect of these factors.

Parameters of selective sorption of Co, Cu, Zn, and Cd by a soddy-podzolic soil and a chernozem

The adsorption and ion-exchange behavior of Co, Cu, Zn, and Cd were studied in two soils of different genesis. The sorption parameters and selectivity coefficients of the Me-Ca ion exchange were determined using the Langmuir and Freundlich adsorption isotherms and two models of ion-exchange sorption based on the mass action law (a polyfunctional ion exchanger and a mixture of two ideal exchangers) for describing the relationships between the dissolved and sorbed metal forms. It was shown that simple models provided information for better understanding of the behavior of metals in sorption and ion-exchange processes, but the conclusions about the sorption of different metals in a specific soil or a specific metal in different soils based on these models can be different.

The effect of aggregate size on water retention and pore structure of two silt loam soils of different genesis

Aggregate size distribution and pore structure affect many soil functions and root growth. The aggregate structure is associated with soil genesis and management practices applied. In this study the effects of various size ranges of aggregates (<0.25, 0.25–0.5, 0.5–1, 1–3, 3–5, and 5–10 mm) and undisturbed soil from the plough layer (0–15 cm) of two types of soils (Haplic Phaeozem and Eutric Fluvisol) of the same silty loam textural group on water retention curves (WRC) and pore size distribution (PSD) were assessed. A greater bulk density and lower humus content characterized the Eutric Fluvisol as compared to the Haplic Phaeozem. The WRC was determined using standard Richards chambers in drying process and expressed as the degree of saturation. Equivalent PSD was derived from the WRC. Resin impregnated sections from the layer of 0–8 cm showed that the Eutric Fluvisol, compared with the Haplic Phaeozem, had coarser pores and aggregates. The degree of saturation in beds of aggregates <0.25, 0.25–0.5 and 0.5–1 mm compared to beds of aggregates 1–3, 3–5 and 5–10 mm was greater at higher values of pressure head for both soils, and for undisturbed soil it was greater for the Haplic Phaeozem than for the Eutric Fluvisol at lower values of pressure head. The inverse relationship was true at higher values of pressure head. The derivative curves of PSD showed that the beds of aggregates and undisturbed soils exhibited multi-peak PSD. The pore radius peaks within the textural (primary) pore system were more defined in beds of aggregates <0.25 mm than in beds of coarser aggregates, whereas in the case of the structural and macropore peaks it was often the reverse. Greater magnitude and narrower shape of the peaks in the undisturbed Haplic Phaeozem compared to the Eutric Fluvisol indicated a more heterogeneous nature of the pore system in the former. The PSD data are discussed in relation to aggregate size distribution and stability of the soil aggregates. The results of this study can be helpful in predicting storage and transmission functions of surface aggregated soils.

Spectroscopic Method for Estimation of Soil Organic Carbon

The amount of soil organic carbon (OC) is a good indicator of a soil's productivity potential. Thus, OC analyses are routinely used to evaluate the soil's potential to supply N during a cropping season, or to assess the potential adsorption of a herbicide. Two methods are currently used to determine OC in soil. Both have some limitations for use in processing large numbers of samples for routine analyses. The dry combustion procedure requires expensive instrumentation, while the wet digestion procedure is rather lengthy and the disposal of Cr can be a problem. This study describes a new method for a relatively inexpensive, accurate, and rapid determination of OC in soil. Finely ground soil samples are equilibrated with an extracting solution of 0.25 M KOH and 0.05 M Na₂-EDTA (ethylenediaminetetraacetic acid) for 2 h at 85 °C. After cooling, absorbance of the extract was measured at 260 nm. An empirical equation is used to obtain an indirect estimate of soil OC. The empirical equation was developed from comparative analysis between the dry combustion and the proposed spectrophotometric method (r² = 0.89) by using a series of soils of different genesis and development. The method was further evaluated by analysis of samples from two soil profiles not used in the development of the equation, and the results were in close agreement with those obtained from dry combustion.