MONITORING OF ATMOSPHERIC AND SOIL WATER COMPOSITION IN FOREST ECOSYSTEMS: MILESTONES AND OUTLOOK

The article provides an overview of Russian and foreign studies on assessment of the composition of atmospheric fallout and soil waters in forest ecosystems. The conclusion was made that little attention is given to the transformation of precipitation chemical composition by forest ecosystems, taking into account the influence of the species composition of the stand and the mosaic structure of the biogeocenosis (areas below the crowns, between the crowns, and open sites). European studies usually look at long-term development of the composition of atmospheric fallout and lysimetric waters, detecting long-term trends in composition changes of atmospheric and soil waters and identifying the factors driving these changes. In Russia, no such long-term (lasting for more than 10 years) continuous observations on the effect of man-made pollution on the composition and properties of atmospheric and soil waters were carried out. This task is very relevant for Russia and, especially, for its industrial regions.

Interaction of ions of heavy metals and organic toxicants with humic substances in system ‘atmospheric precipitation - lysimetric waters - lake waters’ of the Reserve of the European Territory of Russia: climatic, technogenic, geochemical fact

<p>The reactions of toxicants with organic substances of a humic nature are complex and depend on many geochemical factors. Differences in the mechanisms of the selected toxicants binding with organic natural substances of various natural waters - atmospheric precipitation, lake waters (acidic and alkaline), lysimetric waters are especially interesting. Due to significant concentration differences, features of functional groups and size distribution of components, the inactivation features of humic substances are selective and highly variable. We studied the waters of an acid lake near the city of Valday (Valday National Park, conditionally a background lake) and alkaline lake Valday (city of Valday, local technogenic influence). Near each lake there was a sediment collector (a container for collecting atmospheric precipitation) and a lysimeter (a container under the soil for collecting soil moisture) under the humus horizon (about 20 cm). Particular attention was paid to soil (lysimetric) waters with varying degrees of anthropogenic impact. We considered the behavior of a large group of heavy metals, as well as benzopyrene. To assess the composition and qualitative features of organic substances, gas chromatography-mass spectrometric methods of analysis were used. Chromatographic methods were used to assess the molecular weight distribution of the components. Possible reaction mechanisms were studied by IR spectral methods. Evaluation of the reactivity of organic substances was carried out by the methods of dynamic light scattering (zeta potential, MM, size) using the "Zeta-sizer nano". In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. For separation, exchange technique and fluorometric evaluations were used. We conducted research in the period 2015-2020, sampling was carried out in spring, summer, autumn. Thus, we studied the circulation (in miniature) of changes in the protective properties of humic substances, depending on a large number of factors.</p>

Growing miscanthus on radioactively contaminated soils and regularities of 137 CS redistribution in the system «Soil-Plant-Lysimetric waters»

Purpose. Investigate the patterns of transition of 137 Cs radionuclide from soil to biomass and lysimetric waters depending on the elements of technology for growing giant miscanthus on solid fuel on contaminated soils. Methods. Lysimetric, biomorphological, radiometric, statistical, comparative and computational. Results. The article presents the results of research to study the accumulation of the radioactive isotope 137 Cs in the biomass of giant miscanthus and its transition into lysimetric waters. According to the research results, the level of 137 Cs radionuclide accumulation in miscanthus plants on contaminated soils depends on its concentration in the soil and elements of cultivation technology. It was found that in the variants where the bioenergy crop was grown on soils contaminated with radionuclides, the accumulation of 137 Cs in the biomass in the range of 14.7–18.6 Bq/kg and in the lysimetric waters of 4.36–4.57 Bq/l was observed, respectively. Fertilization with mineral fertilizers together with defecation and treatment with miscanthus rice before planting with the microbial preparation Polymyxobacterin in combination with BioMAG helped to increase the yield of dry biomass by 28% of control. Conclusions. The use of mineral fertilization in combination with liming, inoculation of miscanthus rhizomes with the microbial drug Polymyxobacterin and pre-planting treatment with organo-mineral fertilizer BioMAG significantly increases the yield of dry biomass, reduces the content of 137 Cs in biomass and lysimetric waters. The accumulation of 137 Cs in the biomass of miscanthus when grown on soils contaminated with radionuclides did not exceed the permissible level (DR), and the use of elements of technology helped to reduce the content of 137 Cs by 12–21% compared to control variants. The use of the fertilizer complex «mineral fertilizers + defect + Polymyxobacterin + BioMAG» resulted in the lowest accumulation coefficients of 137Cs, which are 0.07 in the biomass of miscanthus and 0.02 in lysimetric waters, respectively.

Agroecological assessment of fluorine in soils and agricultural plants of steppe landscapes of Odessa region

The materials of long-term research of the features of the content and distribution of fluorine in southern chernozems are highlighted. The purpose of this work is to investigate the effects of irrigation and chemical meliorants on the fluorine accumulation in soils and crops. To achieve this goal, the following tasks were set: to determine the content of fluorine in soils and plants in conditions of irrigation and application of phosphorus fertilizers (phosphogypsum); to carry out ecological assessment of southern chernozems in terms of accumulation and migration of fluorine in soil, plant resistance to fluorine accumulationand translocation. The research was conducted within the irrigation areas of Odessa region. Bulk and movable forms of fluorine were determined by the potentiometric method in the southern chernozems of different reclamation state (non-irrigated, irrigated and irrigated reclaimed). The content of movable fluorine in agricultural plants was determined by the author’s method. It was established that the contest of bulk fluorine is the highest in the non-irrigated chernozems, but does not exceed the MPC. In irrigation, the number of bulk forms of fluorine decreases due to their dissolution and migration from the top layer to the depth of the soil profile. The content of soluble forms of fluorine increases significantly in all components of agrolandscape under the influence of irrigation and especially the introduction of phosphogypsum. It was determined that the combined application of phosphorous fertilizers and manure leads toa decrease of the fluorine content in soils, lysimetric waters and agricultural plants. The degree of mobility of fluorine compounds in the studied chernozems during irrigation and especially the introduction of phosphogypsum increases. The level of fluorine content in lysimetric waters and the coefficient of water migration correlate with its content in soils. A positive correlation was found between the fluorine content in the roots of maize, oats, wheat ear and soil while its absence between the content of fluorine in the stems and leaves. The introduction of mineral and organic fertilizers together enhances the ability of plants to absorb fluorine from chernozem soils. The active contamination rate for all tested plants is higher than one, which can cause their inhibition. When resuming irrigation of chernozem soils, there will be a need for increased doses of mineral, including phosphorus fertilizers. Despite the low solubility of fluorine compounds, conducted research has shown that irrigation and application of phosphogypsum significantly increases the soluble forms of fluorine, which can adversely affect the pollution of agrolandscapes and public health.

Nitrogen balance and mineral nitrogen content in the soil in a long experiment with maize under different systems of N fertilization

The effect of different systems of N fertilization on nitrogen balance and N transformation in the soil was studied in long-term stationary experiments (1991–2002) with successive growing of maize. Average dry matter yield for the control without fertilization in the period 1991–2002 was 11.67 t of dry matter per ha, which was by 2–2.9 t less than for fertilization treatments. Statistically significant differences between the control and fertilization treatments were determined for the first time in the 4th experimental year. Average nitrogen uptake by the aboveground biomass was116 kgN/ha for the control, 162–170 kg N/ha for fertilization treatments. All experimental treatments had a negative balance of N inputs and outputs, and it was –1394 kg N/ha for the control (for 12 experimental years). After the application of mineral fertilizers, a lower content of total carbon and nitrogen was measured in the topsoil compared to the control and treatments with organic fertilization. The changes in the nitrogen regime of soil were characterized by the content of extractable nitrogen and carbon in extractions by 0.01M CaCl2. With respect to the content of mineral nitrogen and easily extractable organic nitrogen and carbon in the topsoil the control was most stable followed by farmyard manure treatment. Soil lysimeters were installed in these experiments (depth60 cm, size0.2 m2). For an eight-year period (1994/2002)11.78 kgN-NO3–/ha were determined in lysimetric waters. These values for fertilization treatments ranged from 21.0 to58.2 kgN-NO3–/ha. Straw application reduced nitrate contents in lysimetric waters.

The influence of modified pratotechnics of unmanaged grasslands on the amount of mineral nitrogen in lysimetric waters of the rhizosphere

In 2001–2004, the influence of various ways of farming unmanaged grasslands on the mineral nitrogen content in lysimetric waters was monitored. Field trials with 11 variants were performed 420 m above sea level, at depths of 0.2 and 0.4 m, 4–5 times annually. The average amount of N_min released per ha per year in lysimetric waters ranged from 0.84 to 5.12 kg. The upper layer to a depth of 0.2 m had a higher content. The conclusive difference, in comparison with properly farmed control, was with the black fallow and in the variant where fallow followed mulching. With the exception of this method of farming the pratotechnics of unmanaged grasslands – mulching did not increase the load of rhisosphere, either by the overall mineral nitrogen, or by the concentration of N-NO₃^–. Even by using fallow for a four-year period, a conclusive increase in the content of N_min was not observed.

The development of above-ground biomass in unmanaged grasslands and its influence on the leakage of water and the amount of elements found

The influence of various forms of farming on unmanaged grasslands was monitored with regard to the accumulation of the above-ground biomass (litter + mulching) and its influence on the leakage of rainfall and the amount of elements in lysimetric waters. In 2001–2005, the highest accumulation was observed in variants 1× mulched in the later term and on green fallow (on average 2.11–1.13 t of dry matter/ha). In comparison with the control site, a conclusive increase always occurred. An interannual increase of dry matter amounted to 0.4–5.2% of the total above-ground biomass. A negative correlative dependency on rainfall leakage on this material was discovered; at a depth of 0.4 m 4–10% of the rainfall leaked, but it had a significant influence on the wash out of Ca, Mg and S. The leakage of water affected a wash out of N_min, P, K, Ca, Mg and S more than the weight of dry matter of the above-ground biomass. With the exception of P, the elements showed a downward tendency over five years. The above-mentioned forms of farming annually increased the accumulation of the above-ground biomass by 0.05–0.16 t of dry matter/ha; however, they do not endanger underground waters by washing out minerals. After a five-year period, a disturbance of the ecological stability of grassland did not occur.