Humus substances in the swamp ecosystems of taiga zone of Western Siberia

Eutrophic peatlands with a predominantly humate type of humus is dominated according to content of hydrophobic humus substances accumulated in the solid phase of peat. Oligotrophic peatlands with fulvate type of humus are characterized by minimal storages. Mesotrophic peatlands occupy a transitional position, both in terms of storage and in terms of the humus type – humate-fulvate. Hydrophilic components of the water phase are characterized by fulvate humus, regardless of the type of peatland, but differ in the proportion of the contribution of humus substances in the amphiphilic system of swamp ecosystems. It is the highest in the thickness of the oligotrophic peatland almost 31%, slightly lower in the mesotrophic – 25% and much less in the eutrophic – 6%. Structural features of macromolecules of humic acids of swamp waters of various genesis are determined. The humic acids of mesotrophic waters are adjacent to the group of reduced compounds, they are more enriched with aromatic structures and carboxyl groups in relation to oligotrophic waters. The humic acids of oligotrophic waters belong to a group of oxygenated compounds, have low enrichment of nitrogen, contain more methoxyl carbon and carbohydrates (polysaccharides). These structural features are caused by geochemistry of waters feeding the peatlands and specific mechanisms of humic acids synthesis on the swamps of different genesis. The volume of dissolved organic carbon stock from wetland ecosystems through system of taiga rivers of left bank of Middle Ob is 805 kt per year.

Metal storage capacity evaluation of humic and himatomelanic acids hydroxymethyl derivatives obtained from brown coal

Humic substances represent the most extensive and reactive class of natural compounds. A more nature-saving way is to obtain humus substances from solid combustible minerals and waste from their processing. The ability of these compounds to form stable complexes with heavy metals, which increases with their directed chemical modification, has been experimentally confirmed. The effectiveness of the phenol-formaldehyde condensation method for the modification of initial humus substances has been confirmed. The interaction of humic and himatomelanic acids with formaldehyde leads to an increase in sorption activity in comparison with the initial humic acids with respect to heavy metals. This aspect has been studied and confirmed in model experiments with copper ions. Key words: humic substances, brown coal, humic and himatomelanic acids, directed chemical modification, hydroxymethyl (methyl) derivatives, heavy metals, copper ions, complex formation.

Influence of the peculiarities of using typical chernozem of the Kursk region on the molecular weight composition of labile humus substances

polydisperse compounds. Under the influence of agricultural use, the dispersion of LHS increases, and the molecular weight composition of LHS is trans-formed towards the accumulation of fractions with lower molecular weights in their composition. As a result, the number average molecular weight of LHS decreases from 15230 amu. in LHS virgin chernozem up to 11180-12770 amu. near LHS chernozem under permanent crops and fallow. The replacement of permanent steam with a deposit does not fundamentally affect the degree of dispersion of LHS and the values of the molecular weights of the fractions. There is only a tendency towards an increase in the relative content of fractions with high molecular weights. This is reflected in the value of the average molecular mass of LHS, which increased from 11180 amu in the variant with permanent vapor to 12530 amu. LHS has deposits. Keywords: TYPICAL CHERNOZEM, GEL-CHROMATOGRAM, FRACTION, MOLECULAR MASS OF FRACTION, AVERAGE MOLECULAR MASS, LGS (LABILE HUMUS SUBSTANCES)

DecoMSW: A Methodology to Assess Decomposition of Municipal Solid Waste for Initiation of Landfill Mining Activities

Biochemical decomposition of municipal solid waste (MSW) in landfills leads to the generation of leachate, gases and humus substances. In this context, a methodology to assess D ecomposition of MSW, designated as DecoMSW, has been developed; based on a series of tests conducted on samples of the fresh MSW and those retrieved from the active bioreactor landfill (BLF) cells of age from 13 to 48 months. Furthermore, spatial and temporal variation in the (i) physical (composition) and (ii) chemical (pH, volatile solids, total organic carbon, elemental analysis, ammonium and nitrate-nitrogen, biomethanation potential, lignocellulosic content) characteristics of the MSW samples exhumed from the landfill have been established. Finally, these characteristics were correlated vis-à-vis the respective values of the fresh MSW. From this exercise, it has been observed that except for nitrate-nitrogen, all other chemical parameters of MSW decrease exponentially with time until 20 months, and beyond that, they remain constant, which is an indication of stabilization of MSW. In short, it has been demonstrated that DecoMSW is instrumental in assessing the state of decomposition of MSW with respect to time in the BLF and facilitates initiation of the landfill mining activities.

Effect of biopreparations on the decomposition of plant residues of crops in typical chernozem

Aim. To identify the effect of biological preparations applied with or without nitrogen fertilizers for crop by-product, their incorporation into the soil on the decomposition of plant residues and composition of mobile humus substances in typical slightly eroded chernozem.Materials and Methods. The study was carried out in the field experimental station of Kursk FARC in the cycles of cereal and cereal-row crop rotations in variants with by-product treated with biopreparations; with applied biopreparations + nitrogen fertilizers; with applied nitrogen fertilizers and without biopreparations. To study decomposition the content of unhumified organic matter was determined in the topsoil by the monolith method after by-product incorporation into the soil and 3045 days after their decomposition. Simultaneously the composition of mobile humus substances in the soil was determined.Results. The decomposition of crop by-product and after harvesting and root residues mixed with it in the soil and treated with biopreparations or nitrogen mineral fertilizers was studied for the first time. The peculiarities of the effect of the factors studied on the degree of plant residue decomposition and the composition of mobile humus substances were shown.Conclusion. It was determined that treating the by-product of barley, buckwheat and sunflower with bioproducts, both with applied nitrogen fertilizers and without them, contributed to the increase in the degree of plant residue decomposition as compared with the control and nitrogen mineral fertilizer application. In the years which are favourable according to hydrothermal conditions the improved quality of mobile humus substances of the soil influenced by biopreparations are noted and under extreme conditions the tendency to the improvement of their quality is observed.

DOC trend in Arctic lakes as a response to air pollution reduction by Kola North Smelter, Russia (1980-2018): possible mechanisms of transformation of organic substances

<p>The phenomenon of increasing DOC levels in water systems over the last decades is confirmed by numerous studies (Driscoll et al., 2003; Stoddard et al., 1999; Skjelkvale et al., 2001a; Montein et al., 2007; Evans et al., 2008; Clark et al., 2013).  The increasing of organic matter content in lake waters is being also observed for the totality of lakes in the Kola North, more markedly in forest and water-logged subregions. This conforms to the data reported by Skjelkvale et al. (2001a) which demonstrates the significant increase of DOC. Montein et al. (2007) explain the increased DOC levels by reduction in strong acid flow and return of water chemistry to its natural parameters of specifying organic matter concentrations in water.</p><p>Clark et al. (2013) demonstrated that natural humus substances are capable of producing strong organic acids and increase water acidity. It is known that DOC level has a direct relationship with water color. In analyzing long-term study data with regard to the group of 75 lakes (obtained during 1990-2010) DOC is increased year-over-year, but the color decreased.</p><p>More evident dependence the increasing the content of DOC on reduced color from year to year (Fig.). The following chemical processes developing in water can explain this phenomenon.</p><p>Figure.  The correlation between the change of DOC (ΔDOC) and color (ΔColor) - file  </p><p><img src="data:;base64,%20" width="2296" height="3246"></p><p>The water color is predominantly determined by large molecules of humus acids which molecular weight >1000 Da. Macromolecular organic substances of humus type can be dissociated in water with formation of a free proton, as well as enter into reactions of decomposition (hydrolysis) and disproportionation with formation of low-molecular weight fragments. Its fragments also are dissociated of proton (see the diagram below). The above processes may be catalyzed by non-organic strong acids supplied from anthropogenic and natural sources. The diagram of the organic substances destruction of humus origin is given below, where R<sub>i  </sub>means non-symmetrical fragments of a natural polymer, Х<sub>i</sub>H - functional groups of organic substances of humus origin, and n - number of protons.</p><p>When strong acids get into a water environment humus acids are degraded into fractions.  It could be supposed that the organic matter structure undergoes changes in natural waters, as the fraction of high-molecular weight humus acids decrease. As a consequence of interaction between humus substances and protons the humic acids precipitate to form bottom sediments, whereas fulvic acids remain in water. Fulvic acids are characterized by lower molecular weights (from 500 to 2000 Da) and exert an insignificant effect on the water color. This phenomenon is well proved in a study published by Clark et al. (2013). However, to define more exactly this phenomenon, further experimental work is required.</p><p>Financing RSF 18-17-00184</p><p> </p><p> </p>

The influence of diatomite rock on humus substances of sod-podsolic soil in conditions of agro ecosystems and physical-chemical mechanism of their interaction

The paper provides an assessment of physical and chemical changes of humus substances in the sludge-colloidal fraction, isolated from the sod-podsolic sandy loamy soil, during its interaction with the diatomite rock of the Inzen deposit in conditions of agro ecosystem of the Nizhny Novgorod Region. The experience was a 3-year (2015-2017) microfield experiment, laid down on one of the fields of Elitkhoz. The diatomite was added to soil once during the summer season of 2014 in doses of 3, 6 and 12 t/ha, on which winter wheat, barley and peas were subsequently grown (varieties are zoned in the Volga-Viatskiy Region). Each year, upon completion of crop cultivation, a silo-colloidal fraction was isolated from selected soil samples by the Kachinsky gravimetric method and analyzed on an IR-Fourier-spectrometer, determining absorption spectra in frequency range of 4000-400 cm-. In soil samples the content of specific organic substance (humus) was also determined by the Thurin method with spectrophotometric termination. The studies revealed that interaction of diatomite with the organic soil matrix resulted in organosilanes RnSiH4-n (930 cm-), organosilanes oxygen-free Si-CH3 (1253 cm-) and oxygen-containing compounds Si-O-CH3 (1110 cm-), as well as siloxane bonds of Si-O-Si (570 cm-). The obtained facts directly indicate formation of silicon-containing organo-mineral complexes in sludge-colloidal fraction and participation of silicon in their formation. It is evident that an active diatomite represented by various silicon acids (HnSiOm) was involved in formation of these bonds. The use of diatomite has helped to maintain content of humus substances in soil at the control level, which can also confirm effects of interaction of silicon substances with organic part and, as a result, prevent its degradation. Based on the obtained results and analysis of scientific literature, a mechanism is proposed for possible physical-chemical interaction of active silicon substances with an organic component of the sludge-colloidal fraction of the sod-podsolic soil, which consists in polymerization of silicon on organo-mineral complexes (bonds -Si-O-Si-), as well as in interaction of the hydrolyzed part of humus substances with silicon with subsequent formation of organosilanes, which are subsequently connected with an organic Si-O-CH3 matrix. Due to the fact that organic matter of soils is involved in the formation of ecological stability of soil cover the established effects make it possible to speak about the increase of agro ecological stability of humus substances in sod-podsolic soil due to the use of diatomite rocks.