Humus acids as reserve of water-soluble organic matter in irrigated chernozems of Near-Ob are

It has been shown the role of carbon of dissolved organic matter (C DOM) in humus composition of irrigated chernozems as well as participation of humus substances proper in the formation of DOM. It has been found out that in chernozem long-term irrigated with weakly alkaline water the yield of C DOM is reliably higher than in nonirrigated soil when used even ordinary water extraction. It accounts for 53 and 40 mg l–1 respectively. It is attributed to the fact that because of influence of irrigative water the pH range became wider to some extent and alkalinity of soil medium became stronger and consequently the solubility of DOM increased. It has been noted that that the same tendency that is decrease is observed in depthwise distribution of humus and C DOM. As it should be expected, in irrigated soil processed with irrigative water the content of C DOM is somewhat higher (by 7–10 mg l–1) in the studied part of the profile as a whole. At the same time the relative role of C DOM in humus composition increases with increasing pH, up to 3 % of total organic soil carbon. It has been examined the interaction of irrigative water free of DOM with preparations of humus acids extracted from soil. Drown coloration of irrigative water is evidence of separation of DOM from humus acids. Moreover, the yield of C DOM proved to be three times higher in case of irrigative water than distilled one and accounted 120 and 350 mg l–1 respectively. This comparative experiment is an evidence of the fact that humus acids can be served as a source of DOM, especially in the event if more accessible organic matter is not available. Thus, long-term irrigation of chernozems in case of unsatisfactory application of organic fertilizers leads not only to biological and irrigational humus losses but also humus losses by way of transformation of humus acids into DOM

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>

STUDY OF STRUCTURAL AND FUNCTIONAL COMPOSITION OF SOIL HUMUS ACIDS OF EURO-ARCTIC REGION BY MOLECULAR ABSORPTION SPECTROSCOPY (UV / VISIBLE)

Results of the structural and functional composition of soil humus acids in the Euro-Arctic Region are presented. The molecular absorption spectroscopy (UV / visible) was used to evaluate eco-protective role of soils in relation to heavy metals, which is especially important for the sensitive soils of the Arctic, formed under the influence of cryogenic processes. Different types of soils of the Euro-Arctic region: gleyish easy loamy pelosi on loamy moraine (Kanin Peninsula, Cape Kanin Nos); humus peat oligotrophic soil (Kolguev Island, Bugrino village); typical non-calcic loamy gley soil (Vaigach Island); gray humous iron sandy lithozem (Archipelago Franz Josef Land, Heys Island) were analyzed. An alkaline solution of sodium pyrophosphate was used to extract humus acids for investigate of the structural and functional composition. Humic, fulvic and gimatomelanic acids were extracted from a humus by conforming solvents with additional fulvic acids extraction by adsorption chromatography using activated carbon as a sorbent. UV mini-1240 spectrophotometer (Shimadzu) was used to record the UV / visible spectra using 0.005% alkaline solutions (0.1 N NaOH) of humus acids. It was demonstrated that humic and gimatomelanoic acids of humus peat oligotrophic soil have more developed peripheral aliphatic component. These acids have more ability to bind heavy metals and show their eco-protective role. The humus acids of other types of soils region have a more developed aromatic component in the Euro-Arctic. Such parameters as: calculated by the Pieravuori formula aromaticity, extinction coefficient Е0.005%1cm,465, adsorption ratio D400 /D600, characterizing the degree of humification and the adsorption ratio D465 / D650, characterizing the degree of aromatic nucleus condensation and conjugate fragments were used in the quantitative assessment of the nature of humus acids. Quantitative analysis of UV/visible spectra confirmed that the maximum barrier mechanism with respect to heavy metals will be the humic and gimatomelanoic acids of humus-peat oligotrophic soil, due to the high content of phenolic and carboxyl groups in these molecules, oxidation and a more developed chain of conjugated bonds in them in comparison with other acids. However, it was found that in all types of soils studied the process of humus formation proceeds mainly by a degradation type, that is, in the direction of formation of fulvic acids. Forcitation:Prilutskaya N.S., Korel'skaya T.A., Popova L.F. Study of structural and functional composition of soil humus acids of euro-arctic region by molecular absorption spectroscopy (UV / visible). Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 97-103

The influence of humus acids of peloids and its components on free radical processes

The effect of individual components of humic substances of peloid on free radical oxidation processes has been investigated under conditions of oxidative stress induced in albino rats. Biological activity of peloids was determined using such parameters as the general antioxidant activity, activity superoxide dismutases, catalases and glutathione peroxidases on the third and tenth day of the experiment. Results indicate that the state of oxidative stress can be corrected on the third day of the experiment. Humic acids restore not only normal physiological redox systems, but also increase the activity of antioxidant enzymes on the 10th day.

Heteroassociates of Pinacianol Cation in Aqueous Solutions: Formation and their Interaction with Organic Multiply Charged Anions

The formation of heterogeneous associates has been studied between the cation of the cyanine dye as pinacyanol chloride (PNC) and multiplies charged anions arsenazo (AR II) or humus acids (HA) in aqueous solutions. The accompanying spectral changes have been analyzed. The equilibrium constants of association (Kas) were determined, and logKas values were equal in the range 1.73-3.09 for associates PNC with HA. The effect of humus acids on PNC -AR II causes to destruction of the associate and the competition of the anions of HA with AR II is observed.

Migrational activity of elements and chemical soil pollution during deposit exploitation in Amur River region and Okhotsk Sea region

We studied mechanisms of geochemical soil systems formation. This work provides geochemical characteristics of soils under the influence of mining enterprises. It also shows the mechanisms of sewage water enrichment by heavy metals during sulphidic deposit exploitation and their interaction with soil substance. We also describe migrational activity of elements and the conditions of their concentration in the soil volume. It is shown that migrational activity of elements depends on both their chemical nature and the level of aggressive fractions of humus acids and background-forming elements (Fe and Mn) content. The level of heavy metal concentration in soils formed in the area of influence of deposits showed to be exceeded. We suggest new approach to complex evaluation of element reallocation mechanisms in soils.