A. A. Vasil’ev

Influence of iron-containing pigments on the color of soils on alluvium of the Middle Kama plain

The study of the color in the CIE-L*a*b* system proved that, among the soils developed on the recent and ancient alluvium in the Perm Cis-Urals region, there are no soils composed of only brown horizons: the low-redness topsoils occur even in the automorphic soils. The color of the bulk of the soils does not depend on the total content of Fe-(hydr)oxide particles. The soils developed on the two-layered deposits are an exception, since the color of the lower layer of the heavy loam is affected by hematite-containing clay particles. In the upper horizons of other automorphic soils, red pigment is produced rather by Fe-containing hydroxides (feroxyhyte δFeOOH and Fe-vernadite Fe-δMnO2) than by hematite αFe2O3. The gleyed horizons are rich in free iron compounds (up to 3.2% (Fe2O3)d) that exert a weak effect on the redness. An identification procedure of the horizons showing hydromorphic features is developed, including the color control both in the untreated samples and in the samples in which the organic substance has been oxidized with H2O2. The soil becoming green after the organic matter oxidation appears to be a distinctive feature of the hydromorphic horizons, while reddening is a property of the automorphic horizons.

The influence of technogenic and natural factors on the content of heavy metals in soils of the Middle CisUrals region: The town of Chusovoi and its suburbs

The content of heavy metals in the soils of the Middle CisUrals (the town of Chusovoi and its vicinities) is controlled by both natural and technogenic factors. The enrichment of the parent rocks in Cr, Pb, Zn, and Cu, which influences the chemical composition of the soils, is the most important among the natural factors. Among the other natural factors, the gleying and washing of the alluvial soils with flood water are significant. The technogenic contamination of the urban soils reaches its maximum in the technozems, where the content of Cu, Zn, Pb, and Cr exceeds their clarkes by 4–8 times. The index of technogeneity (the share of technogenic metals referring to their total content) is high for the bulk of metals in technozems, in particular, ranging within 36–97%. The technogeneity sequence is the following for the urban soils: Cr > Zn = Mn > Pb > Cu > Fe. The soil contamination with metals is confined to the depression where the metallurgical plant is operating, and it significantly falls already at a distance of 2–3 km in the settlements located at higher topographic positions.

Hydrogenic heavy metal pollution of alluvial soils in the city of Perm

The differences in the sources and compositions of the pollutants among the alluvial soils within the city of Perm were revealed. Heavy metal pollution of hydrogenic origin is caused by unpurified sewage water. The main source of pollution of the urbanozems and replantozems of the city is the aerial input of heavy metals. The lead content in the alluvial soils of the city was twice lower and the mean Zn and Ni contents were 1.5 and 4.0 times higher than in the urbanozems and replantozems, respectively. The concentrations of Sr, Zn, Ni, Cu, and Cr did not correlate positively with the content of clay particles in the fine earth of the alluvial soils. The higher pollution of the light-textured soils showed that, nowadays, its main source was sewage water but not sludge. In the alluvial soils, small Fe-rohrensteins are formed. They serve as microgeochemical barriers for some part of the microelements. The Pb and Zn contents in the rohrensteins of the soils of the Las’va river basin reached 440 and 890 mg/kg, respectively. In the upper horizon of this soil, the contents of Pb and Zn in the rohrensteins were 42 and 17% of their concentration in the fine earth, respectively.

Contents of heavy alkaline-earth (Sr, Ba) and rare-earth (Y, La, Ce) metals in technogenically contaminated soils

The contents of heavy alkaline-earth (Sr and Ba) and rare-earth (Y, La, and Ce) metals have been studied in two technogeochemical anomalies and in the soils of Perm and Chusovoi. The soils are contaminated with barium, lanthanum, and cerium in the territory of the Cherepovets technogeochemical anomaly formed due to the atmospheric emissions from the Severstal metallurgical works. Strontium, barium, and yttrium are accumulated in the soils of the Revda technogeochemical anomaly formed by aerial emissions from the Mid-Urals copper smelter. The portion of technogenic strontium reaches 43–84% near the metallurgical works, while that of barium and yttrium, 47–63 and 28–32%, respectively. In Perm, the urban soils are polluted with technogenic alkaline-earth metals, i.e., strontium and barium, with their content reaching 31–48%. In Chusovoi, the calcareous horizons of the soddy soils are enriched in strontium and depleted in barium. The eluvial-illuvial distribution of the rare-earth metals is registered in the soddy-podzolic soil. The soils of the terrace are contaminated with barium. The technozem is contaminated with all the metals (barium and yttrium, in particular).

Iron minerals in soils on red-earth deposits in the Cis-Ural region

In soils developed from the red-earth deposits in the Cis-Ural region (Perm oblast), hematite does not ensure the theoretically possible redness due to the concealing effect of rivaling pigments, i.e., humus in the upper horizons and Fe(II) in the gleyed horizons. The soil color depends on the minimal (spring) values of the hydrogen partial pressure index rHmin rather than on the average value of this index rHav. The hematite content decreases in the gleyed and humus horizons (despite the absence of the morphological features of gley in the latter due to the concealing effect of humus). The gley horizons are heterogeneous with respect to the state of iron. Upon the maximum wetting in the gley horizons of the mucky-humus gley soil, hematite is being reduced to Fe(II), which is proved by the low values of rHmin (<19). In a less humified dark humus gley soil, the values of rHmin exceed 19, which points to the inherited gley features in this soil. In the mucky-humus gley soil, an inverse dependence between the magnetic susceptibility χ and EHmin is observed upon EHmin <320 mV. In this case, the degree of reduction of the highly magnetic iron oxides rises from 0.3 to 1.0 due to a decreasing portion of maghemite γFe2O3 and an increasing portion of magnetite Fe3O4.

The role of iron compounds in fixing heavy metals and arsenic in alluvial and soddy-podzolic soils in the Perm area

In Perm, alluvial soils are strongly contaminated with heavy metals (Zn, Cu, and Ni, in particular) due to the ingress of liquid sewage. The concentration of a number of chemical elements is far higher in Fe-rohrensteins (tubular concretions around plant roots) of alluvial soils as compared to the fine earth. Ni and Cu are associated with Fe in rohrensteins of alluvial soils. The soddy-podzolic soils are in general less contaminated at a distance of 30 km to the northwest of Perm. Their contamination results from aerosols emitted by Perm industrial enterprises. Fe-Mn nodules that concentrate Ni and As are formed in hydromorphic podzolic soils. Mn oxides represent a separate phase carrying heavy metals and metalloids (manganophiles). Oxianions (As, Cr, and P) are closely bound to Fe in nodules, which are formed because of the alternating redox regime in soddy-podzolic soils. However, oxianions are not associated with Fe in rohrensteins of alluvial soils.

Specific features of iron behavior in soddy-podzolic and alluvial gleyed soils of the Middle Cis-Urals region

The regime of observations revealed that the Eh dynamics in soddy-podzolic and alluvial soils in the Middle Cis-Urals region depends not only on the rate of iron (hydr)oxides reduction but also on the rate of opposite reactions in the gleyed horizons. Both processes depend on the temperature. The Eh value decreases on heating in automorphic soils, when the reduction of Fe(III)-(hydr)oxide particles accelerates. On the contrary, in gley soils, the Eh decreases on cooling, probably, because of the reactions opposing the reduction of Fe(III)-(hydr)oxide particles, including Fe(II) fixation on the surface of mineral particles. Fe(III)-(hydr)oxides are, for the most part, preserved in gleyed soils of the Cis-Urals; the content of (Fe2O3)dit reaches 3.3% with iron minerals being usually represented by goethite.The increase in moistening influences the soil parameters (i.e., the redoxpotential rH and the content of conventional red pigment Hemconv) in an intricate manner. Both direct and reverse branches on the curve of the Hemconv-rH dependence point to the equilibrium and nonequilibrium conditions in the soil. The reverse branch probably stands for the initial phase of gleying in strongly humified soils, where, despite extra electrons in the solution, the brown pigment in the form of Fe(III)-(hydr)oxides is preserved.

Selectivity of reagents used to extract iron from soil

The selectivity of the Tamm and Mehra-Jackson reagents to iron (hydr)oxides was verified chemically by comparing the efficiencies of the two methods of iron extraction: parallel (commonly adopted) and sequential, i.e., by calculating the difference ΔFe = [Fedit − (Feox(paral) + Fedit(seq))]. The expected equality of the extracted iron (i.e., ΔFe ∼ 0) is rarely observed. A positive balance reaching ΔFe = (0.5−0.8)% predominates upon iron extraction from forest soils of the Cis-Ural region. This is probably due to the stable Fe(II)-oxalate forming in the course of the Tamm extraction, which is incompletely dissolved by the dithionite-citrate-bicarbonate (DCB). On the contrary, a negative balance with ΔFe reaching −0.4% predominates in the steppe soils of the Stavropol region. This may be caused by Fe(II) minerals (pyrite and siderite) acting as catalyzers in Tamm’s extract, while being weakly soluble in the DCB. To follow the additivity principle for the Tamm and Mehra-Jackson extracts, we suggest a modification of the Schwertmann criterion KSch = (Feox: Fedit(paral)), which sometimes exceeds 1, to KSchm = Feox: (Feox + Fedit(seq)), which is always less than 1. The values of the modified Schwertmann criterion better agree with the color of the Cis-Ural forest soils expressed in the CIE-L*a*b* optical system as compared with the initial Schwertmann criterion. In the steppe soils, the use of the modified criterion makes it possible to replace the illogical values of KSch = 1.11−1.37 by the quite acceptable KSchm = 0.68−0.83.

Heavy metal content in soils of suburban areas of the city of Chusovoi

The content of heavy metals in soils of garden plots in the city of Chusovoi exceeds the maximum allowable content in agrozems of the second bottom of the Chusovaya River. The method of measuring the specific magnetic susceptibility of soils allows, with a high probability, revealing territories polluted with Ni, Cu, Zn, Cr, and Mn.

Effect of feeding starter mixed feed to suckling pigs on their reproductive qualities

Feeding starter mixed feed to piglets from age 7 to 60 days reduced the age of the first mating and number of unfertilized replacement gilts, increased the number of piglets born alive and piglet birth weight, increased the volume of ejaculate and sperm number of boars, and reduced the number of pathological and immature sperm.