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The succession of natural vegetation on the former arable soils triggers the processes of postagrogenic restoration of soil ecological functions specific of a particular bioclimatic zone. We analyze the postagrogenic dynamics of a set of soil characteristics in the upper (0–5 and 5–10 cm) layers of former arable horizon by the case study of the chronosequence of Retic Albic Podzols (agrosoddy podzols, southern taiga, Kostroma oblast, Russia) withdrawn from agricultural use 15, 20, and 45 years ago. The following soil characteristics are determined: pHKCl; the contents of soil organic carbon (SOC), total nitrogen (TN), and dissolved carbon and nitrogen (DOC and DON); basal respiration (BR) rate; carbon of microbial biomass (Cmic); and relative indicators of the state of microbial community. In addition, absolute (HIX1) and relative (HIX2) humification indices of dissolved organic matter (DOM) are assessed for the soil layer of 0–5 cm in the studied soil chronosequence, as well as the stratification ratio (SR (0–5 : 5–10)). The following changes are observed in the upper layers of the former arable horizon over 45 years of postagrogenic succession: (1) a statistically significant decrease in the pHKCl and humification index of DOM; (2) an increase in the SOC, TN, and Cmic contents and BR rate; and (3) a considerable stratification according to the SOC and TN contents and microbial properties. The highest values of SR for the SOC and TN are observed in the soil of the old-aged forest; for the microbial properties, in the 45-yr-old abandoned soil. Thus, the main characteristics and ecological functions of Retic Albic Podzol gradually restore during the secondary succession on the former arable land in the southern taiga zone.

The spatiotemporal variability of CO2 emission from soils of Kursk under different land uses, pollution levels, and soil geneses has been assessed. Data on the seasonal dynamics of CO2 emissions in background (forested recreational areas) and urban soils under the anthropogenic impact are presented. Seasonal dynamics of soil СО2 emission depends on a number of factors: season, type of soil, organic matter content, anthropogenic modifications of soil profiles, hydrothermic conditions, and heavy metal pollution. Soil hydrothermic conditions to a greater extent determine the intensity and characteristics of the seasonal dynamics of soil CO2 emission with a maximum in summer. In anthropogenic soils, multidirectional transformation of soil CO2 emissions is noted. The intensity of CO2 emission from soils of various geneses is quite different. Heavy metal pollution of the soil has an ambiguous effect on the CO2 emission processes. The CO2 emission rate from Urbic Technosol increased by 16.4% in comparison with that from the background Luvic Chernozem (Loamic, Pachic), while for Technic Greyzemic Phaeozem (Loamic) this parameter decreased by 47% in comparison with the background Greyzemic Phaeozem (Loamic). In Carbic Podzols polluted by heavy metals, the averaged CO2 emissions are generally similar to those from the background soils unpolluted by heavy metals.

Background. Several theories have been proposed to explain the podzolization process. Currently, the role of organic matter in both weathering and immobilization in the illuvial horizon is clearly stated. The origin of soil organic matter and, accordingly, the various mechanisms of its influence on the soil material, create the basis of these theories. We assume that in the base-poor sandy soils under rich herbaceous vegetation with a well developed sod layer, the process of podzolization may also depend on CO 2 soil formation agent . Materials and Methods. Four localities along a Pinus sylvestris L . self-afforestation chronosequence with pine stands of 10, 20, 40 yrs and an adjacent semi-natural grassland area were investigated in order to determine the patterns of podzolization process on sandy glacial till deposits. Soil pH, exchangeable base, soil cation exchange capacity, total content of soil organic carbon, amorphous Fe, Si and Al and total contents of Al, Fe, Mn, Zn, Cd, Pb, Cu, Co, Ni, Na, K were determined. Statistical analysis of the results was performed using LibreOffice for Linux. Results. During the pine succession, a previously well differentiated into horizons podzolic soil under the grassland vegetation community gradually degrades. Previously well-defined albic and spodic diagnostic horizons disappear, the soil profile becomes more acidic, the soil organic carbon, the base cation content and the base cation saturation decrease, the leaching rate of aluminium and iron increases. Secondary podzolization features in the soil profiles were detected 40 years after the onset of afforestation. The podzolization has not been intensive enough to develop fully fledged albic and spodic diagnostic horizons over such a short period. Conclusions. Based on the obtained soil morphological, physical and chemical properties, three most important agents of podzolization are proposed as principal for the studied area. The main gent under pine forest is fulvic acids that are produced during coniferous litter decomposition. Low molecular weight organic acids and carbon dioxide produced to the rhizosphere by roots and a root associated microbiota are mainly involved in the podzolization process under the grassland ecosystem. Keywords : podzols, reforestration, carbon dioxide soil formation agent Received 15 May, 2021 ● Revision 28 May, 2021 ● Accepted 02 June, 2021 ● Published 30 June, 2021

The total concentrations of metals (Fe, Mn, Cu, Ni, Cr, Sr) and their mobile forms extracted by an ammonium acetate buffer (pH = 4,8) were studied in soils samples collected from Nadym-Pur interfluve (West Siberia), near the northern limit of the taiga zone. The heavy metal content was determined in 55 background soil samples and in 25 pyrogenic ones. Gross content was determined on a spectrometer "SPECTROSCAN MAX-GV" using x-ray fluorescence analysis. Mobile forms of metals were determined on a ContrAA 700 atomic absorption spectrometer by flame and electrothermal methods. The statistics are calculated using the Excel software package. The study confirmed the weak accumulation of metals in the soils of the northern regions of Western Siberia. The total content below the soil world average for Fe is 5 times, Mn - 3 times, Sr - 2 times, Cr - 1,4 times. The content of mobile forms varies widely depending on the amount of organic matter. The percentage of mobile forms of metals from the total content was: Cr - 0.84%, Fe - 1,2%, Sr - 3,8%, Mn - 8,7%, Ni - 15%. In the profile of podzols, the distribution of mobile forms of metals has an eluvial-illuvial character. Mn and Sr accumulate intensively in the surface organogenic horizons, and the Fe content increases in the BF horizon. Minimum values are marked in horizon E. In pyrogenic soils, there is an increase in the content of mobile forms of metals due to the intake of ash. Metal content usually not exceeded the maximal permissible concentrations for soils.

Global significance of iron (Fe) and aluminum (Al) for the storage of organic matter (OM) in soils and surface sediments is increasingly recognized. Yet specific metal phases involved or the mechanism behind metal–OM correlations frequently shown across soils remain unclear. We identified the allocation of major metal phases and OM to density fractions using 23 soil samples from five climate zones and five soil orders (Andisols, Spodosols, Inceptisols, Mollisols, Ultisols) from Asia and North America, including several subsurface horizons and both natural and managed soils. Each soil was separated into four to seven density fractions using sodium polytungstate with mechanical shaking, followed by the sequential extraction of each fraction with pyrophosphate (PP), acid oxalate (OX), and finally dithionite–citrate (DC) to estimate pedogenic metal phases of different solubility and crystallinity. The concentrations of Fe and Al (per fraction) extracted by each of the three reagents were generally higher in meso-density fractions (1.8–2.4 g cm−3) than in the lower- or higher-density fractions, showing a unique unimodal pattern along the particle density gradient for each soil. Across the studied soils, the maximum metal concentrations were always at the meso-density range within which PP-extractable metals peaked at 0.3–0.4 g cm−3 lower-density range relative to OX- and DC-extractable metals. Meso-density fractions, consisting largely of aggregated clusters based on SEM observation, accounted for on average 56 %–70 % of total extractable metals and OM present in these soils. The OM in meso-density fractions showed a 2–23 unit lower C : N ratio than the lowest-density fraction of the respective soil and thus appeared microbially processed relative to the original plant material. The amounts of PP- and OX-extractable metals correlated positively with co-dissolved C across the soils and, to some extent, across the density fractions within each soil. These results led to a hypothesis which involves two distinct levels of organo-metal interaction: (1) the formation of OM-rich, mixed metal phases with fixed OM : metal stoichiometry followed by (2) the development of meso-density microaggregates via “gluing” action of these organo-metallic phases by entraining other organic and mineral particles such as phyllosilicate clays. Given that OM is mainly located in meso-density fractions, a soil's capacity to protect OM may be controlled by the balance of three processes: (i) microbial processing of plant-derived OM, (ii) dissolution of metals, and (iii) the synthesis of organo-metallic phases and their association with clays to form meso-density microaggregates. The current hypothesis may help to fill the gap between well-studied molecular-scale interaction (e.g., OM adsorption on mineral surface, coprecipitation) and larger-scale processes such as aggregation, C accrual, and pedogenesis.

The water-soluble components originated in coniferous litters desorb into solution the native organic substances from the solid phase of the eluvial horizons of podzols and podzolic soil. In podzols, the water-soluble organic matter (WSOM) extracted from litter and then passing through the E horizons are sorbed by the BFH horizons if their concentration in solution exceeds 35 mg C/L. The sorption ranges from tens to hundreds of milligrams of carbon per kilogram of the BFH horizon. The WSOM can be sorbed by the BT horizons of podzolic soil when the concentration of organic substances in the liquid phase is higher than in podzols. The model experiments with minerals show that kaolinite and illite interact with the soluble substances percolating from the litter and selectively extract more hydrophilic and less aromatic components with relatively low molecular weights. On the contrary, goethite interacts with the WSOM prevalently sorbing hydrophobic components, substances of phenolic nature, components enriched in aromatic carbon, and substances with molecular weights less than 7 kDa. The spectral characteristics of WSOM change after the sorption interaction with minerals: the fluorescence associated with the humus substances with the longest conjugation chain decreases or disappears, while new fluorophores containing fragments of phenolic and/or protein structures emerge. The presence of kaolinite and illite in the eluvial horizons and their interaction with WSOM most likely contribute to the transformation of WSOM composition and appearance of the properties maximally favorable for their sorption on iron hydroxides in the lower horizons.

Estimates of the spatial heterogeneity of the organic matter distribution in forest soils determined by the influence of the species and spatial structure of phytocenoses are relevant for many environmental problems, including the calculation of carbon sinks and modeling of the dynamics of forest ecosystems. We analyzed the data on the organic carbon (Corg) and total nitrogen (Ntot) contents in the O (forest litter) and AY (humus) horizons of Entic Podzols in the Prioksko-Terrasnyi Reserve (54.89° N, 37.56° E). The studied site is located in a coniferous–deciduous forest formed after overgrowing of the cutting area of pine stands. We sampled the O and AY horizons along transects between trees of different species, i.e., near the trunks, under the crown, and in the intercrown space. The contents of Corg and Ntot in the O horizon varied within 17.6–44.9 and 0.84–1.79%, respectively. The ranges for the AY horizon were greater: 0.71–8.5% (Corg) and 0.035–0.33% (Ntot). The relationship between the contents of Corg and Ntot in the O and AY horizons was close to linear (rs = 0.72 and rs = 0.96, respectively). We also obtained similar C : N ratios for the both horizons. The litter thickness and the content of Ntot in the O horizon, as well as the content of Corg in the AY horizon, significantly differed in different parts of the transects (P < 0.05). The differences in the litter thickness and the Corg content in the O horizon under the crowns of different tree species were also significant. In samples from the AY horizon taken in intercrown spaces, the Ntot content correlated with the demand of plant species of the ground cover for soil fertility. The data obtained reflect the influence of specific features of spatial patterns of surface and root litterfall in multispecies communities of mixed forest stands on the spatial variability of Corg and Ntot contents in soil.

The content and profile distribution of 137Cs in iron-illuvial dwarf and shallow-podzolic podzols (Albic Podzols) under bilberry-lichen and green-lichen-bilberry pine forests in the located near the Kola Nuclear Power Plant have been analyzed. The pollution density (reserve) of 137Cs in the root-inhabited layer (0–30 cm) in the studied soils was significantly lower than the established control level of 37 000 Bq/m2 and amounts to 530–2459 Bq/m2. A significant part of 137Cs (60 to 90%) was concentrated in mineral horizons. It has been shown that the pollution density of 137Cs in the observation zone of a nuclear power plant was mainly due to global fallout. The greatest influence on 137Cs accumulation in the studied soils was exerted by the organic matter reserve.

The composition of water-soluble organic matter (WSOM) of coniferous- deciduous, coniferous, and moss litter was studied. Litter type affects the composition of WSOM. Sphagnum litter contains less N and dissolved organic carbon (DOC), but more carbohydrates, the WSOM from this litter is characterized by the lowest extinction coefficients Е254. WSOM from mixed litter with a predominance of birch litter had a maximum content of N and a small amount of soluble phenolic (SP) substances. WSOM from litter of pine needles differ from the rest by having a lower content of carbohydrates, the maximum amount of SP and hydrophobic fractions. All investigated WSOM were characterized by high rates of decomposition: half-decomposition time of their stable fractions was 2–4 months. WSOM from pine litter at pH ~ 6.5 were absorbed by the BF horizon of iron–illuvial podzol, starting from the concentration of DOC of 100 mg/L. Substances from birch–spruce litter were adsorbed insignificantly under similar conditions.

The changes in the total soil carbon storage and the pools of labile and potentially mineralizable organic matter in Entic Folic Podzols of the Khibiny Mountains (Murmansk region, NW Russia) caused by wildfires of high and moderate intensity and during the post-fire succession are discussed. Although a moderate-intensity wildfire has no statistically significant impact on the total soil carbon pool, it triggers the active erosion processes leading to the carbon losses comparable to the direct pyrogenic carbon losses in a high-intensity fire. In the postfire soil restoration, the type of organic carbon accumulation changes: the surface carbon accumulation in the form of peat is characteristic of the control site, while up to half of soil carbon is accumulated in the mineral horizons at late stages of the postpyrogenic succession. A high-intensity fire leads to almost complete destruction of labile, microbial, and potentially mineralizable carbon pools in both the organic (pyrogenic) and mineral horizons. A moderate-intensity fire does not cause any statistically significant changes in these pools as compared to the control. The restoration dynamics of the labile and potentially mineralizable pools of organic matter in the pyrogenic horizons of soil differ: the trend of a steady increase in the pools of labile and microbial carbon is observed for three years after the fire and later, while the pool of potentially mineralizable carbon reaches its maximum three years after the fire and then becomes stabilized at this level.

Immobilized metal affinity chromatography (IMAC) has been used to fractionate organic compounds in alkaline extracts from forest soils of the Komi Republic by their ability to form complexes with copper ions. An algorithm for chromatographic fractionation of substances into the groups of homogeneous molecular compounds is proposed by selecting the separation conditions; this algorithm comprises sequential change in pH and ionic strength of the eluent. As is shown, the alkaline extract contains three fractions, the components of which differ in their ability to form complexes with copper. The humic substances of iron-illuvial podzol (Albic Podzol), podzolic (Glossic Retisol), and peaty-podzolic gleyic (Histic Retisol) soils are shown to differ in their relative contents of ligand-forming organic compounds. The maximum content (according to Corg) of copper complexones is recorded in the organic matter of forest litters of the examined soils (14–21 g/kg). The corresponding values of the organic matter content in the eluvial horizons are 0.5–1.5 g/kg. The highest content of the carbon compounds able to bind copper ions is characteristic of podzolic soils, while the organic matter components of podzols and peaty-podzolic gleyic soil display somewhat lower affinity for copper. The proposed algorithm can be used to assess the soil vulnerability to heavy metal pollution.

Mineralization resistance of water-soluble organic matter (WSOM) extracted from litter of podzol becomes higher upon the interaction with mineral horizons. Both the portion of WSOM susceptible to mineralization and its mean decomposition rate decrease two and three times, respectively, after its migration through the E eluvial horizon. Sorption in the BF horizon enhances the stability of the input organic matter. The relative content of mineralized carbon decreases to 2% (eight times). In natural soils, adsorbed organic matter may be even more resistant to mineralization due to lower temperatures and biological activity and thus represent the basis for the formation of humus reserve. Taking into account the calculated mineralization rate, the organic carbon accumulation in the BF horizon as a result of WSOM sorption may reach 13.5 mg/100 g per year, but it depends on the concentration of organic substances in soil solutions, hydrological regime, and other factors.

The relevance of the research is related to the need for environmental monitoring of subarctic zone soils change in the Tyumen region at the stage of developing hydrocarbon deposits in modern conditions of transformation of the region into strategic base of Russia. The aim of the research is to evaluate the transformation of physical state and chemical composition of soils in subarctic zone of the Tyumen region under the influence of natural conditions and technogenic stress.Methods: landscape-geochemical and statistical, soil-geochemical studies, methods for determining chemical composition of organic and inorganic pollutants of soils, decoding of space images. Results. It is shown, that under the influence of anthropogenic load, which began in 1972, synlitogenic soils of floodplain are the most resistant to physical transformation and post-lithogenic soils – podzols – are the least resistant. The structure of soils, determined by the features of their formation and transformation should be considered the indicator of physical stability of soils. Podzols are the most susceptible to chemical transformations (on heavy metals), and floodplain soils and organogenic soils are the least susceptible; on organic matter – the soils of floodplains and organogenic soils, respectively. The indicator of chemical stability of soils is their ability to accumulate, move, release and transform inorganic and organic contamination. The area of physically transformed soils of this site at the stage of industrial development of the territory since 1972 has increased from 10,734 km2 (2008) to 11,705 km2 (2012).

Vegetation emissions of volatile organic compounds (VOCs) are intensively studied world-wide, because oxidation products of VOCs contribute to atmospheric processes. The overall aim of this study was to identify and quantify the VOCs that originate from boreal podzolized forest soil at different depths, in addition to studying the association of VOC concentrations with VOC and CO2 fluxes from the boreal forest floor. This is the first published study that measures belowground VOC concentrations at different depths in a podzol soil combined with simultaneous flux measurements from the boreal forest floor. The VOC concentrations were determined by sampling VOCs from air inside soil layers using the gas collectors and adsorbent tubes. Forest floor VOC fluxes were determined using a dynamic enclosure technique. All the VOC samples were analysed using a thermal desorption-gas chromatograph-mass spectrometer. More than 50 VOCs, dominated by monoterpenes and sesquiterpenes, were detected in the air space in the soil during two measurement campaigns. The O-horizon was a significant monoterpene source, because it contained fresh isoprenoid-rich litter. Belowground monoterpene concentrations were largely decoupled from forest floor monoterpene fluxes; thus, it seems that production processes and storages of VOCs partly differ from those VOCs that are simultaneously released from the forest floor. Both fluxes and concentrations of the monoterpenes and sesquiterpenes correlated with the CO2 fluxes in autumn, indicating that VOC release was driven by microbial activity. This is the first study where below-ground VOC concentrations were quantified in situ, and for this reason, this study provides valuable insights to the VOC sources present in soils.

Fe(III) oxides stabilize soil organic matter by forming Fe organo-mineral associations (Fe-OMA). Under anoxic conditions, Fe-OMA may be destabilized by microbial dissimilatory iron reduction that releases aqueous Fe(II) and also possibly adsorbed or co-precipitated organic matter. Soil spodic horizons that accumulate Fe-OMA are ideal natural materials to study such impact. Here, we study three spodic horizons from pedons (P) of increasing age: P-270 yrs, P-330 yrs and P-530 yrs. Their contents of total carbon and short range ordered (SRO) Fe oxides increase with soil age from, respectively, 1486 to 3618 and 13 to 249 μmol g−1. The samples were incubated for 96 h under anoxic conditions, with and without Shewanella putrefaciens (a model dissimilatory Fe(III)-reducing bacteria) in a minimal medium devoid of any pH buffer and external electron donor. The concentration of dissolved Fe(II), total Fe and organic C was monitored at 9 time steps. With increasing age, both the rate and extent of microbial Fe(III) reduction increased after S. putrefaciens addition. In P-270 yrs, P-330 yrs and P-530 yrs, respectively, the microbial reduction rates were 0.004, 0.026 and 0.114 fmol Fe(II) h−1 cell−1 while the amounts of released Fe(II) were 0.23, 0.32 and 1.98 μmol Fe(II) g−1, both being strongly correlated with SRO Fe oxides content. Dissolved organic carbon (DOC) was released with or without S. putrefaciens in all samples (up to 73 μmol OC g−1 after 96 h in P-530 yrs). Adding S. putrefaciens significantly increased DOC release, but only in P-270 yrs. Podzol development thus increases the impact of anoxia on Fe(II) release since organic matter accumulation impedes Fe oxide crystallization, thereby amplifying Fe availability for Fe reducing microbes. The evolution of Fe oxide content and crystallinity thus affects the fate of both C and Fe in soils., SCOPUS: ar.j, info:eu-repo/semantics/published

Recently, the interest in mushroom consumption has been growing, since their taste and low calorific value are appreciated, but also due to their nutritional value. In determining the usefulness of mushrooms in the human diet, it is important to consider the conditions of their occurrence to perform the assessment of bioaccumulation of minerals. The aim of the study was: (a) to determine the content of selected macronutrients (P, K, Ca, Mg, Na) in fruiting bodies of Boletus edulis, Imleria badia, Leccinum scabrum and the soils, (b) to determine their bioaccumulation potential taking into account the habitat conditions, and (c) an attempt to estimate their role in covering the requirement for macronutrients of the human organism. The research material was obtained in the NW of Poland: Uznam and Wolin, the Drawa Plain and the Ińsko Lakeland. In the soil, we determined the content of organic matter, pH, salinity and the content of absorbable and general forms of macronutrients. The content of macronutrients in mushrooms was also determined. Chemical analyses were performed using the generally accepted test methods. The study showed that in NW Poland, B. edulis grew on the acidic soils of Arenosols, and I. badia and L. scabrum grew on Podzols. The uptake of K, Mg and Ca by the tested mushrooms was positively, and P and Na negatively correlated with the content of these elements in the soil. The acidity of the soil affected the uptake of K and Mg by mushrooms. There was no effect of the amount of organic matter in the soil noticed on the content of macronutrients (except sodium) in mushrooms. Among the studied macronutrients, none of the mushrooms accumulated Ca, while P and K were generally accumulated in the highest amounts, regardless of the species. Each of the other elements was usually accumulated at a similar level in the fruiting bodies of the species we studied. The exception was I. badia, which accumulated higher amounts of Mg compared to B. edulis and L. scabrum. Mushrooms can enrich the diet with some macronutrients, especially in P and K.

Soil organic matter is a key resource base for agriculture. However, its content in cultivated soils is low and often decreases. This study aimed at examining the effects of long-term application of chicken manure (CM) and spent mushroom substrate (SMS) on organic matter accumulation, acidity, and hydraulic properties of soil. Two podzol soils with sandy texture in Podlasie Region (Poland) were enriched with recycled CM (10 Mg ha−1) and SMS (20 Mg ha−1), respectively, every 1–2 years for 20 years. The application of CM and SMS increased soil organic matter content at the depths of 0–20, 20–40, and 40–60 cm, especially at 0–20 cm (by 102–201%). The initial soil pH increased in the CM- and SMS-amended soil by 1.7–2.0 units and 1.0–1.2 units, respectively. Soil bulk density at comparable depths increased and decreased following the addition of CM and SMS, respectively. The addition of CM increased field water capacity (at –100 hPa) in the range from 45.8 to 117.8% depending on the depth within the 0–60 cm layer. In the case of the SMS addition, the value of the parameter was in the range of 42.4–48.5% at two depths within 0–40 cm. Depending on the depth, CM reduced the content of transmission pores (&gt, 50 µm) in the range from 46.3 to 82.3% and increased the level of residual pores (&lt, 0.5 µm) by 91.0–198.6%. SMS increased the content of residual pores at the successive depths by 121.8, 251.0, and 30.3% and decreased or increased the content of transmission and storage pores. Additionally, it significantly reduced the saturated hydraulic conductivity at two depths within 0–40 cm. The fitted unsaturated hydraulic conductivity at two depths within the 0–40 cm layer increased and decreased in the CM- and SMS-amended soils, respectively. The results provide a novel insight into the application of recycled organic materials to sequester soil organic matter and improve crop productivity by increasing soil water retention capacity and decreasing acidity. This is of particular importance in the case of the studied low-productivity sandy acidic soils that have to be used in agriculture due to limited global land resources and rising food demand.

Soil organic matter (SOM) represents a major reservoir of stored carbon (C). However, uncertainties regarding the composition and origin of stabilized SOM hinder the implementation of sustainable management strategies. Here, we synthesize data on the contribution of plant- and microbial-derived compounds to stabilized SOM, i.e., aggregates and mineral-associated organic matter (MAOM), and review the role of environmental factors influencing this contribution. Extrapolating amino sugar concentrations in soil based on molecular stoichiometry, we find that microbial necromass accounts for ~50% (agroecosystems) or less (forest ecosystems) of the C stabilized within aggregates and MAOM across studies. This implies that plant biomolecules, including lipids, lignin, and sugars, might account for a substantial portion (≥50%) of the organic matter protected by minerals and aggregates. Indeed, plant-specific sugars and lipids can each account for as much as 10% of organic C within mineral soil fractions, and most reported quantities of plant-specific lipids and lignin in mineral soil fractions are likely underestimates due to irreversible sorption to minerals. A relatively balanced contribution of plant and microbial biomolecules to stabilized SOM in aggregates and MAOM is inconsistent with recent suggestions that stable SOM is comprised mostly of microbial compounds. Land use and soil type appear to profoundly affect the contribution of plant and microbial compounds to stabilized SOM. Consistent with studies of bulk soils, favorable conditions for microbial proliferation in grasslands or fertile Chernozems or Luvisols appear to increase the contribution of microbial compounds, while less favorable conditions for microbial proliferation in forest soils or Podzols/Alisols appear to favor the abundance of plant compounds in stabilized SOM. Combined with a tight link between substrate quality and the abundance of microbial compounds in stabilized SOM, and a potentially inverse relationship between substrate quality and the abundance of plant compounds, these results provide evidence that plant biomolecules might be preferentially stabilized by organo-mineral interactions in some ecosystems. Various areas warrant further research. For example, difficulties in distinguishing direct and indirect effects of temperature and precipitation on the composition of stabilized SOM may be overcome by long-term observational studies that include climate manipulations. Knowledge gaps in the contribution of plant and microbial compounds to stabilized SOM in soil layers below 30 cm depth may simply be closed by extending the sampling depth. Moreover, a refined focus on soil fauna, with potentially strong effects on microbial and plant compounds in stabilized SOM, will provide new insights into SOM dynamics. Future studies should quantify both microbial and plant biomolecules in mineral soil fractions to allow direct comparisons and overcome limitations in existing data. For example, because biomarker-based estimates of microbial-derived C can only indirectly estimate the maximum amount of plant-derived C, exhaustive studies of plant biomarker concentrations could be conducted, including estimates of plant-specific lipids, sugars, and lignin (and biomarkers released following mineral dissolution). Generally, more integrative studies, e.g., combining molecular and isotopic tracers of organic matter inputs with targeted sampling of mineral fractions, are required to improve knowledge of the formation and persistence of stabilized SOM.

Summary • In order to understand the phytohormone-like activity of humic substances (HS) with respect to vegetation, different forest ecosystems were considered. For this study, 32 soil horizons from a large area of northern Italy typical for silver fir ( Abies alba ) were evaluated. • The development of organic and humic matter in the five silver fir forest types was assessed by quantifying chemical and biochemical parameters. Phytohormone-like activity of HS was evaluated by measuring auxin-like (indoleacetic acid (IAA)-like) and gibberellin-like (GA-like) activities as well as invertase and peroxidase activities. • Differences between ecosystems were obtained by comparing the five silver fir types with previous work in beech forests, which investigated three large groups: thermophilous, mesophilous and acidophilous. In these eight forests it was reconfirmed that acid conditions were essential for the release of the IAA-like activity, whereas neutral conditions promoted GA-like activity. • Humic substances are of ecological importance because their phytohormone-like activity stands out not only within the five silver fir forest types, but also between the silver fir and beech types. Our results demonstrated a different collocation of the hormone-like activity along the profile in accordance with the different growth conditions, seed germination and the first stage of seedling growth. Humic substances evoke the greatest response on seed germination and on the first stage of seedling growth, particularly in stressed environmental conditions.

The problems of prospecting for deposits in covered by surface sediments territories that arose in the 20th century contributed to the development of ideas about the migration and concentration of chemical elements and their forms in the supergene zone. The theory of "jet-like" migration of chemical elements appears. All this contributed to the development of geochemical methods of prospecting for deposits by secondary dispersion halos, in particular, gold deposits. However, information on the migration and concentration of gold in loose sediments is insufficient to this day. Forms of gold and arsenic, as one of the main pathfinder, were researched in eluvial, illuvial and parent material horizons of podzol soil at the Novye Peski gold deposit. Forms of gold and arsenic were studied with sequential extraction method. Results of this study showed that main forms of gold are water-soluble, bound to organic matter and “insoluble”, for arsenic: bound to Fe and Mn-(oxy)hydroxides and bound to organic matter. The form bound to organic matter was considered in detail and gold and arsenic were analyzed in humic and fulvic acids solutions extracted from podzolic soil. It was determined that gold is mainly bound to humic acid (HA), arsenic – to fulvic acid. Due to the prevalence of form of gold bound to humic acid, the modelling process of different gold and arsenic (III) contents sorption on solid humic acid were observed and data on quantity of adsorbed ions per unit mass of HA and recovery ratio were obtained. More than 90 % gold recovery rate was observed for concentrations less 10 µg/cm3 and for arsenic it was in a range 8 – 15 %.

This chapter presents the genesis, characteristics, classification, distribution, and land uses of the 10 soil grade groups (Human-made soils, Organic soils, Andosols, Podzols, Fluvic soils, Red-Yellow soils, Stagnic soils, Eutrosols, Brown Forest soils, and Regosols) in the Soil Classification System of Japan. Human-made soils are referred to soils formed through an anthropogenic process, especially in anthropized areas such as urban, industrial, traffic, mining, and waste disposal areas. Organic soils are formed under wetland conditions where the rate of organic matter production exceeds the rate of organic matter decomposition. Andosols are mainly derived from volcanic ejecta or tephra and form during a long period of pedogenetic soil formation process have unique and distinctive properties among soils, such as their fluffy and light surface properties, high humus content, and very high phosphorus-fixing capacity. Podzols are characterized by the eluviation of aluminum (Al) and iron (Fe) from the albic E horizon and their illuviation in the spodic B (Bs) horizon. Fluvic soils are young soils developed from recent alluvial deposits. Red-Yellow soils are a red or yellow color, low accumulation of organic matter, low base saturation, and strong weathering. Stagnogley soils are distributed in terraces, hills, and mountainous areas having a shallow groundwater table. Eutrosols are characterized by high base saturation, that is, with a eutric condition. Brown Forest soils are relatively young soils, are widely distributed in a rather wide range of temperate, and warm temperate zones in humid (high precipitation) climates without fresh volcanic ash deposition. Regosols are very weak weathering soils, which are divided into four groups: Volcanogenous Regosols, Sandy Regosols, Lithosols, and Terrestrial Regosols.

Podzols are soils in which organic acid and mineral leaching results in the formation of a B horizon, which often contains a high amount of organic carbon. As Podzols cover large areas of the globe (±12% in European forests), carbon stocks of Podzols are important in the context of climate change mitigation. However, the dynamics of carbon storage in Podzols are not yet fully understood. In this study pyrolysis-GC/MS was used to investigate organic matter (OM) transformation from leaf litter to stabilized OM in the B horizon. It was analysed how OM transformation differed for different stages of Podzol development (leaf litter > incipient > active > buried) and for different vegetation types (deciduous, coniferous, mixed) in a temperate climate. The consequences for carbon storage in Podzols were evaluated. Identified pyrolysis products (1 0 5) were assigned to different chemical groups (lignin phenols, aliphatics, etc.) and relative abundances were calculated. The relative abundance of (lignin) phenols decreased from 42 to 58% in leaf litter and fermentation material to 34–49% in A and B horizons of incipient Podzols, to 14–47% in active Podzols, and to 10–18% in buried Podzols. At the same time, the relative abundance of aliphatics increased from 10 to 14% in leaf litter and fermentation material to 19–27% in the A and B horizons of incipient Podzols, to 13–56% in active Podzols, to 27–63% in buried Podzols. Vegetation type did not cause large changes in the OM composition. Incipient Podzols had a soil OM composition similar to the illuvial dissolved OM (DOM) input, as the buildup of stabilized OM has just started. Concluding, the soil OM composition changes for different Podzol development stages (incipient > active > buried), and stabilization of aliphatics increases when the relative input of illuvial DOM, and thus of lignin phenols, decreases.

Biochar is one of the most widely used ameliorants for soil amendment, which is known as factor which rises crop yields and levels of soil biological activity. Nowadays, it is under investigated how biochar application affects the dynamics of the humic components and whole soil organic matter (SOM) and the processes of its alteration. This investigation is aimed to evaluate the influence of biochar on the content, composition, and transformation of humic acids (HAs) as the main component of the SOM. The incubation experiment was carried out on three Podzol Antric soils, with varying amounts of initial total organic carbon. The incubation time was 90 days, using biochar gravimetric doses of 0.1 and 1.0%. The biochar was produced by fast pyrolysis of birch and aspen wood at 550 °С. Humus composition was analyzed for the organic matter fractions extracted with 0.1 M NaOH (containing HAs 1 + fulvic acids (FAs) 1) and 0.1 M Na4P2O7 (containing HAs 1 + FAs 1 + HAs 2 + FAs 2). Isolated HAs were characterized for their elemental composition (C, N, H, and S) and molecular composition with the use of solid-state 13C nuclear magnetic resonance (13C-NMR) techniques. We found that 0.1% of biochar amendment does not influence SOM mineralization, but 1.0% of biochar increases the mineralization by 15–18%. This process is accompanied by changes in the composition and properties of the HS. The increased proportion of HA aromatic fragments in biochar indicates an increasing of their stability. However, in soils with high humus content and a significant amount of insoluble matter, the processes of mineralization and the growth of HAs are taking place simultaneously. The replenishment of HAs could be the outcome of both the intensification of the transformation processes (mineralization and humification) of the more sustainable insoluble matter compounds and the humification of the biochar itself. The influence of biochar on humification in Podzol Antric soils was revealed on the basis of incubation experiment. Both negative and positive changes under biochar in HS system were demonstrated. The active decrease of humus total contents and also the labile HS ought to qualify as negative changes. The increase of HA chemical maturity that leads to the stability of humus in whole as well as the intensive new HA formation thought to qualify as positive changes.

Soil organic matter (SOM) plays an important role in environmental sustainability, since it is involved in carbon and nutrient cycling. Consequently, it is a key factor to consider in studies concerning global climate change and agronomy. Among the main components of SOM are humic substances (HS), which are divided, according to their solubility, into humic acid (HA), fulvic acid (FA), and humin (HU) fractions. Study of the chemical properties of this organic matter is important for understanding the biogeochemical processes occurring in the soil. The aim of this work was to determine the metals iron (Fe) and aluminum (Al), using flame atomic absorption spectrometry (FAAS) and laser-induced breakdown spectroscopy (LIBS), in order to elucidate the role of organic matter in the transport of these metals in Amazonian soils. The results showed that FA was important for Al, while the HA fraction was more selective towards Fe. The translocations of these metals to deeper profiles in two different soils involved either young and less humified organic matter, or older organic matter with a low degree of humification. Therefore, these two humic fractions were involved in the process of soil podzolization, with FA having a predominant role in the transport of Al, while HA was mainly responsible for the transport of Fe.

In podzols important environmental issues converge, including dissolved organic matter (DOM) transport, DOM-metal binding, and carbon storage in the subsoil. Therefore, it is important to understand the formation and degradation of podzols in relation to (changes in) environmental conditions. For this purpose a Holocene barrier island with coastal sand dunes (Ilha Comprida, SE Brazil) was chosen as study area. The island is build-up of five geomorphic units that have different age (from >5000 to 325 y BP), vegetation (restinga ecosystems), soil hydrology (flat units or units with ridges and swales) and drainage (poorly drained, well-drained, and improved drainage). Representative profiles were studied for each geomorphic unit, resulting in 100 samples from A, E, B, and C horizons, from which soil organic matter (SOM) was isolated by alkaline extraction. To better understand carbon sources and dynamics, we additionally sampled litter from different vegetation types and DOM from various sources. The molecular composition of SOM, DOM and litter was analyzed with pyrolysis gas chromatography mass spectrometry (pyrolysis-GC/MS). Comparing the pyrolysates of all samples (DOM, SOM and litter) factor analysis demonstrated that the major difference in molecular composition (factor 1) was related to the contribution from DOM (phenol, acetic acid, benzofurans, pyridine, benzene and naphthalene) or in-situ root material (straight chain aliphatics and methoxyphenols from the biomacromolecules suberan and lignin, respectively). The contribution from DOM or roots was characteristic for a profile i.e. without much change with depth. Factor 2 reflected decomposition processes, and showed that the predominantly DOM-derived B horizons were relatively enriched in aromatics compared to DOM, indicating selective decay and/or selective precipitation. In geomorphic units with swales and ridges that received DOM via groundwater flow from the catchment area, the B horizon was predominantly DOM-derived; these profiles showed large differences in the contribution from black carbon (BC; (poly)aromatics), with the younger profiles showing a larger contribution from BC in precipitated DOM. B horizons with a relatively large contribution from in-situ root materials were found in well-drained soils and in some of the poorly drained soils without lateral groundwater flow from the catchment area, i.e., the flat geomorphic unit without ridges and swales. Microbial material (N-containing compounds and sugars) was associated with relatively recent SOM and with well-drained conditions at present. i.e., well-drained profiles, and profiles with improved drainage.

Transformation of water-soluble organic substances entering mineral horizons of podzol from the forest litter was studied in a model column experiment. The concentration of organic matter in the solution after its interaction with the E horizon increased by 10–44% due to the release of native soluble organic matter. This was accompanied by changes in the quality of water-soluble organic matter: the portion of hydrophobic components increased, the coefficients of extinction at 254–280 nm decreased, and the portion of low-molecular-weight compounds slightly decreased with a corresponding increase in the portion of high-molecular-weight compounds. Upon the interaction of water-soluble organic substances with the E horizon, the pH values first decreased and then slightly increased, which could be due to sequential desorption of organic acids of different strengths. Dissolved organic substances from the E horizon were partly sorbed in the BF horizon at the rate of about 65 mg С/100 g, or 22% of Corg in the BF horizon. The sorption resulted in the removal of mainly hydrophobic medium- and high-molecular-weight (>7000 Da) organic substances from the solution. As judged from the coefficients of extinction in the UV area, the sorbed substances were characterized by a higher aromaticity in comparison with the substances remaining in the solution. The sorption of organic substances in the BF horizon was accompanied by the rise in the pH of the solution, which corresponded to binding of organic anions on the surface of iron hydroxides according to the mechanism of ligand exchange with OH ions.

This study aims to contribute toward a better understanding of the current biodiversity patterns existing in the Atlantic Forest of the state of Rio de Janeiro from a paleo-ecological approach. Three soil profiles, each formed from distinct source materials under varied climate and vegetation conditions were selected from the coastal regions of Rio de Janeiro, Brazil. Soil horizon samples for chemical and physical characterization were collected from 10 cm-interval depths, and the total organic carbon was determined in addition to performing isotype and phytolithic analyses. The phytolithic analysis associated with the isotopic techniques (δ13C) permitted the characterization of three stages of paleo-environmental evolution for the studied soils, presenting valid trends that indicate small variations within the phytosociological structure of the vegetation along a Spodosols line in the studied areas. These stages indicated that the phytolithic assemblage was formed from a vegetation profile containing more trees, adapted to conditions colder than the existing vegetation, although no environmental changes were detected using the isotopic data. The milder temperature conditions may have favored the pedogenetic processes of the spodic B horizon formation as well as the maintenance of the organic matter contained in the soil. This study serves as the first draft for the paleo-environmental association among the regions where the analyzed profiles are found.

Because of its rapid temporal variation, humus characterization is one of the most useful approaches when studying the influence of multiple variables on soil. The aim of this study is to describe the elevation effect on terrestrial humus formed under Scots pine stands that developed on homogeneous parent material in the Moncayo Massif (NE Spain). The humus forms evolved from Dysmull to Hemimoder and Humimor with elevation. These morphological and analytical changes are considered a consequence of the increasing soil constraints (acidity, podzolization) and decreasing temperatures with elevation, which reduce soil biological activity and lead to an accumulation of soil organic matter. About 10 Mg organic C/ha in the low altitudinal pinewood stand and 54 Mg C/ha in the top stand were stored in the O horizons. The total organic C also increased significantly with elevation in the Ah horizon. However, the pH and the size of aggregates decreased with increasing elevation in the Ah horizon.

Soils of low-mountain landscapes in the northwest of Karelia have been studied. The soil cover of the studied area is mainly represented by Al–Fe-humus soils (Podzols); thin soils (Leptosols) are widespread. Characteristic morphological features of all the studied soils are relatively shallow profiles, high stone content, and underlying by hard bedrock with fine earth material in crevices between large boulders. The studied soils have the high carbon and low nitrogen content, which points to unfavorable conditions of organic matter transformation. The content of most macro- and microelements is not high, which is typical for soils of the region; the content of copper and zinc exceeds the regional background two–three times. Regularities of the vertical zonality in the properties of soils of mountain ecosystems manifest themselves in decreasing thickness of the soil profile at higher altitude above sea level in parallel to decreasing thickness of the layer of loose rocks, while the stone content increases. In soils of the forest-tundra zone, the organomineral horizon with the high organic matter content is formed immediately under the forest litter. The litter horizon is the soils of this zone is characterized by increased concentrations of calcium, magnesium, phosphorus, and zinc.

Morphology of podzol profiles can be used to improve our understanding of soil formation and degradation processes. The morphology of a podzol chronosequence was studied for a 1800 m long cliff perpendicular to the coastline at the southern coast of the Island Ilha Comprida (Sao Paulo, Brazil). The large variation in hydrological conditions with time (surfaces with ages from 6000 to 300 yrs BP) and space (topography) allowed studying the relation between podzol morphology and drainage conditions, both during soil formation and degradation. On the oldest two surfaces, the podzols formed under poorly drained circumstances. Uplift during their formation resulted in (1) very deep Bh horizons and (2) degradation of the upper B horizon as a result of improved drainage. On the younger surface most podzols were poorly drained, but well-drained podzols and transitions occurred in beach ridges. In the cliffs on the southern coast of the island, improved drainage of the poorly drained podzols resulted in degradation of the B horizon. This degradation exhibits various forms, including (1) complete removal of the B horizon down to an underlying clay layer, (2) degradation of the B horizon along root channels with preferential vertical water transport, (3) degradation of the upper B horizon resulting in a diffuse EB transition, and (4) areas of organic matter (OM) depletion related to microbial activity, sometimes combined with burrowing. Type (2) degradation may result in a convoluted EB transition, the formation of islands of B horizon in the deepening E horizon, and formation of E horizon tongues into the Bh. Recent (post degradation) OM bands were found in E and B horizons. A thorough study of podzol morphology can be used to reconstruct several stages of their formation and degradation in relation to drainage conditions.

Soils are a large reservoir of organic carbon, and plays a significant role in its accumulation and storage. The goal of this study is to provide a generalized estimate of soil organic carbon (SOC) stocks at dominant types of forest soils in the European North-East of Russia. The soil cover of the studied territory is mostly formed by Histic Retisols (HsR), Haplic Retisols (HpR) and Albic Podzols (AP). We used the results of our own SOC estimates and the ones of soil profile descriptions that were published for the region of investigation. The calculation was carried out for organic horizons and depths of 0–30, 0–50 and 0–100 cm including the organic horizon. The literature data lacks bulk density (BD) information. We calculated the mean BD value for soil horizons based on our BD determinations conducted for the studied soil groups in various parts of the region. The obtained BD values differed for separate soil groups. Relatively high BD of mineral horizons was obtained for HsR, low BD – for AP. Larger BD of organic layer for HpR is explained by accumulation of comparatively well-decomposed organic matter on the soil surface. The BD of organic layers was comparable for AP and HsR. The SOC stocks in all soil groups were characterized by a wide variation with differences between minimal and maximal values changing from 4 to 13 times. A closer spread was for HpR. The highest SOC stocks in 1 m depth were calculated for HsR with the mean value of 12.66 ± 0.13 kg m−2. The SOC content in HpR was 7.69 ± 0.12 kg m−2 and in AP – 3.80 ± 0.09 kg m−2. The organic layer share varied from 24 to 35% in SOC stocks of the 1 m profile. The depth of 0–50 cm concentrates 70–78% of SOC of the 1 m soil profile. According to the mean SOC stocks data and the area of the soil groups we estimated SOC stocks concentrated in main soil groups in the Komi Republic.

Global warming can lead to a significant transformation of the structure of terrestrial ecosystems and changes in the mode of functioning of their components. In this connection, studies of soil respiration, particularly of the biological activity of soils under forest exposed to warm impact of flaring flare are of scientific and practical interests. A long-term experimental plot was established in a lichen pine forest on the Albic Podzols (Arenic) (Khanty-Mansi Autonomous Area-Yugra). Sampling and measurements were carried out in the areas at the distances of 70, 90, and 130 m from the flare with the strong, moderate, and weak heating effects, respectively. In the zone of the maximum heating effect, the soil temperature was by 1.3°C higher, and the rate of CO2 emission from the surface in situ was greater by 18% compared to the zone with weak impact of the flare. Along with increasing CO2 emissions, organic matter accumulated due to increasing the stable pool. The parameters of the microbial biomass, basal respiration, and the input of labile organic matter pool increased with the distance from the flare.

International audience; The complex behaviour of Zn and Cu at the soil-river interface was investigated in soil and riverine water samples from the Rio Negro basin, a secondary tributary of the Rio Amazonas, using their stable isotope compositions. This acidic and organic river drains two types of intensely weathered terrains: podzols in its upstream part, and lateritic soils downstream. Bulk soil particles, suspended particulate matter (SPM) as well as colloidal fractions were sampled across the whole basin during low and high water stages.In the basin, Zn and Cu are mostly exported from lateritic soils and transported by organic colloids where significant losses are observed in the downstream part of the river. The use of delta Zn-66 and delta Cu-66 measurements reveals distinct stories for these two metals in suspended sediments and colloids. In the colloids, the constant delta Zn-66(coll) across the basin is induced by the same weak association mode between Zn and organic ligands, regardless of the origin of the water. By contrast, in SPM, the speciation of Zn and thus delta Zn-66(SPM) differ according to the type of drained soils. Zn is associated with organic complexes in particles exported with water draining podzol whereas Zn2+ is incorporated in the structure of the remaining kaolinite clays in lateritic output.The stronger reactivity of Cu than Zn with organic ligands induces its complete complexation. Copper is controlled by refractory particulate organic matter (POM) and by reactive colloidal organic matter; the latter being enriched in delta Cu-65 due to stronger binding interactions than in POM. While the Cu content remains constant in the upstream part of the Rio Negro, downstream, the decrease of SPM and colloidal Cu fluxes is associated with a constant delta Cu-65(SPM) and with an increase of delta Cu-65(coll) at the Rio Negro outlet. Geochemical mass balance modelling, based on SPM, Cu and Zn fluxes in SPM and their associated isotopic signatures, confirms distinct host phases for Zn and Cu, and identifies the most probable places where losses of these two metals occur. In colloids, the observed Cu isotope fractionation (from 0.24 to 0.45%) superimposed on the significant Cu-coll loss is assumed to result from a new isotopic equilibrium in a low velocity and high productivity zone: Cu-rich colloids enriched in Cu-63 aggregate and settle down, whereas the remaining heavy Cu is partially complexed on strong organic ligands secreted by phytoplankton, forming new Cu-colloids

Here, we aimed to assess the contamination of Podzol soils in a subalpine zone of the Karkonosze Mountains. Cu, Pb, and Zn concentrations in the soil and the patterns of their speciation are discussed in relation to the possible influence of airborne industrial emissions and the stage of degradation of dwarf mountain pine stands. The study was conducted in the Karkonosze, a mountain range in the Sudetes, on the boundary between Poland and the Czech Republic. We examined Podzols derived from granites under dwarf mountain pine stands at two stages of degradation (without visible degradation vs. dead). These two sites were 100 m apart, at an altitude of 1400 m above sea level (upper mountain forest zone). Soil samples were collected from all distinguished soil horizons and their basic soil properties and heavy metal (Cu, Pb, and Zn) concentrations (and their speciation) determined by sequential extraction according to the method of Zeien and Brummer. The Cu concentrations in these soils were relatively low, typical for soils derived from granite and did not differ considerably within soil profiles. The residual Cu fraction was a predominant one in all mineral horizons. The Pb concentrations in the surface organic horizons were clearly higher than those in similar horizons of European lowland forest soils. This distribution of Pb in the mineral horizons was apparently associated with soil colloid distribution that developed in the process of podzolization, indicating the minimum concentrations in eluvial E horizons and enhanced concentrations in illuvial Bh horizons. The organically bound fraction made up about 40% of total Pb in the Bh horizons. Zn concentrations were highest in the deepest parts of the soil, where the predominant fraction was residual, while relatively high amounts of easily mobilizable Zn were present in ectohumus. Very high concentrations of Pb in ectohumus have most likely been caused by a long-distance transport of anthropogenic emissions. The concentrations of Pb or other metals found in soils cannot be considered to have been the principal causes of the ecological disaster observed in the Karkonosze Mountains. The highest concentrations of Pb in ectohumus, as well as its high contributions in the organically bound fraction, confirm a crucial role of organic matter in Pb accumulation in soils.

Forest floor carbon (C) sequestration has been negatively correlated with manganese (Mn) availability, possibly due to reduced efficacy of Mn-peridoxase enzymes produced by Agaricomycete fungi. I examined a soil C and Mn dataset from a podzolization gradient, along with fungal sporocarp Mn concentrations, to potentially corroborate this finding. An inverse power relationship between soil C and soil Mn content across temperate rainforests was confirmed, which provides further evidence of a Mn bottleneck in C turnover. Average Mn concentrations of saprotrophic sporocarps were greater than those of ectomycorrhizal fungi, and displayed a similar inverse correlation with increasing soil C. The absence or limited effectiveness of select saprotrophic fungi across Mn-depleted forest soils may be one mechanism behind impeded turnover of recalcitrant organic matter.

Background We applied Fourier-Transformed Infrared Spectroscopy (FTIR) techniques in combination with selective humus extractions to investigate in situ the chemical features of organic matter in three soil profiles recently developed from Dutch sand dunes, under well-documented vegetation sequence and containing a relatively simple mineral-organic matter system. Water-soluble and alkaline-soluble extracts were also studied to match the changes of humus in the soil residues. Results Diffuse Reflectance Infrared Fourier Transform (DRIFT) and transmission spectra differed in resolution and sensitivity. DRIFT was superior in revealing structural information on the organic matter present in the soil samples whereas transmission spectra showed higher resolution for the bands of inorganic material at lower spectral frequencies. Differences between H and B horizons were due to the amount of hydrophilic organic acids, partly unsaturated, that were extracted by alkali. Extractable carboxylic acids and other hydrophilic compounds such as peptides and carbohydrates were larger in the less developed soils under pine and crowberry than in the more advanced profiles under beech. Humin residues from both H and B horizons retained unextractable aliphatic components and carboxylic groups involved in strong complexes with minerals, thereby confirming other findings that showed the largely aliphatic character of the unextractable humic fraction. Accumulation of poorly-soluble organic materials in these soils occur by protection from biodegradation due both to complexation with soil minerals and to a process by which apolar humic constituents form a separate hydrophobic phase where no biological activity can take place. Transport of poorly soluble compounds from H to B horizons, noticed especially in the more developed profiles, may have occurred through humic aggregates containing hydrophobic phases. Conclusions This work shows that the DRIFT technique in combination with soil chemical treatments can be suitably employed to investigate the changes of organic matter in whole soil samples and represents a valid tool to investigate the role of organic matter in soil profile development.

Knowledge of the interactions of soil organic matter (SOM) with metal species is important in order to obtain information concerning the fates of the metals in environment, whose reactive functional groups present in SOM can provide high complexation capacity. The aim of this study was to evaluate the interactions involving humic acids (HA) and fulvic acids (FA), extracted from Amazonian soils, with Cu(II) and Al(III) ions, using fluorescence quenching spectroscopy. The obtained results showed that the data for the humic fractions of the Amazonian Spodosols could be fitted with one to one complexation model, which provided the best representation of the changes in fluorescence quenching after addition of Cu(II) or Al(III) ions. It was found that the HA presented fewer complexation sites and lower stability constants, compared to the FA samples. Furthermore, the FA showed selective interaction with the metals, while the HA fraction was less selective and could be associated its homogeneous structure. The results showed that the humic acids required 10 times more carbon in their structures than fulvic acids for complexing a metal atom. This behavior can be associated to the fact that the Fulvic Acid fraction has higher mobility and greater interaction during the profile when compare humic acids. Hence, given the diversity of metals to which the HA has affinity, this soil fraction appears to be mainly responsible for soil fertility, while the FA fraction has higher mobility and greater interaction with water.

Active land disturbance of soil and environments appears even in remote landscapes of tundra and forest tundra. Wildfires become a frequent factor of soil degradation and intensification of permafrost degradation, also affecting the global balance of carbon, especially content and distribution of polycyclic aromatic compounds. Mature unaffected by fire sandy-textured podzols soils were investigated in comparison with the same soil strongly affected by surface fire in the end of August 2016 in surroundings of the Pangody settlement, Nadym district, Yamal region. Data obtained showed an intensive morphological transformation of the topsoil layers, decreasing total organic matter and apparently increasing the humus enrichment by nitrogen. Wildfires also result in complete transformation of the fractional composition of the polycyclic aromatic compounds. The sum of PAHs increases intensively as well as benzo(a)pyrene content in soils. Therefore, soils of the cryolithozone become more faced to the wildfires during the last decades. Even one-time fire effect results in serious transformation of soil geochemical state.

Purpose: The research aimed to investigate properties and functions of soils constructed from alkaline mining wastes of different origin to remediate the industrial barren resulted from long-term emissions of the copper-nickel factory in the Subarctic region (Kola Peninsula, Russia). Conventional indicators of the remediation effectiveness (pH and metal content in geochemical fractions) were related to the indicators of soil functions such as biomass production, accumulation of organic carbon, microbial activity, and soil respiration. Materials and methods: The experimental area included two sites with polluted and degraded Podzol and Histosol soils located in 1.5 and 0.7 km from the nonferrous (Cu-Ni) smelter, respectively. At the sites, artificial soil constructions were made from mining wastes or quarry sand covered by the vermiculite layer with lawn grasses planted on top. Plant biomass was collected every year starting from the experiment set-up. In 5 to 8 years, soil samples were collected on the layer basis, and chemical, biological, and morphological properties were analyzed. Sequential fractionation of metals was conducted using a modified Tessier’s scheme. The microbial biomass and its respiration activity were determined. Micromorphological studies were conducted using an optical microscope. Soil respiration was measured on-site by IRGA with simultaneous observations of soil moisture and temperature. Results: The plant growth and residues' deposition at both experimental sites triggered carbon accumulation and resulted in 2–3 times higher content of organic carbon in the upper constructed soil layer compared to the initial content in mining wastes. Carbon accumulation was a key driver for the development of soil microbial communities and had a positive effect on the metal immobilization. This effect was strengthened by high pH inherited from the alkaline wastes and resulted in the performance of constructed soils as geochemical barriers. In their upper layers, where the root biomass was the highest, about 30–60% of Cu and Ni were bound by organic matter. In the underlying polluted soil, the most toxic water-soluble metal fraction was completely neutralized; and the metal concentrations in exchangeable fraction decreased by a factor of four improving the habitat conditions of the microbiome. Organic matter accumulation by clay material with the formation of organo-mineral films was found in the vermiculite-lizardite variant. Conclusion: Soil constructions made from alkaline mining wastes in the Subarctic supported the development of plant and microbial communities, organic matter accumulation, and metal immobilization. This technology allows protecting the environment from further pollution under the continuous emissions of the copper-nickel factory.

Made available in DSpace on 2020-12-10T19:49:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-11 Natural Environment Research Council Gordon and Betty Moore Foundation European Research Council EU Seventh Framework Programme Royal Society of London Research Merit Award Sao Paulo Excellence Chair We investigate the edaphic, mineralogical and climatic controls of soil organic carbon (SOC) concentration utilising data from 147 primary forest soils (0-30 cm depth) sampled in eight different countries across the Amazon Basin. Sampled across 14 different World Reference Base soil groups, our data suggest that stabilisation mechanism varies with pedogenetic level. Specifically, although SOC concentrations in Ferralsols and Acrisols were best explained by simple variations in clay content - this presumably being due to their relatively uniform kaolinitic mineralogy - this was not the case for less weathered soils such as Alisols, Cambisols and Plinthosols for which interactions between Al species, soil pH and litter quality are argued to be much more important. Although for more strongly weathered soils the majority of SOC is located within the aggregate fraction, for the less weathered soils most of the SOC is located within the silt and clay fractions. It thus seems that for highly weathered soils SOC storage is mostly influenced by surface area variations arising from clay content, with physical protection inside aggregates rendering an additional level of protection against decomposition. On the other hand, most of the SOC in less weathered soils is associated with the precipitation of aluminium-carbon complexes within the fine soil fraction, with this mechanism enhanced by the presence of high levels of aromatic, carboxyl-rich organic matter compounds. Also examined as part of this study were a relatively small number of arenic soils (viz. Arenosols and Podzols) for which there was a small but significant influence of clay and silt content variations on SOM storage, with fractionation studies showing that particulate organic matter may account for up to 0.60 of arenic soil SOC. In contrast to what were in all cases strong influences of soil and/or litter quality properties, after accounting for these effects neither wood productivity, above-ground biomass nor precipitation/temperature variations were found to exert any significant influence on SOC stocks. These results have important implications for our understanding of how Amazon forest soils are likely to respond to ongoing and future climate changes. Inst Nacl de Pesquisas da Amazonia, Cx Postal 2223, BR-69080971 Manaus, Amazonas, Brazil Univ Estadual Paulista, Dept Ecol, BR-15506900 Rio Claro, SP, Brazil Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England Imperial Coll London, Dept Life Sci, Silwood Pk Campus,Buckhurst Rd, Ascot SL5 7PY, Berks, England Univ Catolica Santisima Concepcion, Fac Sci, Dept Environm Chem, Concepcion, Chile James Cook Univ, Sch Trop & Marine Sci, Cairns, Qld 4870, Australia James Cook Univ, Ctr Terr Environm & Sustainabil Sci, Cairns, Qld 4870, Australia Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Av Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP, Brazil Univ Estadual Paulista, Dept Ecol, BR-15506900 Rio Claro, SP, Brazil Natural Environment Research Council: NE/D005590/1 Natural Environment Research Council: NE/B503384/1 Natural Environment Research Council: NE/D01025X/1 Natural Environment Research Council: NE/I02982X/1 Natural Environment Research Council: NE/F005806/1 Natural Environment Research Council: NE/I028122/1 Gordon and Betty Moore Foundation: 1656 European Research Council: 291585 EU Seventh Framework Programme: GEOCARBON283080 EU Seventh Framework Programme: AMAZALERT-282664

Pit hearth features form a common phenomenon in the Mesolithic of North-West Europe, and the Netherlands and adjacent parts of Germany and Belgium in particular. Using soil micromorphology, we investigated the genesis and taphonomy of several pit hearth features, embedded in sandy podzolic soils from Kampen (the Netherlands). This is one of the first studies to investigate one of such pits in its entirety, instead of only the lower, charcoal-rich fill. Our results show that the upper fill of these pits contains considerable amounts of non-charred degraded organic matter. The lower fill typically contains fragments of charcoal and some wood tar, but also black coatings around sand grains, that is interpreted as charred humus from a podzol B-horizon. These coatings indicate that material from the upper horizons of a podzol profile – e.g. in the form of turves - was used to control a fire on the floor of the pit. Fine charred material postdepositionally leached from the pit feature into the underlying deposits, associated with increased formation of limped clay coatings. This indicates that ash-induced alkaline charcoal degradation and associated clay translocation played a role in this process. The Kampen case provides strong evidence that fine charred organic material may contaminate underlying archaeological or sedimentary units.

We investigate the edaphic, mineralogical and climatic controls of soil organic carbon (SOC) concentration utilising data from 147 pristine forest soils sampled in eight different countries across the Amazon Basin. Sampling across 14 different World Reference Base soil groups our data suggest that stabilisation mechanism varies with pedogenetic level. Specifically, although SOC concentrations in Ferralsols and Acrisols were best explained by simple variations in clay content – this presumably being due to their relatively uniform kaolinitic mineralogy – this was not the case for less weathered soils such as Alisols, Cambisols and Plinthosols for which interactions between Al species, soil pH and litter quality seem to be much more important. SOC fractionation studies further showed that, although for more strongly weathered soils the majority of SOC is located within the aggregate fraction, for the less weathered soils most of the SOC is located within the silt and clay fractions. It thus seems that for highly weathered soils SOC storage is mostly influenced by surface area variations arising from clay content, with physical protection inside aggregates rendering an additional level of protection against decomposition. On the other hand, most of SOC in less weathered soils is associated with the precipitation of aluminium-carbon complexes within the fine soil fraction and with this mechanism enhanced by the presence of high levels of aromatic, carboxyl-rich organic matter compounds. Also examined as part of this study were a relatively small number of arenic soils (viz. Arenosols and Podzols) for which there was a small but significant influence of clay and silt content variations on SOM storage and with fractionation studies showing that particulate organic matter may accounting for up to 0.60 of arenic soil SOC. In contrast to what were in all cases strong influences of soil and/or litter quality properties, after accounting for these effects neither wood productivity, above ground biomass nor precipitation/temperature variations were found to exert any significant influence on SOC stocks at all. These results have important implications for our understanding of how Amazon forest soils are likely to respond to ongoing and future climate changes.

International audience; Spatial Variation in the Molecular Composition of Dissolved OrganicMatter from the Podzol Soils of a Temperate Pine ForestEmmanuelle Maria,†Pierre Crançon,‡Gaëtane Lespes,†and Maxime C. Bridoux*,‡†Universitéde Pau et des Pays de l’Adour (UPPA)/CNRS, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement,UMR IPREM 5254, Technopôle Hélioparc, Av. du Président Angot, 64000 PAU, France‡CEA, DAM, DIF, F-91297 Arpajon, France*SSupporting InformationABSTRACT:In podzols, the production and mobilization ofdissolved organic matter (DOM) account for a considerableloss of carbon from the forestfloor. The dynamics of DOM inthe podzol soils of a pine forest result from complexinteractions between water infiltrations, weathering, biologicaltransformation, and retention-mobilization mechanisms. How-ever, little is known about how the molecular composition ofDOM changes spatially in the podzol soil as it moves from theupper horizons (organic (O) and eluvial (E)) to the illuvialhorizon (B(h/s)) to the groundwater. In this study, DOMsamples were collected in the upper (A1) and accumulation(Bh) horizons of a sandy permeable podzol with a hydrologyoccurring exclusively through drainage of shallow water (no surface runoff), as well as from the groundwater. Samples wereconcentrated on a Strata-X-AW solid-phase extraction cartridge and directly infused using electrospray ionization in the negativemode coupled with an LTQ-Orbitrap mass spectrometer. Over 2300 monoisotopic molecular formulas of CHO and CHONwith molecular weights up to 600 Da, assigned mainly to lignin-like compounds (53%), tannins (22%), condensed aromatics(14%), protein-like compounds, lipids (3%), aminosugars/carbohydrates (1%), and unsaturated hydrocarbons, were identifiedin DOM from the upper podzol horizon (A1), indicating that leaching of plant debris dominates the DOM pool released in thesoil seepage waters. Among all molecular formulas detected, 31% were unique to A1, while only 6.9% were only detected in Bhand 12.9% in Gw. Van Krevelen diagrams of these unique formulas clearly highlighted an evolution of the OM molecularcomposition along the podzol soil profile, from the upper horizon, through the accumulation horizon, to the groundwater with ashift from the high-oxygen, plant-derived compounds (tannins-like and lignin-like) to the low-oxygen classes (unsaturated andcondensed hydrocarbon), suggesting a reduction process either microbially mediated or via preferential adsorption of oxygen-functionalized DOM compounds to mineral surfaces

This article presents a stationary field test on light clay loam conducted to study the influence of organic and mineral fertilizers and their combinations on the fertility and productivity of this soil. The efficiency of using organic (PMC of 80 t/ha) and mineral (NPK) fertilizers in combination is shown for a sixfield crop rotation. The average crop yield of potato, annual grass, and perennial grass for two crop rotation phases was 3.9, 4.4, and 6.6 t/ha of dry matter, respectively. The fertilizers, especially organic-mineral ones, contributed to the increase in starch content in potato to 13–13.6% (11.6% in the reference sample) as well as the increase in crude protein content in annual and perennial grass to 14.4 and 15.2%, respectively (10.3 and 11.6% in the control sample). It has been noted that organic and organic-mineral fertilizer systems produce a positive effect on the organic matter content in soil.

Relationships between soil C and N stocks and soil formation, climate, and vegetation were investigated in a gridded database connected to the National Forest Inventory in Norway. For mineral soil orders, C and N stocks were estimated to be 11.1–19.3 kg C·m−2 and 0.41–0.78 kg N·m−2, respectively, declining in the following order: Gleysols > Podzols > Brunisols > Regosols. Organic peat-type soils stored, on average, 31.3 kg C·m−2 and 1.10 kg N·m−2, whereas shallow Organic folisols stored, on average, 10.2 kg C·m−2 and 0.34 kg N·m−2. For Norway’s 120 000 km2 of forest, the total of soil C stocks was estimated to be 1.83 Gt C, with a 95% CI of 1.71–1.95 Gt C. Podzolic soils comprise the largest soil group and store approximately 50% of the forest soil C. Sixty percent of the soil C stock in Podzolic soils was stored in the mineral soil, increasing with temperature and precipitation. Poorly drained soil types store approximately 47% of the total forest soil C in Norway. Soils with water saturation have large C stocks mainly in the forest floor, suggesting that they are more susceptible to forest management and environmental change. Soil C stocks under pine and spruce forests were similar, although pine forests had larger C stocks in the forest floor, while spruce forests had the highest C stocks in the mineral soil compartment. C stocks in the forest floor increase from dry to moist ground vegetation, while ground vegetation nutrient classes reflect better the C and N stocks in the mineral soil.

Understanding the effects of elevation and related factors (climate, vegetation) on the physical and chemical soil properties can help to predict changes in response to future climate or afforestation forcings. This work aims to contribute to the knowledge of soil evolution and the classification of forest soils in relation to elevation in the montane stage, with special attention to podzolization and humus forms. The northern flank of the Moncayo Massif (Iberian Range, SW Europe) provides a unique opportunity to study a forest soils catena within a consistent quartzitic parent material over a relatively steep elevation gradient. With increasing elevation, pH, base saturation, exchangeable potassium, and fine silt-sized particles decrease significantly, while organic matter, the C/N ratio, soil aggregate stability, water repellency and coarse sand-sized particles increase significantly. The soil profiles shared a set of properties in all horizons: loamy-skeletal particle-size, extreme acidity (pH-H2O

Irregular wetting, water repellency, and preferential flow are well-documented properties of coastal sandy podzols, though little is known about the effect of fire on unsaturated zone processes in this environment. This study investigates water repellency at and below the soil surface in two coastal sandy podzols following bushfire. Water drop penetration time tests were applied to burned and unburned soils at a high dune field site in South East Queensland, Australia. It was found that the mean water drop penetration time of the burned soil was four times that of the unburned soil, but both soils were largely non-repellent. Post-fire repellency peaked below the surface in a patchy layer, in contrast to the laterally extensive layer reported in other studies, and high organic matter content in the soil did not appear to significantly influence repellency post-burn. Non-parametric statistics were used to quantify the high spatial variability in water repellency, which was ultimately insufficiently captured by atypically large (n = 1000 drop) datasets. This study confirms the presence of naturally occurring repellency and patchy infiltration in sandy soils while demonstrating that conclusively describing the influence of fire is challenging in a soil with heterogeneous infiltration characteristics. With respect to this uncertainty, it appears that fire does not increase soil water repellency such that infiltration and runoff processes due to fire-induced water repellency would differ post-burn.

The specificity of cultural layer transformation by soil forming processes was examined in humid (Moscow region) and arid (Kalmykia) zones of Russia. The objects studied in the two regions are the Dunino and Ar-Dolong settlements. The former is attributed to the Early Iron Age and the latter to the Bronze Age. Archaeological excavations in both places revealed numerous ancient artifacts occurring in situ which prove the sites having been inhabited in the past. Though located in different natural zones, the investigated objects have two features in common: sandy parent material and the leading role of the anthropogenic factor in the past. Morphological examination was supplemented with analysis of chemical properties (organic and inorganic matter, total phosphorus, pH). At the arid site, humic acids extracted from the organic matter in the ancient cultural layer have been dated by radiocarbon. Simultaneously, the background soils were also studied. Though both ancient settlements were abandoned for a long time, the cultural layers have not been buried under later sediments. They stayed exposed and subjected to transformations by soil-forming processes. The duration of the latter was different at the two sites, not exceeding 2 ky in the humid zone and about 3.0–3.5 ky in the arid zone. After people had left the settlements, younger soils developed in the course of pedogenesis, their morphology being similar to the zonal soils. Integrated analyses of soils enable determination of how far the natural processes have gone in the cultural layer transformation. The determination of the total phosphorous provides a means for cultural layer diagnosis with confidence, long after the settlement had been abandoned. It is possible to determine the trends for human-made soil development in different climate zones, from Arenosol to Podzol and Arenosol to Andosol in humid and arid zones respectively. In the course of time, the cultural layers of ancient settlements are being transformed into zonal soils, no matter the geographical location of the region. However, the rate of transformation, both of individual soil features and of the entire soil profiles is variable. Transformation rate of ancient non-buried cultural layers is higher in the humid environment than in the arid environment.

Information on structural composition of organic matter (OM) in particle-size fractions of soils along a climo-biosequence is sparse. The objective of this study was to examine structural composition and morphological characteristics of OM in particle-size fractions of soils along a climo-biosequence in order to better understand the factors and processes affecting structural composition of soil organic matter. To explore changes in structural composition of OM in soils with different pedogenesis, the A-horizon was considered for further analyses including particle-size fractionation, solid-state13C nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Due to the increase in the thickness of organic layer with increasing elevation, the A-horizon was situated at greater depth in soils of higher elevation. The relationship between relative abundances of carbon (C) structures and particle-size fractions was examined using principal component analysis (PCA). It was found that alkyl C (20.1-73.4%) and O-alkyl C (16.8-67.7%) dominated particle-size fractions. The proportion of alkyl C increased with increasing elevation, while O-alkyl C showed an opposite trend. Results of PCA confirmed this finding and showed the relative enrichment of alkyl C in soils of higher elevation. Increase in the proportion of alkyl C in 250-2000 μm fraction is linked to selective preservation of aliphatic compounds derived from root litter. SEM results showed an increase in root contribution to the 250-2000 μm fraction with increasing elevation. For the

Data on the input of plant falloff and organic matter decomposition on the surface of the peaty podzolic-gleyic humus-illuvial (Gleyic Podzol) soil under a mature blueberry pine forest in the middle taiga are presented. The fractional composition of the falloff was determined, and constants of decomposition for its components were calculated. The carbon flux to the atmosphere due to the mineralization of plant residues is estimated at 251 g/m2. A close positive correlation (r = 0.71; P < 0.05) was found between the carbon dioxide emission measured using a gas analyzer and the soil temperature at the depth of 10 cm. The CO2 emission for a growing period calculated from the data on its dependence on soil temperature in different years varied from 243 to 313 g C/m2 and was related to weather conditions.