Search

Very different soil types occur across a few tens of meters on dolostone, in a never glaciated karst landscape in the Lombard Pre-Alps (Selvino, Italy). This substrate is locally enriched in well-crystallized sand-grained quartz. The quartz content is responsible for the localized genesis of Podzols. Other soil types observed in the area include strongly rubified (Terra Rossa) horizons (paleosols), preserved in the most protected dolostone cracks. Non-rubified Luvisols and Cambisols were observed in karst dry valleys and dolines while Rendzic Leptosols/Phaeozems were common on the steepest slopes. Such a variety of soils was explained assuming different parent materials (dolostone, silica-rich dolostone, with different amounts of aeolian inputs, ascertained using textural properties, mineralogy, micromorphology, total element composition, mass balance calculations, rare earth elements, and stable elements. Many soils were highly polycyclic, with different layers associated to different parent materials and characterized by different pedogenic processes evidencing different ages. We were thus able to distinguish the horizons mainly developed from the dissolution of the dolostone from those formed in Pleistocene loess. The geochemistry of all surface soil horizons, including Podzols and Rendzic Leptosols/Phaeozems, apparently formed from pure or quartz-rich dolostone dissolution, has been influenced by recent aeolian additions (likely Saharan dust), with deeply modified effects according to different pedogenetic processes acting locally. Saharan dust, in fact, significantly increased metal and rare earth elements contents compared to the substrate, also in the youngest and least weathered soil types.

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory req

The boreal forest biome serves as a valuable resource, both as a source of wood, pulp and biofuel, and as a sink of atmospheric carbon (C). A large proportion of C is sequestered to the soil of the boreal biome, however belowground processes are still poorly understood. Biogeochemical processes occurring in the soil are influenced by fungal communities and activity. Different processes and microbial communities exist throughout the soil profile due to differences in physico-chemical and biological properties. Boreal forest soils are commonly podzolized, with stratified layers of organic and mineral soil referred to as horizons. With intensifying forest harvesting practices, it is important to build our knowledge of fungal community function in each horizon and establish predictions of the effects intensified forest harvesting may have on these communities. The main objectives of this microcosm-based study were to characterise the fungal communities present in each horizon and investigate how these are affected by different degrees of organic matter depletion, simulating a gradient of intensity in forest harvesting. We used a microcosm experiment with Pinus sylvestris seedlings and reconstructed soil profiles containing decreasing amounts of organic material to simulate increasing intensification of forestry. Fungal communities were characterised by high throughput DNA sequencing and statistical analysis. The 20 most abundant fungi accounted for over 80% of the DNA sequences, and there were statistically distinct communities in the O, E and B horizons. Piloderma sphaerosporum was the most abundant species in the O horizon and Suillus bovinus the most abundant in both the mineral horizons. Fungal species richness was significantly higher in the E horizon layers with an overlying O horizon compared to systems where the O horizon was removed completely (simulating extreme loss of organic matter due to intensive biomass harvesting). Fungal species richness was not otherw

In the upper part of the solum of mineral soils, soil organic and mineral constituents co-evolve through pedogenesis, that in turn impacts the transformation and stabilization of soil organic matter (SOM). Here, we assess the reciprocal interactions between soil minerals, SOM and the broad composition of microbial populations in a 530-year chronosequence of podzolic soils. Five pedons, derived from beach sand, are studied. From young to old soils, net acidification parallels mineral dissolution and the formation of eluvial and illuvial horizons. Organo-mineral associations (OMA) accumulate in the illuvial B horizon of the older soils (330–530 years). Apart from contributing to SOM stabilization and protection, organo-mineral compounds progressively fill up interparticle voids. The subsequent loss of porosity leads to horizon induration, decrease of hydraulic conductivity, which promote redoximorphic processes. While recalcitrant SOM is preserved in the topsoil of the old soils, the largest quantity of protected SOM occurs in the indurated, temporalily waterlogged B horizons, through both the OMA accumulation and inhibition of microbial decomposition. SOM protection is thus both time- and horizon-specific. The microbiota also evolve along the chronosequence. Fungi dominate in all horizons of the younger soils and in the topsoil of the older soils, while bacteria prevail in the cemented B horizons of older soils. This shift in microbial community composition is due to the interdependent co-evolution of SOM and minerals during pedogenesis. Our results call for considering the microenvironment and parameters inherent to decomposer microorganisms to understand SOM protection processes in soils.

In the upper part of the solum of mineral soils, soil organic and mineral constituents co-evolve through pedogenesis, that in turn impacts the transformation and stabilization of soil organic matter (SOM). Here, we assess the reciprocal interactions between soil minerals, SOM and the broad composition of microbial populations in a 530-year chronosequence of podzolic soils. Five pedons, derived from beach sand, are studied. From young to old soils, net acidification parallels mineral dissolution and the formation of eluvial and illuvial horizons. Organo-mineral associations (OMA) accumulate in the illuvial B horizon of the older soils (330-530 years). Apart from contributing to SOM stabilization and protection, organo-mineral compounds progressively fill up interparticle voids. The subsequent loss of porosity leads to horizon induration, decrease of hydraulic conductivity, which promote redoximorphic processes. While recalcitrant SOM is preserved in the topsoil of the old soils, the largest quantity of protected SOM occurs in the indurated, temporalily waterlogged B horizons, through both the OMA accumulation and inhibition of microbial decomposition. SOM protection is thus both time- and horizon-specific. The microbiota also evolve along the chronosequence. Fungi dominate in all horizons of the younger soils and in the topsoil of the older soils, while bacteria prevail in the cemented B horizons of older soils. This shift in microbial community composition is due to the interdependent co-evolution of SOM and minerals during pedogenesis. Our results call for considering the microenvironment and parameters inherent to decomposer microorganisms to understand SOM protection processes in soils., SCOPUS: ar.j, info:eu-repo/semantics/published

Soil microorganisms living in close contact with minerals play key roles in the biogeochemical cycling of elements, soil formation, and plant nutrition. Yet, the composition of microbial communities inhabiting the mineralosphere (i.e., the soil surrounding minerals) is poorly understood. Here, we explored the composition of soil microbial communities associated with different types of minerals in various soil horizons. To this effect, a field experiment was set up in which mineral specimens of apatite, biotite, and oligoclase were buried in the organic, eluvial, and upper illuvial horizons of a podzol soil. After an incubation period of two years, the soil attached to the mineral surfaces was collected, and microbial communities were analyzed by means of Illumina MiSeq sequencing of the 16S (prokaryotic) and 18S (eukaryotic) ribosomal RNA genes. We found that both composition and diversity of bacterial, archaeal, and fungal communities varied across the different mineral surfaces, and that mineral type had a greater influence on structuring microbial assemblages than soil horizon. Thus, our findings emphasize the importance of mineral surfaces as ecological niches in soils., QC 20170609

Soil microorganisms living in close contact with minerals play key roles in the biogeochemical cycling of elements, soil formation, and plant nutrition. Yet, the composition of microbial communities inhabiting the mineralosphere (i.e., the soil surrounding minerals) is poorly understood. Here, we explored the composition of soil microbial communities associated with different types of minerals in various soil horizons. To this effect, a field experiment was set up in which mineral specimens of apatite, biotite, and oligoclase were buried in the organic, eluvial, and upper illuvial horizons of a podzol soil. After an incubation period of two years, the soil attached to the mineral surfaces was collected, and microbial communities were analyzed by means of Illumina MiSeq sequencing of the 16S (prokaryotic) and 18S (eukaryotic) ribosomal RNA genes. We found that both composition and diversity of bacterial, archaeal, and fungal communities varied across the different mineral surfaces, and that mineral type had a greater influence on structuring microbial assemblages than soil horizon. Thus, our findings emphasize the importance of mineral surfaces as ecological niches in soils.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

The interplay between geology and biology has shaped the Earth during billions of years. Microbe-mineral interactions are prime examples of this interplay and underscore the importance of microorganisms in making Earth a suitable environment for all forms of life. The present thesis takes an interdisciplinary approach to obtain an integrated understanding of microbe-mineral interactions. More specifically it addresses how the composition and distribution of biogenic weathering agents (siderophores) differ with regard to soil horizon and mineral type in situ, what siderophore type soil microorganisms produces under laboratory conditions, what role microbial surface attachment plays in mineral weathering reactions and what central roles and applications siderophores have in the environment. Podzol, the third most abundant soil in Europe, and most abundant in Scandinavia, was chosen for a field experiment, where three minerals (apatite, biotite and oligoclase) were inserted in the organic, eluvial and upper illuvial soil horizons. The study started with an investigation of the siderophore composition in the bulk soil profile and on the mineral surfaces (paper I), which was followed by a study of the siderophore producing capabilities of microorganisms isolated from the soil profile under laboratory conditions (paper II). Subsequently, a study was done on the impact of microbial surface attachment on biotite dissolution (paper III). Finally, the roles of siderophores in nature and their potential applications were reviewed (paper IV). The major findings were that the concentration of hydroxamate siderophores in the soil attached to the mineral surfaces was greater than those in the surrounding bulk soil, indicating that the minerals stimulate the microbial communities attached to their surfaces to produce more siderophores than the microorganisms in the bulk soil. Each mineral had a unique assemblage of hydroxamate siderophores, that makes the mineral type one of the ma, At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: In press.

Binnen Noord-Holland neemt het Gooi in aardkundig opzicht een bijzondere positie in. Het is de enige grotere opduiking van Pleistocene afzettingen en daarbij ook nog eens uitermate gevarieerd en, voor een aardkundig monument, groot. Vanwege deze grootte wordt in dit artikel stilgestaan bij de aardkundige en historische ontstaanswijze van meerdere excursiepunten.

Soil solution samples were taken from two sites (Horröd and Hasslöv) in the south part of Sweden to evaluate how soil solution chemistry responded to different treatmentswith dolomite and wood ash. At Horröd, samples were taken four years after application of wood ash, 4.28 ton ha-1 and dolomite, 3.25 ton ha-1. At Hasslöv dolomite, 3.45 ton ha-1 and 8.75 ton ha-1 was applied and samples were taken 15 yr later. It was found that treatment with dolomite at one site (Hasslöv) resulted in higher pH values (<2 pH units) and higher nitrification. It was also found at this site that the total Al and the inorganic Al concentrations decreased with dolomite treatment. The Ca, Mg, DOC, Fe, SO4 2- and Cl- concentrations, mainly in the topsoil, were found to be higher at both sites, following dolomite treatment; Ca and Mg concentrations were 2–8 times higher (<820 mgrM) than in controls (<70 mgrM). Wood ash was found to have less impact. The PO4 concentration in the O2 horizon at Hasslöv decreased due to dolomite-treatment. ANOVA (Analyse of Variance) and PLS (Partial Least Square) were used to evaluate the data from the two sites.

Organic acids have been hypothesised to play a central role in long-term soil pedogenic processes such as podzolisation and also in short-term rhizosphere processes such as nutrient mobilisation. Their spatial and temporal patterns in soil, however, are poorly understood. This study was designed to quantify the rate of microbial decomposition of three low molecular weight organic acids (citrate, oxalate and acetate) as a function of soil depth (O, A, E, B and C horizons) in three podzolic coniferous forest soils and to assess their contribution to total soil CO2 fluxes. Soil solution extraction indicated that generally, most organic acids were present in the highest concentration in surface O horizons (10-100 muM) declining with soil depth. Correspondingly, the rate of organic acid mineralisation was also greatest in the surface organic horizons. In contrast, the mineral horizons possessed low rates of biodegradation which appeared not to be due to a lack of microbial activity but moreover due to strong sorption to the solid phase preventing microbial uptake. Concentration-dependent mineralisation experiments indicated that decomposition could be adequately described by a single Michaelis-Menten kinetics equation. The results showed that generally most horizon samples had the greatest mineralisation capacity for citrate or oxalate (V-max =< 1-340 nmol g(-1) h(-1)) in comparison to acetate. The V-max values typically declined with soil depth. Km values ranged from 10 to 7000 muM, however, if adsorption was accounted for the Km values decreased (< 1-5000 muM) especially in B horizons. Calculations of the contribution of organic acids to total soil respiration indicated that between <0.1 and 47% of total CO2 production from an individual horizon could be accounted for by organic acid mineralisation alone. The findings are discussed in the context of soil forming and rhizosphere processes.

The aim of this study has been to clarify how the radiumdistribution in soils affects the radon emanation. Thedistribution of radium, uranium and thorium has been determinedusing sequential extractions. In the study, soils from twodifferent locations were investigated. In the first part the applicability of the sequentialextraction method for determining Ra distribution in differentsoil types was investigated, using a simple sequentialextraction method. Sampled soils were clay, sand and till fromthe vicinity of the Stockholm Esker. The main part of Rnemanating Ra was associated with Fe oxides in the soil. Themethods applied provided information about the radon risk ofthe soil, but, inorder to gain more information on theprocesses governing Ra distribution and radon emanation insoils, a more detailed sequential extraction procedure would bedesirable. The second part consisted of a detailed study of theradionuclide distribution and the geochemistry in a podzolisedglacial till from Kloten in northern Västmanland. A moredetailed sequential extraction procedure was used, and thespecific surface area of samples was measured. Samples weretaken from E, B, and C horizons; radium and thorium wereenriched in the B horizon, whereas uranium had its maximumconcentration in the C horizon. Extractable radium primarilyoccurred in the exchangeable pool, possibly organicallycomplexed, whereas extractable uranium and thorium were mainlyFe oxide bound. Oxide-bound Ra was important only in the Bhorizon. The radon emanation was not correlated with the amountof exchangeable Ra, but instead with the oxide bound Ra.However, the amount of oxide-bound Ra was too small to accountfor all the emanated Rn, thus, exchangeable Ra was interpretedas the main source of emanated Rn. This exchangeable Ra wasmore emanative in the B horizon than in the C horizon. Theexplanation is the larger surface area of the B horizonsamples; the specific surface area appears to be the maingoverning parameter for Rn ema, NR 20140805

The aim of this study has been to clarify how the radiumdistribution in soils affects the radon emanation. Thedistribution of radium, uranium and thorium has been determinedusing sequential extractions. In the study, soils from twodifferent locations were investigated. In the first part the applicability of the sequentialextraction method for determining Ra distribution in differentsoil types was investigated, using a simple sequentialextraction method. Sampled soils were clay, sand and till fromthe vicinity of the Stockholm Esker. The main part of Rnemanating Ra was associated with Fe oxides in the soil. Themethods applied provided information about the radon risk ofthe soil, but, inorder to gain more information on theprocesses governing Ra distribution and radon emanation insoils, a more detailed sequential extraction procedure would bedesirable. The second part consisted of a detailed study of theradionuclide distribution and the geochemistry in a podzolisedglacial till from Kloten in northern Västmanland. A moredetailed sequential extraction procedure was used, and thespecific surface area of samples was measured. Samples weretaken from E, B, and C horizons; radium and thorium wereenriched in the B horizon, whereas uranium had its maximumconcentration in the C horizon. Extractable radium primarilyoccurred in the exchangeable pool, possibly organicallycomplexed, whereas extractable uranium and thorium were mainlyFe oxide bound. Oxide-bound Ra was important only in the Bhorizon. The radon emanation was not correlated with the amountof exchangeable Ra, but instead with the oxide bound Ra.However, the amount of oxide-bound Ra was too small to accountfor all the emanated Rn, thus, exchangeable Ra was interpretedas the main source of emanated Rn. This exchangeable Ra wasmore emanative in the B horizon than in the C horizon. Theexplanation is the larger surface area of the B horizonsamples; the specific surface area appears to be the maingoverning parameter for Rn ema, NR 20140805

The aim of this study has been to clarify how the radiumdistribution in soils affects the radon emanation. Thedistribution of radium, uranium and thorium has been determinedusing sequential extractions. In the study, soils from twodifferent locations were investigated. In the first part the applicability of the sequentialextraction method for determining Ra distribution in differentsoil types was investigated, using a simple sequentialextraction method. Sampled soils were clay, sand and till fromthe vicinity of the Stockholm Esker. The main part of Rnemanating Ra was associated with Fe oxides in the soil. Themethods applied provided information about the radon risk ofthe soil, but, inorder to gain more information on theprocesses governing Ra distribution and radon emanation insoils, a more detailed sequential extraction procedure would bedesirable. The second part consisted of a detailed study of theradionuclide distribution and the geochemistry in a podzolisedglacial till from Kloten in northern Västmanland. A moredetailed sequential extraction procedure was used, and thespecific surface area of samples was measured. Samples weretaken from E, B, and C horizons; radium and thorium wereenriched in the B horizon, whereas uranium had its maximumconcentration in the C horizon. Extractable radium primarilyoccurred in the exchangeable pool, possibly organicallycomplexed, whereas extractable uranium and thorium were mainlyFe oxide bound. Oxide-bound Ra was important only in the Bhorizon. The radon emanation was not correlated with the amountof exchangeable Ra, but instead with the oxide bound Ra.However, the amount of oxide-bound Ra was too small to accountfor all the emanated Rn, thus, exchangeable Ra was interpretedas the main source of emanated Rn. This exchangeable Ra wasmore emanative in the B horizon than in the C horizon. Theexplanation is the larger surface area of the B horizonsamples; the specific surface area appears to be the maingoverning parameter for Rn ema, NR 20140805

The aim of this study has been to clarify how the radiumdistribution in soils affects the radon emanation. Thedistribution of radium, uranium and thorium has been determinedusing sequential extractions. In the study, soils from twodifferent locations were investigated. In the first part the applicability of the sequentialextraction method for determining Ra distribution in differentsoil types was investigated, using a simple sequentialextraction method. Sampled soils were clay, sand and till fromthe vicinity of the Stockholm Esker. The main part of Rnemanating Ra was associated with Fe oxides in the soil. Themethods applied provided information about the radon risk ofthe soil, but, inorder to gain more information on theprocesses governing Ra distribution and radon emanation insoils, a more detailed sequential extraction procedure would bedesirable. The second part consisted of a detailed study of theradionuclide distribution and the geochemistry in a podzolisedglacial till from Kloten in northern Västmanland. A moredetailed sequential extraction procedure was used, and thespecific surface area of samples was measured. Samples weretaken from E, B, and C horizons; radium and thorium wereenriched in the B horizon, whereas uranium had its maximumconcentration in the C horizon. Extractable radium primarilyoccurred in the exchangeable pool, possibly organicallycomplexed, whereas extractable uranium and thorium were mainlyFe oxide bound. Oxide-bound Ra was important only in the Bhorizon. The radon emanation was not correlated with the amountof exchangeable Ra, but instead with the oxide bound Ra.However, the amount of oxide-bound Ra was too small to accountfor all the emanated Rn, thus, exchangeable Ra was interpretedas the main source of emanated Rn. This exchangeable Ra wasmore emanative in the B horizon than in the C horizon. Theexplanation is the larger surface area of the B horizonsamples; the specific surface area appears to be the maingoverning parameter for Rn ema, NR 20140805

Geochemical, mineralogical, micromorphological, microbiological, hydrochemical and hpdrological joint investigations were performed at two coniferous podzolic sites in the north of Sweden and at one in the south of Finland. Mycorrhizal fungi were found to create numerous pens (3-10-mu m diameter) in many weatherable mineral grains in the eluvial (E) horizon. During the growing season, identified low molecular weight (LMW) organic acids such as citric, shikimic, oxalic and fumaric acids comprised 0.5-5% of the DOC and 0.5-15% of the total acidity in soil solutions. Between 20% and 40% of the dissolved Al was bound to the identified LMW organic acids. Mineral dissolution via complexing LMW acids, probably exuded in part by the mycorrhiza hyphae, is likely to be a major weathering process in podzols. We found no evidence for a decreasing C/metal ratio of the migrating organo-metal complexes that could explain the precipitation of secondary Fe and AL in the illuvial (B) horizon. Instead, microbial degradation of organic ligands resulting in the release of ionic,Al and Fe to the soil solution may he an important process facilitating the formation of solid Al-SI-OH and Fe-OH phases in the podzol B horizon. However, within the B horizon transport as proto-imogilite (PI) sols might be possible. In the B horizon, the extractable,Al and Fe was predominantly inorganic. The large specific surface area (SSA) removable by oxalate extraction, the high point of zero charge salt effect (PZSE), the low cation exchange capacity (CEC) and the high sulphate exchange capacity (SEC), painted to the presence of short-range ordered variable charge phases. Imogolite type material (ITM) was indeed identified in all B horizons by IR spectroscopy and crystalline imogolite was found in the deep B horizon of one profile. Mossbauer spectroscopy indicated that Fe in the form of ferrihydrite was formed by intergrowth with an Al-Si-OH phase. The high amounts of Fe and Al transported from the O to the, QC 20100525

Weathering and supply of nutrients derived from minerals to plants is known to be stimulated by plant symbiotic mycorrhizal fungi. Nutrients are generally thought to pass the bulk soil solution before plant uptake. Jongmans et al. [Jongmans, A.G., van Breemen, N., Lundstrom, U.S., van Hees, P.A.W., Finlay, R.D., Srinivasan M., Unestam, T., Giesler, R., Melkerud, P.-A., Olsson, M., 1997. Rock-eating fungi. Nature, 389, 682-683] showed that (ectomycorrhizal) fungi drill innumerable narrow cylindrical pores (diameter 3-10 μm) into weatherable minerals in podzol E horizons. The fungi probably form micropores by exuding strongly complexing low-molecular weight organic acids at their hyphal tips, causing highly local dissolution of Al silicates. Micropores occurred in all thin sections of podzols under Pinus sylvestris and Picea abies available from Sweden (3), Finland (2), Switzerland (2), Denmark (2) and the Netherlands (3), but not in the few available thin sections of non-podzolic soils under broadleaves. Many weatherable minerals in the podzol E horizon appeared to be perforated, as opposed to few if any in the abruptly underlying B horizon, suggesting a link to podzolization. High concentrations of Al and Si in organic surface horizons under boreal and temperate conifers can be explained by transfer by hypha of weathering products from the minerals to mycorrhizal roots in the O horizon, followed by release of weathering products that are not taken up by the plants. Rock-eating ectomycorrhizal fungi suggest a more direct role for plants in podzolization than hitherto realized, providing tight coupling between podzolization and mineral weathering. Preliminary observations, however, indicate that mycorrhizal fungi do not play a role in podzolization under Kauri (Agathis australis) in New Zealand. (C) 2000 Elsevier Science B.V.

The mobilization of Al, Fe and Si in podzols is often associated with the weathering of silicate minerals in the E horizon, downward migration, and their accumulation lower in the soil profile. This study investigated Al, Fe, and Si concentrations in soil water (centrifugation samples) and estimated leaching losses from the humus layer in comparison with those in the mineral E and B horizon. Concentrations of total soluble Al and Fe in soil water were higher in the O and E horizons than in B horizon samples, but not significantly different between the two uppermost horizons. Si concentrations were higher in the E than in the O horizon. The amount of Al and Fe leaching from the E horizon (i.e. input to the B horizon) compared to amount leaching from the O horizon (i.e. the input to the E horizon) ranged from 92% to 163%. Calculated leaching losses from the lower B horizon were less than 3% of the input to the B horizon. The results suggest that a large part of the illuviated Al and Fe in the Bs horizon is derived from the O horizon. Similar values for the Si ranged from 56% to 61% (comparing E horizon output with E horizon input). Budget estimates available for one of the investigated podzols indicated that biocycling via above-ground litter explained < 12% of the estimated annual input of Al and Fe to the forest floor. Inputs of Al and Fe due to upward flow of capillary water accounted for about 26% of the Al and Fe in the O layer. The results show that there is a considerable pool of Si Al, Fe in the humus layer. This pool plays an important part in the present day biogeochemical cycling of these elements in podzolic soils. Several mechanisms possibly involved in the transfer of Al, Fe and Si from the mineral soil to the humus layer are discussed.

The chemical structure of soil organic matter from the eluvial (Aeh) and (illuvial) Bh horizon of a Podzol was studied in primary organo-mineral associations by 13C CPMAS NMR spectroscopy and acid hydrolysis. In Podzols, organic matter is leached from the forest floor and Aeh horizons into the Bh horizon, where it is intimately associated with the mineral phase. In the Aeh horizon the majority of the residual organic matter was present in methylene structures, contributing 42% to the organic matter associated with the clay fraction. In the Aeh horizon decreasing particle size was typically accompanied by increasing ratios alkyl C-to-O–alkyl C, suggesting increasing decomposition of polysaccharides for the residual organic matter. The illuvial Bh horizon, containing high proportions of iron- and aluminum-oxides and hydroxides, was higher in aromatic carbon, while polysaccharides were similar and methylene carbon were smaller than in the Aeh horizon. In the particle size separates proportions of polysaccharides were constant, resulting in decreasing ratios alkyl C/O–alkyl C. Proportions of hydrolyzable amino acids were larger in the Aeh horizon (52% of the total N) than in the Bh horizon (21%), both for bulk soils and size separates. Our results suggested that in Bh horizons of Podzols, aromatic structures and also presumably labile structures like polysaccharides can be stabilized by organo-mineral associations.

The distribution of carbon and nitrogen in four podzol profiles and four humus podzol profiles developed on a chronosequence of sand dunes and spanning a time interval in excess of 105 years is discussed in detail. Both total carbon and nitrogen decline rapidly with increasing depth through the A horizons, increasing again at the top of the B horizon but once more decreasing with increased depth. Some of the more highly developed profiles contain large "pipes" of A 2 material penetrating the B horizon. The trend in the carbon to nitrogen ratios in these profiles are uncharacteristic of podzols in general, and show an increase with increasing depth through the B horizon. This behaviour is explained by the low nitrogen content of the fulvic acid fractions of these profiles. Investigations into the nature of the organic matter in both the A and B horizons of the profiles using separation techniques for fulvic acid and humic acids along with ultraviolet, visible, infrared and 13c-nuclear magnetic resonance spectroscopic techniques are also described in detail. These techniques demonstrate that the organic matter in the A horizons is largely particulate in nature but is more humified and thereby more readily extracted from the B horizons. The organic matter in the B horizons increases in pH, fulvic acid, carboxylic acid and polymethylene content with increasing depth. The colloidal stability of the organic matter in the presence of aluminium and iron also increases. The humic acid content, dromaticity, average molecular weight, the degree of disorder in the aliphatic materials as well as the heterocyclic ring content decrease with depth through the B horizon. The fulvic acid materials appear very similar in structure to polymaleic acid or to a polymeric hydroxy acid. A mechanism governing the formation of these podzols based on the chemical and physical behaviour of the organic matter in the presence of colloidal aluminium and iron is also proposed. This mechanism adequa

The weathering and formation of minerals in Podzols and the hypotheses on the mechanism of podzolization are discussed in accord with the composition of active fraction (colloids and soil solution) and physico-chemical parameters (pe-pH) of horizons of Ortic Podzols from Galicia (NW Spain). Two different geochemical environments are established in Ortic Podzols. The first one, that includes surface horizons (A and E), is characterized by the predominance of dissolution of primary minerals through a mechanism of "acid-complexolysis” and by the nearly total absence of mineral formation. Under these conditions, only kaolinite can be stable, being promoted by high temperatures and a lowering in the activity of organic matter. lmogolite, halloysite and gibbsite are always unstable. In the second environment, represented by the spodic horizons (Bh and Bs), the conditions are controlled by weaker acids than above (CO2, hydroxy-AI ions .... ), the weathering mechanisms range from hydrolysis to moderately acid hydrolysis and the geochemical processes are defined as “aluminosiallitization” or “monosiallltization”. Kaolinite is always a stable mineral, and metastable phases like imogolite, gibbsite and sometimes halloysite can be precipitated from soil solution or formed as the mineralization of organic ligands proceeds. The mechanism of podzolization supported by experimental data is the migration of organo-metallic complexes, and there are not evidences that justify the presence of protoimogolite in surface horizons. lmogolite or protoimogolite must not be considered as typical phases of surface horizons during podzolization, but as characteristic components of environments with moderate acidity and low organic matter activity. This kind of conditions occurs in spodic horizons of Ortic Podzols and in surface (A) and weathering (B) horizons of acid soils without albic horizons.

peer-reviewed, Inventories of forest soil carbon (C) stocks are necessary to determine spatial and temporal C stock changes and support climate change mitigation policy development. Afforested podzols and peaty podzols were sampled to measure their soil organic carbon (SOC) concentration and bulk density (BD), with the aim of improving baseline soil organic carbon density (SOCD) estimates for Irish forests. Podzols are not always distinguished from peaty podzols and both qualify as mineral soil types. The estimated SOCD for the podzol sites ranged from 129–139 Mg C ha−1, while the peaty podzols had 229–385 Mg C ha−1. The major disparity in their SOCD implies the need to disaggregate podzols and peaty podzols in conducting soil C inventories, with the need for development of C emission factors for peaty podzols to reduce uncertainty in SOCD estimates. Soil bulk density (BD) is a principal component in estimating the stock of any soil nutrient or other substances, such as organic carbon. There are several well-known methods of estimating soil BD such as coring, clod, and pit excavation, with variants of each method covered in the literature. In many older soil surveys, for reasons related to cost or the time and resources available to complete the work, the soil BD was not measured, often due to a high volume of rock fragments (RFs) in the soil. This study used the core and pit excavation methods to sample short rotation forestry (SRF) soils and determine their SOC concentration, BD, and RF content, and used those to estimate the SOCD to a depth of 40 cm. Novel methods of sampling and calculating BD for soils with high RF content were also devised, with results that compared more favourably to the pit excavation results than provided by the core method. Using SRF biomass for bioenergy has the potential to contribute to the Irelands increasing commitments under the EU Renewable Energy Directive to use more renewable energy and reduce greenhouse gas (GHG) emissions by 2020 and beyond.

peer-reviewed, Inventories of forest soil carbon (C) stocks are necessary to determine spatial and temporal C stock changes and support climate change mitigation policy development. Afforested podzols and peaty podzols were sampled to measure their soil organic carbon (SOC) concentration and bulk density (BD), with the aim of improving baseline soil organic carbon density (SOCD) estimates for Irish forests. Podzols are not always distinguished from peaty podzols and both qualify as mineral soil types. The estimated SOCD for the podzol sites ranged from 129–139 Mg C ha−1, while the peaty podzols had 229–385 Mg C ha−1. The major disparity in their SOCD implies the need to disaggregate podzols and peaty podzols in conducting soil C inventories, with the need for development of C emission factors for peaty podzols to reduce uncertainty in SOCD estimates. Soil bulk density (BD) is a principal component in estimating the stock of any soil nutrient or other substances, such as organic carbon. There are several well-known methods of estimating soil BD such as coring, clod, and pit excavation, with variants of each method covered in the literature. In many older soil surveys, for reasons related to cost or the time and resources available to complete the work, the soil BD was not measured, often due to a high volume of rock fragments (RFs) in the soil. This study used the core and pit excavation methods to sample short rotation forestry (SRF) soils and determine their SOC concentration, BD, and RF content, and used those to estimate the SOCD to a depth of 40 cm. Novel methods of sampling and calculating BD for soils with high RF content were also devised, with results that compared more favourably to the pit excavation results than provided by the core method. Using SRF biomass for bioenergy has the potential to contribute to the Irelands increasing commitments under the EU Renewable Energy Directive to use more renewable energy and reduce greenhouse gas (GHG) emissions by 2020 and beyond.

peer-reviewed, Inventories of forest soil carbon (C) stocks are necessary to determine spatial and temporal C stock changes and support climate change mitigation policy development. Afforested podzols and peaty podzols were sampled to measure their soil organic carbon (SOC) concentration and bulk density (BD), with the aim of improving baseline soil organic carbon density (SOCD) estimates for Irish forests. Podzols are not always distinguished from peaty podzols and both qualify as mineral soil types. The estimated SOCD for the podzol sites ranged from 129–139 Mg C ha−1, while the peaty podzols had 229–385 Mg C ha−1. The major disparity in their SOCD implies the need to disaggregate podzols and peaty podzols in conducting soil C inventories, with the need for development of C emission factors for peaty podzols to reduce uncertainty in SOCD estimates. Soil bulk density (BD) is a principal component in estimating the stock of any soil nutrient or other substances, such as organic carbon. There are several well-known methods of estimating soil BD such as coring, clod, and pit excavation, with variants of each method covered in the literature. In many older soil surveys, for reasons related to cost or the time and resources available to complete the work, the soil BD was not measured, often due to a high volume of rock fragments (RFs) in the soil. This study used the core and pit excavation methods to sample short rotation forestry (SRF) soils and determine their SOC concentration, BD, and RF content, and used those to estimate the SOCD to a depth of 40 cm. Novel methods of sampling and calculating BD for soils with high RF content were also devised, with results that compared more favourably to the pit excavation results than provided by the core method. Using SRF biomass for bioenergy has the potential to contribute to the Irelands increasing commitments under the EU Renewable Energy Directive to use more renewable energy and reduce greenhouse gas (GHG) emissions by 2020 and beyond.

submitted to: European Journal of Forest Research(ISSN 1612-4669)