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1

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Retention and release of dissolved organic matter in Podzol B horizons (2001)

Zysset, M. ; Berggren, D.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 52 (2001), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The main objectives were to study the effects of pH on the retention and release of organic matter in acid soil, and to determine the main differences in results obtained from batch experiments and experiments in columns. We took soil material from the B horizons of a Podzol at Skånes Värsjö (southern Sweden). In batch experiments, soil was equilibrated with solutions varying in pH and concentration of dissolved organic C. In Bh samples, the release of dissolved C gradually increased with increase in pH. In the Bs1 material there was a minimum at pH 4.1, and in the Bs2 soil the minimum occurred at pH 4.6. The ability to retain added dissolved C increased in the order Bh 〈 Bs1 〈 Bs2.The column experiment was run for 160 days under unsaturated flow conditions. Columns were packed with Bh, Bh + Bs1 or Bh + Bs1 + Bs2 samples to calculate mass balances for each horizon. Solutions either without any dissolved organic C or ones containing 49 mg C dm−3 with pH of 4.0 or 3.6 were used to leach columns. The pH of input solutions only little affected the concentration of dissolved C in the effluent. Relative proportions of hydrophobic substances decreased with increasing column length and decreasing pH. For input solutions containing dissolved C, near steady state was achieved for both the Bs1 and Bs2 horizons with approximately 25% dissolved organic matter retention. Thus, no maximum sorption capacity for dissolved C could be defined for these horizons. This behaviour could not have been predicted by batch data, showing that column experiments provide useful additional information on interactions between organic compounds and solid soil material.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00399.x

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2

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Content and bioavailability of organic forms of nitrogen in the O horizon of a podzol (1999)

Johnsson, L. ; Berggren, D. ; Kårén, O.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 50 (1999), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: It is often thought that the most important source of nitrogen for plants and microorganisms comes from amino acids and amino sugars when they are hydrolysed in acid conditions. We did a microcosm experiment to test the hypothesis. In the experiment spruce seedlings (Picea abies L. Karst) were grown for 145 days in soil taken from a podzol Oa horizon under a long-term nitrogen fertilization experiment (control and N-treated soil). Net changes in different pools of organic N were determined using standard fractionation (acid hydrolysis and pyrophosphate extraction). During the experiment the amino acid and amino sugar pools decreased significantly (14% and 15% for the control and 10% and 17% for the N treatment), whereas no significant change was observed in the non-amino acid plus non-amino sugar fraction. On a per organic C basis there was even a significant increase in the non-amino acid plus non-amino sugar fraction of 11% for the control and 8% for the N treatment. Pyrophosphate extractions suggest that amino acids or amino sugars associated with the humin fraction were more accessible to microbes and plants than those associated with the humic acid, fulvic acid and hydrophilic substances. The long-term N fertilization (about 73 kg N ha−1 was added annually as NH4NO3 during a 24-year period) resulted in an enrichment of all major fractions of organic N, i.e. amino acids, amino sugars and non-amino acids plus non-amino sugars. This enrichment was largely the result of small increases in all of the amino acids rather than large increases in just a few.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00256.x

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3

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Aluminium solubility mechanisms in moderately acid Bs horizons of podzolized soils (2001)

Gustafsson, J. P. ; Berggren, D. ; Simonsson, M. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 52 (2001), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The processes controlling the retention and release of aluminium in acid forest soils are still subject to controversy, and therefore a universal hypothesis as to what mechanisms are operating has not been firmly established. By studying the Bs horizons of Swedish and Swiss podzolized soils, and by analysing data in the literature, we have found that aluminium hydroxide, and in some cases also poorly ordered imogolite, may control Al solubility in moderately acid (pH 〉 4.2–4.3) Bs horizons. The strongest evidence in support of the presence of a quickly reacting Al(OH)3 pool came from the temperature dependence of Al solubility in a Bs horizon, which was consistent with the reaction enthalpy of an Al(OH)3 phase such as gibbsite, and from the observation that the ion activity product for Al(OH)3 was the same regardless of whether equilibrium was reached from over- or undersaturation. The pool of Al(OH)3 is commonly small and may be completely dissolved after large additions of acid. This may be explained by the continuing redissolution of reactive Al(OH)3 to form less soluble imogolite-type phases. By using the same methods it was found that soil suspensions did not reach equilibrium with poorly ordered imogolite even after 17 days. Thus, imogolite probably does not control Al solubility in the short term in many soils despite the common occurrence of this mineral. This is due to the relatively slow kinetics of imogolite formation and dissolution, especially at low temperatures and at small solution H4SiO4 concentrations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00400.x

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4

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Modelling the solid–solution distributions of protons, aluminium, base cations and humic substances in acid soils (1995)

TIPPING, E. ; BERGGREN, D. ; MULDER, J. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

European journal of soil science 46 (1995), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: wham, an equilibrium chemical model for soils, waters and sediments, centred on a discrete-site/ electrostatic model of humic substances (HS), has been used to analysae batch titration data for organic and mineral horizons of acid soils. In most cases, tolerable fits were obtained by optimizing the soil contents of HS and aluminium, while keeping the model parameters (site densities, equilibrium constants, electrostatic terms) fixed. The optimized contents agreed reasonably with those estimated by chemical extraction. For some mineral soil samples, low in HS and high in aluminium, fitting of the titration data was improved by assuming the formation and dissolution of A1(OH)3 and adjusting its solubility product. Solid-solution distributions of base cations (Na+, Mg2+, K+, Ca2+, NH+4) could be explained by non-specific counterion accumulation, with a small degree of selectivity. The WHAM sub-model for fulvic acid sorption accounted approximately for observed aqueous-phase concentrations of organic carbon and organically-complexed aluminium.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2389.1995.tb01814.x

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5

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Solubility of Aluminum and Silica in Spodic Horizons as Affected by Drying and Freezing (1999)

Simonsson, M. ; Berggren, D. ; Gustafsson, J.P.

Springer

Soil Science Society of America journal 63 (1999), S. 1116-1122

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ISSN: 1435-0661

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: 3+ changed only slightly, implying a higher Al solubility in all of the soils. Furthermore, dissolved silica increased by up to 200% after drying, except in a soil that almost completely lacked oxalate-extractable Si. We suggest that drying enhanced the dissolution of ITM by disrupting soil organic matter, thus exposing formerly coated mineral surfaces. In the soil where dissolved Si did not change with drying, it had been demonstrated that Al–humus complexes controlled Al solubility. We suggest that fissures in the organic material caused by drying may have exposed formerly occluded binding sites that had a higher Al saturation than had sites at the surface of humus particles.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/

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6

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Magnetic and Mössbauer effect study of laves phases of U x Fe100−x (x=32, 33.3 and 35) (1989)

Vaishnava, P. P. ; Dwight, A. E. ; Berggren, D. ; [et al.]

Springer

Hyperfine interactions 51 (1989), S. 949-954

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ISSN: 1572-9540

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract 57Fe Mössbauer effect measurements have been made on U x Fe100−x (x=32, 33.3, and 35) samples at 300 and 78 K. Laves phase structure was maintained for all three samples. Mössbauer spectra of the three samples were found to be a symmetric quadrupole doublet at 300 K. Such spectra were converted into a set of two overlapping six lines pattern at 78 K. The values of the hyperfine fields have been found to vary systematically with the iron content in the samples. The Curie temperatures, as determined by the ac susceptibility measurements, have been found to increase by increasing the amount of iron in the samples.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02407807

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