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  • 1. De la Rosa, M. P.
    et al.
    Holmström, Sara J. M.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sposito, G
    Tebo, B. M.
    Bargar, J
    Systematic study of the effect of pH on the structure and reactivity of Mn oxide produced by Bacillus sp., strain SG-1: Gordon Research Conferences - Environmental Bioinorganic Chemistry 2006. Proctor Academy , Andover, NH, USA, 18-23 June, 2006 ; Poster2006Conference paper (Refereed)
  • 2.
    Dijkstra, F. A.
    et al.
    Laboratory of Soil Science and Geology, PO Box 37, 6700 AA Wageningen, PAYS-BAS.
    Geibe, Christine
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Breemen, N.
    Laboratory of Soil Science and Geology, PO Box 37, 6700 AA Wageningen, PAYS-BAS.
    The effect of organic acids on base cation leaching from forest floor under six north American tree species2001In: European Journal of Soil Science, ISSN 1351-0754, E-ISSN 1365-2389, Vol. 52, no 2, p. 205-214Article in journal (Refereed)
    Abstract [en]

    Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor samples were analysed for exchangeable cations and forest floor solutions for cations, anions, simple organic acids and acidic properties. Citric and lactic acid were the most common of the acids under all species. Malonic acid was found mainly under Tsuga canadensis (hemlock) and Fagus grandifolia (beech). The organic acids were positively correlated with dissolved organic carbon and contributed significantly to the organic acidity of the solution (up to 26%). Forest floor solutions under Tsuga canadensis contained the most dissolved C and the most weak acidity among the six tree species. Under Tsuga canadensis we also found significant amounts of strong acidity caused by deposition of sulphuric acid from the atmosphere and by strong organic acids. Base cation exchange was the most important mechanism by which acidity was neutralized. Organic acids in solution from Tsuga canadensis, Fagus grandifolia, Acer rubrum (red maple) and Quercus rubra (red oak) were hardly neutralized while much more organic acidity was neutralized for Acer saccharum (sugar maple) and Fraxinus americana (white ash). We conclude that quantity, nature and degree of neutralization of organic acids differ among the different tree species. While the potential for base cation leaching with organic acids from the forest floor is greatest under Tsuga canadensis, actual leaching with organic anions is greatest under Acer saccharum and Fraxinus americana under which the forest floor contains more exchangeable cations than does the strongly acidified forest floor under Tsuga canadensis.

  • 3. Duckworth, O W
    et al.
    Holmström, Sara J M
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Peña, J
    Sposito, G
    Biogeochemistry of iron oxidation in a circumneutral freshwater habitat2009In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 260, no 3-4, p. 149-158Article in journal (Refereed)
    Abstract [en]

    Iron(II) oxidation in natural waters at circumneutral pH, often regarded as an abiotic process, is frequently biologically mediated at iron-rich redox gradients. West Berry Creek, a small circumneutral tributary that flows through a mixed coniferous forest in Big Basin State Park, California, contains localized iron (hydr)oxide precipitates at points along its course where anoxic groundwater meets oxygenated creek water. These mixing zones establish redox gradients that may be exploited by microbes forming microbial mats that are intimately associated with iron (hydr)oxide precipitates. Water sampling revealed strong correlations between the concentrations of aqueous inorganic species, suggesting a rock-weathering source for most of these solutes. Liquid chromatography-electrospray ionization-mass spectrometry techniques detected significant concentrations of organic exudates, including low molecular mass organic acids and siderophores, indicating that active biogeochemical cycling of iron is occurring in the creek. X-ray diffraction and elemental analysis showed the precipitates to be amorphous, or possibly poorly crystalline, iron-rich minerals. Clone libraries developed from 16S rDNA sequences extracted from microbial mat communities associated with the precipitates revealed the presence of microorganisms related to the neutrophilic iron oxidizing bacteria Gallionella and Sideroxydans. Sequences from these libraries also indicated the presence of significant populations of organisms related to bacteria in the genera Aquaspirillum, Pseudomonas, Sphingomonas, and Nitrospira. These geosymbiotic systems appear to be significant not only for the biogeochemical cycling of iron in the creek, but also for the cycling of organic species, inorganic nutrients, and trace metals.

  • 4.
    Essén, Sofia
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bylund, Dan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Moberg, M
    Uppsala University.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Quantification of hydroxamate siderophores in soil solutions of podzolic soil profiles in Sweden2006In: Biometals, ISSN 0966-0844, E-ISSN 1572-8773, Vol. 19, no 3, p. 269-282Article in journal (Refereed)
    Abstract [en]

    Concentrations up to 2 and 12 nM of the hydroxamate siderophores ferrichrome and ferricrocin, respectively, were identified in soil solutions of podzolic forest soils at four sites in both northern and southern Sweden. No ferrichrysin was detected. As with the dissolved organic carbon and low molecular mass organic acids, the highest concentrations of the siderophores were found in the upper layers i.e. the mor layer, the eluvial and upper illuvial horizons. At the southern sites, the concentrations of ferrichrome and ferricrocin were both of similar magnitude and did not differ between the two sites. In contrast, soil solutions at the two northern sites contained more ferricrocin than ferrichrome; the ferricrocin concentrations were also higher at the northern sites than at the southern sites. Analyses were performed by high performance liquid chromatography with a porous graphitic carbon column on which ferrichrome, ferricrocin and ferrichrysin were separated. Detection by electrospray ionization mass spectrometry (ESI-MS) combined with on-line sample pre-concentration, by means of column-switching, enabled detection limits of 0.1-0.2 nM for ferrichrome, ferrichrysin and ferricrocin. The structural identities of the siderophores were further verified by MS/MS fragmentation. Fragmentation of ferrichrome, ferricrocin and ferrichrysin occured mainly via peptide cleavage. The most intense fragments were typified by the loss of one of the three iron(III) chelating hydroxamate residues, i.e N5-acyl-N5-hydroxy ornithine.

  • 5.
    Geibe, Christine E
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara J. M
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    van Hees, Patrick A. W
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Impact of lime and ash applications on soil solution chemistry of acidified podzolic soils.2003In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 3, no 4, p. 77-96Article in journal (Refereed)
    Abstract [en]

    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.

  • 6. Hoffland, Ellis
    et al.
    Kuyper, Thomas W
    Wallander, Håkan
    Plassard, Claude
    Gorbushina, Anna A
    Haselwandter, Kurt
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Landeweert, Renske
    Lundström, Ulla S
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Rosling, Anna
    Sen, Romin
    Smits, Mark M
    van Hees, Patrick A W.
    Man-Technology-Environment Research Centre, Dept of Natural Sciences, Örebro University, Örebro, Sweden .
    Nico van Breemen, Nico
    The role of fungi in weathering2004In: Frontiers in Ecology and Environment, ISSN 1540-9295, Vol. 2, no 5, p. 258-264Article in journal (Refereed)
    Abstract [en]

    No rock at the Earth’s surface escapes weathering. This process is the primary source of all the essential elements for organisms, except nitrogen and carbon. Since the onset of terrestrial life, weathering has been accelerated under the influence of biota. The study of biological weathering started at the end of the 19th century. Although the role of bacteria (Eubacteria, Archaea) has attracted a lot of interest, until recently the role of fungi has largely been neglected. More recently, however, fungal weathering has become an increasingly important focus of biogeochemical research.

  • 7.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Siderophore promoted dissolution of goethite: Effects of Mn substitution2006In: The 232nd ACS National Meeting San Francisco, CA, USA, September 10-14, 2006, 2006Conference paper (Refereed)
  • 8.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Structure and reactivity of bacteriogenic Mn oxides exposed at different pH2006In: The 232nd ACS National Meeting San Francisco, CA, USA, September 10-14, 2006, 2006Conference paper (Refereed)
  • 9.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Systematic study of the effect of pH on the structure and reactivity of Mn oxide produced by Bacillus sp., strain SG-12006In: XAFS13, Stanford University, Stanford, CA, USA. July 9-14, 2006, 2006Conference paper (Refereed)
  • 10.
    Holmström, Sara J M
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Organic acids and siderophores in forest soil solution2003Doctoral thesis, comprehensive summary (Other academic)
  • 11.
    Holmström, Sara J M
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla S
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Hees, Patrick A. W.
    Finlay, Roger D
    Siderophores in soil solution and their production by an ectomycorrhizal fungus.2001In: Proceedings. 8th Nordic IHSS Symposium on humic substances - characterisation, dynamics, transport and effects. 28-30 May 2001, Fredriksberg, Denmark, International Humic Substances Society, Nordic Chapter , 2001Conference paper (Other academic)
  • 12.
    Holmström, Sara J M
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Van Hees, Patrik A. W.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Finlay, Roger D
    Siderophores in soil solution and production by an ectomycorrhizal fungus.2002In: Proceedings. First European Workshop on Mineral Weathering by Fungi. Wageningen, The Netherlands, 17-19 October 2002, 2002Conference paper (Other academic)
  • 13.
    Holmström, Sara J M
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Rosling, A
    Finlay, R D
    van Hees, P A W
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Contribution of ectomycorrhizal fungi to biogeochemical processes during iron and calcium limitation: Meeting abstract2009In: GEOCHIMICA ET COSMOCHIMICA ACTA, Pergamon Press, 2009, p. A546-A546Conference paper (Refereed)
  • 14.
    Holmström, Sara J. M.
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sposito, G
    Siderophore promoted dissolution of a series of Mn-substituted goethites: AGU (American Geological Union) 2005 Fall Meeting San Francisco, USA, 5-9 December 2005; Oral presentation2005Conference paper (Refereed)
  • 15.
    Holmström, Sara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Finlay, Roger
    van Hees, Patrick
    Siderophores in forest soil solution2004In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 71, no 2, p. 247-258Article in journal (Refereed)
    Abstract [en]

    Siderophores in soil solution of coniferous forest soils have been chemically identified for the first time. We have identified the siderophores ferrichrome and ferricrocin in soil solution of the upper organic layer by High Performance Liquid Chromatography Mass Spectrometry (HPLC-MS). The soil solutions were sampled from mor layers of podzolic soils from the south and the north of Sweden and from a mor layer overlying granitic rock and intensively colonised by ectomycorrhizal hyphae. Ferrichrome was found in nanomolar concentrations in all soil solutions investigated and ferricrocin only in the soil solution from the mor layer covering a rock and in the soil solution from the north of Sweden. The findings are discussed in relation to the possible role of fungal hyphae and siderophores in weathering minerals in podzolic soils under coniferous forests. Citric and oxalic acid are able to dissolve minerals via complexation of cations from the mineral. Siderophores should be, kinetically and thermodynamically even more efficient complexing agents for trivalent cations than oxalic and citric acid. The present study provides direct for presence of siderophores in soil solution.

  • 16.
    Holmström, Sara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Norrman, S.A.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Hees, P.A.W.
    Essén, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Siderophores in Soil Solution: 9th Nordic IHSS Symposium on Humic Substances - Abundance and functions of natural organic matter species in soil and water; Sundsvall 2003-05-19-2003-05-212003Conference paper (Other scientific)
    Abstract [en]

    Siderophores in soil solution of coniferous forest soils have been chemically identified. The siderophores ferrichrome and ferricrocin were identified in soil solution of the upper organic layer and also in the liquid medium of a cultivated ectomycorrhizal fungus by High Performance Luquid Chromatography Mass Spectrometry (HPLC-MS).

  • 17.
    Holmström, Sara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Riise, Gunnhild
    Tau Strand, Line
    Geibe, Christine
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Van Hees, Patrick
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Wu, Qinglan
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of lime and ash treatments on DOC fractions and low molecular weight organic acids in soil solutions of acidified podzolic soils2003In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 3, no 4, p. 97-120Article in journal (Refereed)
    Abstract [en]

    Dissolved organic carbon (DOC) fractions and different low molecular weight organic acids (LMWOAs) were determined in soil solutions from two lime or ash treated Norway spruce sites in the south of Sweden. At Hasslöv, 3.45 t ha-1 or 8.75 t ha-1 dolomite were applied 15 years before sampling. Horröd was treated with 4.28 t ha-1 ash and 3.25 t ha-1 dolomite and sampled four years later. Propionate (7–268 M) and malonate (2–34 M) were the LMWOAsfound in the highest concentrations at Hasslöv. Two other LMWOAs dominated at Horröd, namely citrate (18–64 M)and fumarate (5–31 M). The differences in concentration of most of the determined LMWOAs at Hasslöv were significantly increased due to treatment. The LMWOAs comprised between 1.1–6.3% of the DOC at Hasslöv and 4.5–17.6% at Horröd. At Hasslöv normally 3–10% of the total acidity (TA) was due to LMWOAs and the average specific buffer capacity was 74 ± 22 mmol mol-1C.The total DOC concentration in the mor layer solution was 16 mM for the dolomite treated plots compared to 10 mM at the untreated plot. A major part of the increase in DOC at the treated plots apparently had a hydrophobic character and was of high molecular weight corresponding to 3–10 kDa. The concentration of DOC < 1 kDa in the control and treated plots was similar.

  • 18.
    Holmström, Sara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Hees, Patrick
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Modelling of aluminium chemistry in soil solution of acidified and lime treated podzolic soil2004In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 127, no 3-4, p. 280-292Article in journal (Refereed)
    Abstract [en]

    Soil solutions were taken from untreated and lime treated Norway spruce sites in the south of Sweden. At the limed sites 3.45 t ha−1 (L) or 8.75 t ha−1 (H) dolomite were applied 15 years before sampling. The mean concentration of inorganic Al (AlQR) in the untreated control plots (C) was 37 μM and the concentration of AlQR decreased when the dosages of dolomite treatments increased. For the H plots, with high doses of dolomite treatment the mean concentration of AlQR was 17 μM. The total Al (Altot) also decreased by dolomite treatment, from 72 μM to 56 μM. Propionate (7–268 μM) and malonate (2–34 μM) were the low molecular weight organic acids (LMWOAs) found in the highest concentrations at Hasslöv. The differences in concentration of most of the determined LMWOAs were significantly increased due to treatment. The citrate average concentration for the different plots varied between 2.8 μM and 5.1 μM and the concentration of oxalate had concentrations between 1.7 μM and 2.6 μM. The experimental concentration of Al bound to LMWOAs obtained by ultrafiltration (<1000 Da) of the soil solution was in the mor layer on average 12% for the C plot and the L plots and 4% in the H plots. In the AE horizon the figures were 15% for the C plot and about 7% for the treated L and H plots, and in the Bhs horizon 9% for both the C, L and H plots. Two chemical equilibrium models were evaluated: Winderemere Humic Aqueous Model (WHAM) and a model treating the high molecular weight organic acids as monoprotic. The concentrations of inorganic Al, Al bound to identified LMWOAs and high molecular weights acids in soil solution (mor, AE and Bhs) from untreated and lime treated soil were calculated. The modelled inorganic Al values of the control plot were similar to the concentrations found in the soil solution (AlQR). For the dolomite treated plots the concentration of AlQR (0–40 μM) was higher in soil solution than that modelled by WHAM and the monoprotic model. The experimental concentration of Al bound to LMWOAs obtained by ultrafiltration (<1000 Da) of the soil solution was comparable but always higher than the modelled values. The modelling confirms that an appreciable part of the Al is strongly complexed with LMWOAs in the organic and eluvial horizons of the podzolized soil, suggesting that LMWOAs are efficient weathering agents and important for the formation of the eluvial horizon in podzols. Saturation indices (SI) for two solid Al phases were also calculated, including crystalline gibbsite and proto-imogolite (PI). The SIs for both the C and the treated plots (L and H) showed very broad ranges for the different horizons investigated, indicating undersaturation as well as oversaturation with respect to gibbsite and proto-imogolite.

  • 19.
    Lundström, Ulla
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Bain, DC
    Taylor, AF
    Van Hees, PA
    Geibe, Christine E
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara J
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Melkerud, PA
    Finlay, R
    Jones, DL
    Nyberg, L
    Gustafsson, JP
    Riise, G
    Tau Strand, L
    Effects of acidification and its mitigation with lime and wood ash on forest soil processes in southern Sweden: A Joint Multidisciplinary Study2003In: Water , Air and Soil Pollution: Focus, ISSN 1567-7230, Vol. 3, no 4, p. 167-188Article in journal (Refereed)
  • 20. Moberg, M
    et al.
    Nilsson, E
    Holmström, Sara J. M.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla S
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, J
    Markidies, K
    Fingerprinting siderophores by the exchange of iron by gallium and subsequent column- switched LC-ICP-MS.2003In: 16th IMSC (The International Mass Spectrometry Society);Edinburgh, Scotland, 2003-08-31 - 2003-09-05, 2003Conference paper (Other academic)
  • 21. Moberg, M.
    et al.
    Nilsson, E. M.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, J.
    Markides, K.
    Fingerprinting metal-containing biomolecules after reductive displacement of iron by gallium and subsequent column-switched LC-ICP-MS analysis applied on siderophore.2004In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 76, no 9, p. 2618-2622Article in journal (Refereed)
    Abstract [en]

    Column-switching liquid chromatography followed by lowresolution ICPMS was evaluated as a tool for speciation analysis of metal-containing biomolecules. The strategy was applied on siderophores, strong iron chelators of low molecular weight (M-w < 1500). Prior to the LC-ICPMS analysis, reductive displacement of iron by gallium was performed using ascorbate as the reducing agent to increase the sensitivity. Different experimental conditions during the exchange reaction were tested using ferrichrysin and ferrichrome for evaluation. A reaction time of 30 min and a pH of 3.9 gave an exchange yield of 27 and 83% for ferrichrysin and ferrichrome, respectively. A gradient elution profile was also developed to separate gallium-chelated siderophores on a PGC column. Detection limits for standard solutions of ferrichrysin and ferrichrome in the low-nanomolar range were obtained by monitoring the gallium-69 isotope. The combined use of LC-ICPMS and LC-ESI-MS/MS was also evaluated as a tool to identify unknown metal complexes, here siderophores, in field soil solution samples.

  • 22. Moberg, My
    et al.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Markides, Karin
    Novel approach to the determination of structurally similar hydroxamate siderophores by column-switching capillary liquid chromatography coupled to mass spectrometry2003In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1020, no 1, p. 91-97Article in journal (Refereed)
    Abstract [en]

    In this study a new approach to determine three different siderophores (ferrichrome, ferrichrysin, ferricrocin) in natural soil solutions as well as in cultures of fungi is presented. The method includes enrichment of the analytes on a short pre-column, packed with C18 material, and subsequent highly selective separation of the analytes on a capillary porous graphitic carbon (PGC) column. In contrast to normal C18 packing materials, porous graphitic carbon offers chromatographic resolution between the three very similar analytes. The selectivity of the method is enhanced even further by the electrospray ionization (ESI) mass spectrometric detection. The combination of a short pre-column and a packed capillary separation column results in a method with high sensitivity. Reported detection limits, defined as the concentration giving the signal-to-noise ratio 3:1, is 27.7 pM for ferrichrome, 46.1 pM for ferricrocin and 37.4 pM for ferrichrysin.

  • 23.
    van Hees, P. A. W.
    et al.
    Man-Technology-Research Centre, Department of Natural Sciences, Örebro University, S-701 82 Örebro, Sweden.
    Jones, D. L.
    Nyberg, L.
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Godbold, D. L.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Modelling low molecular weight organic acid dynamics in forest soils2004In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 37, no 3, p. 517-531Article in journal (Refereed)
    Abstract [en]

    Low molecular weight organic acids such as citrate and oxalate have been hypothesized to play a key role in rhizosphere ecology and pedogenesis. A mathematical site-specific model, DYNLOW, was constructed to describe the temporal and spatial dynamics of these organic acids in coniferous forest soils using the modelling software STELLA®. Experimentally derived values for biodegradation, adsorption, and daily values of soil temperature, moisture and hydrological flow were used to parameterize the model. The model describes the dynamics and downward movement of oxalate and citrate through the horizons (O, AE, E, Bhs, Bs) of three podzolic soil profiles in Sweden. After calibration, the model predicted average soil solution organic acid concentrations ranging from <1 to 90 μM, which was in agreement with experimental measurements (<1 to 116 μM). The model results indicated that microbial degradation of organic acids was in quantitative terms the biggest process regulating soil solution concentrations. Primary production rates of organic acid in the soil were predicted to be high (<1 to 1250 nmol g−1 soil d−1) in comparison to the amount present at steady state in the soil solution pool (<0.1 to 240 nmol g−1 soil). The downward transfer of organic acids between soil horizons due to mass flow was predicted to be a small flux (<0.1 to 3% of the total loss) compared to that lost by microbial biodegradation. The model predicted that the amount of basal soil respiration that could be attributable to the microbial turnover of organic acids was on average 19±22% of the basal CO2 production across all sites and horizons for citrate and 7±7% for oxalate. The model results are discussed in the context of pedogenesis, forest soil respiration and organic matter production.

  • 24. Van Hess, Patrick
    et al.
    Nyberg, Lars
    Holmström, Sara
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Lundström, Ulla
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pools and fluxes of cations, anions and DOC in limed and ash treated forest soils.2003In: Water, Air and Soil Pollution: Focus,, ISSN 1567-7230, Vol. 3, no 3, p. 145-165Article in journal (Refereed)
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    Vestin, Jenny
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Nambu, Kei
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Holmström, Sara J.M.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Hees, P.A.W.
    Jones, D.L.
    Söderberg, U.
    Lundström, Ulla S.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The impact of soil parent material on soil chemical conditions, needle composition and tree growth2003Conference paper (Other academic)
1 - 25 of 25
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