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  • 1
    Electronic Resource
    Electronic Resource
    Ammonium fluoride extraction for determining inorganic sulphur in acid forest soils (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 51 (2000), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Current methods for determining inorganic sulphur (S) in aerated mineral soil horizons often result in underestimates. To overcome this defect we developed a new method combining a batch extraction with 0.5 m NH4F solution at a soil:solution ratio of 1:5 with a subsequent analysis of the mobilized SO42– by ion chromatography. The ammonium fluoride extraction enables us to characterize inorganic sulphate in non-calcareous forest soils. It is more efficient than conventional procedures in which inorganic S is extracted with phosphate or bicarbonate solution. In contrast to the extraction with strongly alkaline reagents (NaOH, KOH, LiOH), the NH4+–NH3 buffer system in NH4F prevents the pH of the suspension from exceeding 9.0 and thus the undesired conversion of organic S into SO42– by auto-oxidation and hydrolysis of ester sulphate. In a comparison we demonstrated that the inorganic S in six German forest soils is underestimated by up to 50% or 200 kg S ha−1 in the uppermost 60 cm, if it is assessed by extraction with 0.016 m KH2PO4 or 0.5 m NaHCO3 instead of 0.5 m NH4F. Conversely, the pool of ester sulphate is overestimated almost threefold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.2000.00299.x
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  • 2
    Electronic Resource
    Electronic Resource
    Speciation of sulphur in soils and soil particles by X-ray spectromicroscopy (2003)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 54 (2003), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Current wet chemical methods for the speciation of sulphur (S) in soils are inaccurate and do not allow one to assess the S speciation of individual soil particles and colloids. X-ray microscopy and Near Edge X-ray Absorption Fine structure Spectroscopy (NEXAFS) can be used to study individual species of S at the K-adsorption edge. We have used these techniques to identify and quantify S species in bulk soil, soil particles and colloids from Oh and Bh horizons of two forested Podzols. The partitioning of soil sulphur as determined on bulk samples of the Oh horizons by X-ray spectromicroscopy agreed fairly well with the results of a conventional S speciation for the soil at Schluchsee, and reasonably well for that at Rotherdbach. The NEXAFS analyses on individual soil particles revealed that they are richer in reduced organic sulphur than the bulk soil for the Schluchsee Oh and richer in sulphate for Rotherdbach Oh. The techniques can be used reliably to separate and quantify sulphur species with different oxidation states in the soil. The combination of X-ray transmission and sulphur fluorescence images with unfocused and focused NEXAFS spectra at the K-adsorption edge of sulphur at specific microsites allowed us to compare the distribution of S species in bulk soil with that of distinct soil particles and soil colloids. Moreover, we can use it to assess the spatial distribution of different S species on soil particles on a scale of a few hundred nanometres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.2003.00543.x
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  • 3
    Electronic Resource
    Electronic Resource
    Extractability and dissolution kinetics of pure and soil-added synthesized aluminium hydroxy sulphate minerals (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 49 (1998), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Various extractants used in current analytical procedures for the fractionation of sulphur (S) in soils were compared with respect to their ability to dissolve Al hydroxy sulphate minerals of defined composition (basaluminite, K alunite, mixtures of basaluminite and Na alunite). The minerals were synthesized and aged in the laboratory at 20°C and 50°C. The dissolution kinetics at 20°C of these Al hydroxy sulphates in deionized water, 0.02M HCl and 0.02M NaOH were also investigated.The dissolution stability of the Al hydroxy sulphate minerals increased in the order basaluminite 〈 K alunite 〈 Na alunite. The dissolving power of the reagents used increased in the order H2O ≤ 0.016M KH2PO4≪ 0.02M HCl ≈ acidic NH4 oxalate ≈ 0.5M NaHCO3 〈 Na2 CO3/NaHCO3 〈 0.1M NH4F 〈 0.5M NH4F 〈 0.05M NaOH ≤ 0.05M LiOH. In Al hydroxy sulphate-containing soils, inorganic S is probably understimated and ester sulphate S overestimated, if the inorganic S pool is assessed by extraction with KH2PO4, Ca(H2PO4)2 or NaHCO3 solutions. The dissolution of all studied Al hydroxy sulphates, particularly that of K and Na alunite, in H2O and 0.02 M HCl is strongly delayed by kinetic restraints. Thus it seems unlikely that Al3+ or SO2−4 activites in soil solutions are strictly regulated by precipitation/dissolution equilibria of these minerals except for horizons with extraordinarily slow seepage water movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1998.4940669.x
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamics of aqueous aluminum species in a podzol affected by experimental MgSO4 and (NH4)2SO4 treatments (1992)
    Springer
    Water, air & soil pollution 65 (1992), S. 153-173 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Chemistry of aqueous Al in a podzol on a Norway spruce (Picea abies [L.] Karst.) site in the Black Forest (SW Germany) and changes induced by experimental applications of MgSO4 were studied. Soil solution taken from the O, E and BC horizons were analyzed for the fractions ‘labile monomeric Al’, ‘non-labile monomeric Al’, and ‘acid-reactive Al’. The activities of ‘inorganic monomeric Al’ species and the saturation indices (SI) of the soil solution with respect to Al-bearing minerals were calculated using the equilibrium speciation model WATEQF. On the untreated plot, soil leachates are characterized by Altot concentrations of 0.1 mg L−1 (mineral soil). In the O horizon, the fractions ‘acidsoluble Al’ and ‘non-labile monomeric Al’ (mainly organically complexed Al) together comprise 80% of Altot. In the leachates from the mineral soil Al3+ prevails, being 50% of Altot. Al-F-complexes make up 5 to 10% in all horizons. MgSO4 and (NH4)2SO4 treatments resulted in an intense Al mobilization up to 50 mg L−1. In this situation, 60% of Altot is covered by Al3+ and 40% by non-phytotoxic Al-SO4-complexes. After rainfall events, mobilized Al is quickly translocated into the subsoil, with water flow through macropores then appearing to be an important mechanism. In both treatments, soil solution chemistry was favorable for the precipitation of the Al(OH)SO4-type minerals alunite and jurbanite. However, a control of Al solubility by this process is not likely due to kinetic restraints. Application of MgSO4 was followed by an increase of the Mg/Al molar ratio in the soil solution, whereas the Ca/Al ratio decreased. After treatment with (NH4)2SO4 both the Ca/Al and the Mg/Al ratios deteriorated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00482756
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  • 5
    Electronic Resource
    Electronic Resource
    Transformation of simulated wet sulfate deposition in forest soils assessed by a core experiment using stable sulfur isotopes (1995)
    Springer
    Water, air & soil pollution 79 (1995), S. 243-260 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effects of elevated atmospheric SO 4 2− deposition on S cycling in forest soils were assessed in an irrigation experiment using stable S isotopes. Over a period of 20 months, core lysimeters of five acidic forest soils from Southern Germany with different parent material and pedogenesis were irrigated with solutions chemically similar to canopy throughfall. Sulfate deposition in three experimental variants corresponded to 23, 42 and 87 kg S ha−1 yr−1. The SO 4 2− used for irrigation had aδ 34S ratio of +28.0‰ CDT (Canon Diablo Troilite standard), differing by more than +25‰ from natural and anthropogenic S in Southern Germany. A combination of chemical and isotopic analyses of soil and seepage water samples was used to elucidate the fluxes and transformations of simulated wet SO 4 2− deposition in each soil core. Retention of experimentally deposited S ranged from 57±5% in coarse-grained soils low in sesquioxides and clay, to 80±8% in loamy soils with high sesquioxide content. The sesquioxide content proved to be the major factor governing S retention. The ratio of S retained as inorganic SO 4 2− (mainly by adsorption) to that incorporated into organic compounds (presumably by microbial synthesis) ranged from 2 to 4. For the organic S pool, the amount of S retained as C-bonded S exceeded by far that immobilized as ester sulfate in four of the five soils. Application of34S-enriched SO 4 2− appears to be a suitable experimental tool to assess fluxes and transformations of deposited S in forest soils, if aerobic conditions are maintained. In contrast to radioactive S tracers, the concept should be applicable not only in laboratory and lysimeter experiments, but also in long term studies of whole forest ecosystems (e.g., experimental watersheds).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01100440
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