| 1. |
- Saccone, L, et al.
(författare)
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Assessing the extraction and quantification of amorphous silica in soils of forest and grassland ecosystems
- 2007
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Ingår i: European Journal of Soil Science. - : Wiley. - 1365-2389 .- 1351-0754. ; 58, s. 1446-1459
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this study was to evaluate different methodologies with regard to their ability to extract the amorphous silica (ASi) content of soils from diverse geochemical settings. The methods used in this work included three acid extraction techniques (oxalate, citrate and acetate) and two alkaline extraction techniques (sodium carbonate and sodium hydroxide) which are more commonly used for the measurement of ASi in aquatic sediments. Our results indicate that the amount of Si extracted from phytolith samples with the acid methods was an order of magnitude lower than the amount of Si extracted using alkaline extractions. When applied to natural soil samples, these extractions show that the acid techniques are only able to extract loosely bound components such as adsorbed Si and Si bound in amorphous matrices with Al and Fe. While sodium carbonate or sodium hydroxide extracted the same amount of ASi in Podzols, sodium carbonate was able to extract only part of the ASi extracted with sodium hydroxide in Chernozems. Pre-treatment of the samples with hydrochloric acid before the sodium carbonate extraction did not increase amounts of ASi extracted. The present work suggests that alkaline methods used commonly for ASi on aquatic sediment samples can be used on a wide variety of soils, even if in some cases a stronger base is required to completely dissolve ASi from certain soil types where older and less reactive ASi fractions are present.
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| 2. |
- Fernandez-Calvino, David, et al.
(författare)
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Assessing the effects of Cu and pH on microorganisms in highly acidic vineyard soils
- 2012
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Ingår i: European Journal of Soil Science. - : Wiley. - 1365-2389 .- 1351-0754. ; 63:5, s. 571-578
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Tidskriftsartikel (refereegranskat)abstract
- Because of the use of agricultural land for wine production and the frequent use of copper (Cu)-based fungicides, Cu concentration has been increasing in soils in many parts of the world. In vineyards with acid parent materials, low soil pH may also encourage Cu toxicity, but it is common to use lime in order to increase the soil pH and improve crop yields. Thus, vineyard soils may have large variations in pH, which will affect the microbial communities, making it difficult to isolate possible toxic effects of Cu on soil microbes. Here, analyses of phospholipid fatty acid (PLFA) patterns and pollution-induced community tolerance (PICT, using leucine incorporation) were used to study the effect of Cu accumulation at small to medium concentrations in acid soils (pH 4.05.8) in vineyards with different land-use history (young, old and abandoned vineyards). The results suggested that soil pH played a dominant role in determining the composition of the microbial community of the soils. Only a small effect of soil Cu could be detected and the effect on microbial community composition was much less than the pH effect. PICT analysis suggested that bacterial communities in old vineyards were more tolerant of Cu than those in the abandoned vineyards. However, increased PICT (Cu tolerance of the bacterial community) was not directly correlated with Cu concentration in the soils. Instead, the estimated Cu tolerance was significantly correlated with soil pH.
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| 3. |
- Persson, Magnus, et al.
(författare)
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A profiling TDR probe for water content and electrical conductivity measurements of soils
- 2010
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Ingår i: European Journal of Soil Science. - : Wiley. - 1365-2389 .- 1351-0754. ; 61:6, s. 1106-1112
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of water content profiles are of great interest in hydrology and soil science. Time domain reflectometry (TDR) is a well-established method for water content measurements; however, most TDR probe designs are suitable for measurements in only a small soil volume. In this article, a 1-m long TDR profiling probe with five measurement sections is described. Unlike most other previous profiling probes, our probe allows for both dielectric permittivity (e) and electrical conductivity (sa) measurements. The accuracy of the e and sa measurements was excellent; the precision of the measurements was, however, significantly poorer than with a 0.20-m long standard three rod TDR probe. The new probe was installed in a field and successfully measured water content profiles during the growing season of 2009. During an infiltration experiment it was shown that because of its geometry, the profiling probe over-estimated the wetting-front velocity. At a 0.10-m depth, the over-estimation was almost 30%. The over-estimate will be less significant at greater depths.
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| 4. |
- Baken, S., et al.
(författare)
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Ageing of vanadium in soils and consequences for bioavailability
- 2012
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Ingår i: European Journal of Soil Science. - : Elsevier. - 1351-0754 .- 1365-2389. ; 63:6, s. 839-847
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Tidskriftsartikel (refereegranskat)abstract
- Total vanadium (V) concentrations in soils commonly range from 20 to 120 mg kg-1. Vanadium added directly to soils is more soluble than geogenic V and can be phytotoxic at doses within this range of background concentrations. However, it is unknown how slow sorption reactions change the fate and effect of added V in soils. This study addresses the changes in V solubility, toxicity and bioavailability in soils over time. Four soils were amended with pentavalent V in the form of a soluble vanadate salt, and extractable V concentrations were monitored over 100 days. The toxicity to barley and tomato plants was evaluated in freshly spiked soils and in the corresponding aged soils that were equilibrated for up to 330 days after spiking. The V concentrations in 0.01 m CaCl2 soil extracts decreased approximately two-fold between 14 and 100 days after soil spiking, and the reaction kinetics were similar for all soils. The phytotoxicity of added V decreased on average two-fold between freshly spiked and aged soils. The reduced toxicity was associated with a corresponding decrease in V concentrations in the isolated soil solutions and in the shoots. The V speciation in the soil solution of the aged soils was dominated by V(V); less than 8% was present as V(IV). Oxalate extractions suggest that the V(V) added to soils is predominantly sorbed onto poorly crystalline oxyhydroxides. It is concluded that the toxicity of V measured in freshly spiked soils may not be representative of soils subject to a long-term V contamination in the field.
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| 5. |
- Boye, Kristin, et al.
(författare)
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Quantification of chemical sulphur species in bulk soil and organic sulphur fractions by S K-edge XANES spectroscopy
- 2011
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 62, s. 874–881-
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Tidskriftsartikel (refereegranskat)abstract
- A new data treatment method for fitting spectra obtained by sulphur (S) K-edge X-ray absorption near-edge structure (XANES) spectroscopy was used to quantify the chemical S speciation at three experimental sites with arable soils receiving the same long-term field treatments. Two treatments, crop residue (CR) incorporation and farmyard manure (FYM) application, with equal applications of mineral nutrients were included in the study. In the new data treatment method, internally calibrated spectra of dilute solutions (30 mm) of model compounds were used to fit the sample spectra. This greatly enhanced the reliability of quantitative determination of contributing S species in soil samples and soil extracts. The results indicated that long-term FYM application shifted S species composition from highly oxidized towards intermediate oxidization in two of the soils, but in the third soil the opposite trend was observed. Sulphur XANES spectroscopy of acetylacetone extracts of physically protected and unprotected organic S in two of the soils revealed that physical protection was not related to S speciation; however, intermediate forms of oxidized S species appeared to accumulate in the residual S pool (not extractable by acetylacetone)
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| 6. |
- Börjesson, Gunnar
(författare)
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Strong pH influence on N2O and CH4 fluxes from forested organic soils
- 2009
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 60, s. 311-320
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Tidskriftsartikel (refereegranskat)abstract
- Greenhouse gas (GHG) emissions from farmed organic soils can have a major impact on national emission budgets. This investigation was conducted to evaluate whether afforestation of such soils could mitigate this problem. Over the period 1994-1997, emissions of methane (CH4) and nitrous oxide (N2O) were recorded from an organic soil site in Sweden, forested with silver birch (Betula pendula Roth), using static field chambers. The site was used for grazing prior to forestation. Soil pH and soil carbon content varied greatly across the site. The soil pH ranged from 3.6 to 5.9 and soil carbon from 34 to 42%.The mean annual N2O emission was 19.4 (+/- 6.7) kg N2O-N ha(-1) and was strongly correlated with soil pH (r = -0.93, P < 0.01) and soil carbon content (r = 0.97, P < 0.001). The N2O emissions showed large spatial and temporal variability with greatest emissions during the summer periods. The site was a sink for CH4 (i.e. -0.8 (+/- 0.5) kg CH4 ha(-1) year(-1)) and the flux correlated well with the C/N ratio (r = 0.93, P < 0.01), N2O emission (r = 0.92, P < 0.01), soil pH (r = -0.95, P < 0.01) and soil carbon (r = 0.97, P < 0.001). CH4 flux followed a seasonal pattern, with uptake dominating during the summer, and emission during winter.This study indicates that, because of the large N2O emissions, afforestation may not mitigate the GHG emissions from fertile peat soils with acidic pH, although it can reduce the net GHG because of greater CO2 assimilation by the trees compared with agricultural crops.
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| 7. |
- Delin, Sofia
(författare)
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Imaging-optode measurements of ammonium distribution in soil after different manure amendments
- 2011
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 62, s. 295-304
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Tidskriftsartikel (refereegranskat)abstract
- The choice of manure application technique can affect both the spatial distribution of ammonium in soil and net nitrogen (N) mineralization, and thereby N availability to crops. In this study we compared net N mineralization and spatial ammonium distribution after different degrees of incorporation of solid chicken manure and cattle slurry into soil. Ammonium-specific fluorescing optodes were assembled with manure applied to soil in closed chambers and the spatial distribution of ammonium in different treatments was measured for 2 weeks. The results indicated that much ammonium from the manures was quickly adsorbed to clay particles. Consequently, the ammonium concentration in the soil solution was threefold higher in the sandy soil than in the clay soil studied. Ammonium was distributed over a larger soil volume from manure applied below the soil surface than from manure applied above. Because the optodes excluded ammonium adsorbed to soil particles, net N mineralization was instead studied in separate incubations using extraction with potassium chloride solution for determination of ammonium and nitrate. When manure was kept concentrated in lumps rather than being mixed with soil, nitrate levels were about five times smaller after 1 week and 5-10% more of the manure N occurred as mineral N after 2 weeks. There were no differences in net N mineralization between surface application and subsurface incorporation. In this study a new technique to visualize and measure ammonium patterns around manure in soil proved to be useful for evaluating ammonium distribution and adsorption, but net N mineralization required incubations.
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| 8. |
- Dijkstra, F. A., et al.
(författare)
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The effect of organic acids on base cation leaching from forest floor under six north American tree species
- 2001
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 52:2, s. 205-214
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Gustafsson, Jon Petter, et al.
(författare)
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Aluminium solubility mechanisms in moderately acid Bs horizons of podzolized soils
- 2001
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 52:4, s. 655-665
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Tidskriftsartikel (refereegranskat)abstract
- 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 eon 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.
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| 10. |
- Gustafsson, Jon Petter, et al.
(författare)
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Cation binding in a mor layer : batch experiments and modelling
- 2003
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 54:2, s. 295-310
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of cation binding in the mor layer is important to correctly assess the biogeochemical cycling of metals and other cations in forested ecosystems. In a series of batch experiments, the binding of cations was examined in two mor layers from central Sweden. We examined the effect of Ca and Al on the binding of Zn, and also the binding of added Pb, Cu and Cd. Two models, WinHumicV and the Stockholm Humic Model (SHM), were tested for their ability to describe the data obtained. We found that for Zn, the pH at 50% sorption was increased from 2.8 to 4.2 after the addition of 3 mM Al. The proton titration data were well described by both WinHumicV and SHM after optimization of the concentrations of 'active' Al and humic substances. Applying generic parameters for cation binding produced deviations between the model simulations and the observations, particularly for the dissolved Pb and Cu concentrations, which were underestimated. A revised set of cation complexation constants was presented that improved the fit, particularly for SHM. For WinHumicV, there were still poor overall fits. The difference in model performance may be due to the greater number of adjustable parameters in the SHM, but probably also to other model-specific differences. According to the SHM simulations, the binding of Ca, Mg and Mn was mainly non-specific, whereas Pb, Cu and Al were bound as mono- or bidentate complexes. For Zn and Cd, binding occurred through both counter-ion accumulation and monodentate complexation.
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