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  • 1
    Language: English
    In: Nutrient Cycling in Agroecosystems, 2012, Vol.93(1), pp.75-88
    Description: Topsoil constituents are eroded from agricultural sites and leached towards drainage channels. This transfer can affect aquatic ecosystems and deteriorate the efficiency of drainage systems and fertilisers. As long as erosion cannot be completely avoided, the recycling of sediments and associated nutrients may offer a sustainable solution to these problems. The aim of our case study at the island Sant Erasmo, lagoon of Venice (Italy) was to assess the ecological problems and potentials of sediment recycling. With our assessment we concentrated on (1) the origin of channel sediments, (2) the benefit of sediment application for increasing the nutrient stocks of the soils, and (3) the risk of heavy metal (HM) contamination of arable soils by sediment application. Samples from soils of horticultural sites, sediments, and waters from adjacent drainage channels and lagoon sediments were analyzed for the concentrations of nutrients (P and K) and HM (Cu, Pb, and Zn). Potentially available channel sediment masses and element stocks were calculated for the soil fertility classes of Sant Erasmo based on local measurements of sediment depths and analyses of aerial photographs by a geographic information system. In a column experiment, leaching of both nutrients and Cu from recently dredged sediments was analyzed. Heavy metal concentrations of soils and channel sediments were much higher than of lagoon sediments. The similarity of the chemical properties of the channel sediments and of top soil samples implies that topsoil material is eroded into the channels. The amount of sediments accumulated in the channels corresponded to soil erosion rates between 2 and 23 t ha −1  a −1 . Channel sediments contained higher concentrations of nutrients and organic carbon but slightly lower concentrations of HM than the soils of adjacent horticultural sites. Sediment P and K yields would be sufficient to replace fertiliser application at the horticultural sites for up to 51 and 35 years, respectively. The column experiment indicated that Cu mobilization induced by oxidation processes is restricted to the first years after sediments are applied to the soils. Our study emphasizes that for a comprehensive assessment of sediment recycling in agricultural systems the available sediment stocks as well as the contents of nutrients and pollutants of the sediment in relation to soils have to be considered.
    Keywords: Phosphorus ; Heavy metals ; Nutrient cycling ; Leaching experiment
    ISSN: 1385-1314
    E-ISSN: 1573-0867
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  • 2
    Language: English
    In: Soil Science Society of America journal, 2011, Vol.75(5), pp.1626-1639
    Description: Soil organic matter (OM) of aggregate coatings and biopore walls can affect the transport of reactive solutes during preferential flow in structured soil. As a nondestructive method, diffuse reflection infrared Fourier transform (DRIFT) spectroscopy, has been proposed for mapping the millimeter-scale OM composition of intact flow path surfaces. The surfaces of such intact soil structures, e.g., aggregate and biopore surfaces, mostly have a distinctive microtopography, however, that affects the intensity of DRIFT signals. Thus DRIFT mapping data require geometric corrections for a quantitative interpretation. This study analyzed a digital terrain model (DTM)-based approach for describing microtopography effects on DRIFT reflectance. A gypsum block model was first used for developing the concept. The surface of the gypsum block had defined channels and pores and was partly coated with defined humic acid (HA). A millimeter-scale DTM of the DRIFT-mapped gypsum block surface was obtained with a laser scanner. The signal intensities at specific wavenumbers were corrected for microtopography effects using surface elevation, slope, and aspect data of the sample surfaces. The corrections were found to be dependent on both the wavelengths and the measured substance (gypsum or HA). The method was then applied to determine the OM composition at intact structural soil surfaces. The DTM-based approach reduced microtopography effects and was compared with an alternative approach in which spectral ratios between specific absorption bands were used for corrections. The results indicated differences in OM composition and local distribution between surfaces of worm burrows and crack walls. The results suggest that DTM correction of a DRIFT-mapped intact soil aggregate surface enhanced the interpretation of the millimeter-scale OM composition. ; p. 1626-1639.
    Keywords: Wavelengths ; Microrelief ; Solutes ; Humic Acids ; Preferential Flow ; Models ; Absorption ; Gypsum ; Burrows ; Coatings ; Reflectance ; Spectroscopy ; Soil
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 3
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2015, Vol.178(2), pp.250-260
    Description: The organic matter (OM) in biopore walls and aggregate coatings may be important for sorption of reactive solutes and water as well as for solute mass exchange between the soil matrix and the preferential flow (PF) domains in structured soil. Structural surfaces are coated by illuvial clay‐organic material and by OM of different origin, , earthworm casts and root residues. The objectives were to verify the effect of OM on wettability and infiltration of intact structural surfaces in clay‐illuvial horizons (Bt) of Luvisols and to investigate the relevance of the mm‐scale distribution of OM composition on the water and solute transfer. Intact aggregate surfaces and biopore walls were prepared from Bt horizons of Luvisols developed from Loess and glacial till. The mm‐scale spatial distribution of OM composition was scanned using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ratio between alkyl and carboxyl functional groups in OM was used as potential wettability index (PWI) of the OM. The infiltration dynamics of water and ethanol droplets were determined measuring contact angles (CA) and water drop penetration times (WDPT). At intact surfaces of earthworm burrows and coated cracks of the Loess‐Bt, the potential wettability of the OM was significantly reduced compared to the uncoated matrix. These data corresponded to increased WDPT, indicating a mm‐scaled sub‐critical water repellency. The relation was highly linear for earthworm burrows and crack coatings from the Loess‐Bt with WDPT 〉 2.5 s. Other surfaces of the Loess‐Bt and most surfaces of the till‐derived Bt were not found to be repellent. At these surfaces, no relations between the potential wettability of the OM and the actual wettability of the surface were found. The results suggest that water absorption at intact surface structures, , mass exchange between PF paths and soil matrix, can be locally affected by a mm‐scale OM distribution if OM is of increased content and is enriched in alkyl functional groups. For such surfaces, the relation between potential and actual wettability provides the possibility to evaluate the mm‐scale spatial distribution of wettability and sorption and mass exchange from DRIFT spectroscopic scanning.
    Keywords: Preferential Flow ; Soil Organic Matter ; Infrared Spectroscopy ; Clay Organic Coating ; Mass Exchange
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 4
    Language: English
    In: Journal of Plant Nutrition and Soil Science, August 2016, Vol.179(4), pp.529-536
    Description: In structured soils, water and reactive solutes can preferentially move through larger inter‐aggregate pores, cracks, and biopores. The surface roughness of such macropores is crucial for describing microbial habitats and the exchange of water and solutes between macropores and the soil matrix together with other properties. The objective of this study was to compare the roughness of intact structural surfaces from the Bt‐horizons of five Luvisols developed on loess and glacial till and to test the applicability of confocal laser scanning microscopy. Samples of 5 to 10 cm edge length with intact structural surfaces including cracks with and without clay‐organic coatings, earthworm burrow walls, and root channels were prepared manually. The surface roughness of these structures was determined with a confocal laser scanning microscope of the type Keyence VK‐X100K. The root‐mean‐squared roughness () the curvature () and the ratio between surface area and base area () were calculated from selected surface regions of interest of 0.342 mm with an elevation resolution of 0.02 µm. The roughness was smaller for coated as compared to uncoated cracks and earthworm burrows of the Bt‐horizons. This reduction of roughness by the illuviation of clayey material was similar for the structural surfaces of the coarser textured till‐Bt and the finer‐textured loess‐Bt. This similarity suggested a dominant effect of pedogenesis and a minor effect of the parent material on the roughness levels of structural surfaces in the Bt‐horizons. An expected “smoothing” effect of burrow wall surfaces by earthworm activity was not reflected in the roughness values compared to those of uncoated cracks at the chosen spatial scale. However, for root channel walls from one loess‐Bt, the roughness was reduced as compared to that of other structures. These results suggest that the surface roughness of the structural surface types should separately be considered when describing preferential flow and macropore‐matrix exchange or analysing root growth, microbial habitats, and colloidal transport in structured soils. The confocal laser scanning microscopy technique was found useful for characterizing the roughness of intact structural surfaces.
    Keywords: Clay Coatings ; Earthworm Burrow ; Micro‐Topography ; Organo‐Mineral Coating ; Preferential Flow ; Soil Structure
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 5
    Language: English
    In: Geoderma, 15 November 2018, Vol.330, pp.212-220
    Description: The significance of biogenic silicon (BSi) for Si cycling in terrestrial biogeosystems has been acknowledged since decades. Its importance originates from the fact that BSi generally is more soluble than silicate minerals and thus i) controls Si fluxes from terrestrial to aquatic ecosystems and ii) plays an important role as source of readily- or plant-available Si (i.e., H SiO ) in soils. In this context, physicochemical surface properties of BSi structures determine their dissolution kinetics. We applied transmission Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) microscopy, and confocal laser scanning microscopy (CLSM) to investigate physicochemical surface properties of different biogenic silica structures. Using these techniques we were able to detect differences on a molecular level (FTIR, DRIFT) and in surface roughness parameters (CLSM) between BSi synthesized by protists (testate amoebae, diatoms) and BSi synthesized by plants (phytoliths) as well as between fresh (extracted from plants) and aged (extracted from soils) phytoliths. While fresh phytoliths showed organic impurities that can be assigned to occluded organic matter, aged phytoliths showed additional impurities of mineral origin. This is due to the fact that the used non-destructive gravimetric extraction of phytoliths is unsuitable for a distinct differentiation between biogenic silica (phytoliths) and non-biogenic (minerogenic or microcrystalline) Si forms in general. We recommend DRIFT microscopy for analyses of phytoliths extracted from soils because this technique allows measurements of selected, single siliceous phytoliths (as well as other BSi structures). Surface roughness parameters of aged phytoliths decreased compared to the ones of fresh phytoliths indicating a decrease of specific surface areas available for dissolution processes. Physicochemical surface properties will help us to better understand the BSi status (BSi quality and quantity) of soils with implications for Si availability in soils and thus Si cycling in terrestrial biogeosystems.
    Keywords: Fresh and Aged Phytoliths ; Testate Amoeba Shells ; Diatom Frustules ; Confocal Laser Scanning Microscopy ; Ftir Spectroscopy ; Drift Microscopy ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 6
    Language: English
    In: Journal of Plant Nutrition and Soil Science, February 2016, Vol.179(1), pp.5-17
    Description: In the clay‐illuvial horizons (Bt) of Luvisols, surfaces of biopores and aggregates can be enriched in clay and organic matter (OM), relative to the bulk of the soil matrix. The OM composition of these coatings determines their bio‐physico‐chemical properties and is relevant for transport and transformation processes but is largely unknown at the molecular scale. The objective of this study was to improve the interpretation of spectra from Fourier transform infrared spectroscopy in diffuse reflectance mode (DRIFT) by using thermograms and released ion intensities obtained with pyrolysis‐field ionization mass spectrometry (Py‐FIMS) for a more detailed analysis of the mm‐scale spatial distribution of OM components at intact structural surfaces. Samples were separated from earthworm burrow walls, crack coatings, uncoated cracks, root channels, and pinhole fillings of the Bt‐horizons of Luvisols. The information from Py‐FI mass spectra enabled the assignment of OM functional groups also from spectral regions of overlapping DRIFT signal intensities to specific OM compound classes. In particular, bands from C=O and C=C bonds in the infrared range of wave numbers between 1,641 and 1,605 cm were related to heterocyclic N‐compounds, benzonitrile, and naphthalene. The OM at earthworm burrow walls was composed of chemically labile aliphatic C‐rich and rather stable lignin and alkylaromatic compounds whereas the OM of thick crack coatings and pinholes was dominated by heterocyclic N and nitriles and high‐molecular compounds, likely originating from combustion residues. In combination with Py‐FIMS, DRIFT applications to intact samples seem promising for generating a more detailed mm‐scale spatial distribution of OM‐related sorption and wettability properties of crack and biopore surfaces that may serve as preferential flow paths in structured soils.
    Keywords: Soil Organic Matter ; Clay Organic Coatings ; Infrared Spectroscopy ; Pyrolysis‐Field Ionization Mass Spectrometry ; Preferential Flow Paths
    ISSN: 1436-8730
    E-ISSN: 1522-2624
    Source: John Wiley & Sons, Inc.
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  • 7
    Language: English
    In: Soil & Tillage Research, March 2018, Vol.176, pp.1-9
    Description: In structured soils, the surfaces of biopores, shrinkage cracks, and inter-aggregate spaces are often enriched in organic matter (OM) as compared to the matrix. The small-scale distribution of OM at macropore surfaces is affecting preferential flow, mass transfer, and OM turnover in macropores. While the mm-scale spatial distribution of the OM composition at intact surfaces could be observed, the distribution of the organic carbon (OC) content remained limited to date due to a suitable approach. The objective was to develop and test a method for quantifying the two-dimensional (2D) OC distribution at intact macropore surfaces at the mm-to-cm scale. We combined diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and OC analyses of reference samples of few milligrams manually separated from macropore surfaces. DRIFT spectra were measured in a mapping approach at intact surfaces from earthworm burrows, cracks with and without clay-organic coatings, and single pore fillings (‘pinholes’) from Bt-horizons of Luvisols developed on loess and glacial till. The sample’s OC contents were determined with elemental isotope ratio mass spectrometry (EA-IRMS) and related to the DRIFT spectra by partial least squares regression (PLSR). The DRIFT mapping spectra were used to predict the 2D spatial distribution of the OC content at intact macropore surfaces via the PLSR models. The maps revealed mm-scale differences in the OC contents of the macropores which were often related to the 2D distribution of the macropore type surfaces. The validation of the PLSR showed R values of 0.77 (loess) and 0.83 (till) between measured and predicted OC contents. The prediction accuracy of the OC values was reduced by the micro-topography of the intact surfaces and by a variable thickness of the clay-organic surface layer. DRIFT mapping spectra from intact soil macropore surfaces were suitable to quantify the 2D OC distribution of the outermost surface layer. The heterogeneous small-scale spatial distribution of the OC contents at macropore surfaces implies a more specific consideration of these macropore walls when studying inter-domain mass transfer and OM turnover in structured soils.
    Keywords: Organo-Mineral Coating ; Infrared Spectroscopy ; Structured Soils ; Luvisols ; Earthworm Burrows ; Agriculture
    ISSN: 0167-1987
    E-ISSN: 1879-3444
    Source: ScienceDirect Journals (Elsevier)
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  • 8
    Language: English
    In: Journal of Plant Nutrition and Soil Science, February 2016, Vol.179(1), pp.29-38
    Description: The surfaces of macropores or aggregates can act as hot spots for biogeochemical processes and solute transport during preferential flow. For the characterization of organic matter (OM) at macropore surfaces non‐destructive methods have been applied such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). However, effects of organic components on DRIFT signal intensities are often difficult to distinguish from those of mineral components. Here, DRIFT spectra from intact earthworm burrow walls and coated cracks were re‐evaluated to improve the interpretation of C–H and C=O bands. We compared DRIFT and transmission Fourier transform infrared (FTIR) spectra of entire samples that were from the same pedogenetic soil horizon (Bt) but different in mineral composition and texture (, glacial till loess). Spectra of incinerated samples were subtracted from the original spectra. Transmission FTIR and DRIFT spectra were almost identical for entire soil samples. However, the DRIFT spectra were affected by the bulk mode bands (, wavenumbers 2000 to 1700 cm). These bands affected spectral resolution and reproducibility. The ratios between C–H and C=O band intensities as indicator for OM quality obtained with DRIFT were smaller than those obtained from transmission FTIR. The results demonstrated that DRIFT and transmission FTIR data required separate interpretations. DRIFT spectroscopy as a non‐destructive method for analyzing OM composition at intact surfaces in structured soils could be calibrated with information obtained with the more detailed transmission FTIR and complementary methods. Spectral subtraction procedure was found useful to reduce effects of mineral absorption bands. The improved DRIFT data may be related to other soil properties (, cation exchange capacity) of hot spots in structured soils.
    Keywords: Drift ; Transmission Ftir ; Coatings ; Intact Surfaces ; Ash Correction ; Spectral Subtraction
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 9
    Language: English
    In: Journal of Hydrology and Hydromechanics, 01 June 2016, Vol.64(2), pp.111-120
    Description: The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i) coated, (ii) not coated (both intact), and (iii) aggregates from which coatings were removed (cut). The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT). A potential wettability index (PWI) was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT) and contact angles (CA) during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA(t) = at−b). For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value (R2 = 0.75). The a parameter was significantly related to the WDPT (R2 = 0.84) and to the PWI (R2 = 0.64). The relations between the b parameter and the WDPT (R2 = 0.61) and the PWI (R2 = 0.53) were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM (R2 = 0.64). In contrast to dry samples, no significant relationships were found between parameters a or b of CA(t) and WDPT or PWI for wet aggregate surfaces. The results suggest that the effect of the SOM composition of coatings on surface wettability decreases with increasing soil moisture. In addition to the dominant impact of SOM, the wettability of aggregate surfaces could be affected by different mineralogical compositions of clay in coatings and interiors of aggregates. Particularly, wettability of coatings could be decreased by illite which was the dominant clay type in coatings. However, the influence of different clay mineral fractions on surface wettability was not due to small number of measurements (2 and 1 samples from coatings and interiors, respectively) quantified.
    Keywords: Aggregates ; Clay and Organic Matter Coatings ; Wdpt ; Contact Angle ; Drift Spectroscopy ; Geography
    E-ISSN: 0042-790X
    E-ISSN: 13384333
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  • 10
    Language: English
    In: Catena, March 2018, Vol.162, pp.255-269
    Description: Fly ash and bottom ash from thermal power stations are industrial wastes which are susceptible to weathering in the environment. First manifestations of transformations occur immediately after deposition of ashes in a disposal site and they continue in technogenic soils (Technosols) developing from the ashes on surfaces of such sites. Technosols developed from bituminous coal and lignite ashes in Poland were studied in order (a) to identify the most important mineral transformations during the first several decades of soil development, and (b) to discuss the evolution of these soils. Mineral transformations can serve as good indicators of pedogenesis in the studied Technosols. Quantitative X-ray diffraction analyses, Fourier transform infrared spectroscopy, optical microscopy, and scanning electron microscope-energy dispersive spectroscopy studies showed that the mineral transformations proceeded more dynamically in Technosols developed from lignite ashes, whereas they were less expressed in soils formed from bituminous coal ashes. Technosols developed from bituminous coal ashes contained mineral phases inherited from ashes (aluminosilicate glass, mullite, quartz, magnetite, hematite, and traces of maghemite and barite) as predominating constituents. Small contents of pedogenic calcite, iron oxyhydroxides, and most likely short-range order Si- and Al-containing phases originated within ~ 60 years of pedogenesis. Technosols developed from lignite ashes contained aluminosilicate glass, quartz, hematite inherited from fly ash, as well as a variety of secondary minerals (vaterite, calcite, bassanite, gypsum, ettringite, hydrotalcite, and brucite) which were formed as an effect of rapid mineral transformations after ash deposition. After about 40 years, pedogenesis (accelerated by reclamation and a few years of intense cultivation) led to the formation of a new mineral assemblage with the predomination of calcite, gypsum, and hydrotalcite. A concept of evolution of the studied Technosols comprising four stages of evolution was proposed: I – formation of ash during combustion of fuel (coal or lignite) in a thermal power station, II – transport and deposition of ash in a disposal site accompanied by the first weathering alterations, III – early pedogenesis, and IV – further (predicted) evolution.
    Keywords: Technosols ; Fly Ash ; Bottom Ash ; Mineral Transformations ; Pedogenesis ; Soil Evolution ; Sciences (General) ; Geography ; Geology
    ISSN: 0341-8162
    E-ISSN: 1872-6887
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