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  • Elsevier (CrossRef)  (16)
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  • 1
    Language: English
    In: Catena, February 2017, Vol.149, pp.381-384
    Description: To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1016/j.catena.2016.10.020 Byline: Thilo Rennert [t.rennert@uni-hohenheim.de] (a,*), Nchia Peter Ghong (a), JAaAaAeA rg Rinklebe ( Keywords Fluvisols; Soil organic carbon; Decomposition; Stabilization; DRIFT spectroscopy; Permanganate-oxidizable carbon Highlights * First comprehensive quantitative study on labile SOM in floodplain soils * Large amounts of less processed SOM in subsoil horizons of floodplain soils * Significant correlation of POXC and other C fractions in well-aerated horizons * Consistency of permanganate-oxidizable C and DRIFT spectroscopy in oxidized horizons Abstract Riverine floodplain soils contain large stocks of soil organic matter (SOM) also in larger depth. Qualitative characterization of SOM, especially in the subsoil horizons of floodplain soils, is scarce. To gain deeper insights into the composition of SOM and the driving parameters of SOM processing, we studied 121 horizons of 18 soil profiles along the Central Elbe River (Germany) by determining permanganate-oxidizable carbon (POXC) and a stability parameter derived from diffuse reflectance infrared (DRIFT) spectroscopy. The absolute and relative amounts of POXC varied between the horizons. While the topsoil horizons contained the largest total contents of POXC (average 923 mg kg.sup.- 1 soil), the largest relative proportions were detected in subsoil horizons characterized by reducing conditions and water saturation (up to 19% of total organic C), which exceeded those reported for terrestrial soils. The absolute contents of POXC were positively and partially highly significantly correlated with those of total organic, hot-water extractable and microbial-biomass C, confirming its nature as slightly processed and relatively labile fraction of SOM. The correlations were distinctly weaker for the reduced horizons, indicating hampered decomposition. The contents of POXC were also positively correlated with the DRIFT stability parameter, expressing the ratio of aliphatic to aromatic C. Our results suggest the presence of a large fraction of less processed SOM in the subsoils of floodplain soils, originating from inputs of particulate organic matter that was buried and weakly decomposed at water saturation, and partially from charcoal particles, also transported by the river water. The results point to a possible limitation of POXC as an indicator of decomposition to soils lacking an aquic moisture regime. Author Affiliation: (a) Fachgebiet Bodenchemie mit Pedologie, Institut fAaAaAeA r Bodenkunde u Standortslehre, UniversitAaAaAeAnt Hohenheim, 70593 Stuttgart, Germa (b) Boden- und Grundwassermanagement, Bergische UniversitAaAaAeAnt Wupperta Pauluskirchstr. 7, 42285 Wuppertal, Germany * Corresponding author. Article History: Received 15 July 2016; Revised 18 October 2016; Accepted 25 October 2016
    Keywords: Fluvisols ; Soil Organic Carbon ; Decomposition ; Stabilization ; Drift Spectroscopy ; Permanganate-Oxidizable Carbon ; Sciences (General) ; Geography ; Geology
    ISSN: 0341-8162
    E-ISSN: 1872-6887
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  • 2
    Language: English
    In: Journal of Colloid And Interface Science, 01 September 2013, Vol.405, pp.44-50
    Description: Cryptomelane-type octahedral molecular sieves (K-OMS-2) were successfully synthesized at ambient pressure and temperature by a simple one-step reaction pathway. We designed three synthesis mixes based on redox reactions of either MnSO or MnCl together with KMnO in aqueous solution. The synthesis products were characterized structurally (XRD, FTIR spectroscopy), morphologically (SEM, BET surface area), and chemically (SEM-EDX, ICP-OES). For all mixes, a precursor octahedral layered K-birnessite (K-OL-1) was formed after 1 d that subsequently transformed into K-OMS-2. This transformation process depends on the pH of the reaction solution, the respective Mn(II) salt and time. We obtained K-OMS-2 materials with BET surface areas between 50.4 and 104.5 m g and different crystallinities. The described method is reliable, reproducible, easy to handle and may be the basis to produce well defined Mn oxides that could be used for remediation and catalysis purposes.
    Keywords: Octahedral Molecular Sieve ; K-Oms-2 ; K-Ol-1 ; Nanowires ; Mn Oxide ; Bet Surface ; Engineering ; Chemistry
    ISSN: 0021-9797
    E-ISSN: 1095-7103
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  • 3
    Language: English
    In: Environmental Pollution, August 2013, Vol.179, pp.315-325
    Description: Mass transfer processes of pollutants from non-aqueous phase liquids (NAPL) may control groundwater pollution at abandoned industrial sites. We studied release kinetics of polycyclic aromatic hydrocarbons (PAHs) from fresh and aged tar phases using a dialysis tubing technique. Time for equilibration ranged from several days to more than three years. For fresh tar materials the release seems to be limited by retarded pore diffusion, while for two of three aged tars diffusion limited release influenced by dissolved organic matter (DOM) was assumed. The equilibration process was driven by solubilization thermodynamics expressed by Raoult's law. Yet, solubility enhancement was observed potentially due to the presence of organic mobile sorbents. The results show that the release of PAHs from tar phases is generally rate limited and partitioning according to Raoult's law is the driving mechanism of the exchanges process. Release of PAHs from tar phases is severely restricted by retarded pore diffusion.
    Keywords: Aging ; Coal Tar ; Manufactured Gas Plant Sites ; Tar Processing Facilities ; Reactive Transport ; Dissolved Organic Matter ; Polycyclic Aromatic Hydrocarbons ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 4
    Language: English
    In: Environmental Pollution, 2011, Vol.159(5), pp.1398-1405
    Description: Arsenic mobility may increase in liquid phase due to association with colloidal Fe oxides. We studied the association of As with Fe oxide colloids in the effluent from water-saturated soil columns run under anoxic conditions. Upon exfiltration, the solutions, which contained Fe , were re-aerated and ferrihydrite colloids precipitated. The entire amount of effluent As was associated with the ferrihydrite colloids, although PO , SiO , CO and dissolved organic matter were present in the effluent during ferrihydrite colloid formation. Furthermore, no subsequent release of As from the ferrihydrite colloids was observed despite the presence of these (in)organic species known to compete with As for adsorption on Fe oxides. Arsenic was bound via inner-sphere complexation on the ferrihydrite surface. FTIR spectroscopy also revealed adsorption of PO and polymerized silica. However, these species could not impede the quantitative association of As with colloidal ferrihydrite in the soil effluents. ► Ferrihydrite (Fh) colloids precipitated from a solution derived from soil. ► Arsenic that was discharged from soil entirely associated with these colloids. ► Arsenic was strongly bound to the Fh surface via inner-sphere complexation. ► A complexation of As by organic species discharged from soil was not detected. ► (In)organic solutes in the solution from soil could not impede the As–Fh association. Natural concentrations of competing (in)organic species in soil-derived solutions do not impede the strong and quantitative association between As and colloidal ferrihydrite.
    Keywords: Iron Hydroxide ; Phosphate ; Silicate ; Carbonate ; Dissolved Organic Matter ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 5
    Language: English
    In: Chemosphere, May 2016, Vol.150, pp.390-397
    Description: Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) combined with a seven steps sequential extraction technique were used to assess the geochemical distribution of chromium (Cr) and lead (Pb) in a contaminated floodplain soil. Total contents of Cr and Pb were 490.3 and 402.1 mg kg , respectively. The residual fraction was 59.5 and 56.3% of total Cr and Pb. The crystalline iron (Fe) oxide was the dominant non-residual fraction of Cr (35.9% of total Cr). Considerable amounts of Pb were found in the organic fraction (35.4%). Using C nuclear magnetic resonance spectroscopy, the soil organic matter was identified as 48.9% aromatic carbon, which indicated that a certain portion of Pb and Cr might be associated with aromatic compounds. The SEM–EDX images demonstrate a concomitant occurrence of Pb, manganese (Mn), Fe, and aluminum (Al) as well as a coexistence of Cr and Fe. The release dynamics of dissolved Cr and Pb as affected by redox potential (E ), pH, Fe, Mn, dissolved organic carbon, and sulfate was quantified using an automated biogeochemical microcosm apparatus. Soil pH decreased under oxic conditions. The release of Cr, Pb, Fe, and Mn increased under acidic oxic (pH = 3.7, E  = 521 mV) conditions due to the associated decrease of pH (7.1–3.7). The mobilization of Cr and Pb was affected by the Fe and Mn. In conclusion, our multi-technique approach identified the geochemical distribution of Cr and Pb and verified major factors that explain mobilization of Cr and Pb in floodplain soils.
    Keywords: Toxic Metals ; Mobilization ; Wetlands ; Scanning Electron Microscope Coupled With Energy Dispersive X-Ray Analysis (SEM–Edx) ; Nuclear Magnetic Resonance Spectroscopy (NMR) ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 6
    Language: English
    In: Geochimica et Cosmochimica Acta, 15 January 2012, Vol.77, pp.444-456
    Description: Recent studies on the microbial reduction of synthetic iron oxide colloids showed their superior electron accepting property in comparison to bulk iron oxides. However, natural colloidal iron oxides differ in composition from their synthetic counterparts. Besides a potential effect of colloid size, microbial iron reduction may be accelerated by electron-shuttling dissolved organic matter (DOM) as well as slowed down by inhibitors such as arsenic. We examined the microbial reduction of OM- and arsenic-containing ferrihydrite colloids. Four effluent fractions were collected from a soil column experiment run under water-saturated conditions. Ferrihydrite colloids precipitated from the soil effluent and exhibited stable hydrodynamic diameters ranging from 281 (±146) nm in the effluent fraction that was collected first and 100 (±43) nm in a subsequently obtained effluent fraction. Aliquots of these oxic effluent fractions were added to anoxic low salt medium containing diluted suspensions of . Independent of the initial colloid size, the soil effluent ferrihydrite colloids were quickly and completely reduced. The rates of Fe formation ranged between 1.9 and 3.3 fmol h cell , and are in the range of or slightly exceeding previously reported rates of synthetic ferrihydrite colloids (1.3 fmol h cell ), but greatly exceeding previously known rates of macroaggregate-ferrihydrite reduction (0.07 fmol h cell ). The inhibition of microbial Fe(III) reduction by arsenic is unlikely or overridden by the concurrent enhancement induced by soil effluent DOM. These organic species may have increased the already high intrinsic reducibility of colloidal ferrihydrite owing to quinone-mediated electron shuttling. Additionally, OM, which is structurally associated with the soil effluent ferrihydrite colloids, may also contribute to the higher reactivity due to increasing solubility and specific surface area of ferrihydrite. In conclusion, ferrihydrite colloids from soil effluents can be considered as highly reactive electron acceptors in anoxic environments.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
    Source: ScienceDirect Journals (Elsevier)
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  • 7
    Language: English
    In: Geoderma, 01 February 2018, Vol.311, pp.15-24
    Description: Soils on riverine floodplains in Central Europe are commonly enriched in soil organic matter (SOM). We analyzed the quantity and qualitative aspects of SOM in three soil profiles with mollic horizons along the Elbe River (Germany) after physical fractionation by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy to gain deeper insights into the composition of SOM and the formation of these soils. In all horizons, the majority of SOM was recovered in the fraction of particulate OM and in that of sand and aggregates, while SOM in the silt and clay fraction always made up 〈 20% of soil organic carbon. The C:N ratios of most fractions did not decrease with depth, indicating less decomposed or pyrogenic OM or both. The presence of pyrogenic OM, as a characteristic feature of floodplain soils, was indicated in almost all physical fractions. As derived from DRIFT spectroscopy, SOM was less qualitatively differentiated among the fractions in the soil with the longest duration of flooding, while qualitative differences of SOM were more pronounced in the more aerated ones. The soils have developed from stratified fluviatile sediments and fulfil the criteria of a mollic horizon, irrespective of differences in the composition of SOM. From a soil-genetic point of view, we strongly suggest to classify these soils as Mollic Fluvisols instead of Fluvic Phaeozems, which would accord to the latest WRB classification.
    Keywords: Fluvisols ; Drift Spectroscopy ; Physical Fractionation ; Particulate Organic Matter ; Pyrogenic Organic Matter ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 8
    Language: English
    In: Water Research, 2002, Vol.36(19), pp.4877-4883
    Description: Blast furnace sludge is a waste originating from pig iron production and contains small amounts of iron-cyanide complexes. Leaching of iron-cyanide complexes from deposited blast furnace sludge into the ground water seems to be possible in principle. We investigated the sorption of the iron-cyanide complexes ferrocyanide, [Fe super(II)(CN) sub(6)] super(4-), and ferricyanide, [Fe super(III)(CN) sub(6)] super(3-), in 22 samples of deposited blast furnace sludge in batch experiments. Subsequently, desorption of iron-cyanide complexes was investigated using 1 M NaCl. Sorption in five samples was evaluated with Langmuir isotherms. The blast furnace sludge samples were neutral to slightly alkaline (pH 7.6-9) and consisted of X-ray amorphous compounds and crystalline Fe oxides primarily. X-ray amorphous compounds are assumed to comprise coke-bound C and amorphous Fe, Zn, and Al oxides. The experiments that were evaluated with Langmuir isotherms indicated that the extent of ferricyanide sorption was higher than that of ferrocyanide sorption. Saturation of blast furnace sludge with iron-cyanide complexes was achieved. Sorption of iron-cyanide complexes in 22 blast furnace sludge samples at one initial concentration showed that 12 samples sorbed more ferrocyanide than ferricyanide. The extent of sorption largely differed between 0.07 and 2.76 mu mol [Fe(CN) sub(6)]m super(-2) and was governed by coke-bound C. Ferricyanide sorption was negatively influenced by crystalline Fe oxides additionally. Only small amounts of iron-cyanide complexes sorbed in blast furnace sludge were desorbed by 1 M NaCl (ferrocyanide, 3.2%; ferricyanide, 1.1%, given as median). This indicated strong interactions of iron-cyanide complexes in blast furnace sludge. The mobility of iron-cyanide complexes in deposited blast furnace sludge and consequently contamination of the seepage and ground water was designated as low, because (i) deposited blast furnace sludge is able to sorb iron-cyanide complexes strongly, (ii) the solubility of the iron-cyanide-containing phase, K sub(2)Zn sub(3)[Fe super(II)(CN) sub(6)] times 9H sub(2)O, is known to be low, and (iii) a worst case scenario of the transport of iron-cyanide complexes within the blast furnace sludge deposit indicated strong retardation of the complexes within the next 100 years.
    Keywords: Iron–Cyanide Complexes ; Sorption ; Desorption ; Blast Furnace Sludge ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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  • 9
    Language: English
    In: Geoderma, February 2013, Vol.193-194, pp.117-121
    Description: The synthesis of pure birnessite (δ-MnO ) by a simple, fast and reliable method is introduced. Birnessite was synthesized by a sol–gel reaction involving the reduction of KMnO by lactate at ambient pressure and temperature. Our method does not include the use of strong acids and bases and does not produce toxic residues. The results from both X-ray diffraction and Fourier-transform infrared spectroscopy, compared with a synthesized reference material, verified our synthesized mineral as birnessite. Secondary electron images showed a micro-porous structure of aggregated birnessite colloids, and consistently, we measured a very large specific BET surface area of 249.15 ± 0.05 m g . Birnessite is known to have a variable mineral formula, and the elemental composition of our mineral is within the range of other birnessites. Birnessite obtained by this procedure could serve as a model mineral for laboratory experiments on the biogeochemistry of Mn, and furthermore it may also have a potential as electron acceptor for remediation purposes. ► Pure birnessite was synthesized by a simple, fast, reliable and inexpensive method. ► This birnessite can serve as a model mineral in studies on the biogeochemistry of Mn. ► It may have potential for the remediation of contaminated soils.
    Keywords: Ftir ; Xrd ; Specific Surface Area ; Manganese Oxide ; Remediation ; Sol–Gel Synthesis ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 10
    Language: English
    In: Catena, June 2017, Vol.153, pp.100-105
    Description: Quantification of Si in its different forms in soil is a prerequisite to understand the geochemical distribution and fate of Si along with their driving biogeochemical processes. However, different Si fractions in floodplain soils have not been quantified yet, and little is known about the biogeochemical processes driving Si fractionation in these soils. Therefore, we applied for the first time a sequential Si extraction scheme to three floodplain soils (Mollic Fluvisols) to separate six Si fractions: mobile Si, adsorbed Si, Si bound to organic matter, Si included in pedogenic oxides and hydroxides, biogenic as well as minerogenic amorphous silica. Residual Si was calculated. The highest Si proportion apart from the residual fraction (Si bound in primary and secondary silicates) was found in minerogenic amorphous silica (up to 5.6% of total Si), followed by Si occluded in pedogenic oxides and hydroxides (up to 0.7% of total Si). Silicon from biogenic amorphous silica amounted to 0.02–0.6% of total Si. The smallest proportion of Si was found in the mobile Si fraction and made up about 0.01% of the total Si. The results of this study demonstrate the importance of the soil water budget (here periodic flooding with prolonged water saturation) on the accumulation of easy-to-mobilise Si, Si occluded in pedogenic oxides and hydroxides and amorphous minerogenic as well as biogenic silica. Reductive dissolution of Fe and Mn oxides may induce Si release into the soil solution, subsequent oxidizing conditions may induce Si accumulation by adsorption, co-precipitation and occlusion of Si on/with newly formed Fe and Mn oxides. These processes are more pronounced in floodplain than in terrestrial soils, thus implying different distributions of Si among soil fractions.
    Keywords: Sequential Silicon Extraction ; Silicic Acid ; Amorphous Silica ; Pedogenic Oxides and Hydroxides ; Floodplain Soils ; Sciences (General) ; Geography ; Geology
    ISSN: 0341-8162
    E-ISSN: 1872-6887
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