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  • 1
    Language: English
    In: Geoderma, 2005, Vol.127(3), pp.177-187
    Description: Dissolved organic matter increases typically in streams draining forested catchments during heavy rainstorms and snowmelt. Tracer methods and model calculations suggest that the storm flow flushing of dissolved organic matter is either due to lateral near-surface flow, i.e. within the organic forest floor, or preferential flow (funnelling) through the mineral soil. Both pathways should deliver forest floor-derived dissolved organic matter to streams that is hardly changed because of little to no interaction with mineral soil material and microorganisms. Here, we investigated the effect of rain storm induced vertical flushing through the mineral soil on the composition of dissolved organic matter in a structured Rendzic Leptosols under 90-year-old European beech ( L.). During two rainstorm periods in autumn 1998 with elevated transport of organic C, N, P and S from the forest floor into the subsoil, we sampled dissolved organic matter in forest floor leachates (sampled by zero-tension plate lysimeters), subsoil solutions (sampled by suction cups at 90 cm depth) and subsoil seepage (sampled by zero-tension plate lysimeters at 90 cm depth). The chemical composition of dissolved organic matter was characterised by fractionation with XAD-8 macroreticular resin, wet-chemical analyses of carbohydrates and lignin-derived phenols, and determination of the δ C. During both rainstorm periods, all tested chemical features of dissolved organic matter in forest floor leachate and subsoil seepage matched each other greatly. In contrast, dissolved organic matter in soil solution contained smaller portions of XAD-8-adsorbable organic C, less lignin-derived phenols, more carbohydrates and showed smaller δ C values than that in forest floor leachates and subsoil seepage. These results suggest a rather direct transfer of organic solutes from the forest floor into the subsoil and probably further to ground and surface waters during heavy rainstorms. Dissolved organic matter leaving the soil in heavy rainstorms by rapid water flow through macropores is likely less biodegradable, more UV-digestible and more reactive towards metals and organic pollutants than that released from soil at low rainfall intensity by matric flow.
    Keywords: Dissolved Organic Carbon ; Dissolved Organic Nitrogen ; Dissolved Organic Phosphorus ; Dissolved Organic Sulphur ; Carbohydrates ; Lignin-Derived Phenols ; Δ 13c ; Xad-8 Fractionation ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 2
    In: PLoS ONE, 2014, Vol.9(2)
    Description: Temperate forests are assumed to be organic carbon (OC) sinks, either because of biomass increases upon elevated CO 2 in the atmosphere and large nitrogen deposition, or due to their age structure. Respective changes in soil OC and total nitrogen (TN) storage have rarely been proven. We analysed OC, TN, and bulk densities of 100 soil cores sampled along a regular grid in an old-growth deciduous forest at the Hainich National Park, Germany, in 2004 and again in 2009. Concentrations of OC and TN increased significantly from 2004 to 2009, mostly in the upper 0–20 cm of the mineral soil. Changes in the fine earth masses per soil volume impeded the detection of OC changes based on fixed soil volumes. When calculated on average fine earth masses, OC stocks increased by 323±146 g m −2 and TN stocks by 39±10 g m −2 at 0–20 cm soil depth from 2004 to 2009, giving average annual accumulation rates of 65±29 g OC m −2 yr −1 and 7.8±2 g N m −2 yr −1 . Accumulation rates were largest in the upper part of the B horizon. Regional increases in forest biomass, either due to recovery of forest biomass from previous forest management or to fertilization by elevated CO 2 and N deposition, are likely causes for the gains in soil OC and TN. As TN increased stronger (1.3% yr −1 of existing stocks) than OC (0.9% yr −1 ), the OC-to-TN ratios declined significantly. Results of regression analyses between changes in OC and TN stocks suggest that at no change in OC, still 3.8 g TN m −2 yr −1 accumulated. Potential causes for the increase in TN in excess to OC are fixation of inorganic N by the clay-rich soil or changes in microbial communities. The increase in soil OC corresponded on average to 6–13% of the estimated increase in net biome productivity.
    Keywords: Research Article ; Agriculture ; Biology ; Chemistry ; Earth Sciences
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: PLOS ONE, 2014, Vol.9(8), pp.urn:issn:1932-6203
    Description: Cognitive bias, the altered information processing resulting from the background emotional state of an individual, has been suggested as a promising new indicator of animal emotion. Comparable to anxious or depressed humans, animals in a putatively negative emotional state are more likely to judge an ambiguous stimulus as if it predicts a negative event, than those in positive states. The present study aimed to establish a cognitive bias test for mice based on a spatial judgment task and to apply it in a pilot study to serotonin transporter (5-HTT) knockout mice, a well-established mouse model for the study of anxiety- and depression-related behavior. In a first step, we validated that our setup can assess different expectations about the outcome of an ambiguous stimulus: mice having learned to expect something positive within a maze differed significantly in their behavior towards an unfamiliar location than animals having learned to expect something negative. In a second step, the use of spatial location as a discriminatory stimulus was confirmed by showing that mice interpret an ambiguous stimulus depending on its spatial location, with a position exactly midway between a positive and a negative reference point provoking the highest level of ambiguity. Finally, the anxiety- and depression-like phenotype of the 5-HTT knockout mouse model manifested - comparable to human conditions - in a trend for a negatively distorted interpretation of ambiguous information, albeit this effect was not statistically significant. The results suggest that the present cognitive bias test provides a useful basis to study the emotional state in mice, which may not only increase the translational value of animal models in the study of human affective disorders, but which is also a central objective of animal welfare research.
    Keywords: Research Article ; Biology And Life Sciences ; Research And Analysis Methods;
    ISSN: 1932-6203
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  • 4
    Language: English
    In: Organic Geochemistry, 2011, Vol.42(10), pp.1271-1278
    Description: ► Using the C-TMAH method, we studied lignin decay in field-exposed leaves & needles. ► Phenol yield and acid/aldehyde ratio indicated wood rot decay vs. time. ► Build up of demethylated lignin from brown rot decay was not found. ► The results were compared with those from other methods applied previously. ► The long assumed lignin preservation was not found using the CuO & C-TMAH methods. We studied the degradation of lignin in leaf and needle litter of ash, beech, maple, pine and spruce using C-labelled tetramethylammonium hydroxide ( C TMAH) thermochemolysis. Samples were allowed to decompose for 27 months in litter bags at a German spruce forest site, resulting in a range of mass loss from 26% (beech) to 58% (ash). In contrast to conventional unlabelled TMAH thermochemolysis, C-labelling allows thermochemolysis products from lignin, demethylated lignin and other polyphenolic litter compounds (e.g. tannins) to be distinguished. Proxies for lignin degradation (phenol yield; acid/aldehyde ratio of products) changed considerably upon correction for the contribution of non-lignin sources to the thermochemolysis products. Using the corrected values, we found increasing acid/aldehyde values as well as decreasing or constant yield of lignin derived phenols normalised to litter carbon, suggesting pronounced lignin degradation by wood-rotting fungi. No indication for build up of demethylated lignin through the action of brown rot fungi on ring methoxyls was found. The results were compared with those of other analytical techniques applied in previous studies. Like C-TMAH thermochemolysis, CuO oxidation showed increasing lignin oxidation (acid/aldehyde ratio) and no/little enrichment of lignin derived phenols in the litter. Molecular lignin degradation patterns did not match those from analysis of total acid unhydrolysable residues (AURs). In particular, the long assumed selective preservation of lignin during the first months of litter decomposition, based on AUR analysis, was not supported by results from the CuO and C TMAH methods.
    Keywords: Geology
    ISSN: 0146-6380
    E-ISSN: 1873-5290
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  • 5
    Language: English
    In: Geoderma, 2011, Vol.162(1), pp.207-214
    Description: In a long-term tillage experiment comparing mouldboard plough and rotary harrow since 1967, litterbags with green maize residues and wheat straw were buried, recovered from soil and analysed for biochemical degradation indices. Our objective was to investigate whether lignin units and neutral and amino sugars give information on microbial degradation after burial periods of 6 and 12 months at two different depths (0–5 and 15–20 cm). Tillage and burial depth had no effects on the content and composition of lignin. In contrast, the extended burial period resulted in higher acid/aldehyde ratios of vanillyl units, due to increasing microbial oxidation, and in higher ratios of cinnamyl/vanillyl units, due to the higher resistance of vanillyl units against microbial degradation. The contents of mannose, bacterial muramic acid, and fungal glucosamine were significantly higher in the plough than in the harrow treatment, due to a higher microbial colonisation. For the same reason, the extended burial period led to significant increases in the contents of mannose, glucosamine, muramic acid, and galactosamine as well as in the GM/AX ((galactose + mannose)/(arabinose + xylose)) ratio. The decline in the fungal C/bacterial C ratio indicated that bacterial colonisation of litter followed fungal colonisation with delay. A greater burial depth led to a lower microbial colonisation and consequently had contrasting effects to those of a longer burial period. Treatment effects on maize residues and wheat straw were generally similar, despite the strong differences in composition. The combination of litterbags and biochemical degradation indices gave further evidence that lower tillage intensity reduces microbial turnover and decomposition activity. ► The harrow exceeded the plough treatment in microbial colonisation of the litter. ► Treatment effects on maize residues and wheat straw were generally similar. ► Biochemical degradation indices reflected burial period and burial depth.
    Keywords: Amino Sugars ; Lignin Units ; Litterbags ; Mouldboard Ploughing ; Neutral Sugars ; Rotary Harrow ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 6
    Language: English
    In: Vadose Zone Journal, 2014, Vol.13(7), p.0
    Description: In temperate spruce forests, dissolved organic matter (DOM) from forest floors is the major source of organic matter entering the mineral soil and thus it determines important soil properties and element cycling through the ecosystem. We examined effects of doubling locally collected throughfall for 6 yr on the concentrations of dissolved organic C (DOC) and properties of DOM (aromaticity, degree of molecule complexity) in the forest floor. Forest floor solutions below the Oi, Oe, and Oa horizons were sampled every 2 to 4 wk using tension lysimeters. For the controls, the average DOC concentrations in 2002 to 2007 were 43.8 + or - 2.6 mg L (super -1) below the Oi, 49.6 + or - 2.7 mg L (super -1) below the Oe, and 61.0 + or - 2.0 mg L (super -1) below the Oa horizon. Doubling throughfall resulted in average DOC concentrations of 37.4 + or - 1.8 mg L (super -1) (Oi), 49.3 + or - 1.6 mg L (super -1) (Oe), and 50.1 + or - 8.0 mg L (super -1) (Oa). The decreases in concentrations due to throughfall addition as well as the effects on DOM properties were, however, not statistically significant. It is commonly assumed that throughfall inputs are linearly related to water fluxes within and from the forest floor. Under that assumption, the results suggest that DOM fluxes are controlled by water fluxes rather than by the quantity of C that can be mobilized from the soil organic matter. Hence, increasing precipitation due to future climate changes presumably will result in enhanced DOM fluxes into the mineral horizons.
    Keywords: General Geochemistry ; Environmental Geology ; Annual Variations ; Aqueous Solutions ; Atmospheric Precipitation ; Bavaria Germany ; Carbon ; Central Europe ; Climate ; Climate Change ; Complexity ; Controls ; Coulissenhieb ; Ecology ; Ecosystems ; Europe ; Fichtelgebirge ; Field Studies ; Forests ; Germany ; Lysimeters ; Organic Compounds ; Podzols ; Quantitative Analysis ; Residence Time ; Soil Solutions ; Soils ; Solutes ; Statistical Analysis ; Temperate Environment ; Throughfall ; Unsaturated Zone ; Water;
    ISSN: Vadose Zone Journal
    E-ISSN: 1539-1663
    Source: CrossRef
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  • 7
    Language: English
    In: Global change biology, 2011, Vol.17(2), pp.1167-1185
    Description: Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH₄), at forests, grasslands, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its δ¹³C signature. Leaching of biogenic DIC was 8.3±4.9 g m⁻² yr⁻¹ for forests, 24.1±7.2 g m⁻² yr⁻¹ for grasslands, and 14.6±4.8 g m⁻² yr⁻¹ for croplands. DOC leaching equalled 3.5±1.3 g m⁻² yr⁻¹ for forests, 5.3±2.0 g m⁻² yr⁻¹ for grasslands, and 4.1±1.3 g m⁻² yr⁻¹ for croplands. The average flux of total biogenic carbon across land use systems was 19.4±4.0 g C m⁻² yr⁻¹. Production of DOC in topsoils was positively related to their C/N ratio and DOC retention in subsoils was inversely related to the ratio of organic carbon to iron plus aluminium (hydr)oxides. Partial pressures of CO₂ in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO₂. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5-98% (median: 22%) of net ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24-105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small solubility of CO₂ in acidic forest soil solutions and large NEE. Leaching of CH₄ proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems. ; Includes references ; p. 1167-1185.
    Keywords: Soil Carbon -- Environmental Aspects ; Green Technology -- Environmental Aspects ; Hydrology -- Environmental Aspects ; Global Temperature Changes -- Environmental Aspects ; Leaching -- Environmental Aspects ; Biogeochemistry -- Environmental Aspects ; Agroecosystems -- Environmental Aspects ; Business Losses -- Environmental Aspects ; Forest Soils -- Environmental Aspects ; Biomes -- Environmental Aspects ; Methane -- Environmental Aspects ; Soil Acidity -- Environmental Aspects ; Carbon Cycle -- Environmental Aspects ; Grasslands -- Environmental Aspects ; Oxides -- Environmental Aspects;
    ISSN: 1354-1013
    E-ISSN: 13652486
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  • 8
    Language: English
    In: Geoderma, 15 June 2017, Vol.296, pp.86-97
    Description: Organic soils are the most important source of dissolved organic carbon (DOC) in surface water. To date, most studies have focused on natural and re-wetted peatlands, but in Central Europe a large proportion of organic soils are drained and under agricultural use. Furthermore, measures such as deep ploughing or sand addition have been conducted to improve trafficability and have resulted in topsoil horizons consisting of a peat-sand mixture. Very little is known about DOC losses from such soils. Moreover, peat soils frequently feature both mobile zones, characterised by active water and solute transport, and immobile zones, which exchange solutes with the mobile zone by diffusion. Surprisingly, however, the effects of this dual porosity on DOC transport have not yet been explored. This study investigated the physicochemical controls on DOC concentrations in a peat-sand mixture by means of a saturated column experiment with undisturbed columns. The soil came from a former bog in northern Germany where peat layers remaining after peat extraction were mixed with the underlying mineral soil by ploughing. Three pumping rates and two levels of electrical conductivity (EC) were applied. The transport properties of the soil were obtained by analysing breakthrough curves of potassium bromide using the transport model STANMOD, which is based on the two-region non-equilibrium concept. The results of the column study were compared to DOC concentrations measured bi-weekly for two years at the field site from where the columns were taken. Despite a similar texture and soil organic carbon (SOC) content, the fraction of the mobile zone in the columns varied between 51% and 100% of total porosity. Thus even heavily degraded organic soils mixed with sand still showed a dual porosity comparable to degraded peat soils. Percolating the columns with the high EC solution caused low pH values, probably due to ion exchange and cation bridging. The combination of high EC and low pH greatly decreased DOC concentrations at the outlet of the columns. DOC concentrations decreased and fluxes increased as the pumping rates increased. Taking pore water velocity in the mobile zone into account could help to explain the differences between the columns. Overall, transport of DOC did not seem to be limited by production of DOC, but by rate-limited exchange processes. In contrast to the column experiment, field concentrations of DOC were much higher and were not related to pH, but increased with higher electrical conductivity. These higher concentrations could be explained by low pore water velocities and the slightly higher SOC content in the field. This first experiment on DOC transport in peat-sand mixtures taking the dual-porosity nature of organic soils into account clearly demonstrated the importance of pore water velocity and thus the residence time for DOC concentrations. While hydrochemical conditions are frequently addressed in laboratory studies, there is a need for improved understanding of their interaction with hydrology and soil-physical properties, especially when attempting to interpret DOC data on different spatial and temporal scales.
    Keywords: Dissolved Organic Carbon ; Dual Porosity ; Tracer Experiment ; Bog ; Water Quality ; Agriculture
    ISSN: 0016-7061
    E-ISSN: 1872-6259
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  • 9
    In: FEMS Microbiology Ecology, 2010, Vol. 73(1), pp.166-177
    Description: A long-term field experiment conducted in a Norway spruce forest at Solling, Central Germany, was used to verify and compare the response of lignin-decomposing fungal communities in soils receiving current and preindustrial atmospheric nitrogen (N) input for 14.5 years. Therefore, we investigated the decomposition of lignin compounds in relation to phenol oxidase activity and the diversity of basidiomycetes containing laccase genes in organic and mineral horizons. Lignin-derived CuO oxidation products and enzyme activity decreased with soil depth, while the degree of oxidative transformation of lignin increased. These patterns did not change with reduced atmospheric N input, likely reflecting a lasting saturation in available N. The laccase gene diversity decreased with soil depth in spring. In autumn, this pattern was only found in the control plot, receiving current N input. Principal component analysis confirmed the depth profile and distinguished a response of the fungal community to reduced N deposition for most organic layers in spring and a roof effect for the Oe layer in autumn. These responses of the fungal community did not translate into changes in enzyme activity and lignin content and decomposition, suggesting that transformation processes in soils are well buffered despite the rapid response of the microbial community to environmental factors.
    Keywords: Soil Ecology ; Degradation Of Organic Matter ; Phenol Oxidase Activity ; Laccase - Encoding Gene Diversity ; Reduction Of N Input
    ISSN: 01686496
    E-ISSN: 1574-6941
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  • 10
    In: Journal of Ultrasound in Medicine, November 2013, Vol.32(11), pp.1979-1986
    Description: OBJECTIVES: Patients with Hashimoto thyroiditis show structural changes of the thyroid that can be identified by a variety of sonographic criteria. We conducted this study to investigate whether there is a correlation between sonography and antibody activity and to assess the role of sonography in the diagnosis and follow-up of Hashimoto thyroiditis. In addition, we present a new classification system (termed the VESINC system [volume, echogenicity, sonographic texture, pseudonodular hypoechoic infiltration, nodules, and cysts]), which helps improve the clarity of sonographic findings.METHODS: The study included 223 consecutive patients with previously diagnosed Hashimoto autoimmune thyroiditis who attended the thyroid clinic of the German Armed Forces Central Hospital in Koblenz for follow-up examinations between 2006 and 2008. Laboratory tests were performed to measure the levels of free triiodothyronine, free thyroxine, thyrotropin, anti-thyroglobulin antibodies (TgAbs), and antithyroid peroxidase antibodies (TPOAbs). Sonography was performed according to a strict protocol. We then assessed whether a correlation existed between antibody activity and the 6 sonographic variables of the VESINC system.RESULTS: Hypoechogenicity, heterogeneity, and pseudonodular hypoechoic infiltration were associated with significantly higher TPOAb activity (P 〈 .001). There were no significant correlations between the other sonographic variables examined (cysts, nodules, and volume) or the biometric data with the TPOAb and TgAb levels. In addition, an assessment of TgAb levels did not show significant differences in correlations with any of the sonographic variables.CONCLUSIONS: Sonography is a noninvasive diagnostic imaging modality that provides information about the level of inflammatory activity. Markedly decreased echogenicity, heterogeneity, and multifocal pseudoinodular hypoechoic infiltration are indicative of a high level of inflammatory activity. The sonographic classification system presented here (VESINC system) can be a useful tool for comparing sonographic findings in a rapid and objective manner during follow-up of Hashimoto thyroiditis.
    Keywords: Anti-Thyroglobulin ; Anti-Thyroid Peroxidase ; Hashimoto Thyroiditis ; Sonographic Patterns ; Sonography
    ISSN: 0278-4297
    E-ISSN: 1550-9613
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