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  • 1
    Language: English
    In: Environmental science & technology, 01 December 2011, Vol.45(23), pp.9984-9
    Description: A mechanistic understanding of carbon (C) sequestration and methane (CH(4)) production is of great interest due to the importance of these processes for the global C budget. Here we demonstrate experimentally, by means of column experiments, that burial of water saturated, anoxic bog peat leads to inactivation of anaerobic respiration and methanogenesis. This effect can be related to the slowness of diffusive transport of solutes and evolving energetic constraints on anaerobic respiration. Burial lowered decomposition constants in homogenized peat sand mixtures from about 10(-5) to 10(-7) yr(-1), which is considerably slower than previously assumed, and methanogenesis slowed down in a similar manner. The latter effect could be related to acetoclastic methanogenesis approaching a minimum energy quantum of -25 kJ mol(-1) (CH(4)). Given the robustness of hydraulic properties that locate the oxic-anoxic boundary near the peatland surface and constrain solute transport deeper into the peat, this effect has likely been critical for building the peatland C store and will continue supporting long-term C sequestration in northern peatlands even under moderately changing climatic conditions.
    Keywords: Methane -- Metabolism ; Soil -- Chemistry ; Water -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 2
    In: Hydrological Processes, 30 October 2013, Vol.27(22), pp.3240-3253
    Description: Exchange of groundwater and lake water with typically quite different chemical composition is an important driver for biogeochemical processes at the groundwater‐lake interface, which can affect the water quality of lakes. This is of particular relevance in mine lakes where anoxic and slightly acidic groundwater mixes with oxic and acidic lake water (pH 330 nmol g d) compared to alternating sites (〈220 nmol g d). Although differences in sulfate reduction rates could not be explained solely by different flux rates, they were clearly related to the prevailing groundwater‐lake exchange patterns and the associated pH conditions. Our findings strongly suggest that groundwater‐lake exchange has significant effects on the biogeochemical processes that are coupled to sulfate reduction such as acidity retention and precipitation of iron sulfides. Copyright © 2012 John Wiley & Sons, Ltd.
    Keywords: Groundwater‐Lake Exchange ; Acid Mine Lake ; Seepage Flux ; Ph‐Profiles ; Chloride Profiles ; Acid Neutralization Processes
    ISSN: 0885-6087
    E-ISSN: 1099-1085
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  • 3
    In: The Foundation Review, 2013, Vol.5(3)
    Description: · Foundation strategy is hampered by a failure to recognize and engage with the complexity and uncertainty surrounding foundation work. This article identifies three common “traps” that hinder foundation capacity to learn and adapt: 1) linearity and certainty bias; 2) the autopilot effect; and 3) indicator blindness. · This article urges foundations to alter their mindset, questions, and processes to foster a more committed approach to strategy and adaptation. In essence, it argues for learning as strategy. · This article draws on literature from systems theory, business strategy, and philanthropic practice as well as data from foundation benchmarking surveys.
    Keywords: Social Welfare & Social Work;
    E-ISSN: 1944-5660
    E-ISSN: 19445679
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  • 4
    In: The Foundation Review, 2013, Vol.5(2)
    Description: · Evaluation in philanthropy – with staff assigned to evaluation-related responsibilities – began in the 1970s and has evolved, along with philanthropy, in the four decades since. What has not changed, however, is a regular questioning of what foundations are doing on evaluation, especially since the world of philanthropy regularly shifts, and changes in evaluation resourcing and positioning tend to soon follow. · This article presents new findings about what foundations are doing on evaluation and discusses their implications. It is based on 2012 research that benchmarks the positioning, resourcing, and function of evaluation in foundations, and follows up on a 2009 study that used a similar design. · The participating foundations were surveyed and interviewed. They were asked about the range of activities they used to produce evaluative information about grantmaking, perceptions about the adequacy staff time and money for evaluation, and how and how well they use evaluative information throughout the life cycle of grantmaking programs and strategies. · Benchmarking research was conducted for the Evaluation Roundtable, a network of foundations seeking to improve how they learn about the results of their grantmaking and enhance the difference they make.
    Keywords: Social Welfare & Social Work;
    E-ISSN: 1944-5660
    E-ISSN: 19445679
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  • 5
    Language: English
    In: Geochimica et Cosmochimica Acta, 2007, Vol.71(12), pp.2989-3002
    Description: Rates of anaerobic respiration are of central importance for the long-term burial of carbon (C) in peatlands, which are a relevant sink in the global C cycle. To identify constraints on anaerobic peat decomposition, we determined detailed concentration depth profiles of decomposition end-products, i.e. methane (CH ) and dissolved inorganic carbon (DIC), along with concentrations of relevant decomposition intermediates at an ombrotrophic Canadian peat bog. The magnitude of in situ net production rates of DIC and CH was estimated by inverse pore-water modeling. Vertical transport in the peat was slow and dominated by diffusion leading to the buildup of DIC and CH with depth (5500 μmol L DIC, 500 μmol L CH ). Highest DIC and CH production rates occurred close to the water table (decomposition constant ∼ 10 –10 a ) or in some distinct zones at depth ( ∼ 10 a ). Deeper into the peat, decomposition proceeded very slowly at about = 10 a . This pattern could be related to thermodynamic and transport constraints. The accumulation of metabolic end-products diminished in situ energy yields of acetoclastic methanogenesis to the threshold for microbially mediated processes (−20 to −25 kJ mol CH ). The methanogenic precursor acetate also accumulated (150 μmol L ). In line with these findings, CH was formed by hydrogenotrophic methanogenesis at Gibbs free energies of −35 to −40 kJ mol CH . This was indicated by an isotopic fractionation of 1.069–1.079. Fermentative degradation of acetate, propionate and butyrate attained Gibbs free energies close to 0 kJ mol substrate. Although methanogenesis was apparently limited by some other factor in some peat layers, transport and thermodynamic constraints likely impeded respiratory processes in the deeper peat. Constraints on the removal of DIC and CH may thus slow decomposition and contribute to the sustained burial of C in northern peatlands.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 6
    Language: English
    In: Global change biology, 2007, Vol.13(8), pp.1771-1785
    Description: We investigated electron transfer processes of dissolved organic matter (DOM) and their potential importance for anaerobic heterotrophic respiration in a northern peatland. Electron accepting and donating capacities (EAC, EDC) of DOM were quantified using dissolved H₂S and ferric iron as reactants. Carbon turnover rates were obtained from porewater profiles (CO₂, CH₄) and inverse modeling. Carbon dioxide was released at rates of 0.2-5.9 mmol m⁻² day⁻¹ below the water table. Methane (CH₄) formation contributed 〈10%, and oxygen consumption 2% to 40%, leaving a major fraction of CO₂ production unexplained. DOM oxidized H₂S to thiosulfate and was reduced by dissolved ferric iron. Reduction with H₂S increased the subsequently determined EDC compared to untreated controls, indicating a reversibility of the electron transfer. In situ redox capacities of DOM ranged from 0.2 to 6.1 mEq g⁻¹ C (EAC) and from 0.0 to 1.4 mEq g⁻¹ C (EDC), respectively. EAC generally decreased with depth and changed after a water table drawdown and rebound by 20 and -45 mEq m⁻², respectively. The change in EAC during the water table fluctuation was similar to CH₄ formation rates. In peatlands, electron transfer of DOM may thus significantly contribute to the oxidation of reduced organic substrates by anaerobic heterotrophic respiration, or by maintaining the respiratory activity of sulfate reducers via provision of thiosulfate. Part of the anaerobic electron flow in peat soils is thus potentially diverted from methanogenesis, decreasing its contribution to the total carbon emitted to the atmosphere. ; Includes references ; p. 1771-1785.
    Keywords: Humic Substances ; Dom ; Thiosulfate ; Peatland ; Sulfide Oxidation ; Doc ; Carbon Cycling
    ISSN: 1354-1013
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  • 7
    In: Limnology and Oceanography, July 2008, Vol.53(4), pp.1393-1407
    Description: The decomposition of deep peat deposits controls the long‐term carbon balance of peatlands but is poorly understood with respect to rates and controls. To rectify this deficiency, we estimated in situ dissolved inorganic carbon (DIC) and methane (CH) production rates from a beaver pond to a central bog dome and related them to organic matter properties, Gibbs free energies of respiration, and δC values of DIC and CH. DIC and CH production decreased from maxima of ~10 nmol cm d near the water table to values 1 m, and there was little differentiation among sites. Deeper into the peat, we measured an accumulation of DIC, CH, and dissolved organic matter (DOM) enriched in aromatic and phenolic moieties, which resulted from the slowness of diffusive vertical pore‐water movement. Lack of transport may have slowed decomposition in two ways: (1) Aromatic and phenolic DOM moieties accumulated, while the release of carbohydrate‐rich DOM from peat was apparently impeded. (2) The accumulation of DIC and CH reduced Gibbs free energy of acetoclastic methanogenesis toward a critical threshold value of ‐25 to ‐20 kJ mol CH. Hydrogenotrophic methanogenesis was energetically more favorable and generally dominated according to an isotopic fractionation between CO and CH of 1.053 to 1.076, but it was apparently impeded by some other factor. We conclude that lateral homogeneity and slowness of decomposition in geologically sealed deep peat deposits are assisted by a lack of solute transport, which facilitates the formation of deep peat deposits over millennia.
    Keywords: Biodegradation ; Dissolved Inorganic Carbon ; Respiration ; Dissolved Organic Matter ; Carbon Isotopes ; Wetlands ; Methanogenesis ; Peat ; Peatlands ; Deposits ; Carbon ; Decomposition ; Free Energy ; Methanogenesis ; Aromatics ; Peat ; Homogeneity ; Dissolved Solids ; Methane ; Carbon ; Decomposing Organic Matter ; Limnology ; Accumulation ; Decomposition ; Peat ; Homogeneity ; Dissolved Solids ; Methane ; Carbon ; Decomposing Organic Matter ; Limnology ; Accumulation ; Decomposition ; Peat ; Freshwater ; Ecosystem and Ecology Studies ; Organic Compounds ; Chemical Processes ; Water Resources and Supplies;
    ISSN: 0024-3590
    E-ISSN: 1939-5590
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  • 8
    In: Global Change Biology, August 2007, Vol.13(8), pp.1771-1785
    Description: We investigated electron transfer processes of dissolved organic matter (DOM) and their potential importance for anaerobic heterotrophic respiration in a northern peatland. Electron accepting and donating capacities (EAC, EDC) of DOM were quantified using dissolved HS and ferric iron as reactants. Carbon turnover rates were obtained from porewater profiles (CO, CH) and inverse modeling. Carbon dioxide was released at rates of 0.2–5.9 mmol m day below the water table. Methane (CH) formation contributed 〈10%, and oxygen consumption 2% to 40%, leaving a major fraction of CO production unexplained. DOM oxidized HS to thiosulfate and was reduced by dissolved ferric iron. Reduction with HS increased the subsequently determined EDC compared to untreated controls, indicating a reversibility of the electron transfer. redox capacities of DOM ranged from 0.2 to 6.1 mEq g C (EAC) and from 0.0 to 1.4 mEq g C (EDC), respectively. EAC generally decreased with depth and changed after a water table drawdown and rebound by 20 and −45 mEq m, respectively. The change in EAC during the water table fluctuation was similar to CH formation rates. In peatlands, electron transfer of DOM may thus significantly contribute to the oxidation of reduced organic substrates by anaerobic heterotrophic respiration, or by maintaining the respiratory activity of sulfate reducers via provision of thiosulfate. Part of the anaerobic electron flow in peat soils is thus potentially diverted from methanogenesis, decreasing its contribution to the total carbon emitted to the atmosphere.
    Keywords: Carbon Cycling ; Doc ; Dom ; Humic Substances ; Peatland ; Sulfide Oxidation ; Thiosulfate
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 9
    Language: English
    In: Analytical chemistry, 17 January 2012, Vol.84(2), pp.947-55
    Description: This work presents near-infrared spectroscopy (NIRS) as an in-line process analyzer for monitoring protein unfolding and protein-lyoprotectant hydrogen bond interactions during freeze-drying. By implementing a noncontact NIR probe in the freeze-drying chamber, spectra of formulations containing a model protein immunoglobulin G (IgG) were collected each process minute. When sublimation was completed in the cake region illuminated by the NIR probe, the frequency of the amide A/II band (near 4850 cm(-1)) was monitored as a function of water elimination. These two features were well correlated during protein dehydration in the absence of protein unfolding (desired process course), whereas consistent deviations from this trend to higher amide A/II frequencies were shown to be related to protein unfolding. In formulations with increased sucrose concentrations, the markedly decreased amide A/II frequencies seen immediately after sublimation indicated an increased extent of hydrogen bond interaction between the protein's backbone and surrounding molecules. At the end of drying, there was evidence of nearly complete water substitution for formulations with 1%, 5%, and 10% sucrose. The presented approach shows promising perspectives for early fault detection of protein unfolding and for obtaining mechanistic process information on actions of lyoprotectants.
    Keywords: Freeze Drying ; Protein Unfolding ; Spectroscopy, Near-Infrared ; Amides -- Chemistry ; Excipients -- Chemistry ; Immunoglobulin G -- Chemistry ; Water -- Chemistry
    ISSN: 00032700
    E-ISSN: 1520-6882
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  • 10
    Language: English
    In: Manual Therapy, June 2012, Vol.17(3), pp.219-224
    Description: Deep cervical flexor (DCF) muscle impairment is common in patients with neck pain. Retraining function is often commenced with a motor relearning approach, requiring the patient to practice and hold a cranio-cervical flexion position in supine lying. Motor relearning requires multiple repetitions which is difficult to achieve if only exercising in supine. This preliminary study investigated the effects of training the DCF with a functional exercise: assumption of an upright lumbo-pelvic and spinal postural position, adding a neck lengthening manoeuvre. The exercise effect was evaluated by changes in sternocleidomastoid (SCM) muscle activity in the cranio-cervical flexion test (CCFT). Twenty subjects with neck pain were randomly assigned to an exercise or control group. The exercise group trained for two weeks. Pre and post-intervention, electromyographic (EMG) signals were recorded from the SCM muscles during the five stages of the CCFT. Results indicated that the exercise improved performance. SCM EMG signal amplitudes decreased across all CCFT stages, albeit significant only at the first and third stages of the test; 22 mmHg (  = 0.043) and 26 mmHg (  = 0.003). No differences were evident in the control group (all  〉 0.05). There was no difference between groups for pain and disability measures. This initial study indicates that a postural exercise, convenient to perform during the working day, improves the pattern of SCM muscle activity in the CCFT. Whilst further research is necessary, these observations suggest the worth of such an exercise to augment other training in the rehabilitation of patients with neck pain.
    Keywords: Neck Pain ; Cervical Flexors ; Cranio-Cervical Flexion Test ; Exercise ; Physical Therapy
    ISSN: 1356-689X
    E-ISSN: 1532-2769
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