<p>... more <p>The degrading impact of wind on agricultural soils has been observed throughout centuries in the Pannonian region of central Europe. Nevertheless, soil loss was not yet quantified and the extent or relevance of the problem are unknown for this agriculturally important region. Especially dry soil surface is highly prone to erosion and as drought periods are expected to become more frequent and severe with changing climate, the risk of wind erosion will increase accordingly. Living windbreaks and similar agro-forestry systems are supposed to be highly effective measures against wind erosion. In an extensive research project, multiple approaches are integrated to obtain a broad view onto the relevance of soil degradation by wind on plot scale and its regional distribution.</p><p>More in detail, case studies are conducted where the soil loss by wind erosion is measured in sediment traps. Data about driving and stabilizing factors like wind speed, soil moisture, vegetation density etc. are measured in high spatial and temporal resolution. The measurements started in December 2019. Besides, wind erosion risk is modelled and mapped on regional scale applying state-of-the-art model procedures. The measurement results are used in an attempt to down-scale the model application and thus create a link to ground-truth data. Information about spatial and temporal variability of the driving factors is used for implementation of stochastic calculation procedures in a sensitivity study which determines the most relevant factors for wind erosion mitigation.</p><p>The used modelling approach also includes the effects of wind shelters what enables a partly evaluation of the existing network of such elements in the Pannonian region. There, the Authority of Land Reform has been supporting and documenting the installation of wind shelters for more than 60 years. Incorporating this data base, quantitative and qualitative statements will be developed about the state of the shelter belts and their relevance concerning erosion rates. Additionally, the potential and actual value of living windbreaks will be determined with special regards to physiological and ecological characteristics, stability under future climate conditions and further ecosystem services in agricultural landscapes.</p>
Fire is a major factor controlling global carbon (C) and nitrogen (N) cycling. While direct C and... more Fire is a major factor controlling global carbon (C) and nitrogen (N) cycling. While direct C and N losses caused by combustion have been comparably well established, important knowledge gaps remain on postfire N losses. Here, we quantified both direct C and N combustion losses as well as postfire gaseous losses (N O, NO and N ) and N leaching after a high-intensity experimental fire in an old shrubland in central Spain. Combustion losses of C and N were 9.4 Mg C/ha and 129 kg N/ha, respectively, representing 66% and 58% of initial aboveground vegetation and litter stocks. Moreover, fire strongly increased soil mineral N concentrations by several magnitudes to a maximum of 44 kg N/ha 2 months after the fire, with N largely originating from dead soil microbes. Postfire soil emissions increased from 5.4 to 10.1 kg N ha year for N , from 1.1 to 1.9 kg N ha year for NO and from 0.05 to 0.2 kg N ha year for N O. Maximal leaching losses occurred 2 months after peak soil mineral N conce...
The relevance of soil greenhouse gas (GHG) fluxes from temperate floodplain forests has yet remai... more The relevance of soil greenhouse gas (GHG) fluxes from temperate floodplain forests has yet remained elusive. We studied the soil methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) dynamics at three forest sites along a flooding gradient in the Danube National Park (Austria) to estimate annual GHG budgets and to assess if and how seasonal flooding affects individual GHG fluxes. Soil surface GHG fluxes were determined along with GHG concentrations in soil air and pore-water at a non-flooded (NF), an infrequently-flooded (IF), and a frequently-flooded (FF) site. Both study years were characterized by dry summers, and only the FF site was flooded during the study period. Soils at all sites were annual CH4 sinks (NF: − 4.50 ± 0.85, IF: − 2.54 ± 0.57, FF: − 0.67 ± 1.06 kg CH4-C ha−1 year−1) and the sink strength correlated positively with soil moisture. Pulse-like CH4 emissions were not observed during or after flooding. Soil N2O fluxes showed large temporal and spatial variations, without any significant differences between sites (average NF: 6.5 ± 7.1, IF: 10.4 ± 14.3, FF: 9.4 ± 10.5 µg N2O-N m−2 h−1). Pulse N2O emissions (up to ~ 80 µg N2O-N m−2 h−1) occurred during freeze/thaw events, but not during or after flooding. Mean annual soil CO2 effluxes at NF and IF were 9.4 ± 1.1 and 9.4 ± 2.1 t C ha−1 year−1, respectively. Soil CO2 efflux was significantly higher at the FF site (18.54 ± 6.21 t C ha−1 year−1). High soil air CO2 concentrations (> 10%) in aerated deeper soil layers indicated a substantial contribution of the usually waterlogged sub-soils to the summertime soil CO2 efflux at the FF site. Overall, our results suggest that the studied temperate floodplain forest soils do not absorb/emit substantially more CH4 and N2O than soils of comparable upland forests, whereas low groundwater level can lead to periodically enhanced CO2 emissions from normally waterlogged soil layers.
Biochar application to agricultural soils has been increasingly promoted worldwide. However, this... more Biochar application to agricultural soils has been increasingly promoted worldwide. However, this may be accompanied by unexpected side effects in terms of trace element (TE) behavior. We used a greenhouse pot experiment to study the influence of woodchip-derived biochar (wcBC) on leaching and plant concentration of various TEs (Al, Cd, Cu, Pb, Mn, As, B, Mo, Se). Three different agricultural soils from Austria (Planosol, Cambisol, Chernozem) were treated with wcBC at application rates of 1 and 3% (w/w) and subsequently planted with mustard (Sinapis alba L.). Soil samples were taken 0 and 7 months after the start of the pot experiment, and leachate water was collected twice (days 0 and 54). The extractability (with NH4NO3) of cationic TEs was decreased in the (acidic) Planosol and Cambisol after wcBC application, whereas in the (neutral) Chernozem it hardly changed. In contrast, anionic TEs were mobilized in all three soils, which resulted in higher anion concentrations in the leachates. The application of wcBC had no effect on Al and Pb in the mustard plants, but increased their B and Mo concentrations and decreased their Cd, Cu and Mn concentrations. A two-way analysis of variance showed significant interactions between wcBC application rate and soil type for most TEs, which indicates that different soil types may react differently upon wcBC application. Correlation and partial correlation analyses revealed that TE behavior was primarily related to soil pH, whereas the involvement of other factors such as electrical conductivity (EC), organic carbon (OC) content and dissolved organic carbon (DOC) was found to be more soil and TE-specific. The application of wcBC may be a useful strategy for the remediation of soils with elevated levels of cationic TEs, but could lead to deficiencies of cationic micronutrients and enhance short-term translocation of anionic TEs towards the groundwater at high leaching rates.
Denitrification is an anaerobic key process by microbes where the NO3- is step-by-step reduced an... more Denitrification is an anaerobic key process by microbes where the NO3- is step-by-step reduced and emitted as NO, N2O and finally N2 gas from the soil. Accurate knowledge on denitrification dynamics is important because the N2O is further reduced to N2 and constitutes the main emission source of this greenhouse gas from agricultural soils. Hence, our understanding and ability to quantify soil denitrification is crucial for mitigating nitrogen fertilizer loss as well as for reducing N2O emissions. Models can be an important tool to predict mitigation effects and help to develop climate smart mitigation strategies. Ideally, commonly used biogeochemical models could provide adequate predictions of denitrification processes of agricultural soils but often simplified process descriptions and inadequate model parameters prevent models from simulating adequate fluxes of N2 and N2O on field scale. Model development and parametrization often suffers from limited availability of empirical dat...
Klimaszenarien fur den Pannonischen Raum weisen auf eine Zunahme der Lange und Anzahl der Trocken... more Klimaszenarien fur den Pannonischen Raum weisen auf eine Zunahme der Lange und Anzahl der Trockenperioden und auf eine Konzentration der Niederschlage auf wenige Ereignisse hin. Ziel der Studie war es, die Auswirkungen von klimainduziertem Stress und Starkregenereignissen auf mikrobielle Eigenschaften in landwirtschaftlichen Boden zu erfassen. Von Oktober 2011 bis November 2016 wurden hierzu in einem Freilandversuch mit kontrollierter Beregnung mehrmals pro Jahr unter anderem Enzymaktivitaten (Cellulase, Xylanase, Protease, Peroxidase und Phenoloxidase) bestimmt. Als Versuchsstandort diente die Lysimeteranlage Hirschstetten im Nordosten Wiens. Je drei Lysimeter pro Bodentyp (Feuchtschwarzerde, sandiger und tiefgrundiger Tschernosem) wurden Trockenperioden und Starkregenereignissen unterworfen („dry“; Variante D). Die Beregnungsmenge und -verteilung fur die ubrigen Lysimeter (Kontrolle) orientierte sich am langjahrigen Niederschlagsmittel. Die Enzymaktivitaten zeigten keine ausgeprag...
GAIA - Ecological Perspectives for Science and Society, 2012
ABSTRACT Organische Reststoffe, die als Biokohle in Ackerböden eingearbeitet werden, können die B... more ABSTRACT Organische Reststoffe, die als Biokohle in Ackerböden eingearbeitet werden, können die Bodenqualität verbessern. Doch die Biokohleproduktion erfordert die Einhaltung standar disierter Qualitätskriterien, um die Gefahr von Schadstoffeinträgen zu minimieren.
Inland surface waters and associated wetlands must not be neglected when global greenhouse gas em... more Inland surface waters and associated wetlands must not be neglected when global greenhouse gas emissions are balanced. Natural lakes, rivers and hydroelectric reservoirs are parts of the surface water system where outgassing of CO2 or CH4 enhances the carbon flux to the atmosphere. For lakes, the carbon emission estimates vary over several orders of magnitude, depending on the age of the lake, depth, area, volume, temperature, input of organic carbon and residence time. Nitrogen input into lakes may be caused by wet atmospheric deposition, by surface runoff from agricultural areas and by wastewater inputs into the tributaries. In most cases, denitrification of nitrate is the dominating source of N2O; only in the case of high ammonium loads and oxygen availability nitrification and subsequent denitrification to N2O and N2 play a major role. Focusing on Lake Neusiedl (Austria) as case study, this study aims at illuminating the regional role of a shallow steppe lake as greenhouse gas e...
Gaia: Okologische Perspektiven in Natur-, Geistes- und Wirtschaftswissenschaften
Holzkohle in den Ackerboden? Dieser Vorschlag ist weder neu noch abwegig. In Form von Biokohle (e... more Holzkohle in den Ackerboden? Dieser Vorschlag ist weder neu noch abwegig. In Form von Biokohle (engl. „biochar“) können uns organische Reststoffe als innovative High-Tech-Bodenadditive begegnen. Moderne Biokohlen versprechen Heilung bei Umwelt-Krankheiten wie Boden-Degradation, Nährstoffmangel von Kulturpflanzen, Treibhausgas-Emissionen des Bodens und Schadstoff-Anreicherung im Grundwasser. Doch auch bei diesen Mitteln ist man vor unerwünschten Nebenwirkungen nicht gefeit - eine sorgfältige Risikoabschätzung tut Not.
ABSTRACT Greenhouse gas emissions of Lake Neusiedl, the westernmost European shallow steppe lake,... more ABSTRACT Greenhouse gas emissions of Lake Neusiedl, the westernmost European shallow steppe lake, were analysed to identify differences between the seasons of the years and between different locations in the pelagic zone and reed belt. Emissions of CO2, CH4 and N2O were measured in gas samples that had been recovered from the gas space of floating chambers operated as closed systems. Sampling periods covered all seasons except winter. Scaled up to the whole lake area (320 km2), the diffusive emissions of spring, summer and autumn totalled to about 79,500 t CO2e, disregarding bubble emissions, winter emissions and plant-mediated emissions. The emission sum consisted of about 57,000 t CO2, 760 t CH4, and 12 t N2O. Approximately one-third of the methane and carbon dioxide emissions originated in the pelagic zone and two-thirds in the reed belt (without plant emissions) whereas nitrous oxide emissions were similar in these two zones. An estimate of ebullitive emissions resulted in additional 1,765 t CH4 that predominantly originated in or near the reed belt from spring to autumn.
Abstract. Forest soils are a significant source for the primary and secondary greenhouse gases N ... more Abstract. Forest soils are a significant source for the primary and secondary greenhouse gases N 2 O and NO. However, current estimates are still uncertain due to the still limited number of field measurements and the herein observed pronounced variability of N trace gas fluxes in space and time, which are due to the variation of environmental factors such as soil and vegetation properties or meteorological conditions. To overcome these problems we further developed a process-oriented model, the PnET-N-DNDC model, which simulates the N trace gas exchange on the basis of the processes involved in production, consumption and emission of N trace gases. This model was validated against field observations of N trace gas fluxes from 19 sites obtained within the EU project NOFRETETE, and shown to perform well for N 2 O (r 2 =0.68, slope=0.76) and NO (r 2 =0.78, slope=0.73). For the calculation of a European-wide emission inventory we linked the model to a detailed, regionally and temporall...
Inland surface waters and associated wetlands must not be neglected when global greenhouse gas em... more Inland surface waters and associated wetlands must not be neglected when global greenhouse gas emissions are balanced. Natural lakes, rivers and hydroelectric reservoirs are parts of the surface water system where outgassing of CO2 or CH4 enhances the carbon flux to the atmosphere. For lakes, the carbon emission estimates vary over several orders of magnitude, depending on the age of the lake, depth, area, volume, temperature, input of organic carbon and residence time. Nitrogen input into lakes may be caused by wet atmospheric deposition, by surface runoff from agricultural areas and by wastewater inputs into the tributaries. In most cases, denitrification of nitrate is the dominating source of N2O; only in the case of high ammonium loads and oxygen availability nitrification and subsequent denitrification to N2O and N2 play a major role. Focusing on Lake Neusiedl (Austria) as case study, this study aims at illuminating the regional role of a shallow steppe lake as greenhouse gas e...
<p>... more <p>The degrading impact of wind on agricultural soils has been observed throughout centuries in the Pannonian region of central Europe. Nevertheless, soil loss was not yet quantified and the extent or relevance of the problem are unknown for this agriculturally important region. Especially dry soil surface is highly prone to erosion and as drought periods are expected to become more frequent and severe with changing climate, the risk of wind erosion will increase accordingly. Living windbreaks and similar agro-forestry systems are supposed to be highly effective measures against wind erosion. In an extensive research project, multiple approaches are integrated to obtain a broad view onto the relevance of soil degradation by wind on plot scale and its regional distribution.</p><p>More in detail, case studies are conducted where the soil loss by wind erosion is measured in sediment traps. Data about driving and stabilizing factors like wind speed, soil moisture, vegetation density etc. are measured in high spatial and temporal resolution. The measurements started in December 2019. Besides, wind erosion risk is modelled and mapped on regional scale applying state-of-the-art model procedures. The measurement results are used in an attempt to down-scale the model application and thus create a link to ground-truth data. Information about spatial and temporal variability of the driving factors is used for implementation of stochastic calculation procedures in a sensitivity study which determines the most relevant factors for wind erosion mitigation.</p><p>The used modelling approach also includes the effects of wind shelters what enables a partly evaluation of the existing network of such elements in the Pannonian region. There, the Authority of Land Reform has been supporting and documenting the installation of wind shelters for more than 60 years. Incorporating this data base, quantitative and qualitative statements will be developed about the state of the shelter belts and their relevance concerning erosion rates. Additionally, the potential and actual value of living windbreaks will be determined with special regards to physiological and ecological characteristics, stability under future climate conditions and further ecosystem services in agricultural landscapes.</p>
Fire is a major factor controlling global carbon (C) and nitrogen (N) cycling. While direct C and... more Fire is a major factor controlling global carbon (C) and nitrogen (N) cycling. While direct C and N losses caused by combustion have been comparably well established, important knowledge gaps remain on postfire N losses. Here, we quantified both direct C and N combustion losses as well as postfire gaseous losses (N O, NO and N ) and N leaching after a high-intensity experimental fire in an old shrubland in central Spain. Combustion losses of C and N were 9.4 Mg C/ha and 129 kg N/ha, respectively, representing 66% and 58% of initial aboveground vegetation and litter stocks. Moreover, fire strongly increased soil mineral N concentrations by several magnitudes to a maximum of 44 kg N/ha 2 months after the fire, with N largely originating from dead soil microbes. Postfire soil emissions increased from 5.4 to 10.1 kg N ha year for N , from 1.1 to 1.9 kg N ha year for NO and from 0.05 to 0.2 kg N ha year for N O. Maximal leaching losses occurred 2 months after peak soil mineral N conce...
The relevance of soil greenhouse gas (GHG) fluxes from temperate floodplain forests has yet remai... more The relevance of soil greenhouse gas (GHG) fluxes from temperate floodplain forests has yet remained elusive. We studied the soil methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) dynamics at three forest sites along a flooding gradient in the Danube National Park (Austria) to estimate annual GHG budgets and to assess if and how seasonal flooding affects individual GHG fluxes. Soil surface GHG fluxes were determined along with GHG concentrations in soil air and pore-water at a non-flooded (NF), an infrequently-flooded (IF), and a frequently-flooded (FF) site. Both study years were characterized by dry summers, and only the FF site was flooded during the study period. Soils at all sites were annual CH4 sinks (NF: − 4.50 ± 0.85, IF: − 2.54 ± 0.57, FF: − 0.67 ± 1.06 kg CH4-C ha−1 year−1) and the sink strength correlated positively with soil moisture. Pulse-like CH4 emissions were not observed during or after flooding. Soil N2O fluxes showed large temporal and spatial variations, without any significant differences between sites (average NF: 6.5 ± 7.1, IF: 10.4 ± 14.3, FF: 9.4 ± 10.5 µg N2O-N m−2 h−1). Pulse N2O emissions (up to ~ 80 µg N2O-N m−2 h−1) occurred during freeze/thaw events, but not during or after flooding. Mean annual soil CO2 effluxes at NF and IF were 9.4 ± 1.1 and 9.4 ± 2.1 t C ha−1 year−1, respectively. Soil CO2 efflux was significantly higher at the FF site (18.54 ± 6.21 t C ha−1 year−1). High soil air CO2 concentrations (> 10%) in aerated deeper soil layers indicated a substantial contribution of the usually waterlogged sub-soils to the summertime soil CO2 efflux at the FF site. Overall, our results suggest that the studied temperate floodplain forest soils do not absorb/emit substantially more CH4 and N2O than soils of comparable upland forests, whereas low groundwater level can lead to periodically enhanced CO2 emissions from normally waterlogged soil layers.
Biochar application to agricultural soils has been increasingly promoted worldwide. However, this... more Biochar application to agricultural soils has been increasingly promoted worldwide. However, this may be accompanied by unexpected side effects in terms of trace element (TE) behavior. We used a greenhouse pot experiment to study the influence of woodchip-derived biochar (wcBC) on leaching and plant concentration of various TEs (Al, Cd, Cu, Pb, Mn, As, B, Mo, Se). Three different agricultural soils from Austria (Planosol, Cambisol, Chernozem) were treated with wcBC at application rates of 1 and 3% (w/w) and subsequently planted with mustard (Sinapis alba L.). Soil samples were taken 0 and 7 months after the start of the pot experiment, and leachate water was collected twice (days 0 and 54). The extractability (with NH4NO3) of cationic TEs was decreased in the (acidic) Planosol and Cambisol after wcBC application, whereas in the (neutral) Chernozem it hardly changed. In contrast, anionic TEs were mobilized in all three soils, which resulted in higher anion concentrations in the leachates. The application of wcBC had no effect on Al and Pb in the mustard plants, but increased their B and Mo concentrations and decreased their Cd, Cu and Mn concentrations. A two-way analysis of variance showed significant interactions between wcBC application rate and soil type for most TEs, which indicates that different soil types may react differently upon wcBC application. Correlation and partial correlation analyses revealed that TE behavior was primarily related to soil pH, whereas the involvement of other factors such as electrical conductivity (EC), organic carbon (OC) content and dissolved organic carbon (DOC) was found to be more soil and TE-specific. The application of wcBC may be a useful strategy for the remediation of soils with elevated levels of cationic TEs, but could lead to deficiencies of cationic micronutrients and enhance short-term translocation of anionic TEs towards the groundwater at high leaching rates.
Denitrification is an anaerobic key process by microbes where the NO3- is step-by-step reduced an... more Denitrification is an anaerobic key process by microbes where the NO3- is step-by-step reduced and emitted as NO, N2O and finally N2 gas from the soil. Accurate knowledge on denitrification dynamics is important because the N2O is further reduced to N2 and constitutes the main emission source of this greenhouse gas from agricultural soils. Hence, our understanding and ability to quantify soil denitrification is crucial for mitigating nitrogen fertilizer loss as well as for reducing N2O emissions. Models can be an important tool to predict mitigation effects and help to develop climate smart mitigation strategies. Ideally, commonly used biogeochemical models could provide adequate predictions of denitrification processes of agricultural soils but often simplified process descriptions and inadequate model parameters prevent models from simulating adequate fluxes of N2 and N2O on field scale. Model development and parametrization often suffers from limited availability of empirical dat...
Klimaszenarien fur den Pannonischen Raum weisen auf eine Zunahme der Lange und Anzahl der Trocken... more Klimaszenarien fur den Pannonischen Raum weisen auf eine Zunahme der Lange und Anzahl der Trockenperioden und auf eine Konzentration der Niederschlage auf wenige Ereignisse hin. Ziel der Studie war es, die Auswirkungen von klimainduziertem Stress und Starkregenereignissen auf mikrobielle Eigenschaften in landwirtschaftlichen Boden zu erfassen. Von Oktober 2011 bis November 2016 wurden hierzu in einem Freilandversuch mit kontrollierter Beregnung mehrmals pro Jahr unter anderem Enzymaktivitaten (Cellulase, Xylanase, Protease, Peroxidase und Phenoloxidase) bestimmt. Als Versuchsstandort diente die Lysimeteranlage Hirschstetten im Nordosten Wiens. Je drei Lysimeter pro Bodentyp (Feuchtschwarzerde, sandiger und tiefgrundiger Tschernosem) wurden Trockenperioden und Starkregenereignissen unterworfen („dry“; Variante D). Die Beregnungsmenge und -verteilung fur die ubrigen Lysimeter (Kontrolle) orientierte sich am langjahrigen Niederschlagsmittel. Die Enzymaktivitaten zeigten keine ausgeprag...
GAIA - Ecological Perspectives for Science and Society, 2012
ABSTRACT Organische Reststoffe, die als Biokohle in Ackerböden eingearbeitet werden, können die B... more ABSTRACT Organische Reststoffe, die als Biokohle in Ackerböden eingearbeitet werden, können die Bodenqualität verbessern. Doch die Biokohleproduktion erfordert die Einhaltung standar disierter Qualitätskriterien, um die Gefahr von Schadstoffeinträgen zu minimieren.
Inland surface waters and associated wetlands must not be neglected when global greenhouse gas em... more Inland surface waters and associated wetlands must not be neglected when global greenhouse gas emissions are balanced. Natural lakes, rivers and hydroelectric reservoirs are parts of the surface water system where outgassing of CO2 or CH4 enhances the carbon flux to the atmosphere. For lakes, the carbon emission estimates vary over several orders of magnitude, depending on the age of the lake, depth, area, volume, temperature, input of organic carbon and residence time. Nitrogen input into lakes may be caused by wet atmospheric deposition, by surface runoff from agricultural areas and by wastewater inputs into the tributaries. In most cases, denitrification of nitrate is the dominating source of N2O; only in the case of high ammonium loads and oxygen availability nitrification and subsequent denitrification to N2O and N2 play a major role. Focusing on Lake Neusiedl (Austria) as case study, this study aims at illuminating the regional role of a shallow steppe lake as greenhouse gas e...
Gaia: Okologische Perspektiven in Natur-, Geistes- und Wirtschaftswissenschaften
Holzkohle in den Ackerboden? Dieser Vorschlag ist weder neu noch abwegig. In Form von Biokohle (e... more Holzkohle in den Ackerboden? Dieser Vorschlag ist weder neu noch abwegig. In Form von Biokohle (engl. „biochar“) können uns organische Reststoffe als innovative High-Tech-Bodenadditive begegnen. Moderne Biokohlen versprechen Heilung bei Umwelt-Krankheiten wie Boden-Degradation, Nährstoffmangel von Kulturpflanzen, Treibhausgas-Emissionen des Bodens und Schadstoff-Anreicherung im Grundwasser. Doch auch bei diesen Mitteln ist man vor unerwünschten Nebenwirkungen nicht gefeit - eine sorgfältige Risikoabschätzung tut Not.
ABSTRACT Greenhouse gas emissions of Lake Neusiedl, the westernmost European shallow steppe lake,... more ABSTRACT Greenhouse gas emissions of Lake Neusiedl, the westernmost European shallow steppe lake, were analysed to identify differences between the seasons of the years and between different locations in the pelagic zone and reed belt. Emissions of CO2, CH4 and N2O were measured in gas samples that had been recovered from the gas space of floating chambers operated as closed systems. Sampling periods covered all seasons except winter. Scaled up to the whole lake area (320 km2), the diffusive emissions of spring, summer and autumn totalled to about 79,500 t CO2e, disregarding bubble emissions, winter emissions and plant-mediated emissions. The emission sum consisted of about 57,000 t CO2, 760 t CH4, and 12 t N2O. Approximately one-third of the methane and carbon dioxide emissions originated in the pelagic zone and two-thirds in the reed belt (without plant emissions) whereas nitrous oxide emissions were similar in these two zones. An estimate of ebullitive emissions resulted in additional 1,765 t CH4 that predominantly originated in or near the reed belt from spring to autumn.
Abstract. Forest soils are a significant source for the primary and secondary greenhouse gases N ... more Abstract. Forest soils are a significant source for the primary and secondary greenhouse gases N 2 O and NO. However, current estimates are still uncertain due to the still limited number of field measurements and the herein observed pronounced variability of N trace gas fluxes in space and time, which are due to the variation of environmental factors such as soil and vegetation properties or meteorological conditions. To overcome these problems we further developed a process-oriented model, the PnET-N-DNDC model, which simulates the N trace gas exchange on the basis of the processes involved in production, consumption and emission of N trace gases. This model was validated against field observations of N trace gas fluxes from 19 sites obtained within the EU project NOFRETETE, and shown to perform well for N 2 O (r 2 =0.68, slope=0.76) and NO (r 2 =0.78, slope=0.73). For the calculation of a European-wide emission inventory we linked the model to a detailed, regionally and temporall...
Inland surface waters and associated wetlands must not be neglected when global greenhouse gas em... more Inland surface waters and associated wetlands must not be neglected when global greenhouse gas emissions are balanced. Natural lakes, rivers and hydroelectric reservoirs are parts of the surface water system where outgassing of CO2 or CH4 enhances the carbon flux to the atmosphere. For lakes, the carbon emission estimates vary over several orders of magnitude, depending on the age of the lake, depth, area, volume, temperature, input of organic carbon and residence time. Nitrogen input into lakes may be caused by wet atmospheric deposition, by surface runoff from agricultural areas and by wastewater inputs into the tributaries. In most cases, denitrification of nitrate is the dominating source of N2O; only in the case of high ammonium loads and oxygen availability nitrification and subsequent denitrification to N2O and N2 play a major role. Focusing on Lake Neusiedl (Austria) as case study, this study aims at illuminating the regional role of a shallow steppe lake as greenhouse gas e...
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Papers by B. Kitzler