The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Thilo Streck - One of the best experts on this subject based on the ideXlab platform.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg–Marquardt algorithm considerably improved the model performance for the period of calibration (2001–2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from −1.24 to −0.15 (Humic Gleysol) and from −0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003–2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N 2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg-Marquardt algorithm considerably improved the model performance for the period of calibration (2001-2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from -1.24 to -0.15 (Humic Gleysol) and from -0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003-2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission. 2007 Springer Science+Business Media B.V.
Marc Lamers - One of the best experts on this subject based on the ideXlab platform.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg–Marquardt algorithm considerably improved the model performance for the period of calibration (2001–2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from −1.24 to −0.15 (Humic Gleysol) and from −0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003–2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N 2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg-Marquardt algorithm considerably improved the model performance for the period of calibration (2001-2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from -1.24 to -0.15 (Humic Gleysol) and from -0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003-2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission. 2007 Springer Science+Business Media B.V.
Chandan Upadhyay - One of the best experts on this subject based on the ideXlab platform.
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redox topotactic reactions in fe ii iii oxy hydroxycarbonate new minerals related to fougerite in Gleysols trebeurdenite and mossbauerite
Hyperfine Interactions, 2012Co-Authors: J M R Genin, O Guerin, Adrien Herbillon, E Kuzmann, Stuart J Mills, Guillaume Morin, Georges Onanguema, Christian Ruby, Chandan UpadhyayAbstract:Fougerite mineral responsible for the bluish-green shade of Gleysols in aquifers was identified as FeII − III oxyhydroxycarbonate, [Fe\(^{\rm II}_{6(1-x) }\)Fe\(^{\rm III}_{6x}\)O12H2(7 − 3x)]2 + · [CO\(_{3}^{2-}\) · 3H2O]2 − where the average ferric molar fraction x = [FeIII/Fetotal] was restricted to the [1/3–2/3] range, up till now. In this paper, Mossbauer spectra of gleys extracted from the schorre of maritime marshes have values of x in the [2/3–1] range. Magnetic properties of homologous chemical compounds studied by Mossbauer spectroscopy are explained with long range order of FeIII ions within Fe cation layers for x = 1/3, 2/3 and 1. Observed values are mixtures of topotactic domains that are in fact minerals with names proposed to IMA: fougerite for x = 1/3, trebeurdenite for x = 2/3 and mossbauerite for x = 1.
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Redox topotactic reactions in Fe II − III (oxy)hydroxycarbonate new minerals related to fougèrite in Gleysols: “trébeurdenite and mössbauerite”
Hyperfine Interactions, 2012Co-Authors: J M R Genin, O Guerin, Adrien Herbillon, E Kuzmann, Stuart J Mills, Guillaume Morin, Christian Ruby, Georges Ona-nguema, Chandan UpadhyayAbstract:Fougerite mineral responsible for the bluish-green shade of Gleysols in aquifers was identified as FeII − III oxyhydroxycarbonate, [Fe\(^{\rm II}_{6(1-x) }\)Fe\(^{\rm III}_{6x}\)O12H2(7 − 3x)]2 + · [CO\(_{3}^{2-}\) · 3H2O]2 − where the average ferric molar fraction x = [FeIII/Fetotal] was restricted to the [1/3–2/3] range, up till now. In this paper, Mossbauer spectra of gleys extracted from the schorre of maritime marshes have values of x in the [2/3–1] range. Magnetic properties of homologous chemical compounds studied by Mossbauer spectroscopy are explained with long range order of FeIII ions within Fe cation layers for x = 1/3, 2/3 and 1. Observed values are mixtures of topotactic domains that are in fact minerals with names proposed to IMA: fougerite for x = 1/3, trebeurdenite for x = 2/3 and mossbauerite for x = 1.
Joachim Ingwersen - One of the best experts on this subject based on the ideXlab platform.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg–Marquardt algorithm considerably improved the model performance for the period of calibration (2001–2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from −1.24 to −0.15 (Humic Gleysol) and from −0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003–2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission.
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Modelling nitrous oxide emission from water-logged soils of a spruce forest ecosystem using the biogeochemical model Wetland-DNDC
Biogeochemistry, 2007Co-Authors: Marc Lamers, Joachim Ingwersen, Thilo StreckAbstract:During the last decades, decision makers and policy have increasingly demanded for regional and national inventories of greenhouse gas emission, such as nitrous oxide (N2O), to develop appropriate strategies and mitigation options. A potential way to derive large-scale estimates of N 2O emission is the use of process-based models, such as PnET-N-DNDC or Wetland-DNDC. While PnET-N-DNDC has been effectively applied for various upland forest ecosystems, the Wetland-DNDC model has not yet been validated with regard to N2O emission. We calibrated and validated the Wetland-DNDC model on the basis of a 4-year field data set of two water-logged soils (Humic Gleysol and Histic Gleysol) of a spruce forest ecosystem. Model calibration by means of the Levenberg-Marquardt algorithm considerably improved the model performance for the period of calibration (2001-2002). The error variance was reduced by up to a factor of two and the modelling efficiency was increased from -1.24 to -0.15 (Humic Gleysol) and from -0.42 to 0.1 (Histic Gleysol). However, the model performance for the period of validation (2003-2004) and particularly for the extreme dry period in summer 2003 was not fully satisfying, notably with regard to the temporal pattern of the N2O emission. 2007 Springer Science+Business Media B.V.
Neli Jordanova - One of the best experts on this subject based on the ideXlab platform.
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The magnetism of soils distinguished by iron/aluminum chemistry: Planosols, Pozdols, Andosols, Ferralsols, and Gleysols
Soil Magnetism, 2017Co-Authors: Neli JordanovaAbstract:In this chapter, detailed magnetic studies of soil profiles of Planosols, Pozdols, Andosols, Ferralsols, and Gleysols give an overview of the diversity and sensitivity of soil magnetic properties to various environmental settings. The magnetic signature of three Planosol profiles consistently demonstrates nonsynchronous distribution of the different magnetic grain-size fractions along the depth, related to the specific hydrologic regimen. Podzols, despite being dominated by amorphous iron oxide forms, show in their magnetic signature the presence of a magnetically soft stable (single-domain) mineral component of pedogenic origin. Magnetism of Andosols, though dominated by lithology-inherited magnetic fraction, could also be used for their pedogenic characterization. Magnetism of highly weathered tropical Ferralsols can be regarded as an ultimate expression of iron oxide transformations under oxic conditions but their magnetic signature needs further elucidation. Magnetic properties of Gleysols demonstrate the effects of reductive dissolution of iron oxides in soils.
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the magnetism of soils distinguished by iron aluminum chemistry planosols pozdols andosols ferralsols and Gleysols
Soil Magnetism#R##N#Applications in Pedology Environmental Science and Agriculture, 2017Co-Authors: Neli JordanovaAbstract:In this chapter, detailed magnetic studies of soil profiles of Planosols, Pozdols, Andosols, Ferralsols, and Gleysols give an overview of the diversity and sensitivity of soil magnetic properties to various environmental settings. The magnetic signature of three Planosol profiles consistently demonstrates nonsynchronous distribution of the different magnetic grain-size fractions along the depth, related to the specific hydrologic regimen. Podzols, despite being dominated by amorphous iron oxide forms, show in their magnetic signature the presence of a magnetically soft stable (single-domain) mineral component of pedogenic origin. Magnetism of Andosols, though dominated by lithology-inherited magnetic fraction, could also be used for their pedogenic characterization. Magnetism of highly weathered tropical Ferralsols can be regarded as an ultimate expression of iron oxide transformations under oxic conditions but their magnetic signature needs further elucidation. Magnetic properties of Gleysols demonstrate the effects of reductive dissolution of iron oxides in soils.