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Qianlai Zhuang - One of the best experts on this subject based on the ideXlab platform.
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equifinality in parameterization of process based Biogeochemistry models a significant uncertainty source to the estimation of regional carbon dynamics
Journal of Geophysical Research, 2008Co-Authors: Jinyun Tang, Qianlai ZhuangAbstract:[1] Numerical Biogeochemistry models suffer from equifinality problem in their parameterizations using eddy flux tower data, which can contribute to diverged estimates of regional carbon dynamics. To date, the uncertainty in regional estimates propagated from the site-level parameterization equifinality has not been well characterized. Here, we use a process-based Biogeochemistry model, the Terrestrial Ecosystem Model (TEM), and a Bayesian inference framework to quantify the influence of parameterization equifinality on the estimates of carbon dynamics in boreal forest ecosystems during the 20th century. By conducting three groups of ensemble regional simulations, we find that, given a certain climate data set being used, (1) in comparison to the effects of random noises in climate forcing, the regional uncertainty due to parameterization equifinality is remarkably greater, (2) the parameterization equifinality results in drastically different decadal variations in the estimation of carbon storage during the 20th century, and (3) the uncertainties associated with parameterization equifinality and random noises in climate forcing vary both spatially and seasonally. We conclude that the equifinality from site-level parameterizations in Biogeochemistry models is an important uncertainty source in estimating regional carbon dynamics. Simply extrapolating the site-level parameterization to large spatial and temporal scales could bias the regional estimates irrespective of regional climate data sets used in our analysis. Ensemble process-based Biogeochemistry model simulations conditioned on observed ecosystem fluxes with Bayesian inference techniques could provide more serious estimates of regional carbon dynamics and their associated uncertainties.
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Equifinality in parameterization of process‐based Biogeochemistry models: A significant uncertainty source to the estimation of regional carbon dynamics
Journal of Geophysical Research: Biogeosciences, 2008Co-Authors: Jinyun Tang, Qianlai ZhuangAbstract:[1] Numerical Biogeochemistry models suffer from equifinality problem in their parameterizations using eddy flux tower data, which can contribute to diverged estimates of regional carbon dynamics. To date, the uncertainty in regional estimates propagated from the site-level parameterization equifinality has not been well characterized. Here, we use a process-based Biogeochemistry model, the Terrestrial Ecosystem Model (TEM), and a Bayesian inference framework to quantify the influence of parameterization equifinality on the estimates of carbon dynamics in boreal forest ecosystems during the 20th century. By conducting three groups of ensemble regional simulations, we find that, given a certain climate data set being used, (1) in comparison to the effects of random noises in climate forcing, the regional uncertainty due to parameterization equifinality is remarkably greater, (2) the parameterization equifinality results in drastically different decadal variations in the estimation of carbon storage during the 20th century, and (3) the uncertainties associated with parameterization equifinality and random noises in climate forcing vary both spatially and seasonally. We conclude that the equifinality from site-level parameterizations in Biogeochemistry models is an important uncertainty source in estimating regional carbon dynamics. Simply extrapolating the site-level parameterization to large spatial and temporal scales could bias the regional estimates irrespective of regional climate data sets used in our analysis. Ensemble process-based Biogeochemistry model simulations conditioned on observed ecosystem fluxes with Bayesian inference techniques could provide more serious estimates of regional carbon dynamics and their associated uncertainties.
Emmanuel Doelsch - One of the best experts on this subject based on the ideXlab platform.
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Application of Synchrotron Radiation-based Methods for Environmental Biogeochemistry: Introduction to the Special Section
Journal of environmental quality, 2017Co-Authors: Ganga M. Hettiarachchi, Erica Donner, Emmanuel DoelschAbstract:To understand the Biogeochemistry of nutrients and contaminants in environmental media, their speciation and behavior under different conditions and at multiple scales must be determined. Synchrotron radiation-based X-ray techniques allow scientists to elucidate the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. The continuous improvement of synchrotron light sources and X-ray beamlines around the world has led to a profound transformation in the field of environmental Biogeochemistry and, subsequently, to significant scientific breakthroughs. Following this introductory paper, this special collection includes 10 papers that either present targeted reviews of recent advancements in spectroscopic methods that are applicable to environmental Biogeochemistry or describe original research studies conducted on complex environmental samples that have been significantly enhanced by incorporating synchrotron radiation-based X-ray technique(s). We believe that the current focus on improving the speciation of ultra-dilute elements in environmental media through the ongoing optimization of synchrotron technologies (e.g., brighter light sources, improved monochromators, more efficient detectors) will help to significantly push back the frontiers of environmental Biogeochemistry research. As many of the relevant techniques produce extremely large datasets, we also identify ongoing improvements in data processing and analysis (e.g., software improvements and harmonization of analytical methods) as a significant requirement for environmental biogeochemists to maximize the information that can be gained using these powerful tools. (Resume d'auteur)
Jinyun Tang - One of the best experts on this subject based on the ideXlab platform.
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equifinality in parameterization of process based Biogeochemistry models a significant uncertainty source to the estimation of regional carbon dynamics
Journal of Geophysical Research, 2008Co-Authors: Jinyun Tang, Qianlai ZhuangAbstract:[1] Numerical Biogeochemistry models suffer from equifinality problem in their parameterizations using eddy flux tower data, which can contribute to diverged estimates of regional carbon dynamics. To date, the uncertainty in regional estimates propagated from the site-level parameterization equifinality has not been well characterized. Here, we use a process-based Biogeochemistry model, the Terrestrial Ecosystem Model (TEM), and a Bayesian inference framework to quantify the influence of parameterization equifinality on the estimates of carbon dynamics in boreal forest ecosystems during the 20th century. By conducting three groups of ensemble regional simulations, we find that, given a certain climate data set being used, (1) in comparison to the effects of random noises in climate forcing, the regional uncertainty due to parameterization equifinality is remarkably greater, (2) the parameterization equifinality results in drastically different decadal variations in the estimation of carbon storage during the 20th century, and (3) the uncertainties associated with parameterization equifinality and random noises in climate forcing vary both spatially and seasonally. We conclude that the equifinality from site-level parameterizations in Biogeochemistry models is an important uncertainty source in estimating regional carbon dynamics. Simply extrapolating the site-level parameterization to large spatial and temporal scales could bias the regional estimates irrespective of regional climate data sets used in our analysis. Ensemble process-based Biogeochemistry model simulations conditioned on observed ecosystem fluxes with Bayesian inference techniques could provide more serious estimates of regional carbon dynamics and their associated uncertainties.
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Equifinality in parameterization of process‐based Biogeochemistry models: A significant uncertainty source to the estimation of regional carbon dynamics
Journal of Geophysical Research: Biogeosciences, 2008Co-Authors: Jinyun Tang, Qianlai ZhuangAbstract:[1] Numerical Biogeochemistry models suffer from equifinality problem in their parameterizations using eddy flux tower data, which can contribute to diverged estimates of regional carbon dynamics. To date, the uncertainty in regional estimates propagated from the site-level parameterization equifinality has not been well characterized. Here, we use a process-based Biogeochemistry model, the Terrestrial Ecosystem Model (TEM), and a Bayesian inference framework to quantify the influence of parameterization equifinality on the estimates of carbon dynamics in boreal forest ecosystems during the 20th century. By conducting three groups of ensemble regional simulations, we find that, given a certain climate data set being used, (1) in comparison to the effects of random noises in climate forcing, the regional uncertainty due to parameterization equifinality is remarkably greater, (2) the parameterization equifinality results in drastically different decadal variations in the estimation of carbon storage during the 20th century, and (3) the uncertainties associated with parameterization equifinality and random noises in climate forcing vary both spatially and seasonally. We conclude that the equifinality from site-level parameterizations in Biogeochemistry models is an important uncertainty source in estimating regional carbon dynamics. Simply extrapolating the site-level parameterization to large spatial and temporal scales could bias the regional estimates irrespective of regional climate data sets used in our analysis. Ensemble process-based Biogeochemistry model simulations conditioned on observed ecosystem fluxes with Bayesian inference techniques could provide more serious estimates of regional carbon dynamics and their associated uncertainties.
Michael Schloter - One of the best experts on this subject based on the ideXlab platform.
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Biogeochemistry of paddy soils
Geoderma, 2010Co-Authors: Ingrid Kögel-knabner, Wulf Amelung, Zhihong Cao, Sabine Fiedler, Peter Frenzel, Reinhold Jahn, Karsten Kalbitz, Angelika Kölbl, Michael SchloterAbstract:Paddy soils make up the largest anthropogenic wetlands on earth. They may originate from any type of soil in pedological terms, but are highly modified by anthropogenic activities. The formation of these Anthrosols is induced by tilling the wet soil (puddling), and the flooding and drainage regime associated with the development of a plough pan and specific redoximorphic features. Redox potential oscillations due to paddy management control microbial community structure and function and thus short-term biogeochemical processes. After flooding, microbial reduction processes sequentially use NO3−, Mn4+, Fe3+, SO42− as electron acceptors, accompanied by the emission of the trace gases N2O, N2, H2S, CH4 and — due to reduction-induced increasing pH — NH3. This results in N losses and low N fertilizer use efficiency. However, transport of atmospheric O2 to the roots via the rice plant's aerenchyma modifies conditions in the rhizosphere, leading to nitrification and methane oxidation, and precipitation of Mn and Fe oxides. High concentrations and fluxes of dissolved organic matter (DOM) in paddy soils from plant debris trigger microbial activity and thus the emission of greenhouse gases. Retention of DOM by soil minerals and its subsequent stabilisation against microbial decay depend on the redox state (e.g. DOM precipitation by Fe2+ under anaerobic conditions). Oscillation in redox conditions may enhance retention and stabilisation of DOM by Fe oxyhydroxides. Induced by the periodic short-term redox cycles, paddy management over long periods has strong effects on long-term biogeochemical processes. Frequent irrigation intensifies mineral weathering and leaching processes. High concentrations of DOM during flooding seasons enhance the changes and the release of structural iron in clay minerals, and support the formation of ferrihydrite. Repeated redox alternations lead to a translocation of iron in various directions, and particularly increase the crystallinity of iron oxides. This results also in higher total iron oxide contents in paddy compared to non-paddy soils. The large accumulation of soil organic matter (SOM) observed in some, but not all paddy soils, is considered to be due to high input of plant residues and charred material associated with retarded decomposition under anaerobic conditions. There is also evidence of SOM stabilisation via occlusion into aggregates and phytoliths as well as interactions with clay minerals and iron oxides. SOM accumulation in paddy subsoils can be explained by downward movement of DOM and its stabilisation by interaction with iron oxides. A specific feature of paddy soils is the coupling of organic matter turnover with mineral transformations and fluxes, which seem to be intensified by the alternating redox conditions with increasing age of paddy soil development. Bioavailability of soil organic N is strongly coupled to SOM cycling and is a crucial parameter determining crop yield. Anaerobic conditions inhibit N mineralization, with a high risk of gaseous N losses. In paddy soils the management-induced, microbially mediated redox processes control the dynamics of soil minerals and soil organic matter, which are strongly related to the microbial accessibility of C and N, but also of Fe
Ganga M. Hettiarachchi - One of the best experts on this subject based on the ideXlab platform.
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Application of Synchrotron Radiation-based Methods for Environmental Biogeochemistry: Introduction to the Special Section
Journal of environmental quality, 2017Co-Authors: Ganga M. Hettiarachchi, Erica Donner, Emmanuel DoelschAbstract:To understand the Biogeochemistry of nutrients and contaminants in environmental media, their speciation and behavior under different conditions and at multiple scales must be determined. Synchrotron radiation-based X-ray techniques allow scientists to elucidate the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. The continuous improvement of synchrotron light sources and X-ray beamlines around the world has led to a profound transformation in the field of environmental Biogeochemistry and, subsequently, to significant scientific breakthroughs. Following this introductory paper, this special collection includes 10 papers that either present targeted reviews of recent advancements in spectroscopic methods that are applicable to environmental Biogeochemistry or describe original research studies conducted on complex environmental samples that have been significantly enhanced by incorporating synchrotron radiation-based X-ray technique(s). We believe that the current focus on improving the speciation of ultra-dilute elements in environmental media through the ongoing optimization of synchrotron technologies (e.g., brighter light sources, improved monochromators, more efficient detectors) will help to significantly push back the frontiers of environmental Biogeochemistry research. As many of the relevant techniques produce extremely large datasets, we also identify ongoing improvements in data processing and analysis (e.g., software improvements and harmonization of analytical methods) as a significant requirement for environmental biogeochemists to maximize the information that can be gained using these powerful tools. (Resume d'auteur)