The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Emmanuel Fritsch - One of the best experts on this subject based on the ideXlab platform.
-
Podzolisation and exportation of organic matter in black waters of the Rio Negro (upper Amazon basin, Brazil)
Biogeochemistry, 2011Co-Authors: Marion Bardy, Thierry Allard, Sylvie Derenne, Marc F. Benedetti, Emmanuel FritschAbstract:In the Rio Negro basin, Podzols develop at the expense of clay-depleted laterites through localized and spectacular weathering fronts. This natural process leads to the remobilization of previously accumulated organic matter (OM) which is redistributed within soil profiles and exported towards rivers, hence their typical black coloration. We investigate the fate of OM in the soil–water continuum in the Rio Negro basin through description of the composition of OM potentially mobile at different stages of Podzol development and exploration of evidence for contributions from different soil horizons to the exportation of OM into waters. OM was water-extracted from seven key soil samples from a sequence representative of the transition between latosol and Podzol on the low elevation plateaux of the Rio Negro basin, thus enabling following both vertical and lateral differentiations. The chemical structure of freeze-dried samples, investigated using ^13C nuclear magnetic resonance and thermally assisted hydrolysis and methylation (THM), shows contrasting features depending on the horizon considered. The bulk features of water extracts were first compared with samples collected in the water-tables and rivers draining the soil sequence. A molecular level comparison was then performed with groundwater draining the well-developed Podzol. This approach evidenced a contribution from deep horizons of well-developed Podzols. It highlights that OM is certainly remobilised after being accumulated in Bh horizons during the development of Podzols through accumulation of OM redistributed from surface horizons. The identification of specific compounds opens new perspective to trace a “Podzolic origin” of OM in drainage networks.
-
Tracing source and evolution of suspended particles in the Rio Negro Basin (Brazil) using chemical species of iron
Chemical Geology, 2011Co-Authors: Thierry Allard, Emmanuel Fritsch, Marion Bardy, Tiphaine Weber, C. Bellot, C. Damblans, Guilherme Bueno, Nadia Regina Nascimiento, Marc F. BenedettiAbstract:Suspended solids found in porewaters obtained in waterlogged soil sequences that included representative laterite–Podzol transitions, associated brooks and major rivers of the Rio Negro watershed (Brazil) were studied using electron paramagnetic resonance (EPR) and Fourier-transform infrared spectroscopies. The main goal was to ascertain sources and track the evolution of suspended matter using a ubiquitous chemical species, FeIII complexed to organic matter (FeOM). Three size fractions were separated by tangential-flow (ultra)filtration: particulate (> 0.2 μm), dense (P) and light (Ps), and colloidal (5 kD < Col. < 0.2 μm) fractions. Quantitative results were acquired for Col. and Ps fractions which are predominantly organic in nature. FeOM concentration (in ‰ dry weight) was determined to be relatively low in suspended solids found in black waters from Podzol porewaters and brooks whereas in the main rivers it was several times higher. FeOM concentrations were also correlated with Fe(II)/Fe(III) ratios in solution; these ratios were high in Podzol porewaters and low in the rivers. Considering that organic complexation of Fe(II) is minor when compared to that of Fe(III), two interpretations were proposed to account for the above observation. First, [FeOM] was assumed to be distributed along a mixing line, with the clear waters from laterites and the black waters from Podzols being its end-members. Consequently, [FeOM] can be used to trace the source of suspended material. Second, dissolved Fe(II) from Podzol areas was considered to be progressively oxidized as pore waters move towards the mainstream. According to this mechanism, iron is complexed by organic matter or precipitated as oxides, thus producing an evolution of colloidal matter. As a result of these mechanisms' action, both the high production of Fe(II) and organic matter at the waterlogged Podzol–laterite transition areas are major factors affecting iron export in the Rio Negro watershed.
-
Occurrence and distribution of non-extractable glycerol dialkyl glycerol tetraethers in temperate and tropical Podzol profiles.
Organic Geochemistry, 2010Co-Authors: Arnaud Huguet, Emmanuel Fritsch, Céline Fosse, Pierre Metzger, Sylvie DerenneAbstract:Glycerol dialkyl glycerol tetraethers (GDGTs) are high molecular weight lipids present in the membranes of archaea and some bacteria. Isoprenoid GDGTs with acyclic or ring containing dibiphytanyl chains are known to be synthesised by archaea. In soil, another type of GDGT, which can be distinguished from tetraethers of archaeal origin by way of the branched nature of the alkyl chain, was discovered recently. Alkyl branched GDGTs were suggested to be produced by anaerobic bacteria and can be used to reconstruct past air temperatures and soil pH. Lipids in soils can take two broad forms: extractable, i.e. recoverable via solvent extraction, and non-extractable, linked to the mineral or organic matrix. The present study aimed at comparing the abundance and distribution of these two pools of GDGTs in two contrasting Podzol environments: a temperate Podzol 40 km north of Paris (France) and a tropical Podzol from the Amazon basin (Brazil). Five samples were collected from the whole profile of the temperate Podzol. Five additional samples were obtained from three profiles of the tropical soil sequence, which are representative of the transition between a latosol and a well developed Podzol. For the first time, we showed that substantial amounts of non-extractable GDGTs can be released after acid hydrolysis of solvent-extracted soils, non-extractable GDGTs representing 25 ± 15% of the total (i.e. extractable + non-extractable) bacterial GDGTs and 29 ± 17% of the total archaeal GDGTs in Podzol samples. This implies that extractable GDGTs can be incorporated into the organic and/or mineral matrix of soil. In addition, we observed that extractable and non-extractable GDGTs could present different distribution patterns, notably suggesting that some extractable GDGTs might be preferentially transferred to the non-extractable pool and/or might be preferentially degraded by soil microorganisms. The relative abundances of bacterial and archaeal GDGTs were compared along the temperate soil profile and the tropical soil sequence. The relative amount of bacterial vs. archaeal GDGTs was shown to be much higher in the extractable than in the non-extractable fraction in the surficial horizons of the temperate Podzol and in the well-developed part of the tropical Podzol, implying that extractable archaeal GDGTs could be preferentially transferred to the non-extractable lipid pool compared to extractable bacterial GDGTs in these horizons. This might be due to the fact that the types of polar head groups associated with bacterial GDGTs differ from, and are more labile than, those associated with archaeal GDGTs.
-
Occurrence and distribution of extractable glycerol dialkyl glycerol tetraethers in Podzols.
Organic Geochemistry, 2010Co-Authors: Arnaud Huguet, Emmanuel Fritsch, Céline Fosse, Pierre Metzger, Sylvie DerenneAbstract:Abstract The abundance and distribution of glycerol dialkyl glycerol tetraethers (GDGTs) were compared in two contrasting environments: a temperate Podzol located 40 km north of Paris (France) and a tropical Podzol from the Amazon Basin (Brazil). Five samples were collected from the profile of the temperate Podzol, including the litter layer. Five others were obtained from three profiles from the tropical soil sequence, which is representative of the transition between a latosol and a well-developed Podzol. GDGTs can occur as core lipids (i.e. as extractable “free” lipids) within the soil organic extract. They may also be present in ester- and/or glycosidic ether-bound form (i.e. as extractable “bound” lipids) in the extract. To date, most studies of GDGTs in soil have considered extractable “free” GDGTs but have not investigated extractable “bound” GDGTs. The extractable “free” and “bound” GDGT pools were therefore both investigated. Accelerated solvent extraction (ASE) was used to extract total extractable (i.e. “free” and “bound”) GDGTs. Half of these extracts was then submitted to acid methanolysis to release ester- and/or glycosidic ether-bound GDGTs, allowing subsequent analysis of total extractable GDGTs using high performance liquid chromatography–mass spectrometry (HPLC/MS). The other half was directly analysed for “free” GDGTs. Branched GDGTs derived from soil bacteria were present in all the samples, along with GDGTs of archaeal origin, although the latter were detected in much lower abundance than bacterial GDGTs. A higher degree of methylation was observed for the alkyl branched GDGTs from the temperate samples than for the tropical ones, in agreement with differences in air temperature. The amount of bacterial and archaeal GDGTs in the surficial sample from the well-developed part of the tropical Podzol was greater than in the latosol and transition profiles. The difference could be related to a lower pH in the developed Podzol than in the other two profiles. Furthermore, branched GDGTs were detected in the litter layer from the temperate Podzol, which may indicate the presence of branched GDGT-producing bacteria in the litter, probably in anoxic microsites. Last, GDGT abundance and distribution were comparable in the extractable “free” and total extractable lipid fractions of most of the soil samples, suggesting that GDGTs mainly occur as “free” lipids in the extracts of all these soils and that similar data concerning past air temperature and soil pH could be derived from both extractable “free” and total extractable GDGT distributions.
-
Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol : Podzol sequence of the upper Amazon Basin
European Journal of Soil Science, 2008Co-Authors: N.r Do Nascimento, Emmanuel Fritsch, C. Grimaldi, M. Bardy, G.t. Bueno, A.j MelfiAbstract:Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the Podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.
Adolpho José Melfi - One of the best experts on this subject based on the ideXlab platform.
-
Influence of pedogenetic processes on the validity of kaolinite crystallinity indices: A case study of an Amazonian Ferralsol-Podzol soil system with white kaolin
Applied Clay Science, 2018Co-Authors: Débora Ayumi Ishida, Antonio Carlos Vieira-coelho, Adolpho José Melfi, Yves Lucas, João Paulo Brasiliano Camargo, Célia Regina MontesAbstract:Abstract Structural defects of kaolinite could be associated with its genetic (weathering, pedogenetic, and hydrothermal) processes. Kaolinite crystallinity indices were evaluated in the context of pedogenetic processes associated with a representative Amazonian Ferralsol-Podzol soil system. This soil system, which is comprised of various types of kaolinitic materials and has a soil dynamics characterized by the progressive replacement of Ferralsols by Podzols, has been evaluated by Hinckley (HI), Aparicio-Galan-Ferrell (AGFI), Lietard (R2), and Amigo (A001) “crystallinity indices” and the “expert system” of Plancon and Zacharie (PZ). The results indicate that the complexity of the kaolinite population, which is due to pedogenetic processes, makes it difficult to interpret the usual kaolinite crystallinity indices. In areas where kaolinites are formed under low aggressive conditions (higher pH and lower dissolved organic carbon, DOC) and in equilibrium with the soil solutions, low-defect phase becomes dominant and there is a good consistency between the “crystallinities” provided by each index. However, in areas where kaolinites are formed under highly aggressive conditions (lower pH and higher DOC), the proportion of low-defect phase decreases. This induces changes in the values of the indices, which do not have the same weight from one index to another.
-
Modelling the genesis of equatorial Podzols: age and implications on carbon fluxes
2017Co-Authors: Cédric Doupoux, Adolpho José Melfi, Célia Regina Montes, Osvaldo José Ribeiro Pereira, Patricia Merdy, Naoise Nunan, Yves LucasAbstract:Abstract. Amazonian Podzols store huge amounts of carbon and play a key role in transferring organic matter to the Amazon river. In order to better understand their C dynamics, we modelled the formation of representative Amazonian Podzol profiles by constraining both total carbon and radiocarbon. We determined the relationships between total carbon and radiocarbon in organic C pools numerically by setting constant C and 14C inputs over time. The model was an effective tool for determining the order of magnitude of the carbon fluxes and the time of genesis of the main carbon-containing horizons, i.e. the topsoil and deep Bh. We performed retro calculations to take in account the bomb carbon in the young topsoil horizons (14C age from 62 to 109 y). We modelled four profiles representative of Amazonian Podzols, two profiles with an old Bh (14C age 6.8 × 103 and 8.4 × 103 y) and two profiles with a very old Bh (14C age 23.2 × 103 and 25.1 × 103 y). The calculated fluxes from the topsoil to the perched water-table indicates that the most waterlogged zones of the Podzolized areas are the main source of dissolved organic matter found in the river network. It was necessary to consider two Bh carbon pools to accurately represent the carbon fluxes leaving the Bh as observed in previous studies. We found that the genesis time of the studied soils was necessarily longer than 15 × 103 and 130 × 103 y for the two younger and the two older Bhs, respectively, and that the genesis time calculated considering the more likely settings runs to around 15 × 103–25 × 103 and 150 × 103–250 × 103 y, respectively.
-
Evaluation of Pedotransfer Equations to Predict Deep Soil Carbon Stock in Tropical Podzols Compared to Other Soils of the Brazilian Amazon Forest
Progress in Soil Science, 2016Co-Authors: Osvaldo José Ribeiro Pereira, Célia Regina Montes, Yves Lucas, Adolpho José MelfiAbstract:According to the soil measurement procedures proposed by the Intergovernmental Panel on Climate Change (IPCC), the sampling depth for SOC stock estimation is centred on the upper soil horizons where root biomass and organic matter inputs are concentrated, depending on soil type and ecosystem, typically between 0 and 0.3 m. However, recent research in areas of Amazonian Podzols has shown that these soils store a great amount of carbon in thick spodic horizons (Bh). The amount of carbon stored in deep Bh horizons of Podzols (down to 3 m) may exceed 80 kg C m−2 in some regions of the Amazon. Thus, a better understanding of the vertical distribution of the SOC in Amazonian soils is an urgent matter considering the volume of carbon stored in Podzols, in a context of global climate change. Given this, the main goal of this research was to test and to propose pedotransfer functions based on several Amazonian soil profiles in order to estimate SOC stock and evaluate different soil attributes that could be used to infer indirectly, soil bulk density. For this propose, we selected around 320 pedons that were collected in the region of the Rio Negro Basin, to model the vertical distribution of SOC stock using a series of negative exponential profile depth functions and parametric/nonparametric functions for Podzols. The derived function parameters were used to predict carbon stock in deep horizons for all studied profiles and to explain the vertical behaviour of the SOC stock in Podzol profiles. The soil bulk density of Amazonian soils was properly modelled by symbolic regression, considering pH, clay content and SOC as the most relevant variables likely to affect soil bulk density values. We observed that the SOC stored in deep horizons of non-Podzolic soils can be modelled by exponential decay equations. However, in Podzol, the vertical distribution of carbon stock is highly complex with a significant increase in deep horizons, which cannot be explained by negative exponential functions. Our findings have shown that the SOC stock of Amazonian soils, excluding Podzols, can be predicted by fitted exponential functions (RMSE: 0.9 kg C m−2). However, the vertical variation of SOC stored in Podzol profiles can be modelled just by complex equations (equal-area spline RMSE: 13.6 kg C m−2; Fourier RMSE 15.9 kg C m−2 and Sum of Sines RMSE: 15.0 kg C m−2) with a large number of parameters. According to the results achieved in this research, we concluded that the SOC stock of Podzols can be indirectly estimated for the whole soil profile by integrating the Sum of Sines and Fourier equations, which is not possible when applying an equal-area spline fitting due to the absence of model parameters. Moreover, spodic horizons store most of the carbon pool of Podzolic regions and the Podzols have more than twice of the capability of storing carbon when compared to other Amazonian soils.
-
A multi-sensor approach for mapping plant-derived carbon storage in Amazonian Podzols
International Journal of Remote Sensing, 2015Co-Authors: Osvaldo José Ribeiro Pereira, Célia Regina Montes, Yves Lucas, Roberta Clemente Santin, Adolpho José MelfiAbstract:The Rio Negro basin is characterized by the extensive occurrence of Podzol-type soils that store large amounts of organic matter in depth, resulting in the storage of carbon able available to the atmosphere with climate change. The quantification of this carbon requires determination of Podzol types and their spatial distribution. Remote-sensing techniques would be helpful in indirect spatializing and segmentation of soil groups in Amazonian Podzols. Here we associated remote-sensing images Shuttle Radar Topographic Mission SRTM, Operational Land Imager sensor/Landsat 8, and Thermal Infrared Sensor/Landsat 8 and field sample data in order to achieve carbon stock mapping. We found that a multi-sensor approach was critical for a proper segmentation of vegetation groups and spatial distribution of areas with different hydrologic soil regimes.
-
Genetic relationships between ferralsols, Podzols and white kaolin in Amazonia
European Journal of Soil Science, 2014Co-Authors: Débora Ayumi Ishida, Yves Lucas, Célia Regina Montes, Osvaldo José Ribeiro Pereira, Patricia Merdy, Adolpho José MelfiAbstract:Summary White kaolin has frequently been observed to be associated with ferralsol-Podzol soil systems in Amazonia. In order to evaluate whether such systems favour kaolin genesis and to identify the associated genetic processes, we studied soil organization, mineralogy and groundwater properties of a ferralsol-Podzol soil system with white kaolin located in the High Rio Negro Basin, Brazil. We found that the kaolin was situated near the ferralsol-Podzol transition and that its thickness was related to the depth of landscape incision by regressive erosion. The kaolin was characterized by silicon, iron and titanium (Ti) leaching and aluminium (Al) absolute accumulation. The groundwater that percolates from the Podzol to the kaolin can enhance kaolinite precipitation, by supplying Al originating from kaolinite dissolution in the overlying Bh, and kaolin bleaching, by low pH and Eh of the percolating waters favouring iron reduction. The system dynamics imply that the quartz dissolution rate in the kaolin is of at least the same order of magnitude as the kaolinite dissolution rate in the overlying Bh. Within the whole system, Ti appeared to be very mobile.
Célia Regina Montes - One of the best experts on this subject based on the ideXlab platform.
-
soil organic matter in Podzol horizons of the amazon region humification recalcitrance and dating
Science of The Total Environment, 2018Co-Authors: Yves Lucas, Célia Regina Montes, S. Mounier, Amanda Maria Tadini, Gustavo Nicolodelli, Giorgio S Senesi, Debora A Ishida, Francisco Eduardo Gontijo GuimaraesAbstract:Characteristics of soil organic matter (SOM) are important, especially in the Amazon region, which represents one of the world's most relevant carbon reservoirs. In this work, the concentrations of carbon and differences in its composition (humification indexes) were evaluated and compared for several horizons (0 to 390 cm) of three typical Amazonian Podzol profiles. Fluorescence spectroscopy was used to investigate the humic acid (HA) fractions of SOM isolated from the different samples. Simple and labile carbon structures appeared to be accumulated in surface horizons, while more complex humified compounds were leached and accumulated in intermediate and deeper Bh horizons. The results suggested that the humic acids originated from lignin and its derivatives, and that lignin could accumulate in some Bh horizons. The HA present in deeper Bh horizons appeared to originate from different formation pathways, since these horizons showed different compositions. There were significant compositional changes of HA with depth, with four types of organic matter: recalcitrant, humified, and old dating; labile and young dating; humified and young dating; and little humified and old dating. Therefore, the humification process had no direct relation with the age of the organic matter in the Amazonian Podzols.
-
Influence of pedogenetic processes on the validity of kaolinite crystallinity indices: A case study of an Amazonian Ferralsol-Podzol soil system with white kaolin
Applied Clay Science, 2018Co-Authors: Débora Ayumi Ishida, Antonio Carlos Vieira-coelho, Adolpho José Melfi, Yves Lucas, João Paulo Brasiliano Camargo, Célia Regina MontesAbstract:Abstract Structural defects of kaolinite could be associated with its genetic (weathering, pedogenetic, and hydrothermal) processes. Kaolinite crystallinity indices were evaluated in the context of pedogenetic processes associated with a representative Amazonian Ferralsol-Podzol soil system. This soil system, which is comprised of various types of kaolinitic materials and has a soil dynamics characterized by the progressive replacement of Ferralsols by Podzols, has been evaluated by Hinckley (HI), Aparicio-Galan-Ferrell (AGFI), Lietard (R2), and Amigo (A001) “crystallinity indices” and the “expert system” of Plancon and Zacharie (PZ). The results indicate that the complexity of the kaolinite population, which is due to pedogenetic processes, makes it difficult to interpret the usual kaolinite crystallinity indices. In areas where kaolinites are formed under low aggressive conditions (higher pH and lower dissolved organic carbon, DOC) and in equilibrium with the soil solutions, low-defect phase becomes dominant and there is a good consistency between the “crystallinities” provided by each index. However, in areas where kaolinites are formed under highly aggressive conditions (lower pH and higher DOC), the proportion of low-defect phase decreases. This induces changes in the values of the indices, which do not have the same weight from one index to another.
-
Modelling the genesis of equatorial Podzols: age and implications on carbon fluxes
2017Co-Authors: Cédric Doupoux, Adolpho José Melfi, Célia Regina Montes, Osvaldo José Ribeiro Pereira, Patricia Merdy, Naoise Nunan, Yves LucasAbstract:Abstract. Amazonian Podzols store huge amounts of carbon and play a key role in transferring organic matter to the Amazon river. In order to better understand their C dynamics, we modelled the formation of representative Amazonian Podzol profiles by constraining both total carbon and radiocarbon. We determined the relationships between total carbon and radiocarbon in organic C pools numerically by setting constant C and 14C inputs over time. The model was an effective tool for determining the order of magnitude of the carbon fluxes and the time of genesis of the main carbon-containing horizons, i.e. the topsoil and deep Bh. We performed retro calculations to take in account the bomb carbon in the young topsoil horizons (14C age from 62 to 109 y). We modelled four profiles representative of Amazonian Podzols, two profiles with an old Bh (14C age 6.8 × 103 and 8.4 × 103 y) and two profiles with a very old Bh (14C age 23.2 × 103 and 25.1 × 103 y). The calculated fluxes from the topsoil to the perched water-table indicates that the most waterlogged zones of the Podzolized areas are the main source of dissolved organic matter found in the river network. It was necessary to consider two Bh carbon pools to accurately represent the carbon fluxes leaving the Bh as observed in previous studies. We found that the genesis time of the studied soils was necessarily longer than 15 × 103 and 130 × 103 y for the two younger and the two older Bhs, respectively, and that the genesis time calculated considering the more likely settings runs to around 15 × 103–25 × 103 and 150 × 103–250 × 103 y, respectively.
-
Evaluation of Pedotransfer Equations to Predict Deep Soil Carbon Stock in Tropical Podzols Compared to Other Soils of the Brazilian Amazon Forest
Progress in Soil Science, 2016Co-Authors: Osvaldo José Ribeiro Pereira, Célia Regina Montes, Yves Lucas, Adolpho José MelfiAbstract:According to the soil measurement procedures proposed by the Intergovernmental Panel on Climate Change (IPCC), the sampling depth for SOC stock estimation is centred on the upper soil horizons where root biomass and organic matter inputs are concentrated, depending on soil type and ecosystem, typically between 0 and 0.3 m. However, recent research in areas of Amazonian Podzols has shown that these soils store a great amount of carbon in thick spodic horizons (Bh). The amount of carbon stored in deep Bh horizons of Podzols (down to 3 m) may exceed 80 kg C m−2 in some regions of the Amazon. Thus, a better understanding of the vertical distribution of the SOC in Amazonian soils is an urgent matter considering the volume of carbon stored in Podzols, in a context of global climate change. Given this, the main goal of this research was to test and to propose pedotransfer functions based on several Amazonian soil profiles in order to estimate SOC stock and evaluate different soil attributes that could be used to infer indirectly, soil bulk density. For this propose, we selected around 320 pedons that were collected in the region of the Rio Negro Basin, to model the vertical distribution of SOC stock using a series of negative exponential profile depth functions and parametric/nonparametric functions for Podzols. The derived function parameters were used to predict carbon stock in deep horizons for all studied profiles and to explain the vertical behaviour of the SOC stock in Podzol profiles. The soil bulk density of Amazonian soils was properly modelled by symbolic regression, considering pH, clay content and SOC as the most relevant variables likely to affect soil bulk density values. We observed that the SOC stored in deep horizons of non-Podzolic soils can be modelled by exponential decay equations. However, in Podzol, the vertical distribution of carbon stock is highly complex with a significant increase in deep horizons, which cannot be explained by negative exponential functions. Our findings have shown that the SOC stock of Amazonian soils, excluding Podzols, can be predicted by fitted exponential functions (RMSE: 0.9 kg C m−2). However, the vertical variation of SOC stored in Podzol profiles can be modelled just by complex equations (equal-area spline RMSE: 13.6 kg C m−2; Fourier RMSE 15.9 kg C m−2 and Sum of Sines RMSE: 15.0 kg C m−2) with a large number of parameters. According to the results achieved in this research, we concluded that the SOC stock of Podzols can be indirectly estimated for the whole soil profile by integrating the Sum of Sines and Fourier equations, which is not possible when applying an equal-area spline fitting due to the absence of model parameters. Moreover, spodic horizons store most of the carbon pool of Podzolic regions and the Podzols have more than twice of the capability of storing carbon when compared to other Amazonian soils.
-
A multi-sensor approach for mapping plant-derived carbon storage in Amazonian Podzols
International Journal of Remote Sensing, 2015Co-Authors: Osvaldo José Ribeiro Pereira, Célia Regina Montes, Yves Lucas, Roberta Clemente Santin, Adolpho José MelfiAbstract:The Rio Negro basin is characterized by the extensive occurrence of Podzol-type soils that store large amounts of organic matter in depth, resulting in the storage of carbon able available to the atmosphere with climate change. The quantification of this carbon requires determination of Podzol types and their spatial distribution. Remote-sensing techniques would be helpful in indirect spatializing and segmentation of soil groups in Amazonian Podzols. Here we associated remote-sensing images Shuttle Radar Topographic Mission SRTM, Operational Land Imager sensor/Landsat 8, and Thermal Infrared Sensor/Landsat 8 and field sample data in order to achieve carbon stock mapping. We found that a multi-sensor approach was critical for a proper segmentation of vegetation groups and spatial distribution of areas with different hydrologic soil regimes.
M. Bardy - One of the best experts on this subject based on the ideXlab platform.
-
Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol : Podzol sequence of the upper Amazon Basin
European Journal of Soil Science, 2008Co-Authors: N.r Do Nascimento, Emmanuel Fritsch, C. Grimaldi, M. Bardy, G.t. Bueno, A.j MelfiAbstract:Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the Podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.
-
Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol – Podzol sequence of the upper Amazon Basin
European Journal of Soil Science, 2008Co-Authors: N.r Do Nascimento, M. Bardy, E. Fritsch, G.t. Bueno, A.j Melfi, C. GrimaldiAbstract:Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the Podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.
-
Al speciation in tropical Podzols of the upper Amazon Basin: A solid-state 27Al MAS and MQMAS NMR study
Geochimica et Cosmochimica Acta, 2007Co-Authors: M. Bardy, E. Fritsch, S. Derenne, Thierry Allard, Christian Bonhomme, Jocelyne Maquet, Redouane Hajjar, Georges CalasAbstract:In the upper Amazon Basin, aluminum previously accumulated in lateritic formations is massively remobilised in soils by Podzolization and exported in waters. We have investigated the speciation of aluminum in the clay-size fractions of eight horizons of waterlogged Podzols lying in a depression of a plateau. The horizons illustrate the main steps involved in the Podzolization of laterites. They belong to eluviated topsoil A horizons and illuviated subsoil Bhs, Bh and 2BCs horizons of weakly and better-expressed Podzols located at the margin and centre of the depression. For the first time, aluminum speciation is quantitatively assessed in soils by spectroscopic methods, namely FTIR, 27Al magic angle spinning (MAS) and multiple-quantum magic angle spinning (MQMAS), nuclear magnetic resonance (NMR). The results thus obtained are compared to chemical extraction data. Solid-state 27Al MAS NMR spectra enable to distinguish Al bound to organic compounds from that incorporated in secondary mineral phases detected by FTIR. MQMAS experiments additionally show that both chemical shifts and quadrupolar constants are distributed for Al nuclei linked with organic compounds. Similar amounts of chelated Al are obtained from NMR spectra and chemical extractions. The study enables to highlight three major steps in the fate of aluminum. (i) Aluminum is first released by mineral weathering, feeds complexing sites of organic matter and accumulates in subsurface Bhs horizons of weakly expressed Podzols (acidocomplexolysis). (ii) Complexes of aluminum with organic matter (Al–OM) then migrate downwards in sandy horizons of better-expressed Podzols and accumulate at depth in less permeable 2BCs horizons. (iii) The minor amounts of aluminum present in the 2BCs horizon of the downslope Podzol show that aluminum is eventually exported towards the river network, either complexed with organic matter or as Al3+ ions after desorption from organic compounds, due to decreasing pH or biodegradation of organic ligands. The direct spectroscopic determination of Al-speciation during the formation of Podzolic soils opens new perspectives to trace metal loads in the rivers of the upper Amazon Basin.
A.j Melfi - One of the best experts on this subject based on the ideXlab platform.
-
Biogeochemistry of an amazonian Podzol-ferralsol soil system with white kaolin
Biogeosciences Discussions, 2012Co-Authors: Y. Lucas, C. R. Montes, S. Mounier, M. Loustau-cazalet, D. Ishida, R. Achard, C. Garnier, A.j MelfiAbstract:Abstract. Podzol-ferralsol soil systems cover great areas in Amazonia and in other equatorial regions, they are an end-member of old equatorial landscape evolution, are frequently associated with kaolin deposits and store and export large amounts of carbon. Their biogeochemistry was usually inferred from soil mineralogy and from spring or river water properties. This paper presents a database for groundwaters sampled in situ in a typical Podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil; the sampling periods allowed to sample under high- and low-level water-table conditions. The compositions of the groundwaters percolating the soil system are consistent with the currently observed mineral and organic paragenesis. The acidity and the site density of the dissolved organic matter (DOM) produced and circulating in the Podzol white sand horizons are similar to what was observed in acid Podzolic temperate zone. The aggressiveness of the white sand groundwater with regard to secondary minerals favours the Podzol development at the expense of the ferralsolic or kaolin material. Some DOM is able to percolate in depth through clayey material with concentrations up to 9.7 mgC l−1 (4.0 on average). This DOM is characterized by high site densities indicating a large proportion of small carboxylic acids. In the deep kaolin and in the ferralsolic horizons, the Si and Al content of the groundwater is controlled by gibbsite and kaolinite precipitation/dissolution and by quartz dissolution. The mobility of Fe, mainly transported as Fe2+, is sensitive to small variations in EH. The bleaching of the deep kaolin at the upper part of the slopes is favoured by the high content of small carboxylic compounds and by the redox conditions of the solutions issuing from the Podzolic horizons. The transfer of Al and Fe result in the precipitation of Al-nodules in slope horizons and of Fe-oxides in the upper downslope horizon. It can be inferred that thick bleached kaolin are likely everywhere presently active giant Podzols are close to a slope gradient sufficient to allow deep percolation of groundwater.
-
Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol – Podzol sequence of the upper Amazon Basin
European Journal of Soil Science, 2008Co-Authors: N.r Do Nascimento, M. Bardy, E. Fritsch, G.t. Bueno, A.j Melfi, C. GrimaldiAbstract:Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the Podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.
-
Podzolization as a deferralitization process: dynamics and chemistry of ground and surface waters in an Acrisol : Podzol sequence of the upper Amazon Basin
European Journal of Soil Science, 2008Co-Authors: N.r Do Nascimento, Emmanuel Fritsch, C. Grimaldi, M. Bardy, G.t. Bueno, A.j MelfiAbstract:Hydrochemical processes involved in the development of hydromorphic Podzols are a major concern for the upper Amazon Basin because of the extent of the areas affected by such processes and the large amounts of organic carbon and associated metals exported to the rivers. The dynamics and chemical composition of ground and surface waters were studied along an Acrisol-Podzol sequence lying in an open depression of a plateau. Water levels were monitored along the sequence over a period of 2 years by means of piezometers. Water was sampled in zero-tension lysimeters for groundwater and for surface water in the drainage network of the depression. The pH and concentrations of organic carbon and major elements (Si, Fe and Al) were determined. The contrasted changes reported for concentrations of Si, organic carbon and metals (Fe, Al) mainly reflect the dynamics of the groundwater and the weathering conditions that prevail in the soils. Iron is released by the reductive dissolution of Fe oxides, mostly in the Bg horizons of the upslope Acrisols. It moves laterally under the control of hydraulic gradients and migrates through the iron-depleted Podzols where it is exported to the river network. Aluminium is released from the dissolution of Al-bearing minerals (gibbsite and kaolinite) at the margin of the Podzolic area but is immobilized as organo-Al complexes in spodic horizons. In downslope positions, the quick recharge of the groundwater and large release of organic compounds lead to acidification and a loss of metals (mainly Al), previously stored in the Podzols.