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Jean-louis Morel - One of the best experts on this subject based on the ideXlab platform.
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Technosol construction with by-products and wastes: Pedogenesis and modelling
2016Co-Authors: Sophie Leguedois, Geoffroy Séré, Françoise Watteau, Christophe Schwartz, Apolline Auclerc, Audrey Boigné, Fabrice Bureau, Estelle Langlois, Jean-louis MorelAbstract:Technosol construction with by-products and wastes: Pedogenesis and modelling. SUMMER SCHOOL ON CONTAMINATED SEDIMENTS: CHARACTERIZATION AND REMEDIATION
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Modelling Pedogenesis of technosols
Geoderma, 2016Co-Authors: Sophie Leguedois, Geoffroy Séré, Jérôme Cortet, Stéphanie Ouvrard, Françoise Watteau, Christophe Schwartz, Hermine Huot, Apolline Auclerc, Jean-louis MorelAbstract:Technosols, soils subjected to a strong human influence and containing significant amounts of artefacts, are characteristic of the Anthropocene. In order to better apprehend their growing importance in our current environment, our knowledge of the evolution and fate of these soils must be improved. The aim of this article is to promote pedogenic modelling for Technosols by proposing an appropriate framework. The paper first defines the characteristics of Technosol Pedogenesis, and then considers the requirements for its modelling in light of general concepts of Pedogenesis, modelling tools and techniques, and 18 selected existing quantitative models. This mixed technical and conceptual analysis allows us to address at once the modelling approach, the choice of processes, the integration of control variables, the time scales, the spatial representation, and the data needed for such a framework. Technosol Pedogenesis is characterised by the soils' anthropic creation, a young age, a climate globally favourable for soil evolution, a surprising level of biological activity, and mostly reactive artefacts as parent materials. Pedogenic processes observed in Technosols are similar to those occurring in more natural soils; however, they generally have fast kinetics and occur in unusual assemblages. We propose that the modelling framework for Technosol evolution should be based on the coupling of process-based models of soil functioning processes and accommodate the peculiar properties of technogenic materials. Our work also highlights modelling features needed for Pedogenesis in general: development of biological and physical models, selection of a comprehensive energy unit, dual-time scale modelling, and multi-scale representation of the soil profile. We propose (i) an adaptation of existing energy metrics (entropy, exergy, emergy or EEMT), (ii) a dual-time scale approach, our original concept, based on resilience patterns in soil changes, and (iii) the development of an existing spatial representation. Constructed Technosols are a relevant experimental model which supplies reliable data on soil evolution, data which are required for the development of pedogenic models. Technosols are emblematic of the issues we face for the management of the soils of the Anthropocene. The design of a modelling framework for Technosol evolution should therefore bring interesting developments for pedogenic modelling in general.
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Pedogenetic Trends in Soils Formed in Technogenic Parent Materials
Soil Science, 2015Co-Authors: Hermine Huot, Marieodile Simonnot, Jean-louis MorelAbstract:Abstract: Soils formed in technogenic parent materials are proliferating, and their Pedogenesis remains inadequately understood. On investigation of soils formed in various technogenic materials reported in the literature and of a Technosol developing on iron industry deposits, potential specificities of Pedogenesis within technogenic materials are discussed. Analyses have shown that pedogenetic processes observed in these soils are similar to those occurring in natural soils. However, some particularities have been highlighted, such as the coexistence of processes rarely encountered simultaneously in natural environments or high rates of soil development during the first stages of weathering. Technogenic materials display highly diverse constituents, wide spatial variability, and temporal discontinuities as a result of human activities. These inherent features, in interaction with other soil-forming factors, may govern Pedogenesis by generating the following conditions: (i) a high diversity of pedogenetic processes, including processes occurring usually in dissimilar climatic regions; (ii) localized processes and distinct rates and orientations of soil development over short distance; and (iii) a succession and/or a superimposition of processes, constrained by the deposition of materials and human operations. This creates the potential for the simultaneity of processes coexisting rarely in natural soils developing in the same climatic region. These soils are likely to have a polycyclic evolution and to evolve toward groups of soils other than Technosols, depending on the dominant processes. Further investigations of the processes and their potential interactions occurring in a larger range of soils formed in technogenic materials are required to better predict the evolution of these soils.
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Modelling Pedogenesis in the Anthropocene
2014Co-Authors: Sophie Leguedois, Geoffroy Séré, Jérôme Cortet, Stéphanie Ouvrard, Françoise Watteau, Christophe Schwartz, Jean-louis MorelAbstract:The objective of this paper is to develop a framework for pedogenetic modelling in the Anthropocene, i.e., the present geological epoch during which humanity has become the main factor impacting the environment. We review the concepts of soil evolution as well as 15 existing quantitative models to determine the features of soil evolution modelling in an Anthropocene context. We emphasise soil-plant interactions by considering the importance of vegetation, both as a provisioning service and as a factor in soil evolution. Our review covers output variables, time scales, spatial representation, model structure, and control variables. Our synthesis in this work demonstrates that the modelling of Pedogenesis in the Anthropocene requires the following specific features: (i) a description of the human impact on soil evolution, (ii) outputs related to ecosystem functions and services, (iii) the integration of a dual time scale (decade and cyclic shorter-term), (iv) multiple and interactive processes modelling, (v) the simulation of vegetation and its feedback on soils, and (vi) a representation of spatial heterogeneities, at least at the profile scale. No specific models of soil evolution in the Anthropocene have been developed thus far; however, certain required characteristics have been integrated into existing soil-plant models. Some others features will require further development, particularly a coherent and tested conceptual cornerstone that enables dual-time-scale modelling and is based on the resilience concept and energy metrics. We thus propose a general framework as a conceptual basis from which we can develop models of Pedogenesis in the Anthropocene.
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characteristics and potential pedogenetic processes of a technosol developing on iron industry deposits
Journal of Soils and Sediments, 2013Co-Authors: Hermine Huot, Marieodile Simonnot, Philippe Marion, Jacques Yvon, Philippe De Donato, Jean-louis MorelAbstract:Purpose Technosols include soils dominated or strongly influenced by human-made materials. Similarly to natural soils, technogenic parent materials submitted to environmental factors undergo weathering and transformation processes. But the Pedogenesis of Technosols remains little known. With this aim in view, a Technosol developing on purely technogenic materials resulting from an iron industry was thoroughly characterized in order to discuss the pedogenetic evolution of this Technosol using knowledge about the Pedogenesis of natural soils.
Christophe Schwartz - One of the best experts on this subject based on the ideXlab platform.
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A micromorphological analysis for quantifying structure descriptors in a young constructed Technosol
Boletín de la Sociedad Geológica Mexicana, 2019Co-Authors: Françoise Watteau, Nouhou-salifou Jangorzo, Christophe SchwartzAbstract:Evaluating soil structure dynamics is a major challenge when analysing or modelling Pedogenesis. Constructed Technosols are considered, by definition, to be good candidates for pedogenetic studies, insofar as their initial characteristics and implementation conditions are controlled. Thus, we developed an approach based on image analysis of soil microstructures in order to specify the structure dynamics of a constructed Technosol. We described and quantified porosity and aggregation descriptors on a microscale (1) from pictures of mesocosms performed during 14 months, using an innovative automatic high-resolution image-acquisition device (Soilinsight®), and (2) from thin sections sampled in situ in a 1 ha field experiment at t0 and t2 (17 months). Plant root system architecture of Lupinus albus and the behavior of introduced earthworms (Lumbricus castaneus) were described using the Soilinsight® device. After 14 months, the pore surface was 10 times greater in the presence of plants and macrofauna than in the control samples. Although the biological activity promoted the genesis of aggregates, their dynamics were irregular. In fact, the proportion of aggregates varied depending on both root age and worm action. In situ, the soil was progressively compacted due to a significant decrease in the number of >2000 µm pores. In the same way, three aggregate descriptors—number, area and shape—were selected as the most significant indicators of soil aggregation evolution during the early stages of Pedogenesis. In conclusion, this approach, based on the quantification of microstructure parameters, did indeed allow the description and monitoring of 2D soil structure dynamics in both field and mesocosms conditions. Completed with 3D soil structure data, this micromorphological analysis could advantageously contribute to the impact of climatic and biological agents modelling on a structural evolution of Technosols during initial Pedogenesis.
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Ranking of wetting–drying, plant, and fauna factors involved in the structure dynamics of a young constructed Technosol
Journal of Soils and Sediments, 2018Co-Authors: Nouhou-salifou Jangorzo, Françoise Watteau, Christophe SchwartzAbstract:Dynamical in situ observation of biological and climatic structuring factors involved in Pedogenesis has not previously been possible in a way that would consider the early stages of Pedogenesis. If studies have explored the effect of pedogenetic factors on soil structure, none have succeeded in ranking them in view of the intensity of their effects. We propose a novel approach for describing the aggregation process for a constructed Technosol obtained from a process of pedological engineering. We focus on agents including plants, macrofauna, and water, and we use (i) a dynamic in situ observation and (ii) the quantification of the evolution of selected descriptors of pores and aggregates. They are quantified from high-resolution images obtained with the SoilinsightA (R) device. Associating those images with each other, movies of interactions between soil and organisms over a 14-month non-destructive soil evolution experiment are made. Agents influencing aggregation-plant roots, earthworms, and water-can be ranked according to their impact on soil structure. During the studied period of evolution, wetting-drying cycles are the first to operate. The intensity of their action on soil structure is dominant at the very first stages of Pedogenesis. Despite this ranking of agents, over the long term, plants and earthworms have a more intense effect on soil structure than wetting-drying cycles. The method applied to observe and quantify soil structure dynamics is thus proposed as a helpful approach to modeling other processes involved in soil functioning and evolution in relation to their ability to fulfill ecosystem services.
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Technosol construction with by-products and wastes: Pedogenesis and modelling
2016Co-Authors: Sophie Leguedois, Geoffroy Séré, Françoise Watteau, Christophe Schwartz, Apolline Auclerc, Audrey Boigné, Fabrice Bureau, Estelle Langlois, Jean-louis MorelAbstract:Technosol construction with by-products and wastes: Pedogenesis and modelling. SUMMER SCHOOL ON CONTAMINATED SEDIMENTS: CHARACTERIZATION AND REMEDIATION
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Modelling Pedogenesis of technosols
Geoderma, 2016Co-Authors: Sophie Leguedois, Geoffroy Séré, Jérôme Cortet, Stéphanie Ouvrard, Françoise Watteau, Christophe Schwartz, Hermine Huot, Apolline Auclerc, Jean-louis MorelAbstract:Technosols, soils subjected to a strong human influence and containing significant amounts of artefacts, are characteristic of the Anthropocene. In order to better apprehend their growing importance in our current environment, our knowledge of the evolution and fate of these soils must be improved. The aim of this article is to promote pedogenic modelling for Technosols by proposing an appropriate framework. The paper first defines the characteristics of Technosol Pedogenesis, and then considers the requirements for its modelling in light of general concepts of Pedogenesis, modelling tools and techniques, and 18 selected existing quantitative models. This mixed technical and conceptual analysis allows us to address at once the modelling approach, the choice of processes, the integration of control variables, the time scales, the spatial representation, and the data needed for such a framework. Technosol Pedogenesis is characterised by the soils' anthropic creation, a young age, a climate globally favourable for soil evolution, a surprising level of biological activity, and mostly reactive artefacts as parent materials. Pedogenic processes observed in Technosols are similar to those occurring in more natural soils; however, they generally have fast kinetics and occur in unusual assemblages. We propose that the modelling framework for Technosol evolution should be based on the coupling of process-based models of soil functioning processes and accommodate the peculiar properties of technogenic materials. Our work also highlights modelling features needed for Pedogenesis in general: development of biological and physical models, selection of a comprehensive energy unit, dual-time scale modelling, and multi-scale representation of the soil profile. We propose (i) an adaptation of existing energy metrics (entropy, exergy, emergy or EEMT), (ii) a dual-time scale approach, our original concept, based on resilience patterns in soil changes, and (iii) the development of an existing spatial representation. Constructed Technosols are a relevant experimental model which supplies reliable data on soil evolution, data which are required for the development of pedogenic models. Technosols are emblematic of the issues we face for the management of the soils of the Anthropocene. The design of a modelling framework for Technosol evolution should therefore bring interesting developments for pedogenic modelling in general.
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Modelling Pedogenesis in the Anthropocene
2014Co-Authors: Sophie Leguedois, Geoffroy Séré, Jérôme Cortet, Stéphanie Ouvrard, Françoise Watteau, Christophe Schwartz, Jean-louis MorelAbstract:The objective of this paper is to develop a framework for pedogenetic modelling in the Anthropocene, i.e., the present geological epoch during which humanity has become the main factor impacting the environment. We review the concepts of soil evolution as well as 15 existing quantitative models to determine the features of soil evolution modelling in an Anthropocene context. We emphasise soil-plant interactions by considering the importance of vegetation, both as a provisioning service and as a factor in soil evolution. Our review covers output variables, time scales, spatial representation, model structure, and control variables. Our synthesis in this work demonstrates that the modelling of Pedogenesis in the Anthropocene requires the following specific features: (i) a description of the human impact on soil evolution, (ii) outputs related to ecosystem functions and services, (iii) the integration of a dual time scale (decade and cyclic shorter-term), (iv) multiple and interactive processes modelling, (v) the simulation of vegetation and its feedback on soils, and (vi) a representation of spatial heterogeneities, at least at the profile scale. No specific models of soil evolution in the Anthropocene have been developed thus far; however, certain required characteristics have been integrated into existing soil-plant models. Some others features will require further development, particularly a coherent and tested conceptual cornerstone that enables dual-time-scale modelling and is based on the resilience concept and energy metrics. We thus propose a general framework as a conceptual basis from which we can develop models of Pedogenesis in the Anthropocene.
Shuichiro Yoshinaga - One of the best experts on this subject based on the ideXlab platform.
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sulfur accumulation in melanudands during development by upbuilding Pedogenesis since 14 15cal ka
Geoderma, 2014Co-Authors: Toko Tanikawa, Yohey Hashimoto, Noriko Yamaguchi, Yoshiaki Ito, Sei Fukushima, Kazuhiro Kanda, Masaharu Uemura, Takayuki Hasegawa, Masamichi Takahashi, Shuichiro YoshinagaAbstract:To understand the contribution of upbuilding Pedogenesis to the accumulation of sulfur (S) in Melanudands, we investigated the vertical distribution of S species using K-edge X-ray absorption near-edge structure (XANES) spectroscopy of S species and vertical variation of δ34S values of total S in two Japanese Melanudands developed above tephra Nt-S, dated at 14–15 cal. ka. These soils have been developed by upbuilding Pedogenesis, in which episodic accumulations of volcanic ash and eolian dust transported from the Asian continent are added incrementally to the soil surface while topdown Pedogenesis occurs concomitantly forming soil horizons. The oxidation states of S compounds determined by XANES analysis varied widely in the soil profiles. The predominant S species was highly oxidized S in ester sulfates and inorganic sulfates (+ 6 oxidation state). Proportions of S with reduced and intermediate oxidation states increased episodically to as much as 66%. Ester sulfate-S was found in the soil horizons with estimated ages less than 10 cal ka. A close correlation was found between ester sulfate-S concentrations and Al-associated organic S concentrations (p < 0.05); indeed, the concentrations themselves were roughly similar. The δ34S values of total S increased with depth in the two soil profiles. These results suggest that episodic deposits of volcanic ash and eolian dust trapped detritus and humus beneath them during the buildup of the soil surface. The organic S compounds in this material might be decayed as topdown pedogenic processes in the soils. Production of ester sulfate-S may be related to the warm and humid climate of the Holocene, which may have accelerated microbial activity responsible for transformation of reduced to highly oxidized S. Ester sulfate-S might have become Al-associated forms and accumulated in the soils due to their high pedogenic mineral contents.
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Sulfur accumulation in Melanudands during development by upbuilding Pedogenesis since 14–15cal.ka
Geoderma, 2014Co-Authors: Toko Tanikawa, Yohey Hashimoto, Noriko Yamaguchi, Yoshiaki Ito, Sei Fukushima, Kazuhiro Kanda, Masaharu Uemura, Takayuki Hasegawa, Masamichi Takahashi, Shuichiro YoshinagaAbstract:To understand the contribution of upbuilding Pedogenesis to the accumulation of sulfur (S) in Melanudands, we investigated the vertical distribution of S species using K-edge X-ray absorption near-edge structure (XANES) spectroscopy of S species and vertical variation of δ34S values of total S in two Japanese Melanudands developed above tephra Nt-S, dated at 14–15 cal. ka. These soils have been developed by upbuilding Pedogenesis, in which episodic accumulations of volcanic ash and eolian dust transported from the Asian continent are added incrementally to the soil surface while topdown Pedogenesis occurs concomitantly forming soil horizons. The oxidation states of S compounds determined by XANES analysis varied widely in the soil profiles. The predominant S species was highly oxidized S in ester sulfates and inorganic sulfates (+ 6 oxidation state). Proportions of S with reduced and intermediate oxidation states increased episodically to as much as 66%. Ester sulfate-S was found in the soil horizons with estimated ages less than 10 cal ka. A close correlation was found between ester sulfate-S concentrations and Al-associated organic S concentrations (p
Leo M Condron - One of the best experts on this subject based on the ideXlab platform.
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Sulfur dynamics during long-term ecosystem development
Biogeochemistry, 2016Co-Authors: Benjamin L. Turner, Leo M Condron, Christine A. M. France, Johannes Lehmann, Dawit Solomon, Duane A. Peltzer, Sarah J. RichardsonAbstract:Long-term soil and ecosystem development involves predictable changes in nitrogen (N) and phosphorus (P) availability and limitation, but far less is known about comparable changes in sulfur (S) despite its importance as an essential plant macronutrient and component of soil organic matter. We used a combination of elemental analysis, X-ray absorption spectroscopy, hydrolytic enzyme assays, and stable S isotope ratios to examine S in soil and leaf tissue along the 120,000-year Franz Josef chronosequence, New Zealand. Total soil S concentrations increased during the early stages of Pedogenesis and then declined as soils aged. There was little variation in soil N:S ratios along the chronosequence other than in the youngest (5 year old) soil, although the carbon (C):S ratio increased markedly in the oldest soils and the P:S ratio decreased continuously along the chronosequence. Foliar S concentrations and N:S ratios varied widely among common plant species but did not change consistently with increasing soil age, although foliar P:S declined for several species in the older stages of the chronosequence. The chemical nature of soil organic S extracted from mineral and organic horizons and determined by S K -edge X-ray absorption near-edge fine-structure (XANES) spectroscopy was dominated by C-bonded S distributed approximately equally in highly-reduced and intermediate oxidation states, although ester-bonded S was also abundant throughout the chronosequence. Soil sulfatase activity expressed on a soil C basis was highest in young soils, indicating low S availability in the early stage of Pedogenesis. Enzymatic C:S and N:S ratios varied little during ecosystem development, although the enzymatic P:S ratio increased continuously along the chronosequence. Stable S isotope ratios (δ^34S) increased along the chronosequence, particularly in the early stages of Pedogenesis, reflecting a shift in S inputs from primary mineral S to oceanic sulfate in atmospheric deposition. Overall, this first comprehensive assessment of S along a long-term soil chronosequence suggests that S availability is low in the earliest stage of Pedogenesis, but then remains stable throughout the progressive and retrogressive phases of ecosystem development, despite pronounced shifts in the chemistry and dynamics of other nutrients.
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Pedogenesis soil mass balance phosphorus dynamics and vegetation communities across a holocene soil chronosequence in a super humid climate south westland new zealand
Geoderma, 2011Co-Authors: Andre Eger, Peter C Almond, Leo M CondronAbstract:Abstract This study quantifies progressive Pedogenesis under a super-humid climate on the west coast of South Island, New Zealand. It focuses on soil morphology, pedogenic oxides, soil mass balance, phosphorus transformation and linking Pedogenesis trajectories to vegetation communities. The study comprises a set of dune ridges of a coastal sand dune complex covered by unmodified conifer (podocarp)-angiosperm forest. The surface ages of the chronosequence range from 370 y to 6500 y. Rapid podzolisation is characteristic for the study area. Within 1000 y, soils reach the Spodosol stage with typical eluvial–illuvial horizons and mobilisation of Fe and Al. This period is also characterised by the most rapid losses of total phosphorus at a rate of 110 g m − 2 ky − 1 , a relative loss of 41%. Beyond 3000 y changes in soil chemistry and losses for all nutrients markedly slow. Soil mass balance shows that the 6500 y soil has lost 75% total P, 62% K, 52% Ca and 54% Na. Soil P fractions substantially change across the gradient. High leaching losses of apatite and non-occluded P in the first hundreds of years coincide with accumulation of organic and occluded inorganic forms in the topsoil and subsoil, which mitigate total P loss. Beyond 1000 y of Pedogenesis, all P fractions decline at similar rates to low, more persistent levels with apatite/non-occluded P being the dominant P form after 6500 y of Pedogenesis. This incipient steady state is assumed to be sustained by the advection of parent material-derived P through surface lowering and reduced biological cycling. Vegetation communities change from more diverse communities on young and less impoverished soils in the first 1000 y to less diverse and less variable communities beyond 1000 y of ecosystem development. The soil evolution-correlated vegetation changes documented in this study are consistent with general schemes of vegetation succession for the west coast of South Island.
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Soil Organic Phosphorus Transformations During Pedogenesis
Ecosystems, 2007Co-Authors: Benjamin L. Turner, Leo M Condron, Duane A. Peltzer, Sarah J. Richardson, Victoria J. AllisonAbstract:Long-term changes in soil phosphorus influence ecosystem development and lead to a decline in the productivity of forests in undisturbed landscapes. Much of the soil phosphorus occurs in a series of organic compounds that differ in their availability to organisms, but changes in the relative abundance of these compounds during Pedogenesis remain unknown. We used alkaline extraction and solution phosphorus-31 nuclear magnetic resonance spectroscopy to assess the chemical nature of soil organic phosphorus along a 120,000-year post-glacial chronosequence at Franz Josef, New Zealand. Inositol phosphates, DNA, phospholipids, and phosphonates accumulated rapidly during the first 500 years of soil development characterized by nitrogen limitation of biological productivity, but then declined slowly to low concentrations in older soils characterized by intense phosphorus limitation. However, the relative contribution of the various compounds to the total organic phosphorus varied along the sequence in dramatic and surprising ways. The proportion of inositol hexakisphosphate, conventionally considered to be relatively recalcitrant in the environment, declined markedly in older soils, apparently due to a corresponding decline in amorphous metal oxides, which weather to crystalline forms during Pedogenesis. In contrast, the proportion of DNA, considered relatively bioavailable in soil, increased continually throughout the sequence, due apparently to incorporation within organic structures that provide protection from biological attack. The changes in soil organic phosphorus coincided with marked shifts in plant and microbial communities, suggesting that differences in the forms and bioavailability of soil organic phosphorus have ecological significance. Overall, the results strengthen our understanding of phosphorus transformations during Pedogenesis and provide important insight into factors regulating the composition of soil organic phosphorus.
Elizabeth Solleiro-rebolledo - One of the best experts on this subject based on the ideXlab platform.
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Late Pleistocene ‐ Holocene palaeosols in the north of Sonora, Mexico: chronostratigraphy, Pedogenesis and implications for environmental history
European Journal of Soil Science, 2014Co-Authors: Tamara Cruz-y-cruz, Sergey Sedov, Guadalupe Sanchez, Teresa Pi-puig, K. Pustovoytov, Hermenegildo Barceinas-cruz, Beatriz Ortega-guerrero, Elizabeth Solleiro-rebolledoAbstract:Summary Red palaeosols of the late Pleistocene-early Holocene, both buried and non-buried, were studied recently in Sonora (NW Mexico) to reconstruct their Pedogenesis as well as the palaeoenvironmental conditions. The alluvial palaeosol-sedimentary sequence of the La Playa archaeological site is a key locality for the buried San Rafael palaeosol, which exhibits a 2Ah-2Bw-2BCk-3Bgk profile and was defined as a Chromic Cambisol. Radiocarbon dates from pedogenic carbonates and charcoal set the soil formation interval between >18000 and 4300calibrated years before present (cal. year BP). Micro-morphological observations together with profile distribution of clay, carbonates, organic carbon, pedogenic iron oxides and rock magnetic properties indicated a strong eluvial-illuvial redistribution of carbonates, moderate silicate weathering and gleying in the lower horizon. Although this soil was much more developed than the overlying syn-sedimentary late Holocene Fluvisols, clay mineral composition and stable carbon isotope signatures of humus and carbonates were similar in both soils. We suggest that Pedogenesis of the San Rafael palaeosol took place under a slightly more humid climate and relative geomorphic stability. This agrees with the regional palaeoclimate reconstruction, which indicates a moister climate during the Late Wisconsin glaciation (MIS 2). An abrupt termination of the San Rafael Pedogenesis marked by disturbance and aridization features in the Ap horizon of the palaeosol could be linked to a global drought around 4200years cal. year BP. Surface Chromic Cambisols in northern Sonora show similar pedogenetic characteristics to the buried red palaeosols of La Playa. They appear to be a relict component of the present day soil mantle.
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Paleosol-sedimentary sequences of the Glacis de Buenavista, Central Mexico: interaction of Late Quaternary Pedogenesis and volcanic sedimentation
Quaternary International, 2002Co-Authors: Elizabeth Solleiro-rebolledo, Sergey Sedov, Jorge Gama-castro, D Flores Román, G. Escamilla-sarabiaAbstract:Abstract Two sections (Buenavista and Ahuatenco) of Late Quaternary paleosol-sedimentary sequences of the Glacis de Buenavista, Morelos, Central Mexico, were studied and interpreted as a regional record of climatic change and interaction of Pedogenesis and volcanic sedimentation. Buenavista is the deepest section and includes seven pedostratigraphic units, with Andosol (surface unit) and Luvisol (all underlying units) types of Pedogenesis. Both types indicate a humid forest environment, the divergency being related to differences in Pedogenesis duration. Albeluvisol with a bleached E horizon in unit 5 indicates cooler but still moist conditions in the final Late Pleistocene, whereas strong vertic properties in unit 4 indicate a climate with contrasting seasonal variation of precipitation during the first part of the Holocene. In the upper part of the Ahuatenco section, Bt horizons of different pedogenetic events form a welded Luvisol profile instead of a set of separate paleosols due to less intensive sedimentation. Material of indurated Cm horizons (tepetates) in the lower part of the Ahuatenco section is a mixture of fresh coarse volcanoclastic components and re-deposited Luvisol clayey material, formed by mass movement associated with volcanic events. The resulting granulometric composition of these layers is favourable for structural collapse and hydroconsolidation, which caused hardening together with subsequent pedogenic illuviation and redoximorphic processes.
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Micromorphology of a Soil Catena in Yucatán: Pedogenesis and Geomorphological Processes in a Tropical Karst Landscape
New Trends in Soil Micromorphology, 1Co-Authors: Sergey Sedov, Elizabeth Solleiro-rebolledo, Teresa Pi-puig, Scott L. Fedick, Ernestina Vallejo-gómez, María De Lourdes Flores-delgadilloAbstract:Development of the soil mantle in karst geosystems of the tropics is still poorly understood. We studied a typical soil toposequence formed over limestone in the northeastern Yucatan Peninsula of Mexico, to assess the pedogenetic and -geomorphological processes which control soil formation and distribution, as well as to understand their relation to landscape development and their influence in -ancient Maya agriculture. The soil cover is dominated by thin Leptic Phaeozems and Rendzic Leptosols in the uplands, and Leptic Calcisols in the wetlands. Upland soils have weathered groundmass containing abundant vermiculitic clay and iron oxides. The combination of thinness and high weathering status is explained by interaction between the intensive Pedogenesis and vertical transport of soil material towards karst sinkholes. In wetlands, biochemical secondary calcite precipitation occurs, accompanied by surface accumulation of algal residues (periphyton crust). In the transitional area, a polygenetic profile (Calcisol over Cambisol) was developed, -indicating recent advance of wetlands. Because of specific Pedogenesis, the upland soils lack many disadvantages of other soils of humid tropics, such as -acidity, low humus content, and poor structure. However, ancient land-use practices had to be adjusted to thin soils, low P availability and soil loss due to karst erosion.
