Philippe AMIOTTE SUCHET - Academia.edu (original) (raw)

Papers by Philippe AMIOTTE SUCHET

<p>In the Bourgogne Franche-Comté region, clim... more <p>In the Bourgogne Franche-Comté region, climate change will lead to an increase of the field evapotranspiration during the crop cycle and a modification of the rainfall distribution within the year, leading to longer and more intense drought periods in summer. This will increase the crop water requirement, while reducing water availability and accessibility, which could negatively impact agricultural productivity and stability. It is thus necessary to evaluate actual and future water deficiency in a way to develop and implement adapted responses (new farming practices, new crops, water storage…). Based on simulated weather data (rainfall and potential evapotranspiration) integrating the effect of climate change until 2100, soil characteristics (texture and depth) and crop water requirement, we estimate the daily water balance at the scale of the Bourgogne Franche-Comté region, France. We use weather data at an 8*8 square-kilometres grid and soil water capacity is estimated at the soil map unit using the methodology developed by Bruand et al. (2004). This methodology estimates the water capacity of each layer of the soil unit based on their texture class (Aisne triangle) and removing the proportion of gravels and rocks considering that their contribution to water storage is negligible. For the 10 main crops of the region in terms of field area (<em>i.e.</em> grassland, winter wheat, winter barley, winter oilseed rape, spring barley, maize, soybean, sunflower, winter peas and spring peas), we calculate the water balance using the methodology developed by Jacquart and Choisnel (1995) at the scale of the intersection between the weather grid and the soil map unit in a way to represent homogeneous pedoclimatic territories. The soil water capacity is thus divided in two reservoirs with no horizontal transfer. Water from the first reservoir (40% of the soil water capacity) is easily accessible to the crop while water from the second reservoir is less and less accessible as the reservoir is emptied. At a daily step, the meeting of the crop water requirement is estimated regarding the water available in the soil reservoirs and the rainfalls. This study enables to estimate the actual water deficiency of the main crops and its potential increase due to climate change. We can thus identify crops that could not be cropped anymore without irrigation in some area and estimate the water required if we want to keep these crops in the future. These results are also important to evaluate if it is possible to developed new practices or water storage in response to the effects of climate change. Our approach allows as well to evaluate and anticipate the possibility to implement new crops requiring less water, avoiding the drought periods or able to access more water in the soil. These results will allow the agricultural sector to develop outlets for these new crops.</p>

Many studies about climate change impacts assessment are published every year. These studies comm... more Many studies about climate change impacts assessment are published every year. These studies commonly use a hydroclimatic modelling chain, whose principle is to feed impact models with climate models outputs. An important step in this process is to test the validity of impact models in a climate change context. However, this step is not frequently applied. The aim of this study is to test the robustness of two hydrological models with distinct conceptualizations: a global and empirical model (GR4J) and a semi-distributed and physically-based model (SWAT). They both have been calibrated and validated over climate contrasted periods. Despite a higher decrease of performance between calibration and validation for the GR4J model, both of them show relative robustness. Moreover, the stability of parameters between the two calibration periods shows that their value are not much influenced by the climate of the calibration period, and consequently remains valid during the entire projection...

Palaeogeography, Palaeoclimatology, Palaeoecology, 2016

Campanian sediments from two French sedimentary basins were studied, using clay mineralogy and st... more Campanian sediments from two French sedimentary basins were studied, using clay mineralogy and stable isotope (δ 13 C and δ 18 O) geochemistry, in order to investigate the Late Campanian Event. The clay fraction of the Campanian sediments from the Tercis-les-Bains section (Aquitaine Basin) and from the Poigny borehole (Paris Basin) is mainly composed of smectite. This background sedimentation was, however, interrupted during the Upper Campanian in the two basins by a substantial increase in detrital inputs, including illite, kaolinite, and chlorite at Tercis-les-Bains, and illite at Poigny. This detrital event, resulting from the enhanced erosion of nearby continental areas triggered by increasing runoff, has also been recognized in the Tethys and South Atlantic oceans. It coincided with a global negative carbon isotope excursion, the Late Campanian Event (LCE). Carbon isotope stratigraphy was used to correlate the two basins with previously studied sections from distant areas. Spectral analysis of the bulk δ 13 C from Tercis-les-Bains suggests a duration of ca. 400 kyr for a pre-LCE negative excursion and ca. 800-900 kyr for the LCE sensu stricto. The detrital event, as characterized by clay mineralogy, spans the interval that comprises the pre-LCE and the LCE, with a duration of 1.3 Myr. Intensification of continental erosion during the LCE may have resulted either from the Late Campanian polyplocum regression and/or from a regional tectonic pulse that triggered the emersion of previous submerged shelf areas and the increase of silicate erosion. As the LCE seems to be recorded at a large geographic scale, it is proposed here that enhanced chemical weathering and an associated decrease in atmospheric pCO 2 levels could have contributed to the long-term Late Cretaceous cooling trend.

Dissolved organic carbon (DOC) is a dynamic component of ecosystem functioning and environmental ... more Dissolved organic carbon (DOC) is a dynamic component of ecosystem functioning and environmental quality. This study demonstrates that different DOC dynamics (mineralization rates, δ13C) occur in forest soils either maintained as native or planted with Douglas fir.

Environmental Research, 2014

This study seeks to determine to what extent trace metals resulting from past mining activities a... more This study seeks to determine to what extent trace metals resulting from past mining activities are transferred to the aquatic ecosystem, and whether such trace metals still exert deleterious effects on biota. Concentrations of Cd, Cu, Pb and Zn were measured in streambed sediments, transplanted bryophytes and wild brown trout. This study was conducted at two scales: (i) the entire Morvan Regional Nature Park and (ii) three small watersheds selected for their degree of contamination, based on the presence or absence of past mining sites. The overall quality of streambed sediments was assessed using Sediment Quality Indices (SQIs). According to these standard guidelines, more than 96% of the sediments sampled should not represent a threat to biota. Nonetheless, in watersheds where past mining occurred, SQIs are significantly lower. Transplanted bryophytes at these sites consistently present higher trace metal concentrations. For wild brown trout, the scaled mass and liver indices appear to be negatively correlated with liver Pb concentrations, but there are no obvious relationships between past mining and liver metal concentrations or the developmental instability of specimens. Although the impact of past mining and metallurgical works is apparently not as strong as that usually observed in modern mining sites, it is still traceable. For this reason, past mining sites should be monitored, particularly in protected areas erroneously thought to be free of anthropogenic contamination.

Plant and Soil, 2009

In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) po... more In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) pool and CO 2 production were studied in soil from a native oak-beech forest and a Douglas fir plantation during a 98-day incubation at a range of temperatures from 8°C to 28°C. The soil organic carbon, water contents and mineralisation rates of soil samples from the 0-5 cm layer were higher in the native forest than in the Douglas fir plantation. During incubation, a temperature-dependent shift in the δ 13 C of respired CO 2 was observed, suggesting that different carbon compounds were mineralised at different temperatures. The initial size of the WEOC pool was not affected by forest type. The WEOC pool size of samples from the native forest did not change consistently over time whereas it decreased significantly in samples from the Douglas plantation, irrespective of soil temperature. No clear changes in the δ 13 C values of the WEOC were observed, irrespective of soil origin. The fate of the WEOC, independent of soil organic carbon content or mineralisation rates, appeared to relate to forest types. Replacement of native oak-beech forest with Douglas fir plantation impacts carbon input to the soil, mineralisation rates and production of dissolved organic carbon.

Global and Planetary Change, 1998

The export of carbon from land to sea by rivers represents a major link in the global carbon cycl... more The export of carbon from land to sea by rivers represents a major link in the global carbon cycle. For all principal carbon forms, the main factors that control the present-day fluxes at the global scale have been determined in order to establish global budgets and to predict regional fluxes. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment yields and of drainage intensity. The consumption of atmosphericrsoil CO by chemical rock weathering 2 Ž depends mainly on the rock type and on the drainage intensity. Our empirical models yield a total of 0.721 Gt of carbon Gt. C that is exported from the continents to the oceans each year. From this figure, 0.096 Gt C come from carbonate mineral Ž. dissolution and the remaining 0.625 Gt C stem from the atmosphere F. Of this atmospheric carbon, 33% is discharged CO 2 as dissolved organic carbon, 30% as particulate organic carbon, and 37% as bicarbonate ions. Predicted inorganic carbon fluxes were further compared with observed fluxes for a set of 35 major world rivers, and possible additional climatic effects on the consumption of atmospheric CO by rock weathering were investigated in these river basins. Finally, we discuss the 2 implications of our results for the river carbon fluxes and the role of continental erosion in the global carbon cycle during the last glacial maximum.

Chemical Geology, 1999

The transfers and origins of dissolved inorganic carbon DIC were studied for a year in a soil-spr... more The transfers and origins of dissolved inorganic carbon DIC were studied for a year in a soil-spring-stream system in the Strengbach catchment, Vosges mountains, France. This 80 ha experimental research basin is located on the eastern side Ž. of the mountains, at an altitude ranging from 883 to 1146 m.a.s.l. and is mainly covered by spruce 80%. Brown acid and podzolic soils developed on a granitic basement, and, as a result, the DIC originates solely from CO generated by oxidation 2 Ž 13. of soil organic matter. The d C in catchment waters is highly variable, from about y22‰ in the springs and DIC piezometers to about y12‰ in the stream at the outlet of the catchment. In the springs, pronounced seasonal variations of d 13 C exist, with the DIC in isotopic equilibrium with the soil CO that has estimated d 13 C of about y24‰ in winter and DIC 2 y20‰ in summer. These seasonal variations reflect an isotopic fractionation that seems only induced by molecular Ž diffusion of soil CO in summer. In stream water, seasonal variations are small and the relatively heavy DIC y12‰ on 2. average is a result of isotopic equilibration of the aqueous CO with atmospheric CO .

Applied Geochemistry, 2000

Knowledge of the impact of N-fertilizers on the weathering-erosion processes of soils in intensiv... more Knowledge of the impact of N-fertilizers on the weathering-erosion processes of soils in intensively cultivated regions is of prime importance. Nitri®cation of NH 4 À fertilizers produces HNO 3 in the basin of the Garonne river, enhancing soil degradation. Their in¯uence on the weathering rates was determined by calculating the consumption rate of atmospheric/soil CO 2 by soil weathering and erosion, and its contribution to the total dissolved riverine HCO 3 À. This contribution was found to be less than 50% which corresponds normally to a complete carbonate dissolution by carbonic acid, suggesting that part of the alkalinity in the river waters is due to carbonate dissolution by an acid other than carbonic acid, probably HNO 3 .

Microbial carbon mineralization in soils leads to the production of different gaseous or dissolve... more Microbial carbon mineralization in soils leads to the production of different gaseous or dissolved components that have environmental impacts. Our study deals with the influence of soil temperature on the production of gaseous and dissolved carbon components during carbon mineralization in forest soils in France. After an incubation of soil samples for 42 days at 4 different temperatures, we determined both size and 13C isotopic signature of dissolved organic carbon and CO2 pools. We also characterised the soil microbial community structure (PLFA profiles). While temperature clearly increases the CO2 production, a low decrease of the dissolved organic carbon pool was observed whatever the temperature of incubation. The isotopic fractionation of the dissolved organic pool was not affected by temperature while a correlation was observed between temperature and isotopic fractionation of the produced CO2. The soil microbial structure was observed to change during incubation. Changes wer...

L'alteration chimique des roches est essentiellement le fait de l'attaque des mineraux pa... more L'alteration chimique des roches est essentiellement le fait de l'attaque des mineraux par l'acide carbonique issu du co#2 atmospherique, via la photosynthese puis la degradation de la matiere organique dans les sols. Ce co#2 dissous, implique dans les reactions d'alteration, est ensuite transporte en solution, principalement sous forme d'ions bicarbonates, par les fleuves vers les oceans. Pour estimer la quantite de co#2 consomme par erosion chimique des roches sur les continents, deux modeles sont developpes dans ce travail. Le premier est un modele geochimique de decomposition des flux d'elements majeurs exportes en solution par les fleuves (modele mega, major element geochemical approach). Le second (gem-co#2 global erosion model) est base sur un ensemble de relations empiriques entre le flux de co#2 consomme et le drainage pour les principaux types de roche affleurant a la surface des continents. Ce modele permet de simuler l'intensite et la distribu...

- Surface runoff and soil erosion are major threats to sustainable agriculture and mapping region... more - Surface runoff and soil erosion are major threats to sustainable agriculture and mapping regional erosion risk is increasingly needed by local, national and international environment agencies. Because erosion results from the interaction of several parameters which vary in space and time, no simple model can take into account all relevant factors, particularly in cultivated areas where human influences are predominant. The aim of this work is to develop a methodology based firstly on Le Bissonnais’s model and to apply it to evaluate the erosion risk on the Santiago Island in Cape Verde archipelago. According to the model, the rainfall erosion map revealed that Santiago Island may be broadly divided into five major erosion risk zones. While bare soils and rain fed sectors are respectively in the severe to extremely severe erosion risk zone with 916 km 2 , this is 91 % of Santiago’s area. The coastal sector of Santiago is generally in the low erosion risk zone; the irrigation and fo...

The flux of atmospheric/soil CO2 consumed by chemical weathering of the continents (FCO2) can be ... more The flux of atmospheric/soil CO2 consumed by chemical weathering of the continents (FCO2) can be estimated from bicarbonate concentrations in surface water. Using data from the bibliography for 232 small monolithologic watersheds, relationships between FCO2 and the runoff (Q) have been determined For the major rock types outcropping on the continents. The models fitted to these relationships are then applied to the Garonne and Congo river basins, in order to calculate the mean CO2 flux consumed in these basins. The results obtained are close to previous estimates bosed on field measurements

HYCCARE Bourgogne est un projet de recherche-action dont l’objectif est de mettre a disposition d... more HYCCARE Bourgogne est un projet de recherche-action dont l’objectif est de mettre a disposition des decideurs locaux des outils qui leur permettront de mieux prendre en compte le risque lie aux impacts du changement climatique sur la ressource en eau.

L'etude porte sur l'adaptation au changement climatique en Bourgogne. Elle vise a definir... more L'etude porte sur l'adaptation au changement climatique en Bourgogne. Elle vise a definir la sensibilite de la ressource en eau des territoires Bourguignons a ces evolutions climatiques et a en estimer les incidences par secteurs geographiques et d'activite. Ce projet pluri-disciplaire a ete mis en place par Alterre Bourgogne dont la tache a ete de federer un reseau d'acteurs regionaux aux competences variees : climatologie, pedologie et hydrologie. La premiere etape, (Ubertosi et al, GFHN 2009), a consiste a estimer la capacite des sols a stocker de l'eau, c'est-a-dire a calculer la taille de leur reserve utile. Ces calculs ont ete realises a partir du referentiel pedologique de Bourgogne aux 1/250000eme. La seconde etape, presentee ici, consiste en la realisation d'un bilan hydrique, spatialise sur la Bourgogne et modelise au pas de temps mensuel et a l'echelle spatiale La notion de changement climatique est abordee ici par une comparaison entre deu...

We propose in this study an initial estimation of the annual organic matter yield induced by chem... more We propose in this study an initial estimation of the annual organic matter yield induced by chemical weathering of carbonates and shales considering their global surface at outcrop and their organic matter content. The calculation also uses data on river fluxes resulting from carbonate rocks and shales weathering in major world watersheds, published by numerous authors [1]. The results obtained from the studied watersheds have been extrapolated to a global scale. Despite rather large incertainty inherent to such an approach, the calculated value [2] of ca. 0.1 Gt implies that the annual organic carbon yield related to carbonates and shales chemical weathering might be a non-negligible component of the global carbon cycle. The calculated yield does not constitute a direct supply to soils and the rivers because a part of the produced organic matter can be mineralised, thus escaping recycling. Depending on the real fate of the organic carbon released from weathered ancient formations,...

<p>In the Bourgogne Franche-Comté region, clim... more <p>In the Bourgogne Franche-Comté region, climate change will lead to an increase of the field evapotranspiration during the crop cycle and a modification of the rainfall distribution within the year, leading to longer and more intense drought periods in summer. This will increase the crop water requirement, while reducing water availability and accessibility, which could negatively impact agricultural productivity and stability. It is thus necessary to evaluate actual and future water deficiency in a way to develop and implement adapted responses (new farming practices, new crops, water storage…). Based on simulated weather data (rainfall and potential evapotranspiration) integrating the effect of climate change until 2100, soil characteristics (texture and depth) and crop water requirement, we estimate the daily water balance at the scale of the Bourgogne Franche-Comté region, France. We use weather data at an 8*8 square-kilometres grid and soil water capacity is estimated at the soil map unit using the methodology developed by Bruand et al. (2004). This methodology estimates the water capacity of each layer of the soil unit based on their texture class (Aisne triangle) and removing the proportion of gravels and rocks considering that their contribution to water storage is negligible. For the 10 main crops of the region in terms of field area (<em>i.e.</em> grassland, winter wheat, winter barley, winter oilseed rape, spring barley, maize, soybean, sunflower, winter peas and spring peas), we calculate the water balance using the methodology developed by Jacquart and Choisnel (1995) at the scale of the intersection between the weather grid and the soil map unit in a way to represent homogeneous pedoclimatic territories. The soil water capacity is thus divided in two reservoirs with no horizontal transfer. Water from the first reservoir (40% of the soil water capacity) is easily accessible to the crop while water from the second reservoir is less and less accessible as the reservoir is emptied. At a daily step, the meeting of the crop water requirement is estimated regarding the water available in the soil reservoirs and the rainfalls. This study enables to estimate the actual water deficiency of the main crops and its potential increase due to climate change. We can thus identify crops that could not be cropped anymore without irrigation in some area and estimate the water required if we want to keep these crops in the future. These results are also important to evaluate if it is possible to developed new practices or water storage in response to the effects of climate change. Our approach allows as well to evaluate and anticipate the possibility to implement new crops requiring less water, avoiding the drought periods or able to access more water in the soil. These results will allow the agricultural sector to develop outlets for these new crops.</p>

Many studies about climate change impacts assessment are published every year. These studies comm... more Many studies about climate change impacts assessment are published every year. These studies commonly use a hydroclimatic modelling chain, whose principle is to feed impact models with climate models outputs. An important step in this process is to test the validity of impact models in a climate change context. However, this step is not frequently applied. The aim of this study is to test the robustness of two hydrological models with distinct conceptualizations: a global and empirical model (GR4J) and a semi-distributed and physically-based model (SWAT). They both have been calibrated and validated over climate contrasted periods. Despite a higher decrease of performance between calibration and validation for the GR4J model, both of them show relative robustness. Moreover, the stability of parameters between the two calibration periods shows that their value are not much influenced by the climate of the calibration period, and consequently remains valid during the entire projection...

Palaeogeography, Palaeoclimatology, Palaeoecology, 2016

Campanian sediments from two French sedimentary basins were studied, using clay mineralogy and st... more Campanian sediments from two French sedimentary basins were studied, using clay mineralogy and stable isotope (δ 13 C and δ 18 O) geochemistry, in order to investigate the Late Campanian Event. The clay fraction of the Campanian sediments from the Tercis-les-Bains section (Aquitaine Basin) and from the Poigny borehole (Paris Basin) is mainly composed of smectite. This background sedimentation was, however, interrupted during the Upper Campanian in the two basins by a substantial increase in detrital inputs, including illite, kaolinite, and chlorite at Tercis-les-Bains, and illite at Poigny. This detrital event, resulting from the enhanced erosion of nearby continental areas triggered by increasing runoff, has also been recognized in the Tethys and South Atlantic oceans. It coincided with a global negative carbon isotope excursion, the Late Campanian Event (LCE). Carbon isotope stratigraphy was used to correlate the two basins with previously studied sections from distant areas. Spectral analysis of the bulk δ 13 C from Tercis-les-Bains suggests a duration of ca. 400 kyr for a pre-LCE negative excursion and ca. 800-900 kyr for the LCE sensu stricto. The detrital event, as characterized by clay mineralogy, spans the interval that comprises the pre-LCE and the LCE, with a duration of 1.3 Myr. Intensification of continental erosion during the LCE may have resulted either from the Late Campanian polyplocum regression and/or from a regional tectonic pulse that triggered the emersion of previous submerged shelf areas and the increase of silicate erosion. As the LCE seems to be recorded at a large geographic scale, it is proposed here that enhanced chemical weathering and an associated decrease in atmospheric pCO 2 levels could have contributed to the long-term Late Cretaceous cooling trend.

Dissolved organic carbon (DOC) is a dynamic component of ecosystem functioning and environmental ... more Dissolved organic carbon (DOC) is a dynamic component of ecosystem functioning and environmental quality. This study demonstrates that different DOC dynamics (mineralization rates, δ13C) occur in forest soils either maintained as native or planted with Douglas fir.

Environmental Research, 2014

This study seeks to determine to what extent trace metals resulting from past mining activities a... more This study seeks to determine to what extent trace metals resulting from past mining activities are transferred to the aquatic ecosystem, and whether such trace metals still exert deleterious effects on biota. Concentrations of Cd, Cu, Pb and Zn were measured in streambed sediments, transplanted bryophytes and wild brown trout. This study was conducted at two scales: (i) the entire Morvan Regional Nature Park and (ii) three small watersheds selected for their degree of contamination, based on the presence or absence of past mining sites. The overall quality of streambed sediments was assessed using Sediment Quality Indices (SQIs). According to these standard guidelines, more than 96% of the sediments sampled should not represent a threat to biota. Nonetheless, in watersheds where past mining occurred, SQIs are significantly lower. Transplanted bryophytes at these sites consistently present higher trace metal concentrations. For wild brown trout, the scaled mass and liver indices appear to be negatively correlated with liver Pb concentrations, but there are no obvious relationships between past mining and liver metal concentrations or the developmental instability of specimens. Although the impact of past mining and metallurgical works is apparently not as strong as that usually observed in modern mining sites, it is still traceable. For this reason, past mining sites should be monitored, particularly in protected areas erroneously thought to be free of anthropogenic contamination.

Plant and Soil, 2009

In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) po... more In the context of land use change, the dynamics of the water extractable organic carbon (WEOC) pool and CO 2 production were studied in soil from a native oak-beech forest and a Douglas fir plantation during a 98-day incubation at a range of temperatures from 8°C to 28°C. The soil organic carbon, water contents and mineralisation rates of soil samples from the 0-5 cm layer were higher in the native forest than in the Douglas fir plantation. During incubation, a temperature-dependent shift in the δ 13 C of respired CO 2 was observed, suggesting that different carbon compounds were mineralised at different temperatures. The initial size of the WEOC pool was not affected by forest type. The WEOC pool size of samples from the native forest did not change consistently over time whereas it decreased significantly in samples from the Douglas plantation, irrespective of soil temperature. No clear changes in the δ 13 C values of the WEOC were observed, irrespective of soil origin. The fate of the WEOC, independent of soil organic carbon content or mineralisation rates, appeared to relate to forest types. Replacement of native oak-beech forest with Douglas fir plantation impacts carbon input to the soil, mineralisation rates and production of dissolved organic carbon.

Global and Planetary Change, 1998

The export of carbon from land to sea by rivers represents a major link in the global carbon cycl... more The export of carbon from land to sea by rivers represents a major link in the global carbon cycle. For all principal carbon forms, the main factors that control the present-day fluxes at the global scale have been determined in order to establish global budgets and to predict regional fluxes. Dissolved organic carbon fluxes are mainly related to drainage intensity, basin slope, and the amount of carbon stored in soils. Particulate organic carbon fluxes are calculated as a function of sediment yields and of drainage intensity. The consumption of atmosphericrsoil CO by chemical rock weathering 2 Ž depends mainly on the rock type and on the drainage intensity. Our empirical models yield a total of 0.721 Gt of carbon Gt. C that is exported from the continents to the oceans each year. From this figure, 0.096 Gt C come from carbonate mineral Ž. dissolution and the remaining 0.625 Gt C stem from the atmosphere F. Of this atmospheric carbon, 33% is discharged CO 2 as dissolved organic carbon, 30% as particulate organic carbon, and 37% as bicarbonate ions. Predicted inorganic carbon fluxes were further compared with observed fluxes for a set of 35 major world rivers, and possible additional climatic effects on the consumption of atmospheric CO by rock weathering were investigated in these river basins. Finally, we discuss the 2 implications of our results for the river carbon fluxes and the role of continental erosion in the global carbon cycle during the last glacial maximum.

Chemical Geology, 1999

The transfers and origins of dissolved inorganic carbon DIC were studied for a year in a soil-spr... more The transfers and origins of dissolved inorganic carbon DIC were studied for a year in a soil-spring-stream system in the Strengbach catchment, Vosges mountains, France. This 80 ha experimental research basin is located on the eastern side Ž. of the mountains, at an altitude ranging from 883 to 1146 m.a.s.l. and is mainly covered by spruce 80%. Brown acid and podzolic soils developed on a granitic basement, and, as a result, the DIC originates solely from CO generated by oxidation 2 Ž 13. of soil organic matter. The d C in catchment waters is highly variable, from about y22‰ in the springs and DIC piezometers to about y12‰ in the stream at the outlet of the catchment. In the springs, pronounced seasonal variations of d 13 C exist, with the DIC in isotopic equilibrium with the soil CO that has estimated d 13 C of about y24‰ in winter and DIC 2 y20‰ in summer. These seasonal variations reflect an isotopic fractionation that seems only induced by molecular Ž diffusion of soil CO in summer. In stream water, seasonal variations are small and the relatively heavy DIC y12‰ on 2. average is a result of isotopic equilibration of the aqueous CO with atmospheric CO .

Applied Geochemistry, 2000

Knowledge of the impact of N-fertilizers on the weathering-erosion processes of soils in intensiv... more Knowledge of the impact of N-fertilizers on the weathering-erosion processes of soils in intensively cultivated regions is of prime importance. Nitri®cation of NH 4 À fertilizers produces HNO 3 in the basin of the Garonne river, enhancing soil degradation. Their in¯uence on the weathering rates was determined by calculating the consumption rate of atmospheric/soil CO 2 by soil weathering and erosion, and its contribution to the total dissolved riverine HCO 3 À. This contribution was found to be less than 50% which corresponds normally to a complete carbonate dissolution by carbonic acid, suggesting that part of the alkalinity in the river waters is due to carbonate dissolution by an acid other than carbonic acid, probably HNO 3 .

Microbial carbon mineralization in soils leads to the production of different gaseous or dissolve... more Microbial carbon mineralization in soils leads to the production of different gaseous or dissolved components that have environmental impacts. Our study deals with the influence of soil temperature on the production of gaseous and dissolved carbon components during carbon mineralization in forest soils in France. After an incubation of soil samples for 42 days at 4 different temperatures, we determined both size and 13C isotopic signature of dissolved organic carbon and CO2 pools. We also characterised the soil microbial community structure (PLFA profiles). While temperature clearly increases the CO2 production, a low decrease of the dissolved organic carbon pool was observed whatever the temperature of incubation. The isotopic fractionation of the dissolved organic pool was not affected by temperature while a correlation was observed between temperature and isotopic fractionation of the produced CO2. The soil microbial structure was observed to change during incubation. Changes wer...

L'alteration chimique des roches est essentiellement le fait de l'attaque des mineraux pa... more L'alteration chimique des roches est essentiellement le fait de l'attaque des mineraux par l'acide carbonique issu du co#2 atmospherique, via la photosynthese puis la degradation de la matiere organique dans les sols. Ce co#2 dissous, implique dans les reactions d'alteration, est ensuite transporte en solution, principalement sous forme d'ions bicarbonates, par les fleuves vers les oceans. Pour estimer la quantite de co#2 consomme par erosion chimique des roches sur les continents, deux modeles sont developpes dans ce travail. Le premier est un modele geochimique de decomposition des flux d'elements majeurs exportes en solution par les fleuves (modele mega, major element geochemical approach). Le second (gem-co#2 global erosion model) est base sur un ensemble de relations empiriques entre le flux de co#2 consomme et le drainage pour les principaux types de roche affleurant a la surface des continents. Ce modele permet de simuler l'intensite et la distribu...

- Surface runoff and soil erosion are major threats to sustainable agriculture and mapping region... more - Surface runoff and soil erosion are major threats to sustainable agriculture and mapping regional erosion risk is increasingly needed by local, national and international environment agencies. Because erosion results from the interaction of several parameters which vary in space and time, no simple model can take into account all relevant factors, particularly in cultivated areas where human influences are predominant. The aim of this work is to develop a methodology based firstly on Le Bissonnais’s model and to apply it to evaluate the erosion risk on the Santiago Island in Cape Verde archipelago. According to the model, the rainfall erosion map revealed that Santiago Island may be broadly divided into five major erosion risk zones. While bare soils and rain fed sectors are respectively in the severe to extremely severe erosion risk zone with 916 km 2 , this is 91 % of Santiago’s area. The coastal sector of Santiago is generally in the low erosion risk zone; the irrigation and fo...

The flux of atmospheric/soil CO2 consumed by chemical weathering of the continents (FCO2) can be ... more The flux of atmospheric/soil CO2 consumed by chemical weathering of the continents (FCO2) can be estimated from bicarbonate concentrations in surface water. Using data from the bibliography for 232 small monolithologic watersheds, relationships between FCO2 and the runoff (Q) have been determined For the major rock types outcropping on the continents. The models fitted to these relationships are then applied to the Garonne and Congo river basins, in order to calculate the mean CO2 flux consumed in these basins. The results obtained are close to previous estimates bosed on field measurements

HYCCARE Bourgogne est un projet de recherche-action dont l’objectif est de mettre a disposition d... more HYCCARE Bourgogne est un projet de recherche-action dont l’objectif est de mettre a disposition des decideurs locaux des outils qui leur permettront de mieux prendre en compte le risque lie aux impacts du changement climatique sur la ressource en eau.

L'etude porte sur l'adaptation au changement climatique en Bourgogne. Elle vise a definir... more L'etude porte sur l'adaptation au changement climatique en Bourgogne. Elle vise a definir la sensibilite de la ressource en eau des territoires Bourguignons a ces evolutions climatiques et a en estimer les incidences par secteurs geographiques et d'activite. Ce projet pluri-disciplaire a ete mis en place par Alterre Bourgogne dont la tache a ete de federer un reseau d'acteurs regionaux aux competences variees : climatologie, pedologie et hydrologie. La premiere etape, (Ubertosi et al, GFHN 2009), a consiste a estimer la capacite des sols a stocker de l'eau, c'est-a-dire a calculer la taille de leur reserve utile. Ces calculs ont ete realises a partir du referentiel pedologique de Bourgogne aux 1/250000eme. La seconde etape, presentee ici, consiste en la realisation d'un bilan hydrique, spatialise sur la Bourgogne et modelise au pas de temps mensuel et a l'echelle spatiale La notion de changement climatique est abordee ici par une comparaison entre deu...

We propose in this study an initial estimation of the annual organic matter yield induced by chem... more We propose in this study an initial estimation of the annual organic matter yield induced by chemical weathering of carbonates and shales considering their global surface at outcrop and their organic matter content. The calculation also uses data on river fluxes resulting from carbonate rocks and shales weathering in major world watersheds, published by numerous authors [1]. The results obtained from the studied watersheds have been extrapolated to a global scale. Despite rather large incertainty inherent to such an approach, the calculated value [2] of ca. 0.1 Gt implies that the annual organic carbon yield related to carbonates and shales chemical weathering might be a non-negligible component of the global carbon cycle. The calculated yield does not constitute a direct supply to soils and the rivers because a part of the produced organic matter can be mineralised, thus escaping recycling. Depending on the real fate of the organic carbon released from weathered ancient formations,...