HAL-BRGM, les publications scientifiques en libre accès du BRGM
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Comment co-construire des indicateurs pour la durabilité des nappes captives ?
No full textWebinaireAs part of the DEESAC project (Sustainability and exploitability of groundwater in confined or covered aquifers) funded by the OneWater program, this webinar presents three cases of collaborative management of confined aquifers in France and internationally:• The Astien aquifers (Hérault, France)• The Great Artesian Basin (Australia)• The deep aquifers of Gironde (France)The study conducted as part of the project analyzed each case in terms of:(i) the history of collaborative management of confined aquifers and how the various stakeholders were gradually involved,(ii) how sustainable management objectives were collectively defined, and how indicators of "good status" were put in place to meet these sustainable management objectives.The webinar took place via videoconference on Thursday, June 5, from 1:30 p.m. to 2:30 p.m.Dans le cadre du projet DEESAC (Durabilité et exploitabilité des eaux souterraines des aquifères captifs ou sous couverture) financé par le programme OneWater, ce webinaire de restitution présente trois cas de gestion concertée des aquifères captifs en France et à l'international: •Les nappes de l’Astien (Hérault, France)•Le Grand Bassin Artésien (Australie)•Les nappes profondes de Gironde (France)L’étude menée dans le cadre du projet a permis d’analyser sur chaque cas :(i) l'historique de la gestion concertée des nappes captives et la façon dont les différents acteurs ont été progressivement impliqués,(ii) comment les objectifs de gestion durable ont été définis collectivement, ainsi que les indicateurs de bon état mis en place pour répondre à ces objectifs de gestion durable.Le webinaire a eu lieu en visio le jeudi 5 juin de 13h30 à 14h30
LCA of metals and minerals supply: a comprehensive analysis of global environmental impacts covering 54 elements
No full textInternational audienceLCA of metals and minerals supply often reveals varying environmental impacts (by orders of magnitude) from one study to another. This variability in impacts may stem from i) coverage of different production routes, ii) different life cycle inventory (LCI) data sources, and iii) different methodological approaches in the modelling. To offer a better understanding of the environmental impacts of metals and minerals supply, this study aims to comprehensively assess these impacts for 54 different elements through LCA.As a first step, this study comprehensively reviews publicly available LCI data (i.e. in literature) related to industrially established supply chains of metal and mineral commodities. This review is accompanied by a data quality/representativeness assessment through the Pedigree approach. In parallel, a market analysis is carried out for each element under study to identify the main producing countries, main in-use applications and associated commodities, global co-/by production patterns, and recycling input rate. Secondly, based on the most relevant LCI datasets selected from the quality and market analysis, LCI models specific to industrial production routes are developed following a harmonised modelling approach (e.g. regarding allocation). Finally, global LCI models, representative of the global market, are derived for each element. This study reviewed a total of 343 LCI datasets representing industrially established production routes, out of which 185 LCI datasets were selected after analysis (for 54 elements). For example, for Lithium (Li), nine production routes were modelled that differentiated the main Li commodities, deposits, and producing countries. The carbon footprint from these different routes overall ranges from 5.9 to 52.4 kg CO2-eq/kg Li commodity, with a market average amounting to 19.8 kg CO2-eq/kg Li2CO3-eq. The high-resolution LCIs developed in this study eventually contribute to securing the impact assessment not only for metal and mineral commodities supply chains, but also for downstream applications relying on these commoditie
Chronologie de l’adaptation des karsts et des versants à la dynamique d’incision quaternaire dans le Bassin parisien : présentation de l'avancement des travaux
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Microbial activity in hot springs: impact on volcanic rock at the weathering front in Lesser Antilles
No full textInternational audienceWith the growing interest in energy transition, the production of energy (geothermal, heat storage, or H₂ storage) is increasingly studied not only in terms of rock properties, fluid composition, and physical properties but also by considering the diversity of life (mostly microbial) hosted by hydrothermal water reservoirs. Volcanic activity and hydrothermalism play a crucial role in shaping these environments, influencing fluid circulation, energy availability, and microbial ecosystems.Here, core samples from the weathering front (25 m depth) of a volcanic geological formation were incubated in contact with geothermal water. These cultures were done un-der the actual prevailing temperature conditions (59°C), in the presence or absence of the associated microbial communities, and with or without the addition of chelating agent. Microbial processes were stimulated by an organic matter supply in microaerophilic condition. Compositions of the microbial community were analysed through 16S rRNA gene sequencing. The presence of bacteria markedly influenced the water geochemistry, i.e. trace metal concentrations (Fe, Mn, Co, Ni) were clearly lower under biotic conditions. In contrast, the As concentration was higher in the presence of bacteria. Microbial communities were affected by the presence of rock and the addition of chelating agent. We have combined 2 approaches to analyze the metabolic potential of the microbial communities, a first using bioinformatics tools and a second one relying on literature comparison. Both methods converge to identify four main metabolic groups represented in the following decreasing order of abundance: fermentative bacteria > S-reducing bacteria > FeIII-reducers > aerobic heterotrophs. Results suggest that thermophilic microbial communities inhabiting hydrothermal water could contribute to trace element leaching from volcanic rocks and to their immobilization in secondary minerals such as metallic sulfides.Therefore, we present here one of the first results on water/rock microorganisms at the weathering front, showing the impact of microbial activities during weathering processes involving hydrothermal circulations into volcanic rocks
Reuse of bottom sediment from reservoirs to cropland is a promising agroecological practice that must be rationalized
No full textInternational audienceIn semi-arid areas, intermittent streams are often equipped with small reservoirs to store water for irrigation and/or groundwater recharge, and to capture sediments lost through erosion. These reservoirs must be periodically desilted to maintain their storage capacity. While bottom sediments are generally considered waste, their reuse in agricultural fields is a centuries-old practice in India. Our study aimed to test the hypothesis that local farmers’ knowledge and current practices can help in understanding and rationalizing this practice. The study relied on both interviews of farmers and physico-chemical analysis of soil and sediment samples collected in a cultivated watershed in South India. First, our results disprove our hypothesis as we found a wide diversity of (i) application rates ranging from light soil amendment to creation of anthropogenic soils, and costs, which were not explained by the distance between reservoirs and fields neither by the field size, suggesting that there is no consensus among farmers on the optimal dose, and (ii) opinions on the impact of sediments on soil functions with the majority citing an improvement in the physical and/or chemical properties of the soil, suggesting that there is no consensus on the sediment impact on soil. Secondly, our results highlight that (i) only farmers with access to irrigation implemented this practice and they sourced sediment from the nearest reservoir, (ii) a slight majority of farmers used less irrigation water and less fertilizer after sediment application, and (iii) differences in sediments and soils composition suggest that sediment application is more likely to improve soil physical structure than nutrient status. The reuse of sediments on cropland could therefore be a promising agroecological practice, likely to increase the resource circularity and the sustainability of cropping systems. However, expressing its potential would require defining optimal application rates, assessing potential risks, sharing knowledge and promoting collective management of the resource
Impact of a mixture of PFAS molecules on the activity and structure of soil microbial communities
No full textInternational audienceImpact of a mixture of PFAS molecules on the activity and structure of soil microbial communities PFAS compounds have emerged as a major concern, due to their effects on human health, widespread occurrence, complex physico-chemical behaviour, very low biodegradability and lack of removal/degradation technologies that could be effective for the very diverse members of this huge family of molecules. Unlike other organic compounds released in environment by anthropogenic activities, such as petroleum hydrocarbons, polychlorinated biphenyls or pesticides, PFAS compounds concentration in the environment is at the parts-per-billion (ppb) and parts-per-trillion (ppt) levels. As a consequence, the microbial communities of most environmental compartments were not exposed to high doses of PFAS, their adaptation strategies largely remain to be explored. They could give useful clues for a better description of the impacts of these molecules and for the development of models of their fate in environment including the biological compartment. Here, 4 different soils presenting contrasting physico chemical properties were artificially contaminated by a mixture of 4 PFAS molecules (PFOS, PFOA, PFHxS and PFBS), in concentrations fixed at 10 mg.kg-1 each and incubated. The impact of PFAS addition was monitored on carbon mineralization activity, enzymatic activities, and evolution of the structure and composition of bacterial, archaeal and fungal communities during 70 days of incubation. The PFAS concentrations were not significantly modified during the incubation, but the mixture of PFAS molecules affected the structure and activity of soil microbial communities differently depending on the type of soil
Les bassins carbonifères-permiens dans la transition énergétique
No full textInternational audienceIntroductionThroughout history, humankind has exploited the energy resources contained within Carboniferous-Permian basins, which have facilitated numerous significant advancements in technology (e.g. the Industrial Revolution would not have been possible without coal). In the contemporary era, the challenges posed by climate change, geopolitical tensions and increasing energy demands underscore the imperative for a deeper understanding of the subsurface domain. This enhanced knowledge is crucial for facilitating a transition towards a low-carbon energy future. Consequently, Carboniferous-Permian sedimentary basins (CPB) have emerged as a critical component of the energy transition and are pivotal to these challenges, offering significant potential for geothermal energy, natural helium and hydrogen exploration, underground storage, and mineral resources.The study of CPB has been predominantly focused in France on the investigation of coal and oil shale resources since the 19th century, and subsequently on uranium since the 1970s. In addition, they have been investigated for oil and gas purposes, albeit with limited success. A significant benefit of this extensive exploration is the substantial amount of seismic data and related deep wells that has been collected. Over the past 15 years, significant efforts have been made in France to enhance and update the geological understanding of the Carboniferous-Permian basins, with a particular focus on their subsurface extensions beneath Meso-Cenozoic sedimentary formations. In collaboration with academic teams, the BRGM- French Geological Survey has initiated several PhD and post-doctoral studies, allocating substantial budgets to the reprocessing of vintage seismic lines, thereby obtaining an updated representation of these basins. In addition to the necessity of depicting the geometry of the basins (extent, depth, thickness, structures…), the success of exploring for new resources is contingent upon a re-evaluation of their geodynamic evolution and an analysis of their sedimentary filling and structural evolution in the context of recent concepts.Geological backgroundThe syn- to late orogenic CPB underwent extensive development around 300 Ma in the internal parts of the Variscan belt. This process was accompanied by widespread intrusive and extrusive magmatic activity, with a crustal or mantle origin, and predominantly felsic and, in some cases, mafic signatures.Today CPB crop out in several limited locations in and around the Variscan basement of France (Pyrenees, Massif Central, Vosges…), in close genetic relationships with major Variscan tectonic structures (e.g., Sillon Houiller, Metz-Hunsrück fault…).In map view, CPB occur as small isolated and disconnected “basins” (Figure 1) with incomplete sedimentary successions and numerous sedimentation and erosional gaps. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath the Meso-Cenozoic sedimentary cover of the Paris, Aquitaine, or South-east basins.MethodsSince the early 2000’, BRGM has initiated an ambitious program to reprocess vintage industrial seismic reflection profiles, whose raw data are freely available. Since that time, approximately 1200 seismic lines have been reprocessed, representing a total of more than 35,000 km. A significant part of this program is dedicated to the study of the CPB, and most of the broader CPB regions have been investigated (Hauts-de-France, Lorraine, Southern Paris Basin) or will be investigated in the near future (e.g. Eastern Aquitaine Basin). The BRGM team makes every effort to recover the vintage raw data, which is not always straightforward, and to use state-of-the-art methods to produce high-quality images. In parallel, BRGM also manage the French deep E&P wells database, necessary to tie the seismic interpretation. Figure 1 Location of Late Carboniferous-Permian basins in France and surrounding areas (modified from Beccaletto et al., 2023)We now present several examples of CPB, focusing on the reprocessed seismic data, their updated geological frame and their most relevant resources.The Namurian-Westphalian Nord-Pas-de-Calais coal basin and its Dinantian substratum - a geothermal perspectiveThe area has been investigated using 21 reprocessed seismic profiles acquired in the 1980's representing a total length of 532 km. In addition, three deep exploration wells have been selected and included into the database in order to provide geological information at depth along the seismic profiles. The estimated depth of investigation is approximately 7-8 km. The study successfully achieved two objectives: (i) the structural and geodynamic evolution of the Northern Variscan front (timing of thrusting and development of the Namurian-Westphalian molasse), and (ii) the geometry (extent, depth, thickness, structural framework) of the Dinantian carbonate substratum of the molasse, known as a geothermal reservoir in neighboring areas (Figure 2, Laurent et al., 2021). These results pave the way for further exploration of the potential for deep geothermal energy in the Haut-de-France region (with the current developments of dedicated projects). Figure 2 Cross-section in TWT through the Northern Variscan front, depicting the main geothermal target (Dinantian limestones) beneath the Namurian-Westphalian molasse (modified from Laurent et al., 2021)The Carboniferous-Permian Lorraine Basin - a multi-resource perspectiveThe Lorraine Basin has been investigated using 11 reprocessed seismic profiles acquired during the 1980's and representing a total length of 438 km. In addition, the seismic interpretation has been tied to 13 deep exploration wells. The estimated depth of investigation is approximately 7-8 km. The study demonstrates the dual geodynamic nature of the basin, with the following characteristics: (i) the deposition of a Westphalian syn-orogenic molassic sequence in a retro-wedge setting, and (ii) the subsequent deposition of a Stephanian syn-rift sequence following the negative tectonic inversion of the previous thrusts (Figure 3, Hemelsdaël et al., 2023). These scientific advances have been accompanied by the considerable development of new uses for subsurface resources, with the Westphalian deposits as the main target. Academic and industrial projects are currently being set up or carried out on a wide range of topics, including CBM, natural H2 exploration, deep geothermal exploration, and CO2 storage (ECBM process). Figure 3 Cross-section in TWT through the Lorraine Basin; most of new uses for subsurface resources are located in the Westphalian sequence (modified from Hemelsdaël et al., 2023)Other Carboniferous-Permian basins, other resourcesSubsurface studies involving the reprocessing and interpretation of vintage industrial seismic and the reinterpretation of deep wells have also been carried out in other CPB. A significant development was the recognition of extensive and substantial CPB beneath the Meso-Cenozoic sedimentary cover of the southern Paris Basin and their tectonic framework (Figure 4, Beccaletto et al., 2023), which led to several studies being conducted across the French territory. Figure 4 Cross-section in TWT through a CPB in the southern Paris Basin (modified from Beccaletto et al., 2023)45-8 Energy Company and BRGM are engaged in collaborative research to explore natural helium in the southern Paris Basin and the Jura fold-and-thrust belt. Preliminary findings indicate that CPB, whether newly discovered or previously identified, demonstrates significant potential as a target for helium production (source rock) and storage (reservoir) in both regions. Additionally, a research initiative is underway that involves the analysis of CPB from a mineral resources perspective. The objective of this project is to undertake a comprehensive study of the outcropping and buried CPB together with their magmatic and metamorphic basement, with the aim of identifying potential mineral occurrences at depth (Figure 5). Figure 5 The buried CPB of the eastern Aquitaine basin as a target for mineral resources ConclusionsIt is evident that this approach, involving the re-use of existing data and driven by updated scientific concepts, has proven to be a valuable strategy. However, it should be noted that these actions represent only the initial steps necessary for future developments. In order to progress towards production phases, it is imperative to acquire new seismic data and to drill new deep wells. While these activities have been undertaken at a local scale, for instance in the Hauts-de-France region, they have not yet been executed at the national scale required.AcknowledgementsL. Beccaletto thanks S. Marc and L. Capar from BRGM for their work on the reprocessing of seismic lines and colleagues from Rennes, Lille, and Nancy universities for our fruitful and ongoing collaboration.ReferencesBeccaletto L., & Bourquin S. (2023) The Brécy depocenter as part of a new northern Massif Central Carboniferous–Permian Basin (France), Comptes Rendus Géosciences, 355, Special Issue 2, 163-190Hemelsdaël R., Averbuch O., Beccaletto L., Izart, A. Marc S., Capar L., Michels R. (2023) A deformed wedge-top basin inverted during the collapse of the Variscan belt: the Permo-Carboniferous Lorraine Basin (NE France), Tectonics, 42, Laurent A., Averbuch O., Beccaletto L., Graveleau F., Lacquement F., Capar L., & Marc S. (2021). 3-D structure of the Variscan thrust front in northern France: New insights from seismic reflection profiles. Tectonics, 40, e2020TC006642
Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco)
No full textInternational audienceUnderstanding groundwater contamination processes in depleted aquifers is needed to improve their integrated management. The present study aims to understand how the conditions prevailing in a depleting detritic unconfined aquifer could affect the salinity and nitrate contamination. The depletion has caused a shift in our alluvial aquifer from dominant very shallow groundwater (< 20 m) in the 1970s to dominant deep groundwater (> 40 m) currently. It was found that (i) groundwater was moderately affected by salinity and nitrate, (ii) the dominant hydrochemical factors are rock weathering, halite dissolution, and reverse ion exchange, and (iii) the nitrate contamination is higher in shallow groundwater but it was detected at all depths. The thick unsaturated zone, which has developed because of the decline of the water table, would have mitigated the surface-borne contamination and reduced the direct effects of evapotranspiration. Using tritium as age indicator, it was suggested that nitrate in deep groundwater could originate from a historical use of fertilizers. In addition, vertical flows induced by decreasing water-table from pumping could transport younger groundwater with high loads of nitrate to mix with older deep groundwater with low nitrate. Serious problems could arise from further mobilization of salts by pumping deep groundwater and from the effects of downward movement of contaminants accumulated in the thick unsaturated zone after sufficient migration time or increases in groundwater recharge rates
Groundwater level and withdrawable volume forecasts in the Adour-Garonne basin (France) to enable sustainable groundwater management
No full textInternational audienceMore than 500 wells are monitoring groundwater level in real time in unconfined aquifers in the Adour-Garonne basin (France) (https://ades.eaufrance.fr/) and ten have been modeled so far to enable six-months groundwater levels forecast using different climatic scenarios. These forecasts are updated on a monthly basis and can be compared to groundwater levels thresholds (https://meteeaunappes.brgm.fr/fr). These groundwater level forecasts can further be used to predict groundwater withdrawable volume using a three-dimensional groundwater flow model in the Garonne, Tarn and Aveyron alluvial plain. Groundwater withdrawal is especially important in the summer, mostly to water crops, and can impact the volume of groundwater reaching the rivers and sustaining their baseflow. This competition in use creates the need to accurately define potential withdrawable volumes.Combining the lumped hydrological models with a three-dimensional groundwater flow model enables to define the potential withdrawable volume based on (1) the summer climatic scenario chosen by the decision maker, (2) the forecasted groundwater level at the end of the low-water season and (3) the status of the groundwater body (critical, balanced, conservative) to achieve at the end of the low-water season. The methodology was developed in the SUDOE AQUIFER project and a decision support tool was created to make the results accessible to groundwater managers and decision makers. These innovative practices will be extended to other regions where increase groundwater pressure forces local authority to develop methods and tools to sustainably manage groundwater bodies
The accurate determination of Perfluorooctane sulfonic acid (PFOS) removal efficiency by integrated-sonochemical system
No full textInternational audiencePerfluorooctanesulfonic acid (PFOS) is one of the most investigated Per-and polyfluoroalkyl substances (PFAS) for being the strongest compound to eliminate and having adverse health concerns. In this work, we have conducted the sonochemical treatment of PFOS simulated water under high (500 kHz) and low (22 kHz) frequencies while monitoring the operational parameters via an integrated sonochemical system. The integrated advanced sonochemical system includes software to monitor treatment power, solution temperature and frequency while allowing distinctive control of the reaction conditions. Considering the lack of calorimetric measurements in earlier studies and the difficulty in achieving comparative outcomes, precise calorimetric measurements and determination of electrical energy per order (E EO ) were performed in this study. The complete PFOS removal was achieved under 500 kHz frequency with optimum parameters including initial pollutant concentration (5 mg/L), ultrasound power density (400 W/L) and solution temperature (25 • C) within 180 min of treatment. The removal and mineralization extents (defluorination) were determined by ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS/MS) and ion-chromatography (IC) analysis. Under optimum conditions, 100 % removal and 99 % mineralization were achieved. The rate constant (k) ranged from 0.011 to 0.031 min -1 (first-order reaction), which increased with the increase in the power density. While the solution temperature did not significantly affect the PFOS removal efficiency, the initial concentration was found to have a prominent effect on the reaction rate constant. However, experiments at low frequency (22 kHz) showed negligible removal efficiency. The specific energy requirement for reaching 90 % removal while considering the power consumed by the ultrasonic system from the main electrical source was determined to be 700 kWh/m 3 , which is much lower than other reported work under similar conditions. This work will be useful for both laboratory and industrial upscaling while acting as a benchmark reference to follow