HAL-IRD
Not a member yet
83947 research outputs found
Sort by
Does fertilizer type drive soil and litter macroinvertebrate communities in a sugarcane agroecosystem? Evidence from a 10-year field trial
No full textInternational audienceMacroinvertebrates play a central role in processes supporting soil fertility. In the framework of the ecological intensification of agriculture, the choice of management practices should be guided by their ability to support these beneficial organisms supplying ecosystem services. This study aims at investigating the specific effect of partial substitution of synthetic fertilizers by locally produced organic fertilizers at a similar level of major nutrient inputs on macroinvertebrate abundance and diversity in sugarcane agroecosystems, on a Nitisol. Invertebrates visible to the naked eye were sampled in 2013, 2016, 2019 and 2023 using the standardized TSBF method on a long-term experimental field trial in Réunion island. The individuals were identified and soil samples were analyzed for physico-chemical properties. Despite the low response of macroinvertebrates to the fertilizer type, total macroinvertebrate abundance increased over time, especially isopods and earthworms. The input of organic carbon via the return of litter to the soil surface and the root turnover after each harvest enables soil macroinvertebrates to be more abundant even after replanting tillage. Mulching and root turnover are therefore important levers to consider for promoting macroinvertebrates in sugarcane agroecosystems.</div
Current constraints to reconcile tropical forest restoration and bioeconomy
No full textInternational audienceLarge-scale forest restoration is vital for delivering a broad array of ecosystem services benefits to society. However, it is often perceived as an economically noncompetitive land use choice. Integrating economic opportunities into restoration aligns socioeconomic and environmental goals, reducing conflicts between forest production and conservation-oriented management decisions. Supply chains focusing on high-value goods can enhance the reach of forest restoration efforts and unite ecological and economic benefits in a multifunctional manner. The bioeconomy has emerged as a potential but critical driver for attracting investments in restoration. We outline the challenges and solutions to reconcile forest restoration and bioeconomy, specifically about (i) native timber production, (ii) non-timber forest products, (iii) biotechnological products, and (iv) intangible ecosystem services. This requires collaborative and multidisciplinary efforts to improve investment in large-scale projects. The intricacies of these issues intersect with research development, market dynamics, legal frameworks, and regulatory paradigms, underscoring the necessity for nuanced and tailored public policy interventions. These integrated approaches should enable tropical countries to lead the global forest-based economy and usher in a new era of forest restoration.</div
Eruptive dynamics of open-vent andesitic volcanoes retrieved from petrological and componentry analysis of recent explosive phases (2021-2022) of Sangay (Ecuador)
No full textco-auteur étrangerInternational audienceSince its reawakening in 2019, Sangay volcano (Ecuador) experienced a continuous, low magnitude eruptive activity that was disrupted by some mild-explosive pulses. Andean communities in central Ecuador and the Guayaquil International Airport have been affected by the ash fallouts. Through componentry, geochemical and petrological analysis, we studied ash and lapilli samples, emitted during the mild-explosive eruptions of 2020–2021 and during the minor eruptions of 2022, to document the changes in eruptive dynamics, constrain the pre-eruptive physical conditions, and identify the potential triggering mechanisms. Major elements whole-rock compositions show a progressive decrease in silica content, from andesitic to basaltic andesitic compositions, and a concomitant increase in magnesium content over time. Componentry, textures and chemical variations in groundmass glass support the idea that Sangay's shallow plumbing system hosts magmas that have evolved in composition, having variable physical properties that control the eruptive dynamics. The change in eruptive style towards more explosive dynamics in 2020–2021 was probably associated with the feeding of a more mafic and gas-rich magma from deep. The consequence, reflected in the groundmass glass chemistry and componentry data, is the “excavation” of the partially crystallized magma stalling in the conduits, which led to the observation of the more diverse compositions in the juvenile material. This work contributes to a better understanding of the eruptive behavior of long-lived, open-vent andesitic volcanoes, and to explore the link between eruptive dynamics and the petrological evolution of magmas
Tree rings reveal the correlation between the Kaindy Lake submerged forest and the historical 1889 M 8.2 Chilik earthquake (Kazakhstan)
No full textInternational audiencePaleoseismic studies are essential to improve earthquake hazard mitigation, a challenging task in the Tian Shan mountains characterized by numerous active faults, frequent strong earthquakes, and abundant triggered landslides. Here, we date the debated formation of Kaindy Lake, the famous landslide-dammed lake in southeastern Kazakhstan, included in the UNESCO World Network of Biosphere Reserves. Our dendrochronological study compares ring-width patterns from dead trees (Picea schrenkiana) still standing in the lake with living trees growing on surrounding slopes and other trees on the landslide debris. Our results place the formation of the lake to just after 1888 A.D. (the last ring of sunken trees) and before 1898 A.D. (the first established trees on the landslide), a period for which only the 1889 A.D. Chilik earthquake (M 8.2) has been reported and caused extensive damages in the region (surface ruptures, landslides). Thus, we propose that the landslide was triggered during this historical earthquake, questioning the previously preferred date of 1911 A.D., and the local common belief. Furthermore, our results indirectly complement previous paleoseismic studies at 8.5 km away, for which the most recent event in the region was poorly defined by geochronological dating, but suggested a surface rupture associated with the 1889 A.D. earthquake. The proximity of the landslide to the surface rupture would place it in the epicentral zone of the Chilik earthquake
Investigation of the effect of ferroelectric polarization on the spin state of spin crossover complexes embedded in a piezopolymer matrix
No full textInternational audienc
When Metal Complexes Evolve, and a Minor Species Is the Most Active: the Case of Bis(Phenanthroline)Copper in the Catalysis of Glutathione Oxidation and Hydroxyl Radical Generation
No full textInternational audienceSeveral copper-ligands, including 1,10-phenanthroline (Phen), have been investigated for anticancer purposes based on their capacity to bind excess copper (Cu) in cancer tissues and form redox active complexes able to catalyse the formation of reactive oxygen species (ROS), ultimately leading to oxidative stress and cell death. Glutathione (GSH) is a critical compound as it is highly concentrated intracellularly and can reduce and dissociate copper(II) from the ligand forming poorly redox-active copper(I)-thiolate clusters. Here we report that Cu-Phen2 speciation evolves in physiologically relevant GSH concentrations. Experimental and computational experiments suggest that at pH 7.4 mostly copper(I)-GSH clusters are formed, but a minor species of copper(I) bound to one Phen and forming ternary complexes with GSH (GS-Cu-Phen) is the redox active species, oxidizing quite efficiently GSH to GSSG and forming HO• radicals. This minor active species becomes more populated at lower pH, such as typical lysosomal pH 5, resulting in faster GSH oxidation and HO• production. Consistently, cell culture studies showed lower toxicity of Cu-Phen2 upon inhibition of lysosomal acidification. Overall, this study underscores that sub-cellular localisation can considerably influence the speciation of Cu-based drugs and that minor species can be the most redox- and biologically- active
Interconnected water scarcities and environmental amenities migration in rural Chile
No full textInternational audienceThis paper explores the repercussions of amenity migration on rural communities' access to water through a comparative analysis of three case studies in Chile. It examines the concept of rural drinking waterscapes to elucidate how access to water is dependent upon a metabolic process, wherein social, political, economic, and technical elements contribute to the construction of rural landscapes. This notion implies paying close attention to the daily practices of water access at the household level through ethnographic methods (multiplying interviews and observations), thus uncovering unregulated water habits and uses. The results underscore the pivotal role played by the State in shaping the desirability of these localities, attracting both capital and upperclass population influx. This socio-demographic shift triggers significant changes in land-use patterns, resulting in an amplified and diversified demand for water. The study identifies that water scarcity is a multifaceted issue, stemming from the intricate interplay of various scarcities occurring simultaneously across different scales. These include: 1) infrastructure scarcity, arising from households' inability to connect to the communal water network; 2) service management scarcity, induced by operational failures that reduce water pressure or increase supply interruptions; 3) economic scarcity, resulting from water organisation budget constraints or residents' inability to meet water bills; and 4) overexploitation scarcity, emanating from the excessive consumption of groundwater resources. Notably, these different forms of scarcity are interconnected. The responses of local populations and governing committees are identified as central to this intricate chain of causation, as they can inadvertently create new scarcity scenarios and exacerbate inequalities.</div
Transport properties of supercritical methane
No full textInternational audienceExperimental results on molecular diffusion in supercritical methane over a wide pressure range reported by Ranieri et al. [Nature Communications 15, 4142 (2024)] are compared with the theoretical expectations based on the Lennard-Jones model. In the low-pressure low-density limit the kinetic approach within the Chapman-Enskog approximation is shown to be adequate. At higher pressures and densities the freezing density scaling approach becomes appropriate. We analyse the transition from the gas-like to liquid-like dynamical behaviour from the perspective of Stokes-Einstein-Sutherland relation between the coefficients of self-diffusion and shear viscosity. This analysis locates the Frenkel dynamical crossover close to the transition from gas-like to liquid-like molecular diffusion in methane observed experimentally. The reported results provide a useful practical tool to estimate the transport properties of supercritical methane in parameter regimes where experimental resultsare not yet available.</div
Ignoring the impact of fermentation could result in substantial misestimation of folate and cobalamin adequacy: a simulation study on injera consumption in the Ethiopian context
No full textInternational audienceB-vitamin content of plant-based foods can be deeply modified by fermentation, particularly the active cobalamin form, which is often considered to be zero in food composition databases. We simulated the consequences of including or excluding the impact of fermentation in estimating folate and cobalamin adequacy using secondary data obtained in a survey of 323 women in Ethiopia plus the vitamin content of injera (fermented flat bread) reported in the literature. As folate content can change during fermentation, the prevalence of inadequacy in scenarios that include the effect of fermentation were higher (90%) or lower (67%) than in the original data. Our simulation based on data obtained using cobalamin producing microorganisms lowered the prevalence of inadequacy to 54%. Ignoring the impact of fermentation may result in substantial misestimation of folate and cobalamin adequacy in Ethiopia and should be evaluated in other contexts in which fermented foods are consumed as staple foods
Impact des Poussières Désertiques sur la Qualité de l'Air et la Santé Publique en Afrique du Nord et de l'Ouest : Analyse des Concentrations de PM10 et Risques Sanitaires
No full textInternational audienceArid and semi-arid regions of northern and western Africa experience high levels of air pollution due to massive emissions of desert dust, primarily from the Sahara, which account for approximately 50% of global emissions. The increasing variability and intensity of sandstorms, associated with climate change, expose populations to alarming concentrations of fine particles (PM10), posing significant public health risks, particularly in terms of respiratory and cardiovascular diseases. With rapid population growth, the region faces major public health challenges related to air quality. In this study, PM10 concentration data collected from multiple sites in West and North Africa through the INDAAF network (International Network to study Deposition and Atmospheric composition in Africa) provide an assessment of the current situation. By comparing these data with World Health Organization (WHO) guidelines, the study highlights the health risks posed by annual and daily PM10 concentrations frequently exceeding critical thresholds. Populations are chronically overexposed to PM10, underscoring the urgency of a tailored public health response to mitigate the health effects of desert dust.Les zones arides et semi-arides du nord et de l'ouest de l'Afrique subissent une pollution atmosphérique élevée en raison des émissions massives de poussières désertiques, principalement issues du Sahara, qui représentent environ 50 % des émissions mondiales. La variabilité et l'intensité croissantes des tempêtes de sable, associées au changement climatique, exposent les populations à des concentrations alarmantes de particules fines (PM10), présentant des risques significatifs pour la santé publique, notamment en matière de maladies respiratoires et cardiovasculaires. Face à une croissance démographique rapide, la région se voit confronter à des défis importants en matière de santé publique lié à la qualité de l’air. Dans cette étude, les données de concentration en PM10 recueillies sur plusieurs sites de l'Afrique de l'Ouest et du Nord à partir du réseau INDAAF (International Network to study Deposition and Atmospheric composition in Africa) permettent de dresser un état des lieux. En comparant ces données aux recommandations de l'Organisation Mondiale de la Santé (OMS), cette étude met en lumière les risques sanitaires posés par des concentrations annuelles et journalières de PM10 fréquemment au-dessus des seuils critiques. Les populations sont surexposées de manière chronique aux PM10, ce qui souligne l'urgence d'une réponse de santé publique adaptée pour limiter les effets de ces poussières désertiques sur la santé