Soil contamination remains a critical environmental concern, necessitating efficient techniques for site characterization and remediation. The radon-deficit technique (RDT) offers a non-invasive approach to identifying organic contamination, relying on the behavior of radon-222 (222Rn) as a tracer. However, RDT results are influenced by environmental variables such as soil moisture, temperature, and atmospheric pressure, potentially leading to uncertainties. This study evaluates the application of machine learning (ML) models—including linear regression (LR), random forest (RF), artificial neural network (ANN), and gradient boosting machine (GBM)—to predict 222Rn activity in soil gas based on environmental parameters. A year-long dataset of continuous measurements was collected from an uncontaminated granite-based site in Madrid, encompassing variables such as soil moisture, ambient and soil temperatures, and atmospheric conditions. ANN and RF models exhibited superior performance in predicting 222Rn variability, identifying soil moisture and ambient temperature as the most influential predictors. The findings demonstrate that ML can significantly enhance the reliability of RDT by accounting for environmental variability, enabling more accurate identification of contamination hotspots. While the application of these models requires substantial datasets, they offer a promising tool for improving the efficacy of contamination screening and long-term remediation monitoring. Further studies are recommended to explore ML’s predictive capacity in contaminated sites and expand the approach to diverse geological contexts.

International audience | This review summarizes how salinity and temperature, two key global factors driven by climate change in freshwater systems, interact with other stressors on organisms in controlled small-scale factorial experiments at the population, individual, or subindividual level (excluding mesocosm and field studies). Despite the growing interest, research following all these criteria remains limited with 156 publications of which 50% analyzed stressors + salinity, 46% stressors + temperature, and only 4% involved the triple combination. Research on the combined effect of temperature and salinity predominantly focused on metals, pesticides, and, to a lesser extent, emergent contaminants, such as microplastics and nanomaterials, encompassing various biological models and responses. In general, increased temperature amplifies the single effect of stressors, whereas salinity leads to a higher diversity of responses, with similar proportions of synergisms and antagonisms. Fish (Salmoniformes, Perciformes, and Cypriniformes) were the most studied organisms. Among Crustacea, only cladocerans of the genera Daphnia and Ceriodpahnia were considered. The present review highlights the need to include other species that play key roles in freshwater food webs and to increase triple combination studies to understand complex interactions and develop adaptation and mitigation strategies to preserve the environment and its services in this changing world.

International audience | <div><p>New Caledonia is a hotspot of biodiversity but holds 25% of the world's nickel resources making mining the main sector of its economic development. Ultramafic massifs are composed of metal-rich laterites and peridotites, such as Co, Fe, Mg and Ni. Natural weathering exacerbated by open-pit mining contributes significantly to sediment transport in rivers and lagoons. In the early 2000s, a new mine was opened in the Koniambo ultramafic massif, a catchment area of the Voh lagoon.</p><p>The main objectives of this study were i) to examine the distribution of metals (Al, Ca, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sb, Sr, Ti, V, Zn) in marine sediment and, ii) to assess the historical deposition fluxes resulting from the weathering of Koniambo massif. Our results confirm that sediments are strongly influenced by continental weathering, with a contribution from volcano-sedimentary rocks (Al, Cu, Pb, Sb, Ti, V and Zn) and ultramafic laterites (Co, Cr, Fe, Mn and Ni). Sediment accumulation rates have been estimated at about 2.7 cm yr -1 near the shore and 4.5 cm yr -1 near the coral reef, which is up to 18 times larger than in the natural ecosystem. Ultramafic laterites account for more than 91% of Ni inputs into the lagoon (10.4 g m -2 yr -1 ), followed by Cr with about 75% of inputs and a sediment deposition flux of 5.04 g m -2 yr -1 . Given the environmental context, this study highlights the importance of examining ecotoxicological risks in order to evaluate the impact of metals on the lagoon's sustainability.</p></div>

International audience | The use of organic plastic additives (OPAs) in food packaging has led to their widespread presence in various foodstuffs. These additives, including mainly flame-retardants, bisphenols, UV-stabilizers and plasticizers, are known for their potential hazards and environmental impact. This review aims to comprehensively assess the contamination of food products by OPAs and evaluate their role as vectors of exposure to hazardous chemicals. A review of recent literature was conducted, focusing on studies that report on the presence and concentrations of OPAs in different food categories, including aquatic products, beverages, cereals, dairy products, eggs, oils, fats, meat, poultry, vegetables, fruits and other food categories. The review also examines regional variations in contamination levels and identifies the pollutants. Significant contamination of foodstuffs by OPAs are highlighted, with varying concentrations reported across different regions and food types. Potential sources of contamination include food-packaging materials and environmental pollution. This review also identifies research gaps and proposes future directions to improve the study of OPAs in food, aiming to enhance the reliability and comparability of findings while supporting efforts to mitigate contamination risks.

International audience | “A Who’s Who of pesticides is therefore of concern to us all. If we are going to live so intimately with these chemicals eating and drinking them, taking them into the very marrow of our bones - we had better know something about their nature and their power.”—Rachel Carson, Silent Spring. In her day, Rachel Carson was right: plant protection products (PPP), like all the other chemical substances that humans increasingly release into the environment without further precaution, are among our worst enemies today (Bruhl and Zaller, 2019; Naidu et al., 2021; Tang et al., 2021; Topping et al., 2020). All compartments of the biosphere, air, soil and water, are potential reservoirs within which all species that live there are impaired. Birds are particularly concerned: PPP are recognized as a factor in the decline of their abundance and diversity predominantly in agricultural landscapes. Due to the restrictions on vertebrates testing, in silico-based approaches are an ideal choice alternative given input data are available. This is where the problem lies as we will illustrate in this paper. We performed an extensive literature search covering a long period of time, a wide diversity of bird species, a large range of chemical substances, and as many model types as possible to encompass all our future need to improve environmental risk assessment of chemicals for birds. In the end, we show that poultry species exposed to pesticides are the most studied at the individual level with physiologically based toxicokinetic models. To go beyond, with more species, more chemical types, over several levels of biological organization, we show that observed data are crucially missing (Gilbert, 2011). As a consequence, improving existing models or developing new ones could be like climbing Everest if no additional data can be gathered, especially on chemical effects and toxicodynamic aspects.

International audience | In Côte d’Ivoire, despite an intense development of artisanal and small-scale gold mining (ASGM) activities in thelast two decades, the environmental impacts of this activity are poorly documented. This study aimed to documentthe concentrations of geogenic and exogenous contaminants potentially released by ASGM (metals and cyanides) indifferent sources (ore, mining wastes) and environmental compartments (soils, surface and ground waters, sediments) inthe Kokumbo area, part of the Au-rich Birimian greenstone belt. Alluvial ore material is enriched in various metal(oid)s (As, Co, Cu, Cr, Fe, Mn, Ni, Sb, and V) compared to the average composition of the upper continental crust whileother metals (Cd, Pb, Ti, Zn) show no geochemical anomalies. High Hg concentrations were found in cyanidationresidues (up to 8.32 mg/kg) and sediments (up to 20.4 mg/kg) compared to unprocessed alluvial ores (0.06 ± 0.01 mg/kg) indicating that Hg used in amalgamation is the source of Hg contamination. Cyanidation residues contain up to100 mg/kg of total cyanides but generally less than 3% are in the form of free cyanides, the most mobile and toxicform. Arsenic concentrations in water are low (&lt; 2.5 μg/L) despite its relatively high content in sediments and soils(76 ± 54 mg/kg), showing a low mobility of As, likely due to its adsorption on iron oxy(hydr)oxides. Apart from Mn,metals have low dissolved concentrations in water except in a stream draining a cyanidation site suggesting that thecyanidation effluent discharge may contribute to metal dispersion in rivers.

Following a number of meetings devoted to knowledge sharing, identification of key issues, and discussing the best ways to move forward, a wide international expert community is now able to provide recommendations regarding the monitoring of seafloor macrolitter through observation and imaging. As the seafloor constitutes a major sink for marine litter including plastics, it is important to acquire robust and extensive data on litter distribution, abundance, types and size ranges across marine habitats. This should be done through widely agreed, harmonised, and non-destructive methods encompassing advanced technologies. Training and capacity building are essential elements in this endeavour. Both new and legacy imagery are needed to establish baseline assessments and trends. Informing policy-making is indispensable for effective action through upstream and targeted measures, with seafloor macrolitter (and megalitter) being a vital part of the evidence base for global mitigation measures.

International audience | There is growing scientific and societal consciousness that the environmental risks and impacts of plant protection products (PPPs) cannot be properly assessed without considering ecosystem services. However, the science on this issue remains incomplete and fragmented, as recently illustrated in a collective scientific assessment that pointed out the limited knowledge on the risks and impacts of PPPs on soil ecosystem services, which are clearly overlooked. Beside soil ecosystem services, certain key players involved in these services are largely overlooked in the scientific literature on the risks and impacts of PPPs, namely soil microbial photosynthetic communities. Here, we followed the principles of evidence-based logic chain approaches to show the importance of considering these microorganisms when studying the impacts of PPPs on certain services provided by soil ecosystems, with a focus on regulating and maintenance services that play a role in the regulation of baseline flows and extreme events. Terrestrial microalgae and cyanobacteria are ubiquitous photosynthetic microorganisms that, together with other soil micro- and macro-organisms, play key roles in the ecosystem functions that underpin these ecosystem services. There is an extensive literature on the ecotoxicological effects of PPPs on different organisms including soil microorganisms, but studies concerning soil microbial photosynthetic communities are very scarce. However, there is scientific evidence that herbicides can have both direct and indirect impacts on these microbial photosynthetic communities. Given that they play key functional roles, we argue that soil microbial photosynthetic communities warrant greater attention in efforts to assess the environmental risks and impacts of PPPs and, ultimately, help preserve or restore the regulating and maintenance services provided by soil ecosystems.