We are entering a new dimension of the Anthropocene age affecting the Earth and its vital biogeochemical cycles in an unprecedented way. The anthropogenically-produced mass (including plastics, titanium dioxide (TiO2), and ultrafine-soot particles) had surpassed all global living biomass with annual fluxes entering the environment estimated at millions of tons. These anthropogenic particles integrate oceans and interact with the biogeochemical cycles, from microscale to nanoscale (or colloidal scale). The main goal of NANO-GATE is to characterize the presence and the biogeochemical cycling of anthropogenic nanoparticles in the Arctic Ocean. Nanoplastics, TiO2, and nano-soots are targeted due to their extensive use in anthropogenic activities, high reactivity against other contaminants in the environment, and expected ubiquity in the AO. Despite its relatively small size and lower direct contact with human activities, the Arctic Ocean (AO) is one of the most exposed oceans to anthropogenic impacts. While the presence of microscale anthropogenic particles starts to be partially documented there is absolutely no data concerning nanoparticles. And yet, even at (ultra)-trace concentration, and due to their high surface specificity, diffusivity and reactivity, nanoparticles are more likely to interact with biota, especially primary producers, and to impact the main biogeochemical cycles. In light of these properties and the increase in anthropogenic material mass entering the global ocean, there is an urgent need to address the pervasiveness of ANP dispersal, particularly in the AO. NANO-GATE will pioneer ANP research in the AO by providing a unique dataset of their distribution and cycling, with the determination of their behavior with key variables specific to the AO. NANO-GATE will provide unprecedented data to support the various Arctic monitoring program agencies and policymakers and list ANPs as an emerging threat.

In the marine environment, macroplastic wastes undergo chemical and physical modifications leading to their fragmentation into microplastics (MPs) and nanoplastics (NPs). Additional MPs and potentially NPs enter the Oceans via rivers and atmospheric deposition. To date, the fate of ocean plastic debris is far to be understood and this is especially true when it comes to small MPs and NPs. Besides, the established presence of MPs in the atmospheric compartment, found in urbanized areas but also in remote locations, and the potential presence of NPs are of growing concern. These plastic particles can influence the Earth’s climate and degrade air quality. A transfer of plastic particles from the oceans to the atmosphere has recently been hypothesized. Literature strongly suggests this sea-to-air transfer of MPs/NPs processes similarly as for the generation of primary marine aerosols (sea spray aerosols) i.e., via the bursting of air bubbles plumes at the ocean’s surface. Nevertheless, the magnitude and significance of this phenomenon for both the marine and atmospheric compartments are still controversial. In this project, we hypothesize these marine MPs and NPs emissions are significant at the global scale and contribute to marine dispersal of MPs and NPs to remote ocean regions, and to terrestrial and cryospheric parts of the Earth system. We propose an innovative and complementary approach to address two objectives: 1. assess the water-to-air transfer of MPs and NPs particles and their co-contaminants via bubble bursting as a function of environmental parameters and plastic particle properties using laboratory experiments, 2. improve ocean and atmosphere models of MPs and NPs, and their coupling, to understand MPs/NPs transport and cycling.

Air quality in school is a crucial sanitary issue that Coop'AIR wants to address with the co-construction of local solutions by the actors of the environment themselves, in collaboration with a multidisciplinary team made up of scientists specialized in fine particles measurements, members of environmental education associations and researchers in information and communication sciences. The approach is based on various means of subject’s appropriation (artistic creation, scientific approach, use of technological or biosourced sensors, dialogue...). It also includes international experience sharing through a dedicated Web platform because as WHO stated "the air quality knows no borders". Empowering pupils to become actors in the evaluation of their environment and in particular of the air they breathe in their classrooms is one of the goals of Coop’AiR. The project aims at investing the school microcosm through transdisciplinarity and participative sciences in order to create a methodology of participative research adaptable to several school contexts on three continents (by taking into account the spatial scale, population density, the socio-cultural aspect...). Coop'AiR arise from the reflection of a solid consortium associating Research and civil society, already sharing several participative research programs on air quality and willing to design this action towards the school environment. Coop'AiR is thought as an experiment of research - implication – action with a vocation to expand after the end of the project to other subjects related to school environment (vegetation, diversity, noise, equality etc ....)

The MICROPRONY project aims to study a unique shallow serpentinized alkaline hydrothermal system located in Prony Bay in the southern lagoon of New Caledonia. The hydrothermal circulation at Prony is created by in-depth serpentinization reactions while the meteoric water percolates through the peridotite, generating very alkaline fluids, rich in H2, CH4, and abiotically formed organic compounds. This system has characteristics similar to those of terrestrial serpentinized sources (ex California, Oman) but also underwater (ex. Lost City). The study of these systems brings important elements for the understanding of the processes at the origin of life on Earth. The main objective of the project - which builds on the results of our previous researches on this site - is to understand the functioning of this ecosystem, focusing on metabolisms using H2, CH4, and abiotically formed organic compounds. Our working assumptions are as follows: i) Prony microorganisms are specific to serpentinized environments and have developed specific metabolic strategies to cope with very difficult living conditions (few or no electron acceptors, extremely high pH); (ii) Contrary to the widely shared assumption that microbial life in the deep subsurface is mainly due to chemiolithoautrophy (the "SLIME" hypothesis), we propose that the organic compounds produced by the serpentine reactions allow the growth of chemoorganotrophic bacteria, in particular, uncultivated relatives of Clostridiales as well as Phyla candidates such as Parcubacteria, Acetothermia, and Omnitrophica, and possibly of methanogenic archaea (Methanosarcinales). These bacteria, along with the methanogens, could thus constitute major primary producers in this type of ecosystem. To respond exhaustively to these two hypotheses, we propose a multidisciplinary approach led by a scientific team that will gather among the best specialists in their field. This approach will incorporate advanced analytical techniques to cover a wide range of spatial resolution. It is subdivided into 5 main tasks: 1) Identify the main microbial actors of the Prony ecosystem and elucidate their functions using cultural and molecular (metagenomic) approaches - 2) Characterize the age, nature and structure of microbial habitats, their associated microflora, and micro-mineral interactions, using a range of isotopic dating techniques, molecular imaging (coupled confocal microscope - Raman/FTIR spectrometry, FISH, SEM), 3) Describe in detail the fluid geochemistry for a robust interpretation of the biogeochemical processes operating at Prony and compare them with those of other terrestrial or marine serpentinized systems using a panel of geochemical analysis techniques. 4) Determine the relative importance of biotic vs abiotic productions, particularly CH4 and other organic compounds (HC, organic acids, etc.) present in fluids, by clumped isotopes thermometry methods (13C and D) - 5) Model the key metabolisms of the Prony microbial ecosystem by integrating on the one hand bioenergetic calculations based on the thermodynamics of metabolic reactions and geochemical data, and on the other hand the functional annotation of metagenomes/metatranscriptomes. The realization of the scientific program proposed here will allow us to exhaustively define the interactions between geochemical and microbiological processes in an environment that may have been abundant on Earth at the beginning of abiogenesis and that can now be compared to that of other planets of the solar system, candidates to host alien life forms (e.g. Europa, Enceladus).

The tipping of some components of the Earth system to new states as a result of global change has become a major concern. The project assumes that tipping points exist in the hydrological cycle and that they could be the cause of the durable hydrological changes observed in part of West Africa, as a result of the 1970-80 severe drought and land use changes. A modeling framework will be specifically developed to verify whether shifts have occurred in the past decades over this region, where and when, whether they could occur in the future in a warmer and more populated world, and what would be their consequences on water resources and hydrological risks. The project promotes an innovative vision of hydrology in which ruptures can play a key role, which could lead to modify the design of adaptation strategies to global change.