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Tracking the Path to Cleaner Cities using Global Urban NO₂ Monitoring from Space
Tracking air pollution is essential for evaluating the effectiveness of urban air-quality and emission-control policies and their impact on public health. Unlike previous satellite-based urban NO₂ studies that typically rely on linear trends, aggregated data, and limited meteorological correction, we use high-resolution TROPOMI observations with an AirGAM framework to estimate meteorology-adjusted, non-linear NO₂ TVCD trends across 5,435 cities worldwide (2019–2024). Daily satellite observations, together with ERA5 meteorology, are used to remove weather and seasonal effects so that trends primarily reflect changes in emissions. 1,400 cities had significant trends, with 79% showing declines, indicating an overall global drop in urban NO₂ TVCD. East Asia, particularly China (99% of cities with significant trend), and Europe (95%) led the global reductions. Cities in the USA with significant trends (n = 14) also experienced a decline. NO₂ TVCD levels increased most sharply in the cities of the Middle East, Central, and South Asia. The most populated examples are Tehran (3.1% yr-1 [95% CI: 0.7–5.5]) and Cairo (1.4% yr-1 [0.1–2.6]).
2026
A pan-European spatial inventory of agricultural land degradation
Agricultural land degradation is a contemporary reality that increasingly threatens food security and socio-economic stability in Europe and worldwide. Monitoring and controlling this environmental problem are complicated missions, considering that land degradation generally occurs as multiple processes in agricultural environments, which have not yet been thoroughly investigated as an integrated multi-process and multi-scale inventory in Europe. Here we developed a detailed multi-scale (continental to sub-regional) inventory of 12 key agricultural land degradation pathways in Europe, including water erosion, wind erosion, soil organic carbon loss, soil salinization, soil acidification, soil compaction, soil nutrient imbalances, soil pollution via pesticides, soil pollution via heavy metals, vegetation degradation, groundwater decline, and aridity. Using various and (generally) high-resolution geospatial datasets of land degradative pathways, which were mapped at critical levels and statistically explored as a spatial footprint at various territorial levels, we highlighted a complex geographical pattern of agricultural degradation across Europe. Our findings revealed that continental agricultural environments are between 1 and 52 % affected by critical levels of individual degradative processes. Essentially, our results highlighted that soil pollution via pesticides (which impacts 52 % of Europe's evaluated agricultural area), soil nutrient imbalances (39 %), soil pollution via heavy metals (31 %), aridity (25 %), water erosion (15 %), and soil compaction (15 %) are the largest threats to European agriculture. Furthermore, using a Land Multi-degradation Index that integrates the critical conditions of all degradative processes, we emphasized that 31 % of pan-European agricultural landscapes are impacted by significant multi-degradation (lands simultaneously affected by at least three co-occurring processes). This general picture of agricultural degradation becomes however increasingly heterogeneous towards the more detailed (national to sub-regional) territorial levels, according to the multiple maps (52) and statistics provided in this unprecedented integrated inventory, which has the potential to support various land degradation-related policies in Europe.
2026
Safeguarding drinking water in north-western europe by modelling the fate of amines from CO2capture
The European Union (EU) net-zero emission target for 2050 requires large-scale deployment of carbon capture and storage (CCS). Amine-based CO2 capture (CC) is the most mature CC technology but may lead to the spread of nitrosamines (NSAs) and nitramines (NAs) in the nearby surroundings. These are carcinogenic compounds that can persist in water resources. Hence, EU's ambition towards carbon neutrality might pose risk of drinking water contamination as well as ecosystem and agricultural crops pollution. We compiled a dataset of planned CCS projects in the Franco-Danish corridor, Europe's future CCS hub, where most capacity will be located by 2030, with at least 40% based on amine technology. Spatial analysis indicates that up to 10.2 million inhabitants, large Natura 2000 reserves, and extensive crop areas may be impacted by NA and NSA deposition, often in regions already under severe water stress. Biogeochemical modelling shows that surface waters with short residence times are highly sensitive to deposition rates, whereas groundwater concentrations depend strongly on the interplay between NA and NSA half-lives and travel times, creating greater uncertainty in aquifers, especially small systems with limited dilution. In both cases, MEA is the most environmentally friendly when emission abatement measures are limited to water wash, compared to piperazine and other emerging solvents. Main findings highlight the need for regional-scale modelling and harmonized regulation to safeguard drinking water, ecosystems, and food security as CCS deployment expands.
2026
Fluoropolymers are widely used across sectors, but their production is associated with emissions of perfluoroalkyl and polyfluoroalkyl substances (PFASs), which are mobile, persistent, and toxic. In this work, we compiled a global inventory of fluoropolymer production plants (FPPs) and assembled PFAS concentration measurements for various media in their vicinity. We identified 52 currently operating FPPs across 11 countries and 41 cities. For 12 FPPs, in 12 different cities, there are peer-reviewed site-specific PFAS measurements specifically attributed to the FPP. At these 12 sites, at least 236 individual PFASs have been detected across multiple environmental media, including surface water, groundwater, air, dust, soils, sediments, plants, animals, and humans, with reported detections at distances of up to approximately 150 km from FPPs. Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl ether carboxylic acids (PFECAs) were most frequently measured, often at concentrations two to three orders of magnitude higher than those measured in regions without nearby FPPs. Using high-resolution population data, we estimate that approximately 14 ± 2 million people (uncertainty reflecting ± 10 km uncertainty in facility locations) live within 10 km of an FPP. These people are potentially affected by FPP-associated contamination, with the largest population shares in China (≈52%), Japan (≈24%), Europe (≈13%), and the United States (≈9%). These regional proportions largely mirror differences in population density and the number of identified production facilities. This inventory reveals the large and complex global scale of PFAS contamination from fluoropolymer production, underscoring the need for expanded systematic monitoring and risk management efforts, including regulation.
2026
Tracing the air–sea exchange of microplastics over the Caspian Sea
The global proliferation of microplastics (MPs) is increasingly recognized as a transboundary environmental issue. At the air–ocean interface, MPs can be emitted via sea spray and transported back to land, while terrestrial MPs can likewise be advected and deposited over the oceans. However, the long-term net exchange of MPs between land and ocean via the atmosphere remains poorly constrained. Here, we investigate coastal atmospheric MPs and their near-surface landward and seaward transport over the southern Caspian Sea. Using a combination of passive air sampling (at seven heights with MWAC collectors) and active sampling (vacuum pump) over periods of 3 days and 2 months, respectively, together with coastal surface sediment samples, we quantified MP concentrations and assessed the influence of meteorological and environmental factors on their distribution. Fibrous MPs dominated all compartments, with airborne concentrations averaging 3.85 MP m−3 and sediment concentrations ranging from 507 to 1476 MP kg−1 (dry weight). Estimated near-surface horizontal fluxes were comparable in magnitude, with a landward influx of ~6566 MP m−2 h−1 and a seaward outflux of ~8039 MP m−2 h−1, indicating broadly balanced coastal transport during the 72 h campaign. To support source attribution, we evaluated co-trapped particulate proxies (sea salt and ash) and combined them with FLEXPART modelling. Trajectory modelling and proxy evidence indicate that most airborne MPs originated from inland sources (e.g., road dust and textile-related fibres), while marine sea-spray contributions were minor during the sampling period. These findings highlight the importance of long-range atmospheric transport in coastal MP pollution and demonstrate how integrating proxy observations with dispersion modelling can help constrain likely source regimes.
2026
Precise estimation of atmospheric pollutant releases is crucial for assessing the impact of environmental accidents. Atmospheric inversion typically relies on a linear model with a source–receptor sensitivity (SRS) matrix, which may contain significant errors or even completely fail to capture the real magnitude of the event. We propose a correction of the SRS matrix formulated as slight shifts in the observation locations, effectively warping the sensitivity field. To constrain these shifts and ensure data-driven corrections, we model them using a Gaussian process prior. This prior not only enforces smoothness and sparsity, but also enables posterior prediction of shifts at previously unseen locations. This key feature provides a mechanism for hyper-parameter tuning: the predicted shift field can be visualized on a map and assessed by an expert. We present a user-friendly framework that combines a Bayesian inversion model with correction and a tuning algorithm based on L-curve-like plots and the maps of predicted shifts. The proposed method is demonstrated on three case studies: the ETEX-I experiment, the 137Cs emissions during the 2020 Chernobyl wildfires, and the 106Ru release in 2017.
2026
Accumulation patterns of polychlorinated alkanes in an Arctic marine food web
Polychlorinated alkanes (PCAs), otherwise known as chlorinated paraffins, are contaminants of emerging Arctic concern where our understanding of their occurrence and trophic transfer in Arctic food webs remains limited. To investigate biomagnification potential of PCAs, we analyzed short-chain PCAs: C10-C13 and medium-chain PCAs-C14-17 in three Arctic species: polar cod (Boreogadus saida), ringed seal (Pusa hispida), and polar bear (Ursus maritimus) and Subarctic capelin (Mallotus villosus) samples collected from the northern Barents Sea in 2017 and 2021. PCAs-C10-13 concentrations were low, but detectable in all species, while PCAs-C14-17 concentrations were mainly below detection limits in the mammals. PCAs did not biomagnify, as the lowest concentrations were found in polar bear (0.7 ng g−1 lw) and the highest in capelin (56.9 ng g−1 lw). The PCA homologue profiles were similar among Arctic species, with PCAs-C10-13 dominating in polar cod and marine mammals, which may suggest a contribution from long-range atmospheric transport.
In contrast, PCAs-C14-17 were most abundant in the Subarctic capelin, likely reflecting a different exposure. Despite differing PCAs-C14-17 concentrations among the two fish species, their PCAs-C14-17 homologue profile was similar, indicating uniform global production trends. Subarctic capelin is increasingly being preyed upon by Arctic predators and may facilitate the biological transport of PCAs-C14-17 into Arctic ecosystems.
These findings suggest that climate-driven shifts in species distribution may have the potential to alter contaminant exposure pathways in Arctic marine food webs.
2026
The ISLAS2020 field campaign during February and March 2020 set out to obtain a unique dataset describing the Arctic water cycle using stable water isotope (SWI) observations. Our observation strategy focused on measuring evaporation, deposition, and precipitation, all of which are commonly sub-grid scale processes in numerical weather and climate models. Uncertain parameterizations for these processes can lead to compensating errors, which can go unnoticed; however, evaporation and precipitation can also be investigated with SWIs, as they are an integrated tracer for processes that atmospheric moisture has undergone. The campaign can be divided into two efforts: a localised field experiment in Ny-Ålesund focused on evaporation and deposition, and a larger precipitation collection network distributed around the Nordic Seas. The Ny-Ålesund field experiment lasted three weeks, from 23 February to 15 March 2020, with temperatures reaching below −30 °C. During these weeks, we obtained near-surface, high-resolution (approx. 20 cm) SWI profiles at two deployment sites. Using a newly developed profiling system, we measured SWI gradients in the lowermost 5 and 2 m over fjord water and snow-covered tundra, respectively. These profiles are complemented by fiber-optic distributed sensing (FODS) columns and ambient conditions from nearby meteorological stations. The FODS columns supply continuous, high-resolution (2 cm or finer) temperature profiles above both locations, whereas the meteorological stations provide information on wind speed and direction. We also made a short deployment to the Zeppelin mountain observatory (472 ma.s.l.) for measurements of the isotopic signal in the free-troposphere. Additionally, numerous water samples from the snowpack in and around Ny-Ålesund were taken, in addition to daily fjord water samples from Kongsfjorden. These samples provide the context for the surface conditions under which profiles were collected. Isotopic connections on the synoptic scale are achieved by linking Ny-Ålesund observations with precipitation sampling at locations across the European Arctic, namely Longyearbyen, Tromsø, Andenes, Ålesund, and Bergen. The resulting dataset provides comprehensive insight into the Arctic hydrological cycle and can facilitate the study of phase change processes and transport of water vapour into and out of the Svalbard region. Datasets from the field campaign are publicly available at the PANGAEA data repository (https://doi.org/10.1594/PANGAEA.971241, Seidl et al., 2024).
2026
Soil degradation in Europe is projected to accelerate under changing land use and climate
Soil degradation threatens food security and environmental sustainability, yet future projections of it are rare. Using projections from 18 global climate models under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) and land-use projections from the Land Use and Climate Across Scales Land Use Change (LUCAS LUC) dataset, we assess future soil vulnerability to degradation by linking a Soil Degradation Proxy (SDP) to climate, land-use, soil characteristics, and socio-economic factors at 7433 observation sites across Europe. We project that by 2071–2100, ~59% of sites may become more vulnerable under the high-emission scenario. Cold forest regions in northern Europe are projected to face increased degradation pressure by ~+0.04SDP. However, some European croplands may improve locally through conversion to secondary lands, reduced human pressures, and natural recovery processes. These regionally specific trends highlight that, while soil degradation remains a major threat, proactive land management can mitigate soil vulnerability under future climate trajectories.
2026
2026