We have developed a methodology for constructing diachronic views of the chemical state of water that infiltrates soils and forms perched aquifers in the north and south of Paris (France). These waters have been drained for centuries and distributed by historic underground aqueducts. The CaCO3 layers deposited by these waters in the aqueducts have been studied.The first challenge is to construct chronologies of these deposits, using uranium-thorium or 14C chronometers and/or lamina counting.Past water quality has been reconstructed using trace elements measured along the growth axis of CaCO3 deposits, combined with isotope analysis (lead, sulfur and strontium) and, in some cases, carbon isotopes.With this methodology, we demonstrate that in Paris, over the last 300 years, the transformation of land use is the most important factor affecting water quality, not only through the presence or absence of building industries, but also through the use of certain materials for construction or embankment. We use this methodology for the study of ancient aqueducts in archaeological sites to discuss water provenance and quality.

The French R&D MUSE project developed a methodology to map the potential multifunctionnality of unsealed soils based on existing data at national scale, in order to consider this information in urban planning. This method gives a partial idea of soil health. The data on rural areas allow mapping 4 ecological soil functions: potential of carbon storage, water storage, agronomic potential, and biodiversity reservoir. The lack of soil maps on urban area conducted to propose a simplified approach. The methodology was developed in collaboration with 3 pilot territories. The aim of this presentation is to establish feedback on the application of the methodology on various geographical and pedo-climatic contexts. The analysis is carried out on more than 10 cases including Rennes Métropole, Ris-Orangis and Savoie Métropole, by checking the objectives of the application, the appropriation by operators and the adaptations proposed. The feedback shows the ability to identify zones to be preserved, developed or disartificialised by crossing with other data. More detailed soil maps contribute to gain precision and are mandatory to design development projects. New methodological developments are proposed also to map soil multifunctionnality in urban areas. The integration of soil quality to reach the "no net land take" target is also in progress. It takes into account a moderation of the potential soil functions by knowledge on pollution risks and remediation projects. The MUSE methodology is getting more and more applied in France, although its application needs some technical skills on soils and geomatics. In this frame, an automation script was developed to standardise the production of the 4 ecological soil function maps. It can be applied at various scales, according to the precision of the available data. The feedback underlines the need to wider characterise urban soil and to bank further the acquired data to improve the knowledge on urban soils.

Urban stormwater management is a major challenge for limiting the degradation of surface aquatic environments. Given the limitations of traditional sewer systems, nature-based solutions are now being implemented at various scales to control the pollutants generated by runoff during rain events. Two main families of solutions can be distinguished: 'decentralised' systems, aimed at limiting runoff at source, and 'centralised' systems, aimed at storing or treating volumes associated with catchment areas of several hectares, potentially mixing rainwater and wastewater. While the first type of solution should be more advantageous, the second is no less relevant, particularly in constrained urban contexts where the scope for building new facilities is limited. In this context, the City of Paris set up an experiment involving an innovative centralised system based on the planted filter concept. The main goal of this project is to evaluate the efficiency of this system to reduce the pollutant loadings of stormwater runoff. Mineral and organic micro-pollutants are specially investigated with a focus on the dissolved phase that is not sufficiently taken into account in the classic depollution systems of rainwater. In order to compare the innovative filter to a “classic” planted filter, two filters were built. The two filters have an area of 600m2. The classical one consists of, from the bottom to the top: 30cm of gravel 20/40 within which drains are installed, 20cm of gravel 8/20, 10 cm of gravel 4/8 containing aeration network and the filtration layer composed of 40 cm of sand 0/4. The innovative filter only differs by the 40-cm filtration layer which consists of 10cm of sand 0/4, 20 cm of Rainclean® (Funke Kunststoffe GmbH, Hamm, Germany) and 10cm of sand 0/4. Rainclean® was specially selected during the preliminary design studies to optimise the treatment of dissolved organic and metallic micropollutants. It has never been tested before in planted filters. Filters receive runoff waters coming from 21ha of the ring road of the city of Paris (1.3 million vehicles/day) but also clear water during dry wheather. Since the beginning of the experiment (in May, 2021), each filters received about 56 m and 90 m of water during rain events and dry weather respectively. These large volumes of clear water could affect the pollution reduction efficiency of the filters with faster exhaustement of the filter media. However this impact still has to clarified. More generally, an assessment of the current functioning of the filters is still necessary. To do so, water sampling to estimate the capacity of the filters to reduce pollution is undergoing.

Two stalagmites from Nerja cave (Andalusia, Spain) were studied. The cave is well known because of its long human occupation from the Upper Palaeolithic to the Chalcolithic and its abundant parietal prehistoric Art. The aims of this study were twofold: i) to compare uranium/thorium (Th-230/U-234) and Carbon-14 (C-14) ages obtained all along the growth axis of the stalagmites in order to understand the consequences of diagenetic processes on the validity of radiometric ages; ii) as one of the stalagmites contains black layers, attributed to combustion soot, to establish when these intense hearths were used and by which culture. Th-230/U-234 and C-14 ages were coupled with mineralogical studies using FTIR (Fourier-transform infrared spectroscopy) and thin section observations. The first stalagmite (GN16-9b) displays Th-230/U-234 ages in stratigraphic order, and compatible with C-14 ages corrected for a few percent of dead carbon. Homogeneous composition of aragonitic crystals characterized by their needle-like texture is observed throughout this speleothem. For the second stalagmite (GN16-7), in contrast,Th- 230/U-234 ages display large significant inversions and discordant results on the upper part and at the base of the stalagmite, suggesting a possible open system behavior for this chronometer. Interestingly, 14C ages are in stratigraphic order all along the stalagmite and are compatible with Th-230/U-234 ages only in its central part. Mineralogical studies display evidence of aragonite to calcite transformation at the top and a complex mineralogical assemblage with interlayered silicates (possibly clays) and calcitic mineralogy for the base of GN16-7. In these parts, discordant Th-230/U-234 ages were measured. In the middle part of the stalagmite, however, where the fibrous aragonite is well preserved, the 14C and Th-230/U-234 ages agree. Our data suggest that in the case of aragonite to calcite transformation as shown here, Th-230/U-234 ages are biased, but C-14 ages seem to remain accurate, as already observed in aragonitic marine bio minerals. C-14 ages obtained are used for the chronology of the soot layer, determined here between 7900 and 5500 years Cal BP, coherent with previous analysis of charcoals in the same sector of the cave. This study highlights the importance of working with at least two chronometers when stratigraphic age verification is not possible, as is the case of some parietal CaCO3 thin layers used for rock art dating. Recent Th-230/U-234 ages published for carbonate deposits on Spanish parietal Art are discussed in light of this demonstration. (C) 2022 Elsevier Ltd. All rights reserved.

ABSTRACT In urban environments, diachronic evolution of water quality can be reconstructed using geochemical analysis of urban secondary carbonate deposits (USCDs), from urban underground structures, similar to speleothems from natural caves. The use of the radiocarbon bomb peak to build their precise chronology was recently tested in two Paris-area urban sites (France). In this study, new samples from contrasted environments in the Paris region were sampled in order to test the sites’ effects on the radiocarbon signal recorded: under wood, under a fountain, in underground aqueducts, in the south and north of Paris. We compared the post-bomb atmospheric radiocarbon record with the one measured at the top of USCDs, and estimated the dead carbon proportion (DCP), between 0 and 40%. USCDs fed by water with a rapid transfer through thin soil (Versailles fountain) had the lowest DCP ( 14 C very close to atmospheric one). Highest DCP were found for USCD from deep underground quarry under urban wood, and intermediate ones for USCDs fed by the waters of perched aquifers. These data support the use of radiocarbon as chronometer for USCDs in contrasted urban contexts, and show that it can be used to determine carbon transport and sources, an important parameter for pollution reconstruction.

Characterizing the physico-chemical properties of urban soils on a large scale remains a significant challenge. The heterogeneity and difficulty of access to these soils lead to very localized studies that are difficult to transfer to a whole urban area. This heterogeneity is mainly explained by the human factor in the formation and evolution of soils, which is a major contributor to the pedogenesis in cities. Throughout their evolution, urban soils undergo contrasting human activities that modify their properties and thus determine the historical trajectories of land use. Characterizing this human pedogenesis factor seems to be an essential condition for a better understanding of the functioning of urban soils and for qualifying them on a large scale. The aim of this work is to describe this human factor by an analysis of the historical trajectories and an evaluation of their impacts on soil properties. . We focus on soils in the conurbation of Paris over the last 70 years. The different historical trajectories were identified thanks to a database provided by a local land use inventory. Results show that 80% of the total surface area is affected by 21 historical trajectories. More than 60% of this area is characterized by single use trajectories showing that most of the area has not changed land use over the last 70 years. The urbanisation of agricultural land, leading to residential areas is a representative trajectory of land use described in the paper that transforms original soils into Technosols.

This study addresses soil contamination in vegetated road shoulders with diffuse inflow of runoff. It aims (i) to characterize the spatial distribution of three metals (copper, lead, zinc) and PAHs, and (ii) to identify influencing factors for the inter-site differences. An extensive sampling campaign was carried out on forty road segments in the Paris region, targeting various distances and soil depths. Copper and zinc contamination was found to be mainly restricted to the first 30 cm from the road, where their concentrations ranged respectively between 40 and 270 mg.kg(-1), and between 150 and 950 mg.kg(-1) (with a few additional extreme values related to the presence of a galvanized steel guardrail). Lead contamination was moderate (< 100 mg.kg(-1) in more than 75% of the sites) and relatively uniform across the width of the shoulders. Conversely, highest PAH concentrations were found further from the road. These differences between contaminants were likely due to the varying importance of wet weather-related processes and atmospheric transport in their dispersion mechanisms. Copper and zinc concentrations correlated well with the traffic density, which alone explained a 69% of the inter-site variability, whereas lead and PAHs did not exhibit such dependence. Soil organic matter was found to control the "ceiling" concentration of metals, thus limiting the maximum amounts that can be intercepted from road runoff. These results illustrate the feasibility of estimating contamination levels on road shoulders, and thus offer interesting perspectives for better consideration of the infrastructures' maintenance needs and improved routine operations. (C) 2020 Elsevier B.V. All rights reserved.

Summary We analysed biomarkers enclosed in carbonate crusts deposited in urban surrounding as tracers of pollution

Surfactants based on polyfluoroalkyl ethers are commonly used in fire-fighting foams on airport platforms, including for training sessions. Because of their persistence into the environment, their toxicity and their bioaccumulation, abnormal amounts can be found in ground and surface water following the operations of airport platforms. As with many other anthropogenic, organic compounds, some concerns are raised about their biodegradation. That is why the Organization for Economic Co-operation and Development (OECD) 301 F protocol was implemented to monitor the oxygen consumption during the biodegradation of a commercial fire-fighting foam. However, a Raman spectroscopic monitoring of the process was also attached to this experimental procedure to evaluate to what extent a polyfluoroalkyl ether disappeared from the environmental matrix. Our approach relies on the use of chemometrics, such as Principal Component Analysis (PCA) and Partial Least Squares (PLS), in order to monitor the kinetics of the biodegradation reaction of one fire-fighting foam, Tridol S3B, containing a polyfluoroalkyl ether. This study provided a better appreciation of the partial biodegradation of some polyfluoroalkyl ethers by coupling Raman spectroscopy and chemometrics. This will ultimately facilitate the design of future purification and remediation devices for airport platforms.

Les ouvrages de filtration végétalisés pour la gestion à la source des eaux pluviales, appelés à l’international des ouvrages de biofiltration, de biorétention ou vegetative filter strips, visent la maîtrise du flux polluant associé aux eaux pluviales urbaines. Ces ouvrages permettent le stockage, la fltration au travers d’un substrat planté et éventuellement l’infiltration de l’eau. L’efficacité épuratoire a été évaluée in situ pour deux systèmes de biofiltration, un accotement filtrant et une noue filtrante, pour un panel diversifié de polluants. Ce panel comprend des éléments traces métalliques (ETM) et des micropolluants organiques – des hydrocarbures aromatiques polycycliques (HAP), des alkylphénols, le bisphénol A (BPA), des phtalates – dans les phases totales et dissoutes. Les polluants essentiellement associés à la phase particulaire (Pb, Zn et HAP) étaient très bien retenus dans les ouvrages (abattements de concentration ›90%) pour la majorité des événements pluvieux. Cependant, une performance dégradée a été observée vis-à-vis des particules pendant la période hivernale, ce qui a été attribué à la taille plus fne des particules pendant cette période. Les abattements des concentrations dissoutes étaient rarement significatifs et tendaient à être bien plus faibles que ceux observés pour les matières en suspension (MES) et les polluants présents sous forme particulaire. De ce fait, des rétentions relativement faibles étaient observées pour les concentrations totales en polluants modérément particulaires, tels que le BPA, les alkylphénols et les phtalates. La rétention des ETM dissous semble avoir été limitée par leur association à la matière organique dissoute, alors que celle des micropolluants organiques dissous était limitée essentiellement par la contamination initiale du substrat filtrant ou par des émissions depuis les matériaux synthétiques de construction. À l’échelle annuelle, la noue filtrante dans sa configuration finale abattait entre 33 et 81% du flux polluant en fonction des polluants.

Urban planning historically considers soils as a support for infrastructures. Hopefully, awareness is increasing on the fact that soils offer many more services than just this one, thanks to their various functions. It is therefore necessary to develop methodologies and tools that allow the urban planners to take into account the opportunities and constraints associated to soils. Considering the existing quality indexes already developed by the researchers, we faced within the MUSE project various difficulties and in particular the lack of knowledge on urban soils in France. We therefore developed a methodology to deal with limited knowledge on urban soils and tested it first on the Nantes metropolis territory (France). Our aim was to map each soil function as well as a soil multifunctionality in such a way that urban planning documents may refer to them. The aim of the multifunction map is to help protecting soils that show various functions, including patrimonial functions. We therefore considered the following functions: carbon storage, water storage and infiltration, storage and filtration of contaminants, agronomic potential, biodiversity reservoir. We did not consider the support and natural resources provision functions. According to the level of knowledge on soils (local/regional/national scales, direct/indirect), we considered three mapping approaches (statistical, global, and calculation) to build function maps, and interpreted them in terms of soil function index (SFI) map. To build the soil multifunctionality quality index (SMQI) map, we crossed the various function index maps using a ponderation according to the territorial issues. These issues derive from discussions with the urban planners of the local authority and the number of functions assessed on each part of the territory (some functions not mapped in the city center). We carried out discussions with the urban planners all along the methodological development process to ensure applicability of the index map produced. The results obtained are very satisfying considering the level of knowledge on soils. The urban planners of the local authority clearly imagine how to use both the soil function maps as well as the soil multifunctionality quality index map. We are nevertheless aware of the limits due to the use of data with different scales of validity (eg. 1 / 250 000 for pedological map; 1/10 000 for soil land-use model; statistical data on C and biodiversity at pedoclimatic scale vs national scale). The comparison with local punctual data helps verifying the degree of confidence of the maps. The methodological development is currently being adjusted and tested on other cities (in particular Marseilles and Châteauroux, France) and further discussed with urban planners at national scale. Efforts are necessary to build a wider and more precise knowledge on urban soils by gathering and sharing existing data. This implies building reference knowledge and by defining the most useful properties to acquire in a systematic way to characterize soils so as to optimise urban planning and development.

Urban soil contamination by heavy metals is one of the foremost challenges for urban soil quality, especially in the urban agriculture context. Urban gardening is a common practice in many industrialized and developing countries. How sources of soil contamination relate to inputs and influence the heavy metal content in soils, however, is not established yet. This study aims to assess the potential of pesticide applications (such as Bordeaux mixture) on soil quality. A set of 104 allotment gardens was selected in three cities in France, and topsoil was sampled and analyzed. The four most abundant metals in urban vegetable garden topsoils were Zn, Pb, Cu, and Cr. The past and/or present industrial and urban activities are not the only cause of the metal contamination in urban vegetable garden soils. Gardens, where pesticides such as the Bordeaux mixture are being used showed significantly higher total Cu values in soils (78 mg kg−1 compared with 49 mg kg−1 for untreated gardens). Even though the risk of metal contamination through vegetable consumption is usually considered low, we clearly identified indicators of anthropogenic Cd, Cu, Pb, and Zn pollution due to pesticides inputs. This link was particularly strong between the use of Bordeaux mixture and increases Cu levels.

By 2017, the book "Soils within cities" (Levin et al., 2017) is moving away from the pedologist's description of urban soils to a broader understanding of urban soils, including the functions and the services they provide. This approach, which complements the naturalistic description of the soil, corresponds to the approach derived from the millennium ecosystems assessment (Morel et al., 2015; Walter et al., 2015). It is considered to be relatively anthropocentric and thus favours the integration of the soil in the urban socio-ecosystem. Considering the soil by both its pedogenesis and functioning in ecosystems induces taking into account the dynamics of this system, but raises, with regard to the literature on urban soils, the existing lack to qualify and quantify the processes of genesis and evolution, especially in relation to ongoing climate change (Baveye et al., 2016). On the other hand, the description of soil ecosystem services (regulation, provisioning, cultural services) immediately reveals the interdependence of soil biophysicochemical processes with those occurring in the hydrosphere, the atmosphere and the biosphere (Adhikari and Hartemink, 2016). In this respect, the soil plays an interface role, but is deeply disturbed in urban areas. The objective of the communication will be to review the status of urban soil in the "urban critical zone" concept. Through methodologies and results from projects implemented in French major cities that have enabled the development of databases, we will review the classification of these atypical soils and the changes in their properties and functions. Through the definition of the services they provide, we will propose a more integrated vision of this compartment of the urban ecosystem, by specifying the forcing caused by its interface position, but also the opportunities of improvement foreseen by the development of solutions for revegetation and de-sealing. We will see how the timeframe of soil evolution in urban zones can influence the data collection of soil parameters and mapping.