Taking into account meteorological data in urban planning increases in relevance in the context of changing climate and enhanced urbanisation. The present article focusses on the nocturnal urban heat ...island intensity (UHII) simulated with a physically based atmospheric model for >200,000 Reference Spatial Units (RSU), which correspond to building patches delimited by roads or water bodies in 42 French urban agglomerations. First are investigated the statistical relationships between the UHII and six predictors: Local Climate Zone, distance to the agglomeration centre, population, distance to the coast, climatic region, and elevation differences. It is found that the maximum UHII of an agglomeration increases proportional to the logarithm of its population, decreases for cities closer than 10 km to the coast, and is shaped by the regional climate. Secondly, a Random Forest model and a regression-based model are developed to predict the UHII based on the predictors. The advantage of the regression-based model is that it is easier to understand than the black box Random Forest model. The Random Forest model is able to predict the UHII with <0.5 K absolute error for 54% of the RSU. The regression-based model performs slightly worse than the Random Forest model and predicts the UHII with <0.5 K absolute error for 52% of the RSU. A future challenge is to conduct a similar investigation at global scale, which is to date limited by the availability of a robust description of urban form and functioning.
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•Physically-based simulation of the urban heat island (UHI) for 42 French cities•Quantification of the relationships between the UHI and geographical factors•Regression-based (RB) and Random Forest (RF) model developed to predict the UHI•RB and RF models predict the UHI with <0.5 K absolute error for about 50% of the building blocks.•The RB model is easier to transfer to practitioners than the black box RF.
Water bodies allow the storage of sediments from their catchment areas, including sediments containing persistent contaminants. This study used visible and near-infrared hyperspectral imaging to ...characterize the composition of sediment deposits collected in Martot Pond (France) and to reconstruct the volume of polycyclic aromatic hydrocarbon (PAH) contaminated sediments in the pond. Additionally, combining this method with polychlorinated biphenyl (PCB) analysis enhanced the age model associated with these sediments. To achieve this, indicators of oxides and chlorophyll a (and its derivatives) were employed to correlate various sediment cores, and to propose a sedimentary filling mode for the pond. Furthermore, one sedimentary unit, which appears homogeneous but of variable size within the pond, exhibited repetitive alternations associated with tidal cycles due to a defect in the Martot dam, corresponding to 34 +/− 3 days. A chemometric approach was used to model PAHs with near-infrared hyperspectral imaging data (validation determination coefficient of 0.85, Root Mean Squared Error of Prediction of 1.64 mg/kg). This model was then applied to other cores, coupled with the sedimentary filling mode in the pond, allowing the reconstruction of the volume of PAH contamination. Thus, this study demonstrates that hyperspectral imaging is a powerful tool for estimating various contaminants in sediments: not only is it much faster than conventional chromatographic methods, it also provides a more detailed understanding of a sample, and even of a site through the correlation of multiple core samples.
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•Reconstruction of the pond PAHs contamination along a transect•PAH modelization with hyperspectral imaging•Oxides and chlorophylls hyperspectral indicators helped correlate sediment cores.•Martot Pond sediments showed tidal cycles due to a dam defect.•PCB analysis improved the age model of Martot Pond sediments.
Agricultural use of organochlorine pesticides (OCPs) increased during the twentieth century but many of them have been progressively banned several decades after their introduction. Nevertheless, ...these lipophilic chemical compounds may persist in soils and sediments. From sediment deposits, it is possible to reconstruct the chronology of OCP releases in relation to former applications through time. Nevertheless, long-term fate of OCPs i.e. source, transfer, and storage through the watershed, is also related to the OCPs-sediment characteristics interactions, and our study showed the significant links between OCPs and labile or refractory organic matter. From sediment cores collected in a mainly agricultural watershed, the Eure River watershed (France), aldrin and lindane widespread applications during the 1950s–1970s have been recorded. While lindane applications declined after that date, according to the temporal trend of the stable isomer of hexachlorocyclohexane (β-HCH), α-, and γ-HCH have been recorded at significant levels in the 2000s, suggesting first local post-ban applications. Nevertheless, the relationships between these OCPs and labile organic matter resulted in an overestimation of the post-ban releases. Also, the detection of stable metabolites of dichlorodiphenyltrichloroethane (DDT) (i.e. 4,4′-DDE) and heptachlor (i.e. heptachlor epoxide) several decades after their ban, revealed the role of old deep soils erosion in the chronology of OCP releases and thus the reemergence of stable transformation products from historical OCPs.
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•Lindane and aldrin showed temporal trends in link with their applications.•Post-ban releases of HCHs and 4,4′-DDE have been recorded.•Temporal trends of OCPs showed significant links with labile or refractory OM.•Recent releases of 4,4′-DDE is due to former used of DDT and erosion of old soil.•Normalized temporal trends showed an overestimation of post-ban releases of lindane.
This article proposes a QGIS plug-in called TempMap, to obtain near surface air temperature maps from an urban meteorological network, the topography description and three parameters describing the ...urbanized surface fraction. The objective being to facilitate the communication and consideration of local climate in French urban planning practices, some methodological choices were done related to the meteorological situation robustness, the choice of the mapped indicator and the availability of the surface data description. The plug-in allows to apply spatial analytical modelling based on a hybrid interpolation and is here applied to the CAPITOUL atmospheric database of Toulouse (France), the MApUCE urban database and the topographical information from the French National Geographical Institute to obtain air temperature maps for four Local Weather Types. The plug-in can be download from GitHub, is compatible with all QGIS versions since 2.14.12. The evaluation of the model results shows an accuracy comparable to the state-of-the-art with a maximum delta between predicted and observed values of ~1 °C. Here French datasets are used but alternative datasets can be used being also possible to modify the output resolution in order to fit the input data resolution and the needs of the study.
Sediments are complex heterogeneous matrices allowing to some extent the recording of past environmental conditions by integrating sediment characteristics, contamination and the microbial community ...assembly. In aquatic environments, abiotic environmental filtering is considered the primary deterministic mechanism shaping microbial communities in sediments. However, the number and relative contributions of geochemical and physical factors associated with biotic parameters (reservoir of microorganisms) complicate our understanding of community assembly dynamics. In this study, the sampling of a sedimentary archive in a site alternately subjected to contrasting inputs from the Eure and the Seine Rivers allowed us to study the response of microbial communities to changes in depositional environment over time. The coupling of the quantification and sequencing of the gene encoding the 16S rRNA with analyses of grain size, organic matter and major and trace metal contents demonstrated that microbial communities reflected contrasting sedimentary inputs over time. Total organic carbon (TOC) was the main factor influencing microbial biomass, while the quantity and quality of organic matter (R400, RC/TOC), major elements (i.e. Al, Fe, Ti) and trace metals (i.e. Zn, Pb, Cu, Cr, Ni, As, Co, Ag, Sb) shaped the structure of the microbial community. Besides the effect of geochemical factors, a specific microbial signature was associated with the contrasting sedimentary sources, highlighting the importance of the microbial reservoir in the assembly of microbial communities. Indeed, the main genera identified in the facies influenced by the Eure River were affiliated with the phyla Desulfobacterota (Syntrophus, Syntrophorhabdus, Smithella, Desulfatiglans), Firmicutes (Clostridium_sensu_stricto_1), Proteobacteria (Crenothrix), Verrucomicrobiota (Luteolibacter), while the contributions of the Seine River were characterised by some halophilic genera Salirhabdus (Firmicutes), Haliangium (Myxococcota) and SCGC-AB-539-J10 (Chloroflexi). This study sheds light on the overall processes determining the assembly of microbial communities in sediments and the importance of associating geochemical factors with reservoirs of microorganisms inherited from sediment sources.
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•Sediment microbial community assembly is impacted by the source of deposit.•Sediment microbial biomass is influenced by TOC content.•Microbial diversity is related to OM quality and major element levels.•Microbial composition is driven by OM quality, and major element and TME levels.•Specific microbial taxa can be identified based on the source of the sediment.
Temporal trends in polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were reconstructed from sediment cores collected in the Martot and Les Damps ponds, downstream of the ...Eure River watershed. PAHs exhibited a positive correlation with fine fractions, but mainly with the refractory organic carbon measured in the sediments, which suggests PAH inputs from materials largely composed of refractory carbon (e.g. soot). Since around the 1940s, PAH concentrations ranged between 2.93–38.20 and 2.27–28.20 mg kg−1 in sediment cores from the Martot and Les Damps ponds, respectively. Based on the temporal distribution of isomers and diagnostic ratios, the PAHs in the sediments were found to be predominantly of pyrogenic origin, particularly in the 1940s–1960s, when PAH levels were particularly high. PCBs also showed an affinity with the fine fraction and with refractory organic carbon, albeit less so than PAHs. Since around the 1940s, PCB concentrations ranged between 0.02–1.57 in Martot Pond and 0.09–1.60 mg kg−1 in Les Damps Pond. The recorded PCB temporal trends were mainly associated with the production, consumption, and banning of these chemicals in France. According to the temporal distribution of PCB congeners, high levels in the 1950s–1970s were linked to “technical mixture” discharges into waterways, which were mainly composed of “low chlorinated congeners”, whereas PCB levels after the 1970s were of atmospheric origin.
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•Temporal trends of PAHs and PCBs were reconstructed from sediment cores.•PAHs and PCBs showed a positive correlation with fine fractions.•PAHs showed a positive correlation with the refractory organic carbon.•PAHs were found to be predominantly of pyrogenic origin.•High levels of PCBs were linked to technical mixture discharges into the river.
Since 1945, a large amount of heterogeneous data has been acquired to survey river sediment quality, especially concerning regulatory metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Large-scale ...syntheses are critical to assess the effectiveness of public regulations and the resiliency of the river systems. Accordingly, this data synthesis proposes a first attempt to decipher spatio-temporal trends of metal contamination along seven major continental rivers in Western Europe (France, Belgium, Germany, and the Netherlands). A large dataset (>12,000 samples) from various sediment matrices (bed and flood deposits – BFD, suspended particulate matter – SPM, dated sediment cores – DSC) was set up based on monitoring and scientific research from the 1950s to the 2010s. This work investigates the impact of analytical protocols (matrix sampling, fractionation, extraction), location and time factors (related to geology and anthropogenic activities) on metal concentration trends. Statistical analyses highlight crossed-interactions in space and time, as well as between sediment matrices (metal concentrations in SPM ≃ DSC > BFD) and extraction procedures (also related to river lithology). Major spatio-temporal trends are found along several rivers such as (i) an increase of metal concentrations downstream of the main urban industrial areas (e.g. Paris-Rouen corridor on the Seine River, Bonn-Duisburg corridor on the Rhine River), (ii) a long-term influence of former mining areas located in crystalline zones, releasing heavily contaminated sediments for decades (Upper Loire River, Middle Meuse section), (iii) a decrease of metal concentrations since the 1970s (except for Cr and Ni, rather low and stable over time). The improvement of sediment quality in the most recent years in Europe reflects a decisive role of environment policies, such as more efficient wastewater treatments, local applications of the Water Framework Directive and urban industrial changes in the river valleys.
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•Assessment of metal contaminations in sediments along Western European Rivers•Sediment monitoring and cores covering the period from the 1960s to the 2010s.•Deciphering of spatial and temporal factors over contamination trends•Secondary influence of the matrix-types and extraction process on metal levels
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•PAHs/PCBs bioaccessible fractions are linked to the rapidly-desorbing fraction (Frap).•Mild extractions with a carboxymethyl-β-cyclodextrin polymer were used to assess Frap.•An ...experimental design showed sediments OM was the most influential factor on Frap.•Bioaccessibility decreases when the number of PAH cycles or PCB chlorines increases.•A great part of As, Cd and Zn were found in the most bioaccessible sediment fractions.
Organic matter (OM), clays, sand or time are factors possibly influencing the bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) from sediments. An experimental design was performed to monitor and quantify this process. The bioaccessible fraction, linked to the rapidly-desorbing fraction (Frap) of contaminants, was assessed through a non-exhaustive extraction using a carboxymethyl-β-cyclodextrin polymer. OM content was the most influential factor as regards Frap. Clay percentage was a slightly influential factor for PAHs while the interaction sand × OM was a slightly influential factor for PCBs. Frap was also determined in a sediment core collected from Martot’s Pond (France). The higher the PAH/PCB concentration in this sediment, the higher the bioaccessible fraction. The relationship between a lower bioaccessibility and a higher number of PAHs cycles or PCB chlorines was linear. OM content impacted on Frap only for PAHs. Sequential extractions of some trace elements were also performed to evaluate their mobility. Cu, Cr, Pb, Ni were the less bioaccessible. A great part of As, Cd and Zn was found in the most bioaccessible sediment fractions. The 40–65 cm section might be considered as the most negatively impacting on the aquatic fauna, due to Cd and Zn high bioaccessible concentrations.
Platinum (Pt) is a Technology Critical Element (TCE) which, since the 1990s, has been mainly used in the industry in catalytic converters for automobile emission control. Previous studies have shown ...Pt contamination of road-side sediments and surface sediments in urban rivers and lakes but few of them have addressed temporal variations. The present work presents historical Pt concentration trends in 137Cs-dated sediment cores from floodplains or secondary channels at the outlets of three major French watersheds (Loire, Rhone, and Seine Rivers) covering the past ∼110 years, i.e., from the 1910s to 2021. Platinum baseline levels in the sediment were estimated for the Loire River (0.76 ± 0.22 μg kg−1 for the period ∼1910-∼1955) and the Rhone River (1.64 ± 0.41 μg kg−1), and historical Pt variations seem to reflect variations in hydrodynamics and grain size composition. Since the early 2000s, Pt concentrations in the Loire and the Rhone River sediments tend to increase (>2.5 μg kg−1) and were attributed to the use of car catalytic converters, an emerging technology since the 1990s using >50 % of European Pt demand. High and variable historical Pt concentrations (up to 14.6 μg kg−1) in the Seine River sediments may reflect legacy Pt sources due to former anthropogenic activities in this watershed, such as the use of Pt-based catalysts for petroleum refinery since the end of the 1940s, coal handling and precious metals refining, probably concealing the likely presence of an emerging traffic-related Pt signal. This first comparison of historical Pt concentration trends in sediments from contrasting watersheds allows to distinguish signals originating from different natural and anthropogenic sources (background level, historical sources, road traffic).
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•Few studies on Pt level in sediment for reconstructing the past geochemical quality•Ad-CSV analysis on selected sediments collected in dated cores in 3 French rivers•Temporal evolution of Pt concentrations (trajectory) between 1910 and 2021•Signals originating from different natural (baseline) and anthropogenic sources•Highest Pt concentrations in the Seine R. to past/historical and emerging sources
Anthropogenic impacts on rivers have increased significantly over the past ~150 years, particularly at the beginning of the industrial revolution. Among other signs, this impact is manifested through ...the addition of trace metals and metalloid elements to rivers. The Eure River watershed in France covers an area of 6017 km2 and is a major tributary of the Seine estuary. It is not exempt from anthropogenic pressures and has been exposed to significant metal discharges over the last 80 years. The average concentrations of metals (i.e., Cr, Co, Ni, Cu, Zn, Ag, Cd, Sb, and Pb), in suspended particulate matter currently transported by the river are high compared to the local geochemical background. Moreover, the lack of correlation between concentration variations and the hydrosedimentary behaviour of the Eure River suggests that the river is currently under anthropogenic pressure. Analysis of sediment cores indicate strong As contamination during the 1940s, Cr, Co, Ni, Cu, Zn, Ag, and Cd contamination during the 1960s and 1970s, and Sb and Pb contamination during the 1990s and 2000s. The enrichment factors calculation suggests that total anthropogenic pressure within the Eure River watershed since the 1940s was comparable or higher than those in many other French watersheds. An estimation of particulate metal flux in 2017 shows that the Eure River watershed contributed to 7, 8, 9, 10 and 16% of total inputs to the Seine estuary in Cr, Cu, Zn, Cd and Pb respectively. Moreover, the estimation of past theoretical flux indicates that during the 1990s the Eure River watershed was the main contributor of particulate Pb to the estuary. The use of Pb isotopes has revealed that this contamination was primarily of industrial origin.
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•We assess and characterise the anthropogenic impacts occurring in the Eure River.•Current particulate TMM concentrations and flux were estimated using TIMS.•Temporal trends of TMM were reconstructed using sediment cores.•A permanent anthropogenic baseline due to industrial contamination was highlighted.•The origin of the Pb contamination can be traced using Pb isotopes.
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