Thomas Gardes
email: thomas.gardes2@univ-rouen.fr

Maxime Debret

Yoann Copard

Edouard Patault

Thierry Winiarski

Anne-Lise Develle

Pierre Sabatier

André-Marie Dendievel

Brice Mourier

Stéphane Marcotte

Barbara Leroy

Florence Portet-Koltalo

Reconstruction of anthropogenic activities in legacy sediments from the Eure River, a major tributary of the Seine Estuary (France)

Keywords: Anthropogenic Activities, Eure River, Legacy Sediments, Sediment Cores, Trace Metals

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Many researchers agree that the Earth has entered a new geological period, the Anthropocene [START_REF] Crutzen | The Anthropocene. Int. Geosphere-Biosphere Programme IGBP[END_REF][START_REF] Crutzen | The "Anthropocene[END_REF][START_REF] Steffen | The Anthropocene: conceptual and historical perspectives[END_REF][START_REF] Lewis | Defining the Anthropocene[END_REF]. While the beginning of this period is the subject of intense debate [START_REF] Lewis | Defining the Anthropocene[END_REF], there is consensus that humans have seriously impacted their environment during this period [START_REF] Steffen | The Anthropocene: conceptual and historical perspectives[END_REF]. Such human activities as agriculture, forestry, mining, and water storage and diversion contribute significantly to landscape change and environmental contamination. The sediments generated by the erosive actions of humans have received increasing attention in recent years and have even been categorised as a particular type, known as legacy sediments [START_REF] James | Anthropocene, Geomorphology of the Anthropocene: Understanding The Surficial Legacy of Past and Present Human Activities[END_REF](James, , 2018)); these are generally defined as alluvial sediments that are deposited as a result of anthropogenic disturbances within a watershed [START_REF] James | Anthropocene, Geomorphology of the Anthropocene: Understanding The Surficial Legacy of Past and Present Human Activities[END_REF]. Among the several sedimentation and storage zones throughout the watershed, there is particular concern about how legacy sediments trapped behind dams are managed (i.e. dredging). Structures such as dams change the flow of a river to achieve particular objectives (e.g. energy production, flood control, and navigation) and serve to modify the hydrodynamic cycle and thus the sediment storage in catchment [START_REF] Nilsson | Fragmentation and Flow Regulation of the World's Large River Systems[END_REF][START_REF] Yang | Dam impacts on the Changjiang (Yangtze) River sediment discharge to the sea: The past 55 years and after the Three Gorges Dam[END_REF].

Many studies have examined the storage of metallic and organic contaminants behind dams (e.g. [START_REF] Shuman | Environmental considerations for assessing dam removal alternatives for river restoration[END_REF][START_REF] Müller | Reservoir sediments -a witness of mining and industrial development (Malter Reservoir, eastern Erzgebirge, Germany)[END_REF][START_REF] Bednarek | Undamming Rivers: A Review of the Ecological Impacts of Dam Removal[END_REF][START_REF] Stanley | Trading off: the ecological effects of dam removal[END_REF][START_REF] Audry | Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France)[END_REF][START_REF] Ashley | The Effects of Small Dam Removal on the Distribution of Sedimentary Contaminants[END_REF][START_REF] Devault | Herbicide accumulation and evolution in reservoir sediments[END_REF][START_REF] Dhivert | Influences of major flood sediment inputs on sedimentary and geochemical signals archived in a reservoir core (Upper Loire Basin, France)[END_REF][START_REF] Evans | Contaminated Sediment and Dam Removals: Problem or Opportunity[END_REF]. Hence, legacy sediments can be viewed as the industrial and agricultural testimonies of past anthropogenic activities in, and can reflect the trajectory of, any studied watersheds. In addition, estuaries are dynamic environments where it is difficult to reconstruct temporal trends of contamination and the origins of these latter from legacy sediments. So, determining the origins of contamination in an estuary requires to study its tributaries.

The Seine River watershed (France) provides an example of a basin experiencing anthropogenic activities. The industrial revolution increased the anthropogenic pressure on the Seine River considerably over a period of about 150 years, resulting in specific and drastic changes in the stream morphology. These modifications meant that the flow of the Seine River was regulated, mainly to facilitate navigation in the nineteenth century [START_REF] Horowitz | Ground-probing radar as a tool for heterogeneity estimation in gravel deposits: advances in data-processing and facies analysis[END_REF][START_REF] Lestel | ArchiSEINE : une approche géohistorique du bassin de la Seine[END_REF]. The morphological modifications also impacted the tributaries of the Seine River. Thus, the Eure River, the most important contributor to the Seine Estuary, saw its outlet diverted 11 km downstream between 1929 and 1939. All these adjustments have promoted the establishment of depositional environments favouring the storage of legacy sediments suitable for reconstructing anthropogenic activities in the watershed. However, if the history of the Seine River is well known, there is less historical information about its tributaries; the latter could potentially be the main source of contamination in the lower reaches of the watershed, i.e., the estuary (e.g. the Gironde Estuary; [START_REF] Audry | Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France)[END_REF][START_REF] Masson | Geochemical signals and source contributions to heavy metal (Cd, Zn, Pb, Cu) fluxes into the Gironde Estuary via its major tributaries[END_REF]. Most sediment cores covering at least the last 70 years were extracted along the Seine Estuary [START_REF] Van Metre | Origins of Sediment-Associated Contaminants to the Marais Vernier, the Seine Estuary, France[END_REF][START_REF] Vrel | Reconstitution de l'historique des apports en radionucléides et contaminants métalliques à l'estuaire fluvial de la Seine par l'analyse de leur enregistrement sédimentaire[END_REF][START_REF] Vrel | Dating of sediment record at two contrasting sites of the Seine River using radioactivity data and hydrological time series[END_REF][START_REF] Kaci | Distinct diversity of the czcA gene in two sedimentary horizons from a contaminated estuarine core[END_REF][START_REF] Kaci | Diversity of active microbial communities subjected to long-term exposure to chemical contaminants along a 40-year-old sediment core[END_REF] and along the fluvial part of the Seine River, upstream from the Poses Dam (Figure 1A; [START_REF] Bonté | Enregistrement sédimentaire de la contamination métallique, Piren-Seine[END_REF][START_REF] Meybeck | Historical perspective of heavy metals contamination (Cd, Cr, Cu, Hg, Pb, Zn) in the Seine River basin (France) following a DPSIR approach (1950-2005[END_REF]Ayrault et al., 2010a;[START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF][START_REF] Tamtam | A 50-year record of quinolone and sulphonamide antimicrobial agents in Seine River sediments[END_REF][START_REF] Ayrault | Lead contamination of the Seine River, France: Geochemical implications of a historical perspective[END_REF][START_REF] Vrel | Dating of sediment record at two contrasting sites of the Seine River using radioactivity data and hydrological time series[END_REF][START_REF] Lorgeoux | Temporal trends of persistent organic pollutants in dated sediment cores: Chemical fingerprinting of the anthropogenic impacts in the Seine River basin[END_REF]. In contrast, there are few sediment records for the tributaries (Figure 1B; Ayrault et al., 2010b;[START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF][START_REF] Ayrault | Lead contamination of the Seine River, France: Geochemical implications of a historical perspective[END_REF]. Unfortunately, the geographic locations of the cores from the Oise and Marne rivers restricted the reconstruction of the sedimentary and contamination history to a limited area of these two tributaries. The best location for coring is at the outlet of a tributary, where the geochemical signatures of the river being studied can best be captured. This is the reason that anthropogenic activities in the Eure River watershed were investigated, for the first time, using sediment cores collected from two ponds near the outlet.

As recently raised by [START_REF] Bábek | Reservoir deltas and their role in pollutant distribution in valley-type dam reservoirs: Les Království Dam, Elbe River, Czech Republic[END_REF], the spatial distribution of sediments in the depositional zones (behind a dam in the case of this study) and thus the spatial distribution of sediment-associated contaminants, is rarely studied. In addition, it is generally accepted that the studied sediment core is representative of the watershed signals, but without the absolute certainty that a local disruption could have disturbed the global recorded signal. Hence, it is difficult to know if the studied sediment core is representative of (i) the whole depositional zones and, (ii) the global signature of the inputs from the whole watershed. To circumvent this uncertainty, sediment cores were collected in our study in two ponds in order to ensure that the recorded sedimentological and geochemical signatures are not disturbed by local inputs and can be considered as representative of the whole watershed. In addition, and for each ponds, the representativeness of the sediment cores was investigated with ground-penetrating radar profiles. Our study also proposes an original coupling between sedimentological and geochemical analyses to assess the deposition conditions and the nature of the sediment deposits as they can influence the temporal trends of trace metal elements TME [START_REF] Dhivert | Influences of major flood sediment inputs on sedimentary and geochemical signals archived in a reservoir core (Upper Loire Basin, France)[END_REF]. Lastly, the morphological changes modifying the depositional conditions have been studied by using historical documentaries as seen in previous studies [START_REF] Pittam | An integrated lake-catchment approach for determining sediment source changes at Aqualate Mere, Central England[END_REF][START_REF] Grygar | Using sedimentary archives to reconstruct pollution history and sediment provenance: the Ohře River, Czech Republic[END_REF].

Hence, combining a comprehensive set of geophysical, sedimentological, geochemical methods and, historical documentaries, our main objectives were to (i) determine the consequences of the morphological modifications of depositional zones during the diversion of the Eure River outlet on the sedimentary dynamic, (ii) determine the nature of these legacy sediment deposits and (iii) reconstruct the temporal trends of anthropogenic activities with a focus on TME considered as markers of industrial activities in the Eure River watershed. This study also discussed the reactivity of the watershed to anthropogenic activities, and the resilience of the system to overcome these stresses.

Material and Methods

Setting

The Seine River flows into the Paris Basin. Sedimentary formations (Jurassic limestone and marls, Cretaceous chalk, carbonaceous alluvial, and Tertiary quartz deposits) cover most of the basin, with carbonate formations dominating [START_REF] Thibert | Exportations naturelles et anthropiques des ions majeurs et des éléments nutritifs dans le bassin de la Seine : approches méthodologiques[END_REF]. The Eure River watershed (Figure 1B) is underlain by a chalk formation from the Upper Cretaceous, covered by sandyclay deposits from the Tertiary and Quaternary deposits [START_REF] Quesnel | Digital mapping in regolith geology[END_REF][START_REF] Laignel | Variabilité du cortège argileux des formations résiduelles à silex de l'Ouest du bassin de Paris[END_REF].

The Eure River is the fourth largest tributary of the Seine Basin in terms of area (6 017 km²), and the fifth in terms of flow at the outlet (Qmean = 22.1 ± 6.7 m 3 s -1 ) for the period from 1971 to 2019 (www.hydro.eaufrance.fr).

Until the end of the nineteenth century, there were numerous islands spread through the channel of the Seine Estuary. At that time, the Eure River outlet was more than 11 km upstream of the present outlet (Figure 2A). Therefore, the studied coring sites at Martot and Les Damps did not exist (see section 2.2) and were in the left branch of the Seine Estuary, which was a dynamic riverine environment, unfavourable to sediment deposition.

Between 1861 and 1864, the Martot Dam (needle dam), the first of its scale in the Seine Estuary, was built in two parts (169.6 m + 135.0 m) across two branches of the Seine River (Figure 2B). During the 1880s, the Poses Dam was constructed further upstream (Figure 1A). These two dams were built in a section of the Seine Estuary where navigation was made difficult by the presence of the islands and natural weirs. The first major modification that impacted the Eure River dates back to the 1930s (1929)(1930)(1931)(1932)(1933)(1934)(1935), when the Eure River outlet was moved 2 km downstream by following a former part of the left branch of the Seine River (Figure 2C). This morphological modification formed a pond connected to the Eure River (Les Damps Pond). The entire section was completely disrupted during the 1930s, and the channel of the Seine River was deeply restructured. During this period, the channel morphology of the Seine River was modified, in some cases by passing through former islands or by filling connections between the many islands present in its channel. Between 1937 and 1939, the Eure River outlet was moved 9 km downstream by following the former branch of the Seine River and was relocated at the Martot Dam. At the same time, a dike was built in the middle of the Martot Dam in the direction of the flow to isolate a pond (Martot Pond). In 1939, the connection between Martot Pond and the Seine River was filled to calibrate the Seine River channel while a connection between Martot Pond and the Eure River was opened thereafter. The Martot Dam became obsolete when the connections between the islands were filled and was partially removed between 1938 and 1941, leaving only the part across the branch of the Eure River (Figure 2D).

The area did not experience further evolution until 2017 when the Martot Dam was removed following the Water Framework Directive (2000/60/CE), to facilitate the continuity of sediment transport.

Sampling sites

Upstream site: Les Damps Pond

Les Damps Pond (formed between 1929-1935) is upstream of the Eure River spillway (Figure 3A). The pond, which has an average depth of 50 cm and an area of less than 1 ha, is connected to the Eure River, even during low water periods, and continually accumulates suspended particulate matter (SPM) from the Eure River watershed (Figure 3B). Because the site is 2 km upstream of a spillway, the tides have no noticeable effect, even in the case of a high tidal coefficient.

The cores were extracted from this pond in January 2015 and 2017, using a gravity corer (UWITEC) and PVC tubes with a diameter of 90 mm. The water-sediment interface was preserved during coring (Table 1).

Downstream site: Martot Pond

Cores were also extracted from Martot Pond (area ~ 7 ha), in the lower reaches of the study area (Figure 3A). Martot Pond is affected by the waters of the Seine River during tidal flows through the Eure River outlet. However, the impact of the tide is limited and temporally variable, as its flow persists for about 3 h and does not occur every day, because the dam, located 200 m downstream from the connection with this pond, stops tidal flows for tidal coefficients lower than 70 (until the removal of the dam in 2017) (Figure 3C). Thus, to ensure Martot Pond was not impacted by the Seine River flow, results from this core site were compared with those from Les Damps Pond. The Martot Dam also regulated the water level in the river and the latter was continuously connected to the Martot Pond, even during periods of low flow.

The cores were extracted from this pond in January and May 2015 and February 2017, using a gravity corer (UWITEC) and PVC tubes with a diameter of 90 mm. The water-sediment interface was preserved during coring (Table 1).

Geophysical investigation: GPR

Ground penetrating radar (GPR) is a non-invasive geophysical technique that detects electrical discontinuities. It is based on the generation, transmission, propagation, reflection, and reception of discrete pulses of high frequency electromagnetic energy (MHz). For several years, it has been particularly used in the study of sedimentary structures and deposition environments in fluvial environments [START_REF] Horowitz | Ground-probing radar as a tool for heterogeneity estimation in gravel deposits: advances in data-processing and facies analysis[END_REF][START_REF] Asprion | Towards realistic aquifer models: three-dimensional georadar surveys of Quaternary gravel deltas (Singen Basin, SW Germany)[END_REF][START_REF] Beres | Using two-and threedimensional georadar methods to characterize glaciofluvial architecture[END_REF][START_REF] Bristow | An introduction to ground penetrating radar (GPR) in sediments[END_REF][START_REF] Neal | Ground-penetrating radar and its use in sedimentology: principles, problems and progress[END_REF][START_REF] Kostic | 3-D sedimentary architecture of a Quaternary gravel delta (SW-Germany): Implications for hydrostratigraphy[END_REF][START_REF] Huggenberger | A Sedimentological Model to Characterize Braided River Deposits for Hydrogeological Applications[END_REF][START_REF] Bábek | Contamination history of suspended river sediments accumulated in oxbow lakes over the last 25 years[END_REF][START_REF] Słowik | Is history of rivers important in restoration projects? The example of human impact on a lowland river valley (the Obra River, Poland). Geomorphology, Emerging geomorphic approaches to guide river management practices[END_REF][START_REF] Gu | Analysis of dynamic sedimentary environments in alluvial fans of some tributaries of the upper Yellow River of China based on ground penetrating radar (GPR) and sediment cores[END_REF]. In this study, the surveys were carried out in an aquatic environment (Water GPR-WGPR) because it is possible to tow the antennas of the geological radar in or behind a boat [START_REF] Mellett | Profiling of ponds and bogs using ground-penetrating radar[END_REF][START_REF] Lin | A combined acoustic and electromagnetic wave-based techniques for bathymetry and subbottom profiling in shallow waters[END_REF][START_REF] Sebok | Using hydrogeophysical methods to assess the feasibility of lake bank filtration[END_REF]. The GSSI SIR 4000 acquisition system (Geophysical Survey System Inc., Salem, USA) was connected to a Trimble GPS with a 400 MHz antenna. The instrumentation was loaded on a high density polyethylene boat. A total of five longitudinal profiles was acquired closest to the sampled cores, at both of the two sites (Figures 3B & 3C). The data were processed with Radan 7 software (GSSI copyright) to obtain interpretable radargrams. A velocity of 0.075 m ns -1 was determined using the hyperbola method and the correlation with sediment cores. This is of the same order of magnitude as the measurements made by [START_REF] Lin | A combined acoustic and electromagnetic wave-based techniques for bathymetry and subbottom profiling in shallow waters[END_REF] (0.076 m ns -1 ) and O'Driscoll et al. (2010) (0.06 m ns -1 ) on comparable sediments.

Sedimentological analysis

Grain size distribution

The grain size distribution can influence the behaviour of chemical compounds. Radioactive tracers ( 210 Pb, 137 Cs, and 241 Am) are preferentially adsorbed onto fine particles [START_REF] Livens | Particle size and radionuclide levels in some west Cumbrian soils[END_REF][START_REF] Walling | Use of radiometric fingerprints to derive information on suspended sediment sources[END_REF][START_REF] Wang | Distribution coefficients of210Pb and210Po in laboratory and natural aquatic systems[END_REF][START_REF] He | Interpreting particle size effects in the adsorption of 137Cs and unsupported 210Pb by mineral soils and sediments[END_REF][START_REF] Monna | Sedimentation rate in the Thau basin (France) according to geochronological, geochemical and stratigraphical data[END_REF][START_REF] Gil-García | New best estimates for radionuclide solid-liquid distribution coefficients in soils, Part 1: radiostrontium and radiocaesium[END_REF] as well as organic and metallic contaminants [START_REF] Horowitz | The relation of stream sediment surface area, grain size and composition to trace element chemistry[END_REF][START_REF] Walling | Storage of sediment-associated nutrients and contaminants in river channel and floodplain systems[END_REF][START_REF] Grosbois | The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)[END_REF][START_REF] Devault | Herbicide accumulation and evolution in reservoir sediments[END_REF][START_REF] Coynel | Spatial distribution of trace elements in the surface sediments of a major European estuary (Loire Estuary, France): Source identification and evaluation of anthropogenic contribution[END_REF]. Thus, the grain size distribution can have a considerable impact on radioactive tracers and TME concentrations along sediment cores [START_REF] He | Interpreting particle size effects in the adsorption of 137Cs and unsupported 210Pb by mineral soils and sediments[END_REF].

Differences in grain size are also excellent indicators of flood events or anthropogenic activities (e.g. changes in land use) [START_REF] Kurashige | Source identification of suspended sediment from grainsize distributions: I. Application of nonparametric statistical tests[END_REF][START_REF] Weltje | Quantitative models of sediment generation and provenance: State of the art and future developments[END_REF][START_REF] Toonen | Lower Rhine historical flood magnitudes of the last 450years reproduced from grain-size measurements of flood deposits using End Member Modelling[END_REF][START_REF] Collins | Sediment source fingerprinting as an aid to catchment management: A review of the current state of knowledge and a methodological decision-tree for end-users[END_REF].

The grain size distribution of the sediment cores was measured by laser diffraction (LS 13320 Particle Size Analyser Beckman Coulter™). The measurements were realised every cm by integrating 1 cm on the DAM15-02 and MAR15-01 cores.

Total organic carbon content

The total organic carbon (TOC) and organic matter (OM) quality can also influence TME concentrations [START_REF] Audry | Early diagenesis of trace metals (Cd, Cu, Co, Ni, U, Mo, and V) in the freshwater reaches of a macrotidal estuary[END_REF][START_REF] Tseng | Speciation of Mercury in a Fluid Mud Profile of a Highly Turbid Macrotidal Estuary (Gironde, France)[END_REF][START_REF] Masson | Copper addition by organic matter degradation in the freshwater reaches of a turbid estuary[END_REF][START_REF] Petit | Anthropogenic sources and biogeochemical reactivity of particulate and dissolved Cu isotopes in the turbidity gradient of the Garonne River (France)[END_REF][START_REF] Coynel | Spatial distribution of trace elements in the surface sediments of a major European estuary (Loire Estuary, France): Source identification and evaluation of anthropogenic contribution[END_REF]. Moreover, variations in TOC and related parameters (e.g. HI and OI) provide information on the hydrological dynamics and anthropogenic impact in a watershed.

The TOC content was measured using Rock-Eval 6 (RE6) pyrolysis ("Turbo" model RE6 pyrolyzer, at the ISTO laboratory, University of Orléans), as described in [START_REF] Copard | Using Rock-Eval 6 pyrolysis for tracking fossil organic carbon in modern environments: implications for the roles of erosion and weathering[END_REF]. The OM quality was obtained from measuring HI (hydrogen index, in mg HC g -1 TOC) and OI (oxygen index, in mg O2 g -1 TOC). HI corresponds to the quantity of HC released relative to TOC, while OI reflects the quantity of oxygen released as CO and CO2 relative to TOC. Used together, these two parameters in the pseudo Van-Krevelen diagram (HI vs OI) can support the identification of the OM origin and its subsequent processes [START_REF] Tissot | Petroleum Formation and Occurrence[END_REF]. These variables were measured on the DAM17-02 (at intervals of 2 cm) and MAR15-01 cores (at intervals of 1 cm).

Magnetic susceptibility

The magnetic properties of accumulated stored sediments are generally used to identify detrital inputs (e.g. from floods) [START_REF] Debret | North western Alps Holocene paleohydrology recorded by flooding activity in Lake Le Bourget, France[END_REF] and anthropogenic modifications (e.g. metallic pollution in soils and sediments) [START_REF] Hanesch | Mapping of heavy metal loadings in soils by means of magnetic susceptibility measurements[END_REF][START_REF] Knab | Surveying the anthropogenic impact of the Moldau river sediments and nearby soils using magnetic susceptibility[END_REF][START_REF] Magiera | Discrimination of lithogenic and anthropogenic influences on topsoil magnetic susceptibility in Central Europe[END_REF][START_REF] Blaha | Determination of anthropogenic boundary depth in industrially polluted soil and semi-quantification of heavy metal loads using magnetic susceptibility[END_REF]. The magnetic properties of the sediment can also be used to determine the origin of the particles [START_REF] Caitcheon | The significance of various sediment magnetic mineral fractions for tracing sediment sources in Killimicat Creek[END_REF]Hatfield andMaher, 2008, 2009;[START_REF] Hatfield | Magnetic Proxies and Susceptibility[END_REF][START_REF] Collins | Sediment source fingerprinting as an aid to catchment management: A review of the current state of knowledge and a methodological decision-tree for end-users[END_REF].

The magnetic susceptibility (MS) of the cored sediments was measured using a Bartington MS2E point sensor as described in [START_REF] Debret | North western Alps Holocene paleohydrology recorded by flooding activity in Lake Le Bourget, France[END_REF]. The MS of the sediment from the DAM15-02, DAM15-03, DAM17-02, MAR15-01, and MAR15-05 cores was determined.

Spectrocolorimetry

Various parameters that can be determined using a spectrocolorimeter, such as reflectance (L*) and the first derivative reflectance spectra (FDS), may be used to determine the nature and the origin of sediment deposits, and sediment dynamics [START_REF] Debret | Spectrophotometer analysis of Holocene sediments from an anoxic fjord: Saanich Inlet, British Columbia, Canada[END_REF][START_REF] Debret | Spectrocolorimetric interpretation of sedimentary dynamics: The new "Q7/4 diagram[END_REF][START_REF] Sebag | Coupled Rock-Eval pyrolysis and spectrophotometry for lacustrine sedimentary dynamics: Application for West Central African rainforests (Kamalété and Nguène lakes, Gabon)[END_REF]. L* describes the lightness of the sediment without any information on the nature of the sediment. FDS provides qualitative information about the major components (such as clay and carbonates) of the sediment deposits. The Q7/4 diagram (700 nm/400 nm ratio vs L*) proposed by [START_REF] Debret | Spectrocolorimetric interpretation of sedimentary dynamics: The new "Q7/4 diagram[END_REF] is used to determine the sedimentary dynamics.

A Konica Minolta CM 2600d was used to measure the intensity of the reflectance of the sediment in the visible domain (360-740 nm with a spacing of 10 nm) as described in [START_REF] Debret | Spectrocolorimetric interpretation of sedimentary dynamics: The new "Q7/4 diagram[END_REF].

These measurements were obtained for the DAM15-02, DAM15-03, DAM17-02, MAR15-01, MAR15-02, MAR15-03, MAR15-04, MAR15-05, and MAR16-02 cores.

Geochemical analysis by XRF core scanning (XRF-CS)

X-Ray fluorescence spectrometry (XRF) is used to determine the major and trace element composition of sediment deposits [START_REF] Richter | The Avaatech XRF Core Scanner: technical description and applications to NE Atlantic sediments[END_REF]. The XRF core scanning data can be used to describe particular TME contamination in sediment cores [START_REF] Battiston | Determination of sediment composition and chronology as a tool for environmental impact investigations[END_REF][START_REF] Dickinson | Heavy metal history from cores in Wellington Harbour, New Zealand[END_REF][START_REF] Lepland | Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway[END_REF][START_REF] Sabatier | Longterm relationships among pesticide applications, mobility, and soil erosion in a vineyard watershed[END_REF][START_REF] Guédron | A hundred year record of industrial and urban development in French Alps combining Hg accumulation rates and isotope composition in sediment archives from Lake Luitel[END_REF][START_REF] Hennekam | Trace metal analysis of sediment cores using a novel X-ray fluorescence core scanning method[END_REF]. The data presented were normalised by Ti (considered as a better "normalising element" than Al) to remove possible variations because of detrital inputs [START_REF] Kylander | High-resolution X-ray fluorescence core scanning analysis of Les Echets (France) sedimentary sequence: new insights from chemical proxies[END_REF][START_REF] Duan | Contamination trends of trace metals and coupling with algal productivity in sediment cores in Pearl River Delta, South China[END_REF][START_REF] Bábek | Geochemical background in polluted river sediments: How to separate the effects of sediment provenance and grain size with statistical rigour?[END_REF][START_REF] Chawchai | Testing commonly used X-ray fluorescence core scanning-based proxies for organic-rich lake sediments and peat[END_REF].

The relative contents of the major and trace elements were measured using an XRF Avaatech core scanner (EDYTEM, University of Savoie Mont Blanc). An X-Ray beam was generated with a rhodium anode and a 125 μm beryllium window, which allows a voltage range from 7 to 50 kV and a current range of 0 to 2 mA. The analytical settings were adjusted at 10 kV and 1 mA to detect light elements, and trace elements (namely Pb, Cu, Zn, and Ni) were detected in a second run, performed at 30 kV for 0.75 mA. Each individual power spectrum was transformed by deconvolution into its relative contents (intensities), expressed in counts per second (cps). Measurements were realised every 5 mm for the MAR15-01 and DAM17-02 cores and every 2 mm for the MAR16-02 and DAM15-02 cores.

TME analysis

Microwave-assisted sediment digestion for particulate trace metal analysis (Pb, Zn, Cu, presented in this study) was performed on samples collected in the MAR16-02 core (0.5 g of dry, powdered and homogenised sediment) with aqua regia (HNO3: 3 mL TraceMetal TM Grade; HCl: 9 mL TraceMetal TM Grade). Following the mineralisation, the solutions were diluted in 100 ml of Milli-Q ® water. Particulate trace metal concentrations were measured by inductively-coupled-plasma atomic emission spectroscopy (ICP-AES) (iCAP 6000 Series, Thermo Fischer ® ) performed with external calibration. The accuracy and precision of the measurements were checked against a certified reference material (Trace Element on Fresh Water Sediment CNS301-04-050, Sigma Aldrich) and the results showed accuracies of ≥ 98 % with a precision of ≤ 4 % (RSD). All of the analyses were carried out in triplicate (standard deviation ≤ 1.1 %).

Short-lived radionuclides

The activities of 210 Pb in excess ( 210 Pbex), 137 Cs, and 241 Am were determined on samples from the MAR15-01 core (at steps of 1, 4, or 6 cm) using a germanium spectrometer with ultra-low background noise at the Laboratoire Souterrain de Modane (LSM). The age model was computed with the serac R package (https://github.com/rosalieb/serac, (Bruel and Sabatier, Submitted).

Results

Sedimentological characterisation of the sediment cores

Les Damps Pond

The sediment cores all showed similar sedimentary facies called U1 (Figures 4A1 &4A2).

The grain size distribution was homogeneous (median (D50) = 29.5 ± 6.7 μm) and showed only one population, centred around the D50. (Figure 4B). The TOC content was high and constant (TOCmean = 5.36 ± 0.47 %). HI and OI were also constant, and the values of HI were higher than those of OI (HImean = 302 ± 23 mg HC g -1 TOC and OImean = 145 ± 10 mg O2 g -1 TOC) (Figure 4C).

The MS values were high and constant between 60 and 90 cm (MSmean = 12 ± 2) but had a peak at 50-60 cm. The values decreased between 50 and 30 cm and were constant above 30 cm (MSmean = 6 ± 1) (Figure 4D).

The values of L* were low and constant (L*mean = 28.5 ± 2.3 %), with values between 22 and 38 % (Figure 4D).

The intensities of FDS were high at wavelengths between 675 and 735 nm. This signature was continuous, and the intensity did not vary, which may mean that the origin of the sedimentary inputs remained the same throughout the sedimentation (Figure 4E).

The Pb/Ti ratio was low and constant (Pb/Timean = 0.64 ± 0.12) between 30 and 80 cm but increased at 30 cm. The values of the ratio were generally high between 0 and 30 cm (Pb/Timean = 2.26 ± 0.58) and decreased from 15 cm to the surface (Figure 4F). The Zn/Ti, Cu/Ti, and Ni/Ti ratios showed the same trend. These three ratios were high between 30 and 80 cm and reached maximum values between 50 and 60 cm (Zn/Timean = 2.04 ± 0.24, Cu/Timean = 1.43 ± 0.71, and Ni/Timean = 0.04 ± 0.01). Around 30 cm, the ratios decreased and were constant between 0 and 30 cm (Figure 4F).

Martot Pond

The sediment cores showed two sedimentary facies delimited by a transition zone at 75-80 cm. In this section, the results from the MAR15-01 core are presented. The upper facies (0-75 cm) is referred to as U1, while the lower facies (75-138 cm) is referred to as U2 (Figure 5A).

• U2 facies:

The grain size distribution was homogeneous (median (D50) = 13.8 ± 7.0 μm) and showed one population centred around D50 (Figure 5B). The TOC content was low and constant (TOCmean = 1.75 ± 0.33 %). HI was constant (HImean = 147 ± 24 mg HC g -1 TOC) and lower than OI (OImean = 260 ± 35 mg O2 g -1 TOC). OI increased, peaked at 103.5 cm (OI = 347 mg O2 g -1 TOC), then decreased. The only exception to this trend was at the depth of 128.5 cm (Figure 5C).

The MS was low and L* was high and constant (L*mean = 44.4 ± 2.1 %), with values between 40 and 50 % (Figure 5D).

The intensities of FDS were high for wavelengths between 365 and 550 nm. A second signature, less intense, was also visible for high wavelengths (675-735 nm). This indicates that several signatures were marked within the facies and the small variations in intensity suggest the origin of the whole U2 facies was unique (Figure 4E).

The Pb/Ti, Zn/Ti, Cu/Ti, and Ni/Ti ratios were low and constant (Pb/Timean = 0.33 ± 0.10, Zn/Timean = 0.54 ± 0.11, Cu/Timean = 0.18 ± 0.05, and Ni/Timean = 0.04 ± 0.01) and were higher only at the transition between the two facies in the 75-80 cm depth interval (Figure 5F).

• U1 facies:

The grain size distribution was homogeneous (median (D50) = 33.9 ± 7.8 μm) and had one population centred around D50 (Figure 5B) as in Les Damps Pond. The TOC content was twice as high in U1 (TOCmean = 3.88 ± 1.49 %) as in U2, and the values were particularly high near the top of the core (TOC = 8.26 ± 0.19 % between 9 and 12 cm). HI increased upwards from the transition between U1 and U2 and stabilised at a depth of 66.5 cm. OI continued to decrease in U1 and stabilised at a depth of 66.5 cm in U1. At the opposite end of the U2 facies, HI was high (HImean = 279 ± 23 mg HC g -1 TOC) and OI was low (OImean = 150 ± 17 mg O2 g -1 TOC) (Figure 5C) as described along the U1 facies in Les Damps Pond.

The U1/U2 transition was marked by a strong increase in MS and a decrease in L*. The MS values were high (MSmean = 25 ± 7) from 45 to 75 cm but were lower (MSmean = 8 ± 4) between 0 and 45 cm (Figure 5D). The L* was lower in the U1 facies (L*mean. = 34.1 ± 4.2 %) than in the U2 facies, and was almost the same as the values between 24 and 40, and decreased next to the top of the core (Figure 5D). The sediment colour was similar to that in the U1 facies in Les Damps Pond.

The intensities of FDS were high at high wavelengths (675-735 nm), but, unlike the U2 facies, low wavelength signatures were not noticeable. This indicates a major change in the nature of the sediment stored in Martot Pond (Figure 5E). Moreover, the signature was continuous and the intensity did not vary as in Les Damps Pond.

The Pb/Ti ratio increased at the U1/U2 transition but remained stable to a depth of 35 cm (Pb/Timean = 1.06 ± 0.15 between 35 and 75 cm). The ratio was higher from 35 to 10 cm (Pb/Timean = 3.17 ± 0.53 between 10 and 35 cm) and trended to decrease closer to the top of the core (Figure 5F). The patterns in the Zn/Ti, Cu/Ti, and Ni/Ti ratios were similar. Indeed, from the transition between U1 and U2, the ratios increased and peaked between 50 and 60 cm (Zn/Timean = 4.79 ± 0.73, Cu/Timean = 1.19 ± 0.20, and Ni/Timean = 0.11 ± 0.01). The ratios decreased from 50 to 35 cm and then stabilised above 35 cm (Figure 5F). The variations in the Pb/Ti, Zn/Ti, Cu/Ti, and Ni/Ti ratios generally followed a similar pattern to those described for Les Damps Pond.

TME concentrations along the U1 facies in Martot Pond

The trends in the Pb/Ti, Zn/Ti, and Cu/Ti ratios for the top 77 cm of the MAR16-02 core and the U1 facies of the MAR15-01 core were similar, which shows that this facies was also well represented within MAR16-02. The Pb, Zn, and Cu concentrations were measured at the depths for which the XRF ratios reached maximum and minimum values within the MAR16-02 core (Figure 6).

The Pb concentration was constant to a depth of 35 cm (Pbmean = 120 ± 28 mg kg -1 ), apart from at 65 cm (Pb = 190 mg kg -1 ). The Pb concentrations increased in the same way as the Pb/Ti ratio, and the concentrations were highest at 12 cm (Pb = 669 mg kg -1 ). Near the top of the core (4 cm), the Pb concentration decreased, similar to the Pb/Ti ratio, and at 299 mg kg -1 it was less than half the maximum concentration at 12 cm but almost 2.5 times the average concentration below 35 cm (Figure 6). The Zn and Cu concentrations were 415 mg kg -1 and 113 mg kg -1 at 77 cm, respectively. The concentrations of these two TMEs peaked at 65 cm (Zn = 905 mg kg -1 , Cu = 399 mg kg -1 ). Between 10 and 40 cm, the Zn and Cu concentrations were less than half and less than a quarter of the maximum concentrations, respectively, and the Zn/Ti and Cu/Ti ratios were also low close to the top of the MAR16-02 core (Figure 6).

The Zn and Cu concentrations at 4 cm were lower than those measured at 77 cm.

Age model of the MAR15-01 core

Recent deposit dating and sedimentation rate estimates have been realised from short-life radionuclides [START_REF] Robbins | Determination of recent sedimentation rates in Lake Michigan using Pb-210 and Cs-137[END_REF][START_REF] Appleby | The calculation of lead-210 dates assuming a constant rate of supply of unsupported 210Pb to the sediment[END_REF][START_REF] Appleby | 241Am dating of lake sediments[END_REF][START_REF] He | Interpreting particle size effects in the adsorption of 137Cs and unsupported 210Pb by mineral soils and sediments[END_REF][START_REF] Mabit | Fallout 210Pb as a soil and sediment tracer in catchment sediment budget investigations: A review[END_REF]. The sedimentation rate was determined from the 210 Pbex by subtracting the 226 Ra activity from the 210 Pbtotal [START_REF] Krishnaswamy | Geochronology of lake sediments[END_REF].

The 137 Cs and 241 Am activities were used to identify nuclear weapon testing with maximum activity in 1963, and the Chernobyl accident in 1986 and are used to confirm the age model established with 10 Pbex.

The activity of 210 Pbex was measured to 80 cm and decreased almost continuously with depth. A sedimentation rate of 12.73 mm y -1 (R² = 0.60) was estimated using the 'constant flux, constant sedimentation rate' (CFCS) model [START_REF] Krishnaswamy | Geochronology of lake sediments[END_REF]) (Figure 7A).

The 137 Cs and 241 Am activities peaked at 60 and 58 cm, respectively, corresponding to the maximum fallout from atmospheric nuclear weapon testing in 1963 [START_REF] Robbins | Determination of recent sedimentation rates in Lake Michigan using Pb-210 and Cs-137[END_REF][START_REF] Appleby | 241Am dating of lake sediments[END_REF] (Figure 7B). There was also a peak in the 137 Cs activity at 40 cm, perhaps related to the Chernobyl accident in 1986 (Figure 7B). An age model was realised for the U1 facies of the MAR15-01 core using the sedimentation rate obtained from the 10 Pbex (Figure 7C).

Discussion

Sedimentary filling in the depositional zones

As the sedimentological parameters are presented for one core from Martot Pond (two cores in the case of Les Damps Pond), it is essential to ensure that the studied cores are representative of sediment records in the entire respective pond. Concerning Martot Pond, a sediment thickness between 2.0-2.5 m is showed by the radargram GPR_MAR_08 (Figure 8A). The reflector R1 made it possible to distinguish two islands without a well-differentiated structure on this scale, which may correspond to parts of the central island that separated the two branches of the Seine River (Figure 2). A second reflector (R2, solid red line) between 350 m and 550 m separates U1 and U2 and this interpretation is justified by the MAR15-02 core in which this limit is observed at 85 cm (corresponding to the transition between U1 and U2 observed on MAR15-01 core at 75-80 cm). Beyond this section, it is more difficult to locate R2, but the position of the MAR15-03, MAR15-04 and MAR15-06 cores, with the aid of some clues, allowed us to position R2 (red dotted line). Geophysical prospecting shows a homogeneous filling within Martot Pond and thus validates the representativeness of the studied core.

Concerning Les Damps Pond, two quality profiles have been obtained (Figures 8B &8C) in which a reflector (R3) showed the lower limit of U1. In this facies, few continuous structures were detectable, probably because of the fine accumulated sediments and the monotony of the sediment as observed in the DAM15-02 and DAM17-02 cores. However, under R3, it was possible to distinguish less powerful reflectors, probably attributed to the presence of a bed of coarser material (Figure 8B). This reflector was therefore interpreted as the upper limit of the former stream-bed of the Seine River. Hence, the two studied sediment cores are representative of the sedimentary records of the entire pond.

Identification of the deposition conditions and sediment origin

The grain size in the U2 facies (D50 = 13.8 ± 7.0 μm) of Martot Pond and in the U1 facies of Martot and Les Damps Ponds (D50 ~ 30 μm) suggests a weak sedimentation dynamic, that is, deposition under very low flow conditions, but also suggests two distinct unidentified origins. U2 was also characterised by an HI/OI ratio <1 (Figure 9A), reflecting the input of material from a terrestrial origin [START_REF] Carrie | Standardisation of Rock-Eval pyrolysis for the analysis of recent sediments and soils[END_REF]. In detail, the values of these two indicators of OM quality reflect an organo-mineral soil horizons origin (A horizon) [START_REF] Disnar | Soil organic matter (SOM) characterization by Rock-Eval pyrolysis: scope and limitations[END_REF].

Conversely, the U1 facies of both ponds are characterised by an HI/OI ratio of approximately 2 (Figure 9A), suggesting that the OM origin is either aquatic [START_REF] Carrie | Standardisation of Rock-Eval pyrolysis for the analysis of recent sediments and soils[END_REF] or, with respect to the HI and OI values, detrital (OH or A horizons) [START_REF] Disnar | Soil organic matter (SOM) characterization by Rock-Eval pyrolysis: scope and limitations[END_REF]. Therefore, OM in the U1 facies is less altered and may have a mix aquatic/terrestrial origin, than that stored in the U2 facies. Spectrocolorimetry data for U2 showed a sedimentary dynamic mainly structured around two end-members which are poles "clayey deposits" and "carbonate deposits" (Figure 9B).

The clayey deposits pole reflects the input of detrital clay sediments while the carbonate deposits pole reflects the input of light sediments because of their carbonate contents. These results were confirmed by FDS and show a predominance of the carbonate signature [START_REF] Debret | Spectrocolorimetric interpretation of sedimentary dynamics: The new "Q7/4 diagram[END_REF]. The U2 facies is therefore the consequence of the sedimentation of a claycarbonate material, with an organic component that had a terrestrial origin. This terrigeneous deposit, which accumulated in a low intensity zone, may be derived from the erosion of the carbonate substratum of the Seine River watershed.

In terms of the U1 facies of both ponds, there was sedimentation consisting of fine sediments enriched in OM. Indeed, the U1 facies is close to the poles of "clayey deposits" and "organic-rich sediment (Chlorophyll-a and by-products)" (Figure 9B). This organic pole, also confirmed by the FDS [START_REF] Debret | Spectrocolorimetric interpretation of sedimentary dynamics: The new "Q7/4 diagram[END_REF], could be explained by high aquatic primary production and also by a less degraded soil OM. Such mixing is also verified by the pseudo Van-Krevelen diagram.

The similar trend of the U1 facies from the two ponds, and the absence of a clear depth distribution in the pseudo Van-Krevelen and Q7/4 diagrams (Figure 9), suggest that (i) SPM are not altered by any processes between the ~10 km separating the two ponds and, (ii) sediment deposits were not submitted to post-depositional alterations (e.g., early diagenesis), probably due to a high sedimentation rate [START_REF] Van Metre | Historical Trends in Organochlorine Compounds in River Basins Identified Using Sediment Cores from Reservoirs[END_REF][START_REF] Horowitz | The effect of mining on the sediment -trace element geochemistry of cores from the Cheyenne River arm of Lake Oahe, South Dakota[END_REF][START_REF] Callender | Transport and accumulation of radionuclides and stable elements in a Missouri River Reservoir[END_REF][START_REF] Callender | Geochemical effects of rapid sedimentation in aquatic systems: minimal diagenesis and the preservation of historical metal signatures[END_REF][START_REF] Audry | Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France)[END_REF]. Hence, there is a common origin of sediments from both U1 facies, corresponding to the inputs from the Eure River (U1 = Eure Unit) and consequently, intrusions of the Seine River into Martot Pond (during tidal flow) do not alter the Eure River signature. Therefore, the U1 facies from Martot Pond was considered as representative of the Eure River signal recorded in sediments, and so was used to build an age model. The U2 facies was deposited before this major change. The history of the study site shows that, before the Eure River oulet was diverted, the present Martot Pond corresponded to the area behind the Martot Dam, supplied by waters from the Seine River. The U2 facies corresponds to sedimentation of material from the Seine River watershed upstream of the dam. Moreover, the GPR prospecting showed that, in some places, the potential lower limit of this unit corresponded to parts of the island seperating the two branches of the Seine River.

The sediment stored in Martot Pond would be useful to study the Eure River basin from the early 1940s. However, the lack of dating means that, to date, the U2 facies (Seine Unit) has not been analysed in detail and will be the subject of a future prospsection.

Identification of an anthropogenic imprint in the Eure River facies

According to the correlation matrix, the major elements (Si, Fe, Al, and Ti) were strongly correlated with each other (0.69 < R < 0.87) (Figure S1). The input of these major elements represents the detrital inputs from the Eure River watershed. The trace elements (Zn, Cu, Ni, and Pb) were not correlated with major elements, demonstrating that their presence within the Eure Unit was not linked to the natural input of the Eure River watershed. In addition, Zn, Cu, and Ni were positively correlated with each other (0.79 < R < 0.88), indicating a common source in the watershed (Figure S1). The lack of correlation between TME and fine particles, as well as the homogeneity of the grain size distribution, indicates that the TME variations were related to anthropogenic contributions rather than lithological variations. This lack is also seen with the OM, because the variation in TOC vs TME is not correlated. Lastly, the sedimentation rate does not control the TME variations, as the latter was estimated as constant over the considered period.

As a consequence, the temporal variations in the semi-quantitative Zn, Cu, Ni, and Pb data were related to changes in the input of particulate TME. These variations may reflect the presence of new sources within the watershed, and may be related to anthropogenic activities that occurred during the second half of the twentieth century.

Reconstruction of Pb history

In large European watersheds, Pb levels generally exhibit similar temporal trends with increases from the 1940s until the 1970s, then decreases until the 1990s (Danube and Rhine Rivers : [START_REF] Winkels | Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta[END_REF]Loire River : Grosbois et al., 2006;Seine River : Le Cloarec et al., 2011;[START_REF] Ayrault | Lead contamination of the Seine River, France: Geochemical implications of a historical perspective[END_REF]Rhône River : Ferrand et al., 2012). Conversely, in the Eure River, Pb levels were stable during the 1960s, increased at the end of the 1980s, and reached a maximum in the 1990s and 2000s followed by a decrease after 2006 (Figure 10). The high Pb/Ti ratio values in Martot Pond in the 1990s and 2000s reflect the high Pb concentrations measured along the MAR16-02 core. This high concentration was also seen in SPM and dissolved load collected in the lower reaches of Eure River from March and September 2009 [START_REF] Chiffoleau | Etude de la signature isotopique des métaux dans l'estuaire de la Seine. Une information essentielle pour le traçage et la discrimination des sources et processus[END_REF]. In detail, the concentrations were 4-5 times (for particulate concentrations: Pbp = 430 and 380 mg kg -1 ; measured on SPM) and 5-10 times (for dissolved concentrations: Pbd = 1400 ng L -1 and 800 ng L -1 ) higher than those measured in the Seine River at Poses and during the same period. [START_REF] Chiffoleau | Etude de la signature isotopique des métaux dans l'estuaire de la Seine. Une information essentielle pour le traçage et la discrimination des sources et processus[END_REF] hypothesised that the high Pb levels were not related to atmospheric input but rather to a cathode-ray tube (CRT) factory containing 1 to 3 kg of Pb [START_REF] Tsydenova | Chemical hazards associated with treatment of waste electrical and electronic equipment[END_REF] in their leaded glass [START_REF] Singh | Solutions and challenges in recycling waste cathode-ray tubes[END_REF]. The CRT factory started operating at Dreux in 1956 and a second factory, specialising in the assembly of CRT TVs and the manufacture of electrical circuits, opened in 1974 in the same industrial site. The Pb content in the sediments showed little evidence of the successive commencement of these two factories (Figure 10). The industrial production increased from 1990 to the 2000s, when the factories were taken over by the Philips Group, increasing the Pb discharge from the site. To illustrate our statement, the European Environment Agency reported a direct release of 3540 kg of Pb into the water in 2001, exposing it as one of the highest European Pb emitters. Between 2002 and 2005, production decreased, as did Pb release (1900 to 1500 kg of Pb into the water in the years 2003 and 2004) ("IREP," n.d.). At the commencement of industrial growth, the Pb/Ti ratio began to increase, and reflecting the instantaneous reactivity of the watershed to this anthropogenic disturbance.

However, the fall in industrial output did not produce a decrease in the Pb/Ti ratio, which continued to rise into the late 2000s when the industrial sites were definitively closed (Figure 10). Again, this signifies that the watershed reacts to anthropogenic changes, however, the decrease in the ratio is slower than initially expected and remains high after the termination of industrial activity. As an example, near the top of the core, the Pb concentration is twice as high as than the average concentration estimated before 1990. As the levels of the Pb/Ti ratio and the Pb concentrations before industrial activity increased (1990s) may correspond to a reference level of Pb concentration in the Eure River, an additional Pb source is expected in the Eure River watershed. Without any other anthropogenic Pb emitters, it is reasonable to conjecture that this is likely related to Pb contaminated soil surrounding the factory and Pb contaminated sediments stored in the riverbanks and channel, which fed Pb into the river during erosion processes. Hence, the watershed was not able to react immediately to the cease of industrial activity, and a resilience period of the system could be identified [START_REF] Holling | Resilience and Stability of Ecological Systems[END_REF][START_REF] Folke | Resilience and Sustainable Development: Building Adaptive Capacity in a World of Transformations[END_REF]. In this case, and due to the erosion of contaminated soil and sediments further realising Pb into the environment, it will be take several years or decades for the river to reach the reference level in Pb concentration. The close relationship between this industrial activity and the observed temporal trends in Pb content suggests that this activity is the main source of contamination but does not allow to state that it is the only one.

Reconstruction of Zn, Cu, and Ni

First, the sharp increase in Zn, Cu, and Ni at the transition between the Seine and the Eure Units shows how the modification of the Seine River channel (for navigation) instantly impacted the quality of the sediments deposited in Martot Pond. The historical trends of Zn, Cu, and Ni, reported by several studies in large European rivers, such as the Danube, Rhine, Loire and Seine basins, show that the concentrations increased between 1940 and the 1970s, then decreased [START_REF] Winkels | Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta[END_REF][START_REF] Grosbois | The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)[END_REF][START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF]. Just as in these watersheds, the Zn, Cu, and Ni contents in the Eure River watershed were high until the 1980s and peaked during the 1960s and 1970s (Figure 10). The strong correlations between these elements suggest a single source to the Eure River, that started before the facies transition, with the Wonder battery factory the likely source. This factory near the Eure River (20 km upstream from Les Damps) manufactured saline batteries (from Zn) and supplied nearly 40 % of the national market in 1966. The history of this industrial activity indicates that in 1971, the factory was the subject of an increased administrative survey by a national agency, prompting reduced discharge into the Eure River (Agence Financière de Bassin "Seine-Normandie," 1971). This survey is recorded in the sedimentary archive and corresponds to the beginning of the decrease in Cu (Figure 10). Due to a global evolution of the industry (relocation, change in type of batteries), this industry declined in the late 1960s, which is reflected in the Zn, Cu, and Ni contents in the sediments. After the termination of industrial activity (1994), the Zn, Cu, and Ni content remains stable. Here, the watershed seemed to react instantly with the change in anthropogenic activity. Even if we had no historical and industrial arguments to state that this industrial site was the single source of TME in the river, we would suggest that it was the main one, which is supported by the close relationship between its activity and the observed trends in Zn, Cu, and Ni content in the studied core.

The stability of the ratios may indicate that TME release has ceased, but this has to be monitored as there is no record of the TME concentrations before the factory opened in 1938 [START_REF] Guermond | Louviers -Le Vaudreuil : l'impact spatial d'un pôle d'emploi comme moyen d'évaluation du changement social[END_REF]. Hence, it is therefore impossible to confirm whether the precontamination levels have been restored or whether contaminants are still being released, even at lower levels, as was the case for Pb.

Conclusion

The modification of the Seine River morphology since the nineteenth century has generated depositional zones in the lower Eure River. The transition between the Seine River and the Eure River units was the marker of one of the last main morphological changes undertaken in the Seine River Estuary.

A geophysical investigation of both ponds showed a homogeneous filling validating the representativeness of the studied sediment cores. Consequently, our results revealed a regional signature and are not linked to some local conditions.

The sedimentary dynamic during deposition and the nature of the sediment were determined to ensure that the TME evolution over time was related to anthropogenic activities.

The study of legacy sediments allowed the reconstruction of the industrial trajectory of the watershed since the 1940s. Our results suggested that the Eure River watershed was submitted to high human pressures that could have affected the Seine Estuary.

We have demonstrated that the watershed is very sensitive to any disturbance though a resilience period occurs that extends beyond the period of these disturbances, due to erosion of contaminated soil and sediment.

In the course of the Anthropocene, sedimentation zones containing contaminated sediments may be impacted by extreme events (e.g. floods) or modified by human activities (e.g. dam destruction, dredging, and channelisation), which may cause a resuspension of these sediments within rivers, constituting a new source of contamination. Such complex processes concern most worldwide rivers, and for the foreseeable future, it will become necessary to determine their own resilience periods. 2003 -1948 (2008-1952) Muids (M1) (Floodplain) 95 cm 2003-1934[START_REF] Bonté | Enregistrement sédimentaire de la contamination métallique, Piren-Seine[END_REF][START_REF] Meybeck | Historical perspective of heavy metals contamination (Cd, Cr, Cu, Hg, Pb, Zn) in the Seine River basin (France) following a DPSIR approach (1950-2005[END_REF][START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF][START_REF] Tamtam | A 50-year record of quinolone and sulphonamide antimicrobial agents in Seine River sediments[END_REF]Ayrault et al., 2010a, 2012[START_REF] Vrel | Dating of sediment record at two contrasting sites of the Seine River using radioactivity data and hydrological time series[END_REF][START_REF] Lorgeoux | Temporal trends of persistent organic pollutants in dated sediment cores: Chemical fingerprinting of the anthropogenic impacts in the Seine River basin[END_REF][START_REF] Vrel | Reconstitution de l'historique des apports en radionucléides et contaminants métalliques à l'estuaire fluvial de la Seine par l'analyse de leur enregistrement sédimentaire[END_REF][START_REF] Vrel | Dating of sediment record at two contrasting sites of the Seine River using radioactivity data and hydrological time series[END_REF][START_REF] Kaci | Distinct diversity of the czcA gene in two sedimentary horizons from a contaminated estuarine core[END_REF], 2016[START_REF] Bonté | Enregistrement sédimentaire de la contamination métallique, Piren-Seine[END_REF][START_REF] Meybeck | Historical perspective of heavy metals contamination (Cd, Cr, Cu, Hg, Pb, Zn) in the Seine River basin (France) following a DPSIR approach (1950-2005[END_REF]Le Cloarec et al., 2009, 2011Ayrault et al., 2010a, 2012[START_REF] Lorgeoux | Temporal trends of persistent organic pollutants in dated sediment cores: Chemical fingerprinting of the anthropogenic impacts in the Seine River basin[END_REF] This study A S e i n e R i v e r S e in e E st u a ry E u r e R iv e r Ayrault et al., 2010bAyrault et al., 2010b[START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF] Others notable sediment cores in the Seine River watershed -Seine River watershed (upstream) (located on the Figure 1B) Seine River at Troyes: TR 01 Le [START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF]Ayrault et al., 2010b, 2012 -Tributaries (located on the Figure 1B): Oise River at Chauny: S01 Le [START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF], Ayrault et al., 2010b, 2012S02 (2005-1954) (2002-1965[START_REF] Vrel | Reconstitution de l'historique des apports en radionucléides et contaminants métalliques à l'estuaire fluvial de la Seine par l'analyse de leur enregistrement sédimentaire[END_REF]PMV,B (1970[START_REF] Callender | Geochemical effects of rapid sedimentation in aquatic systems: minimal diagenesis and the preservation of historical metal signatures[END_REF], GMV,B (1950GMV,B ( -2000) ) C 1986C 1986C 1986C 1986C 1986C 1986C 1986C 1986Chernobyl 1986NWT 1963NWT 1963NWT 1963NWT 1963NWT 1963NWT 1963NWT 1963NWT 1963FF 1955FF 1955FF 1955FF 1955FF 1955FF 1955FF 1955FF 1955 First

4. 3 .

 3 Links with the morphological modification of the Seine and Eure Rivers According to the age model established for the MAR15-01 core, the transition between the U2 facies and the Eure Unit date from around 1954 ± 10 y. The history of the study site showed that Martot Pond was disconnected from the Seine River from 1939. The recently shaped connection between Martot Pond and the Eure River seems consistent with this change, or else dated from the early 1940s. The age model therefore seems consistent with the morphological modification, and the facies change was established at 1939-1944, when Martot Pond was isolated from the Seine River.

Figure 1 .

 1 Figure 1. A. Historic sediment core sites in the lower reaches of the Seine River watershed and sediment core sites in theEure River (present study). The length, time period represented and chemicals elements studied for each core sites are also mentioned; B. The Eure River watershed (present study). The Yonne and Oise rivers sub-watersheds studied inAyrault et al., 2010b and Le Cloarec et al., 2011 are also represented.

Figure 2 .

 2 Figure 2. Morphological modifications of Martot Pond and Les Damps Pond study sites established from several unpublished documents (e.g. maps from "Pont et Chaussées" and meeting minutes) stored at "Voie Navigable de France" (VNF). The cities of Martot, Pont-de-l'Arche et Les Damps have been indicated on the maps to facilitate comparison with the actual study area.

Figure 3 .

 3 Figure 3. A. Study Area; B. Sediment core and GPR profiles locations in Les Damps Pond; C. Sediment core and GPR profiles locations in Martot Pond.

Figure 4 .

 4 Figure 4. A1. Colour log; and B. Grain size distribution and D50; A2. Colour log; C. TOC, HI, and OI; D. Magnetic susceptibility (MS) and reflectance (L*); E. First derivative values; F. Pb/Ti, Zn/Ti, Cu/Ti, and Ni/Ti ratios along the DAM15-02 and DAM17-02 cores collected in Les Damps Pond.

Figure 5 .

 5 Figure 5. A. Colour log; B. Grain size distribution and D50; C. TOC, HI, and OI; D. Magnetic susceptibility (MS) and reflectance (L*); E. First derivative values; F. Pb/Ti, Zn/Ti, Cu/Ti and Ni/Ti ratios along MAR15-01 core collected in Martot Pond.

Figure 6 .

 6 Figure 6. Pb/Ti, Zn/Ti, and Cu/Ti ratios along the upper part of the MAR16-02 core. Pb (dark circle), Zn (dark square) and Cu (dark triangle) concentrations are also presented.

Figure 7 .

 7 Figure 7. A. 210 Pbex; B. 137 Cs and. 241 Am; C. Age model for the MAR15-01 core.

Figure 8 .

 8 Figure 8. Radargram performed with a 400 mHz antenna, migration rate used: 0.075 m ns -1 . Due to the lengths and depths reached and to obtain adequate readability, the x-scales of the 3 profiles are different. For reasons of navigability, all the core sampling points previously presented could not be documented by GPR, in particular the MAR15-01 and DAM15-02 cores A. GPR-MAR_08 radargram, processed and interpreted from Martot Pond. To obtain a 2D information, the MAR15-02, MAR15-03, MAR15-04, and MAR15-06 cores with a simple description distinguishing only the U1 and U2 facies, have been positioned; B. GPR_DAM_03 radargram processed and interpreted from Les Damps Pond. The DAM15-03 and DAM18-02 cores have been positioned; C. GRP_DAM_05 radargram, processed and interpreted from Les Damps Pond. The DAM17-02 core has been positioned.

Figure 9 .

 9 Figure 9. A. Pseudo Van-Krevelen diagram; B. Q7/4 vs L* ratio for the MAR15-01 core (U1 and U2 facies) and the DAM17-02 core.

Figure 10 .

 10 Figure 10. Evolution of Pb/Ti, Zn/Ti, Cu/Ti, and Ni/Ti ratios along the Eure Unit (MAR15-01 core).

Figure S11 .

 S11 Figure S11. Correlation matrix with XRF core scanning data (Al, Si, Fe, Ti, Mn, Zn, Cu, Ni, and Pb), TOC, and grain size (D50, clay (< 2 μm), silt (2-63 μm), and coarse fraction (> 63 μm)) from the Eure Unit of the MAR15-01 core (Pearson correlation, p-value < 0.001 for all the R < -0.6 and R > 0.6).

  [START_REF] Cloarec | Sedimentary record of metal contamination in the Seine River during the last century[END_REF], Yonne River at « Lac de Pannecière »: PAN4 (2008-1950) Ayrault et al., 2010b -Seine Estuary (cores not represented on the Figure): Mud at: VKVN01

  et al., 2012) 1990 Acquisition of the factories by Philips LG 2002 Beginning of the CRT TVs to LCD TVs assembly transition 2005 CRT TVs assembly is stopped (replaced by LCD TVs assembly)

Acknowledgements

This project (OSS 276) was financially supported by the Seine-Normandie Water Agency and the Region Normandie.

Authors thank "Voie Navigable de France" and the "Batellerie" Museum for the access to their historical maps and documents.


Corinne Dupont
email: corinne.dupont@chu-lyon.fr

Pauline Blanc-Petitjean

Marion Cortet

Laurent Gaucher

Marina Salomé

Bruno Carbonne

Camille Le Ray

Frédérique Gaudineau

Pierre Perrotte

Elodie Raynal

Gaël Clouqueur

Catherine Beucher

Pierre-Yves Deneux-Tharaux

Ancel

Dissatisfaction of women with induction of labour according to parity: Results of a population-based cohort study

Keywords: Induction of labour, prenatal education, decision-making, pain management, satisfaction

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Findings:

The response rate was 47.8% (n=1453/3042). Overall, 30% of the nulliparous women were dissatisfied (n=231/770) and 19.7% (n=130/659) of the parous women. The specific independent determinants of dissatisfaction for nulliparous women were antenatal birth classes that failed to include discussion of IoL (OR: 2.68, 95% CI [1.37;5.23]) and lack of involvement in the decision-making process (OR: 1.92, 95% CI [1.23;3.02]). For the parous women, a specific determinant was a delivery that lasted more than 24 hours (OR: 4.04, 95% CI [1.78;9.14]). Determinants of maternal dissatisfaction common to both groups were unbearable vaginal discomfort (respectively, OR: 1.98, 95% CI [1.16;3.37] and OR: 4.23, 95% CI [2.04;8.77]), inadequate pain relief (respectively, OR: 5.55, 95% CI [3.48;

Introduction

The rate of induction of labour (IoL) varies significantly by country, ranging from 12% in Sweden [START_REF] Ekéus | Induced Labor in Sweden, 1999-2012: A Population-Based Cohort Study[END_REF] to 35% in the Netherlands [START_REF] Christiaens | Trends in the medicalisation of childbirth in Flanders and the Netherlands[END_REF].

From 1995 to 2014, this rate doubled in Iceland from 12% to 25% [START_REF] Swift | Obstetric interventions, trends, and drivers of change: A 20-year population-based study from Iceland[END_REF]. In France, a recent study (MEDIP) found a mean rate of around 20%, fluctuating significantly between maternity units providing the same level of care (from 7.7% to 33.0%) [START_REF] Blanc-Petitjean | Labour induction practices in France: A population-based declarative survey in 94 maternity units[END_REF]. This variation may be explained by the low level of evidence for some medical indications for labour induction (Haute Autorite de Sante, 2009): IoL should be clinically justified after weighing the risks of induction against those of continuing the pregnancy. Thus, its use for improving birth outcomes for women at or beyond term remains a controversial subject, but there is no consensus about its optimal timing, which warrants further investigation [START_REF] Keulen | Timing induction of labour at 41 or 42 weeks? A closer look at time frames of comparison: A review[END_REF][START_REF] Middleton | Induction of labour for improving birth outcomes for women at or beyond term[END_REF]. Some observational studies have shown that IoL is associated with an increase in the rate of emergency caesarean sections, compared with expectant management [START_REF] Glantz | Term labor induction compared with expectant management[END_REF][START_REF] Pyykönen | Propensity score method for analyzing the effect of labor induction in prolonged pregnancy[END_REF][START_REF] Zhao | Intrapartum intervention rates and perinatal outcomes following induction of labour compared to expectant management at term from an Australian perinatal centre[END_REF]. Conversely, recent research suggests that in low-risk patients elective IoL at 39 weeks of gestation is associated with a significantly lower caesarean rate [START_REF] Grobman | National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network[END_REF][START_REF] Sotiriadis | Maternal and perinatal outcomes after elective induction of labor at 39 weeks in uncomplicated singleton pregnancy: a meta-analysis[END_REF]. In this situation of uncertainty, the information provided to patients must be clear and their choice must be taken into consideration. The process of shared decision making, which serves to reduces conflict and enhance satisfaction [START_REF] Kinnersley | Interventions to promote informed consent for patients undergoing surgical and other invasive healthcare procedures[END_REF], must be adhered to, especially as IoL has been shown to be associated with lower satisfaction than spontaneous labour [START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF]. The experience of childbirth for women undergoing IoL also differs according to parity [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF].

These points are important because the impact of the experience of childbirth affects mothers' emotional well-being and their early interactions with the child and may contribute to the development of depression or post-traumatic stress [START_REF] Creedy | Childbirth and the development of acute trauma symptoms: incidence and contributing factors[END_REF][START_REF] Skari | Comparative levels of psychological distress, stress symptoms, depression and anxiety after childbirth--a prospective population-based study of mothers and fathers[END_REF].

Accordingly, to improve the experience of patients with IoL, we sought to answer two questions: Which women are most at risk of dissatisfaction? What modifiable determinants of this dissatisfaction might enable us to adapt our practices to reduce its level? Our thorough search of the literature found no population-based studies in a developed country assessing quantitatively the determinants of maternal satisfaction for any method of IoL or any gestational age. In developing countries, only one study has examined this question in a population of women with labour induced, without taking parity into account (Ezeanochie et al., 2013). Our aim is to identify the determinants of dissatisfaction in women whose labour was induced, according to parity.

Methods

The MEDIP study was an observational prospective cohort study, the main objective of which was to evaluate perinatal outcome according to method of IoL in France. Our aim here is to examine one of its secondary objectives maternal dissatisfaction. The MEDIP study took place in November and December, 2015, in 94 French maternity units that accounted for 18% of all French maternity units and covered a sixth of the annual deliveries in France. Their characteristics were similar to those of French maternity facilities as a whole [START_REF] Blanc-Petitjean | Labour induction practices in France: A population-based declarative survey in 94 maternity units[END_REF]. The study consecutively included all women with labour induction and a live fetus. During the data collection period, 15,103 women gave birth in participating maternity units, 3171 (21.0%) of them had IoL with a live fetus, and 3042 (95.9%) agreed to participate in the MEDIP study. For this secondary study objective, the population analysed was the same as that for the principal outcome: women with induction of labour and a live foetus (i.e., the only exclusion criterion was intrauterine foetal death). As no validated scale exists for measuring satisfaction for labour induction, we developed a specific questionnaire based on dimensions of this subject that have been extensively studied, such as pain relief [START_REF] Smith | Acupuncture or acupressure for pain management in labour[END_REF], attention to women's requests, meeting expectations of labour and delivery [START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF] and duration of labour [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF][START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF]; we also considered dimensions that have been explored less frequently, such as vaginal discomfort [START_REF] Boulvain | Intracervical prostaglandins for induction of labour[END_REF][START_REF] Irion | A randomized trial comparing vaginal and cervical prostaglandin gel for cervical ripening and labor induction[END_REF]. The questions were discussed and validated by a scientific committee composed of a multidisciplinary team of perinatal professionals (midwife, gynaecologist/obstetrician), epidemiologists, and user representatives. The selfadministered questionnaire developed by the committee was sent either by postal mail (49.0%) or by email (51.0%) at two months after delivery to all women included in the study (Appendix). Three paper or electronic reminders were sent before treating the woman as a non-responder.

Women's overall satisfaction regarding labour and delivery was measured with a 5-point Likert-like scale. For the analysis of dissatisfaction, the replies not really satisfied, dissatisfied, and very dissatisfied were grouped and defined as "dissatisfied"; the replies very satisfied or satisfied were grouped and defined as "satisfied".

Data about the characteristics of the women, pregnancy, labour, and delivery came from their medical files. The women's characteristics that we studied were: maternal age, region of birth (Europe, North Africa, sub-Saharan Africa, other), marital/partner status, parity (nulliparous, parous), and body mass index (BMI) before pregnancy (kg/m 2 ). The pregnancy characteristics analysed were: status of the maternity unit of delivery (university public, other public, private), spontaneous pregnancy, antenatal birth classes (none; yes but labour induction was not discussed; yes, with labour induction discussed).

The characteristics of labour were the source of labour induction request and woman reaction, with the woman reaction (the woman; the medical staff, and the woman agreed; the staff, and the woman agreed after a long discussion; the staff, and the woman felt she had no choice), indication for IoL (medical indication, no medical indication), mode of staff decision for IoL (staff meeting; individual physician decision; systematically according to a protocol), oral information before IoL, Bishop score (continuous), method of labour induction (cervical ripening or oxytocin administration).

The delivery characteristics were the induction-to-delivery interval (<6 h, [6-12[, [12-24[, >24 h), epidural analgesia, gestational age at birth (<37 weeks of gestation, 37-41 weeks, > 41 weeks), mode of delivery (spontaneous vaginal, instrumental delivery, caesarean), perineal trauma (none, perineal tears, episiotomy), and neonatal hospitalisation. Severe maternal complications included severe postpartum haemorrhage defined by blood loss equal to or greater than 1000 ml or surgical complication or hysterectomy or intrauterine balloon tamponade or transfusion or maternal transfer to intensive care unit.

The variables related to the experience of IoL were: vaginal discomfort (none, tolerable, unbearable), satisfaction with pain relief and/or support during uterine contractions (very satisfied and satisfied vs. dissatisfied and very dissatisfied), ability to express requests and impression they were heard, labour as expected, acceptable duration of labour, and delivery as expected. For these last 4 variables, the replies absolutely agree, agree and more or less agree were grouped and defined as "satisfied", the replies neither yes nor no, more or less disagree, disagree, and completely disagree were grouped and defined as "dissatisfied".

Statistical analysis

The quantitative variables are described by their means and standard deviations (SD), and the qualitative variables as percentages. The association between maternal dissatisfaction and individual characteristics was studied in the univariate analysis separately for nulliparous and parous women and tested with the Chi 2 test or Student t test (all continuous variables normally distributed). The associations were then studied with multivariable logistic regression models.

Because of the interaction observed between parity and satisfaction, we estimated two multivariable logistic models, one for nulliparous and one for parous women. Multivariable mixed models were used to take a random effect for maternity unit into account. The variables that were significantly associated with maternal dissatisfaction in the univariate analysis were included in the multivariable models, except for some collinear variables that would have resulted in over-adjustment. The variables integrated simultaneously in the multivariable models were: source of labour induction request and woman reaction, antenatal birth classes, medical indication for IoL, oral information before IoL, duration of delivery, epidural analgesia, vaginal discomfort, pain relief and/or help during uterine contractions, expression of requests and impression they were heard, mode of delivery, neonatal hospitalisation and severe maternal complications. The method of induction and the Bishop score were not included in the model because they were highly correlated with duration of delivery. The odds ratios (OR) and their 95% confidence intervals were estimated, and Wald tests used to study the significance of the OR in each model. The number of missing data items was specified if > 5%. Statistical analyses were performed with Stata 15 software (Stata Corp., College Station, TX, US).

Ethics

The protocol for the MEDIP study was recorded in the ClinicalTrials.gov database (NCT02477085). The regional ethics committee (Comité de protection des personnes d'Ile de France -2015-May -DAP 21bis), the national ethics committee for the treatment of medical data (Comité consultatif sur le traitement de l'information en matière de recherché -15.609) and the French data protection agency (Commission Nationale de l'Informatique et des Libertés -MMS/VCS/AR1510301) approved this study.

Results

The response rate for the two-month post-delivery questionnaire was 47.8% (n=1453/3042).

Respondents and non-respondents differed significantly for several variables (all p<0.05): respondents were older, more frequently married to their partner and nulliparous, had a lower mean BMI, and differed for place of birth. There were no significant differences in terms of practice-related characteristics, except respondents gave birth at a higher gestational age (p<0.01) and had more frequent perineal tears (p=0.02; Appendix). Among women who responded to the questionnaire, 30% of the nulliparous women were dissatisfied (n=231/770) and 19.7% (n=130/659) of the parous women.

Among the respondents, the pregnancy characteristics of the nulliparous women did not differ significantly between satisfied and dissatisfied women, except for antenatal birth classes (p=0.01; Table 1). Of the IoL characteristics, significant differences were observed for the decision making process for IoL (p<0.01). Dissatisfied nulliparous women had received oral information before IoL significantly less often, had lower mean Bishop scores, and required cervical ripening more often (p<0.01; Table 2). A significantly larger percentage of these dissatisfied nulliparous women had a duration of labour exceeding 12 hours (p<0.01), caesarean delivery, and severe maternal complications (p<0.01), and a smaller percentage had epidural analgesia (p<0.01; Table 3). Every variable related to the experience of loL was significantly associated with dissatisfaction in nulliparous women (p<0.01; Table 4).

In the multilevel logistic regression model, factors significantly associated with nulliparous dissatisfaction included antenatal birth classes that did not discuss IoL (OR: 2.68, 95% CI [1.37; 5.23]), a staff decision for induction about which the woman felt that she had no choice (OR: 1.92, 95% CI [1.23; 3.02]), unbearable vaginal discomfort (OR: 1.98, 95% CI [1.16; 3.37]), dissatisfaction with pain relief or lack of support during uterine contractions (OR: 5.55, 95% CI [3.48;8.86]), lack of attention to requests (OR: 3.81, 95% CI [2.35; 6.19]), caesarean delivery (OR: 5.55, 95% CI [3.41;9.03]) and severe maternal complications (OR: 2.45, 95% CI [1.02; 5.88]; Table 5).

Among the parous women, those who were satisfied and dissatisfied did not differ significantly in their pregnancy characteristics, except for antenatal childbirth classes (p=0.02; Table 1). These groups also differed in their decision making process (p<0.01). Dissatisfied multiparous women had a medical indication for induction more frequently (p<0.01), received oral information before IoL less frequently (p<0.01), had a lower mean Bishop score (p<0.01), and had induction start by cervical ripening more often (p<0.01; Table 2).

Moreover, their duration of labour exceeded 12 hours more often (p<0.01), as did their rates of caesarean delivery and severe maternal complications (p<0.01; Table 3). Again, every variable related to the experience of loL was significantly associated with dissatisfaction in parous women (p<0.01; Table 4).

In the multilevel logistic regression model, factors significantly associated with parous dissatisfaction included duration of labour exceeding 24 hours (OR: 4.

Discussion

This study identified several factors associated with dissatisfaction with IoL. Some differed according to parity, while others were shared between the two groups.

For nulliparous women, the results were consistent with those of a systematic review of qualitative studies suggesting that women who undergo IoL need better preparation about its practical aspects [START_REF] Coates | Women's experiences of induction of labour: Qualitative systematic review and thematic synthesis[END_REF]. Dissatisfaction may be explained by the difference between the expected and actual experience of IoL [START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF]. Moreover, dissatisfaction was also associated with a decision making process not perceived as shared.

Qualitative studies have reported that women usually feel unable to participate in the decision-making process and that they require good quality information in an adequate format at the appropriate moment [START_REF] Coates | Women's experiences of induction of labour: Qualitative systematic review and thematic synthesis[END_REF][START_REF] Lou | Women's experiences of postterm induction of labor: A systematic review of qualitative studies[END_REF]. Evidence-based recommendations for standardising the way to inform women about IoL, during antenatal birth classes or when IoL is decided, are needed [START_REF] Ferguson | Does antenatal education affect labour and birth? A structured review of the literature[END_REF][START_REF] Gagnon | Individual or group antenatal education for childbirth or parenthood, or both[END_REF]. They might help to better involve women and thus contribute to greater satisfaction with IoL.

For multiparous women, the only specific factor associated with dissatisfaction was a duration of delivery greater than 24 hours. Even for these women, who are generally told that this delivery will be faster than their first, the interval between induction and delivery may seem excessive for them. This underlines the importance of avoiding generalisations about the duration of labour to reduce dissatisfaction resulting from unrealistic expectations [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF][START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF].

The factors associated with dissatisfaction that were common to both nulliparous and parous women concerned the experience of labour and delivery. These factors can be regrouped into pain (related to uterine contractions and vaginal discomfort), expectations that are not heard, and outcomes that are not expected after IoL (caesarean section and severe maternal complications). Inadequate pain relief, related to uterine contractions, was the main determinant of dissatisfaction, despite the existence of pharmacological and nonpharmacological methods of analgesia [START_REF] Jones | Pain management for women in labour: an overview of systematic reviews[END_REF][START_REF] Smith | Massage, reflexology and other manual methods for pain management in labour[END_REF][START_REF] Smith | Acupuncture or acupressure for pain management in labour[END_REF]. Studies investigating satisfaction, regardless of study design and socio-economic, cultural, and contextual differences, have reported this systematically, even recently [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF][START_REF] Jay | In labor or in limbo? The experiences of women undergoing induction of labor in hospital: Findings of a qualitative study[END_REF][START_REF] Van Der Gucht | Women's experiences of coping with pain during childbirth: a critical review of qualitative research[END_REF]. Women's experience of pain relief depends on multiple and complex factors, and beyond better consideration and relief of pain during labour, it has been suggested that future research is necessary to explore the role of antenatal childbirth classes to prepare women better for pain management (Van der [START_REF] Van Der Gucht | Women's experiences of coping with pain during childbirth: a critical review of qualitative research[END_REF]. While pain related to uterine contractions is widely known, vaginal discomfort has been poorly assessed. Previous studies have looked only at the vaginal discomfort associated with the insertion of a cannula into the cervix [START_REF] Beckmann | Measuring women's experience of induction of labor using prostaglandin vaginal gel[END_REF][START_REF] Boulvain | Intracervical prostaglandins for induction of labour[END_REF][START_REF] Irion | A randomized trial comparing vaginal and cervical prostaglandin gel for cervical ripening and labor induction[END_REF]. The identification of vaginal discomfort here in women undergoing IoL by oxytocin administration indicates that it is due to other factors, a major one of which is likely to be vaginal examinations. This finding suggests that these should be kept to a minimum [START_REF] Shetty | Women's perceptions, expectations and satisfaction with induced labour--a questionnaire-based study[END_REF]. Among the other shared determinants of dissatisfaction was the lack of an appropriate, personalised response to requests. This is likely to be due to underrecognition of the needs of women undergoing induction, as they require different support than those who have spontaneous labour [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF].

Unexpected IoL outcome (caesarean or severe maternal complications) were also associated with dissatisfaction, which is also known to affect mothers' emotional well-being. Although we found no evidence to support routine debriefing for women who perceive giving birth as psychologically traumatic [START_REF] Bastos | Debriefing interventions for the prevention of psychological trauma in women following childbirth[END_REF], care providers should discuss these events with women during the postpartum period, to help them to feel less guilty and to identify early on the women at risk of depression or post-traumatic stress [START_REF] Dikmen-Yildiz | Longitudinal trajectories of post-traumatic stress disorder (PTSD) after birth and associated risk factors[END_REF][START_REF] Ricbourg | Emotional impact of severe post-partum haemorrhage on women and their partners: an observational, case-matched, prospective, single-centre pilot study[END_REF][START_REF] Simpson | Understanding psychological traumatic birth experiences: A literature review[END_REF].

The strengths of this study include the large sample size, which is for the most part representative of the French population of women giving birth. Although the response rate may be considered a limitation, it is nonetheless consistent with the rate expected for postevent mail questionnaires and has been observed elsewhere [START_REF] Henderson | Women's experience of induction of labor: a mixed methods study[END_REF]. This leads to the question of when the data collection should occur; in this study, it took place two months postpartum, a choice that could result in recall-related bias. However, delaying it until after discharge and using self-administered questionnaires was chosen to avoid "courtesy" or "social desirability" bias but also to prevent the masking of dissatisfaction by the strong positive emotions related to childbirth itself [START_REF] Sando | Methods used in prevalence studies of disrespect and abuse during facility based childbirth: lessons learned[END_REF]. This time point also enabled women to respond before returning to work (usually after 10 weeks post-delivery in France). Another pertinent limitation is the absence of a validated questionnaire to measure women's experience of IoL. A validated tool to report the experience of women undergoing induction was reported, but only after the start of the study and only for cervical ripening [START_REF] Beckmann | Measuring women's experience of induction of labor using prostaglandin vaginal gel[END_REF]. Another limitation concerns other factors potentially related to patient satisfaction that were not evaluated in this study, such as the organisation of the maternity unit and the individual relationship created between the woman and the care provider (Akuamoah-Boateng and Spencer, 2018). However, multivariable mixed models were used to take into account a random effect for the maternity unit and therefore its organisation, but the MEDIP study did not collect data on patient-carer pairs. Such data would be useful in future studies to investigate the effect of individual relationships on satisfaction.

Conclusion

For nulliparas, failure to discuss induction in birth classes and lack of participation in decision making led to dissatisfaction. Labour exceeding 24 hours was associated with reduced satisfaction in parous women. For all women, more attention should be paid to vaginal discomfort, pain and maternal requests; unexpected events also should be discussed postpartum with all women. The results of this study strongly suggest a need to improve the shared decision-making process for IoL

Table 5 )

 5 .

	04, 95% CI [1.78;

Table 1 .

 1 Characteristics of women and pregnancy according to maternal satisfaction, stratified by parity a Missing data: n=110 (14.3%) for nulliparous and n=106 (16.1%) for parous.

	Nulliparous		Parous
	Satisfied n= 539	Dissatisfied n=231	p	Satisfied n=529	Dissatisfied n=130	p

Table 2 .

 2 Induction of labour characteristics according to maternal satisfaction, stratified by parity For women with vaginal delivery; b Maternal complications included severe postpartum haemorrhage defined by blood loss ≥ 1000 ml or surgical complication or hysterectomy or intrauterine balloon tamponade or transfusion or maternal transfer to intensive care

	Nulliparous			Parous
	Satisfied n=539	Dissatisfied n=231	p	Satisfied n=529	Dissatisfied n=130	p

a

Table 4 .

 4 Experience of labour and delivery, associated with maternal dissatisfaction

	Nulliparous			Parous
	Satisfied n=539	Dissatisfied n=231	p	Satisfied n=529	Dissatisfied n=130	p

Table 5 .

 5 Factors associated with maternal dissatisfaction, stratified by parity a

		Nulliparous		Parous
		n=705		n=585
	p	aOR [95% CI] b	p	aOR [95% CI] b

55 [3.48; 8.86] <0.001 9.17 [5.24; 16.02] No consideration of woman's requests <0.001 3.81 [2.35; 6.19] <0.001 5.01 [2.38; 10.52]

  All variables were integrated simultaneously; b Adjusted for maternity unit status, BMI, gestational age; b Severe postpartum haemorrhage defined by blood loss ≥ 1000 ml or surgical complication or hysterectomy or intrauterine balloon tamponade or transfusion or maternal transfer to intensive care Appendix. Characteristics of patients according to whether they responded to the

	questionnaire
		Responder	Non-responder
		n=1453	n=1589	p
	Mean maternal age, years (SD)	31.2 (4.9)	30.5 (5.5)	<0.01
	Place of maternal birth a , n (%)			<0.01
	Europe	1003 (81.9)	833 (63.7)
	North Africa	123 (10.0)	289 (22.1)
	Sub-Saharan Africa	45 (3.7)	99 (7.6)
	Other	54 (4.4)	86 (6.6)
	Living with a partner, n (%)	1286 (97.5)	1314 (94.3)	<0.01
	Nulliparous, n (%)	777 (53.8)	718 (45.5)	<0.01
	BMI before pregnancy, kg/m 2 (SD)	24.5 (5.2)	24.9 (5.2)	0.02
	Status of maternity unit, n (%)			0.26
	University public	415 (28.6)	506 (31.8)
	Other public	520 (35.8)	551 (34.7)
	Private	518 (34.7)	552 (33.5)
	Spontaneous pregnancy, n (%)	1349 (94.3)	1498 (95.7)	0.08
	Medical indication, n (%)	1037 (90.1)	1429 (90.2)	0.94
	Mode of decision, n (%) Mode of delivery Spontaneous vaginal delivery Staff meeting Instrumental delivery Individual physician decision Caesarean According to a protocol Neonatal hospitalisation Gestational age in weeks, n (%) Severe maternal complications b <37 [37-41]	263 (19.0) 826 (59.6) 296 (21.4) 65 (4.5) 859 (59.3)	293 (16.7) 0.063 898 (60.4) <0.001 297 (20.0) 0.064 0.044 96 (6.0) 999 (63.0)	0.63 1.68 [0.97; 2.91] 1.00 5.55 [3.41; 9.03] 2.20 [0.95; 5.06] <0.01 2.45 [1.02; 5.88]	0.831 <0.001 0.149 0.019	1.00 0.86 [0.22; 3.37] 4.61 [2.02; 10.53] 2.13 [0.76; 5.92] 5.29 [1.32; 21.21]
	>41	524 (36.2)	490 (30.9)
	Bishop score, n (%)			0.91
	<4	575 (41.4)	625 (41.5)
	[4-5[	518 (37.3)	552 (36.6)
	≥6	297 (21.4)	331 (22.0)
	Cervical ripening, n (%)	91 (62.7)	970 (61.2)	0.40
	Epidural analgesia, n (%)	1259 (86.7)	1393 (87.7)	0.40
	Mode of delivery, n (%)			0.30
	Spontaneous vaginal	954 (66.0)	1004 (63.5)
	Instrumental vaginal	203 (14.0)	226 (14.3)
	Caesarean	289 (20.0)	350 (22.2)
	Time to delivery <24 h, n (%)	1103 (77.4)	1231 (78.9)	0.34
	Episiotomy b , n (%)	257 (22.3)	237 (19.3)	0.07
	Perineal tear b , n (%)	613 (53.1)	592 (48.2)	0.02
	Postpartum haemorrhage severe, n (%)	38 (2.6)	41 (2.6)	0.95
	Severe maternal complications, n (%)	54 (3. 7)	56 (3.7)	0.78
	Neonatal hospitalisation, n (%)	98 (6.8)	131 (8.3)	0.12

a

Acknowledgements :

The MEDIP study was conducted by Assistance Publique-Hôpitaux de Paris (Département de la recherche Clinique et du développement). The authors thank all the members of the MEDIP study scientific committee: Catherine Crenn-Hebert, Adrien Gaudineau, Frédérique Perrotte, Pierre Raynal, Elodie Clouqueur, Gaël Beucher, Catherine Deneux-Tharaux, and Pierre-Yves Ancel. We also thank all the local investigators for their contribution to this study, the URC-CIC Paris Descartes Necker/Cochin (Laurence Lecomte, Isabelle April) for setting up and monitoring the MEDIP study, all the women who agreed to participate, and the midwives who recruited and included them. We thank Philip Robinson for help in manuscript preparation and Jo Ann Cahn for her careful translation of the manuscript.

The protocol for the MEDIP study was recorded in the ClinicalTrials.gov database (NCT02477085(Commission Nationale de l(3) Funding sources: Data come from the MEDIP study, funded by the national agency for drug safety and health products (ANSM) as part of a call for research projects (No. AAP-2014-030). (4) ClinicalTrials.gov Identifier: NCT02477085 (5) Acknowledgements : The MEDIP study was conducted by Assistance Publique-Hôpitaux de Paris (Département de la recherche Clinique et du développement). The authors thank all the members of the MEDIP study scientific committee: Catherine Crenn-Hebert, Adrien

a Missing data: n=228 (15.7%) for responder and n=282 (17.7%) for no-responder; b For women with vaginal delivery