Quentin Sourisseau
email: quentin.sourisseau@univ-eiffel.fr

Emilie Lepretre
email: emilie.lepretre@univ-eiffel.fr

Sylvain Chataigner
email: sylvain.chataigner@univ-eiffel.fr

Xavier Chapeleau
email: xavier.chapeleau@univ-eiffel.fr

Maxime Deydier
email: maxime.deydier@bureauveritas.com

Stéphane Paboeuf
email: stephane.paboeuf@bureauveritas.com

A new adhesively bonded composite repair for offshore steel structures: strength assessment and fatigue

Keywords: Bonding, Offshore, Reinforcement, Optical fiber sensor

INTRODUCTION

Corrosion of metallic structures in an offshore environment is an ongoing threat due to high temperature and humidity conditions, especially in tropical environments. A bonded repair of these corroded surfaces has several advantages, including short downtime and a non-intrusive repair process. However, repairing corroded areas on large marine structures by bonding FRP patches imposes significant constraints on the design. The patch end is placed in a fully stressed zone (zone subject to unit bending), causing high stresses on the edges of the reinforcement. More generally, designers and engineers have to deal with several difficulties related to the nature of steel-composite assemblies: discontinuity of materials (different properties of materials), nonlinear material properties of the adhesive, singularity constraint at the edges of the patch. A fine understanding of adhesion mechanics and patch strength are essential for designing highly reliable composite repairs. These difficulties of design tend to greatly limit the industrial applications of bonded reinforcements, particularly in an offshore environment. However, it has been proven in the laboratory that these types of reinforcements can have very beneficial effects on the service life of reinforced structures [START_REF] Chataigner | Design and evaluation of an externally bonded CFRP reinforcement for the fatigue reinforcement of old steel structures[END_REF][START_REF] Chataigner | Preventive fatigue strengthening of steel structures with adhesively bonded CFRPs -efficiency demonstration on a real bridge[END_REF]Leprêtre et al., 2018). A Joint Industrial Project (JIP) called "Strength Bond Offshore" (SBO) was thus initiated (Bureau Veritas 2020), in order to: • validate a characterization procedure for the components of the bonded assembly, • standardize the qualification process for bonded composite repairs in an offshore environment,

• define a robust method for predicting the resistance of the bonded patch, • enable a clear assessment of the safety factor to be taken into account in the estimation of design loads. The work presented in this article aims at complying with this last goal. First, the design of the composite patch (carbon fibers/glass fibers/epoxy resin) developed during the SBO project will be detailed by Paboeuf (2021). The studied solution is based on the production and bonding of composite patches by infusion, with a dedicated surface preparation protocol. The preliminary investigations made on all specimens and carried out using fracture mechanics for the dimensioning of the bonded patch are presented in detail by [START_REF] Sourisseau | Development of a robust methodology for the design assessment of bonded reinforcements on steel structures[END_REF] and [START_REF] Sourisseau | Adhesively Bonded FRP Reinforcement of Steel Structures: Surface Preparation Analysis and Influence of the Primer[END_REF]. Only a few significant results will be recalled in this article. To validate the design of the bonded patch, full size specimens were also tests under monotonic loading (traction/bending), as well as fatigue tests (traction) were carried out with fullscale specimens. The obtained results are compared with predictive calculations for typical loading cases encountered on FPSO units.

PATCH DESIGN PRESENTATION

The loads applied to the hull of a ship are mainly related to the effect of the waves and to the loadings of the ship (loads in calm water). Since a ship has a significant length compared to its width and depth, it can be considered as a beam element and is thus submitted to vertical/horizontal bending moment (generated by waves) and shear/bending loads (generated by the vessel's own weight). These induce a large amplitude of in-plane stresses (traction, compression, shear) for the longitudinal elements of the structure: hull and partitions. For wave loads, a Weibull distribution law is defined in Bureau Veritas rules for steel vessels (NR467, 2022) and rules for offshore units (NR445, 2022), with data from guidelines for fatigue assessment of steel vessels and offshore units (NI611, 2020). Within the framework of the dimensioning of a bonded reinforcement of large dimensions, only the global loads of the ship beam are taken into account. They can be summarized as follows (loads due to waves and loads in calm water):

• tensile/compressive loads in steel s xx =+/-225 MPa,

• shear load in steel τxy = 45 MPa.

Note that these values correspond to an extreme loading case for a ship in its original condition (uncorroded), with a probability level of 10 -8 .

The bonded patch must therefore satisfy these resistance criteria while guaranteeing maximum rigidity to regain the lost stiffness of the structure caused by corrosion. As part of this study, the loss of steel thickness to be recovered by the composite patch was evaluated to be equal to approximately 7 mm for a 20 mm thick sheet (30% loss). The design of the bonded patch, under these conditions, led to a proposal for composite layup detailed in Figure 1. Two types of angles (long and short scarfs) at the edges of the patch are proposed and the influence of the variation of this angle (stresses concentrations) on the resistance of the patch is studied. Each stack of unidirectional plies is represented by a color in Figure 1. The grey/blue/black colored layers correspond to the thirty-six carbon fibers plies at a given angle (from 0° to 90°). The green layers represent plies of glass fibers oriented at 0°/90°. Finally, the orange layer corresponds to the steel substrate. It should be noted that the two upper fiberglass plies are only there to protect the carbon part of the patch from external aggressions.

Figure 1: Layup of the bonded patch and studied scarfs geometries.

MANUFACTURING

The chosen manufacturing process for the realization of the different bonded patches is based on the method of impregnation by infusion with surface preparation defined for the project [START_REF] Sourisseau | Development of a robust methodology for the design assessment of bonded reinforcements on steel structures[END_REF][START_REF] Sourisseau | Adhesively Bonded FRP Reinforcement of Steel Structures: Surface Preparation Analysis and Influence of the Primer[END_REF]. Figure 2 shows the stacking process of the different plies before infusion. The used resin is a post-cured epoxy resin (80°C for 16 hours). In order to obtain more information on the mechanical state of the patch during the various tests, optical fiber sensors, for measuring distributed strain, were placed inside the patch for the allthe samples (between the first two plies of glass fibers, close to the surface with the steel) as well as on the surface of the patch for all samples (figure 3). These fibers are polyimide distributed optical fibers that allow a spatial resolution of 1,2mm with noise measurement of ±20% µstrain, paired with an Luna Odisi-b interrogator. The steel sheet has a high elastic limit (900 MPa) to guarantee the absence of yielding before the patch peels off. The produced large specimens (real scale) are then cut with a water jet. The dimensions of the resulting specimens are 2000 mm long and 50 mm wide. The bonded patch is about 1400 mm long, leaving a free length on each side of 300 mm (Figure 4). After cutting, the observation of the specimens showed that some porosities exist in the central part of the patch (the thickest). Their position being in the least mechanically loaded zone makes it possible to limit their influence on the mechanical properties of the patch. The after-test analysis of the sample proved that they were the only defect in and on the samples.

STRENGTH ASSESSMENT OF THE BONDED PATCH UNDER MONOTONIC STRESS

Figure 5 presents the two types of static tests carried out during our investigations. On the left, a tensile test is carried out on an Instron tensile machine with an ultimate capacity of 2500 kN while on the right, 3 points bending test is carried out on a Losen press with a capacity of 300 kN. The distances between supports for the bending test are 1450 mm. These two tests were chosen because they were identified as similar two the two types of solicitation that the patches would encounter in real case application. These tests are made to measure the ultimate states at failure (strain) in the bonded patches as well as the ultimate capacities (force) for the two types of scarfs (short and long) and for the two types of tests (traction and bending). Table 1 summarizes the ultimate forces obtained in each case. The observed failure behavior is purely brittle with linear elastic loading until sudden and total debonding of the patch.

For specimens with a short scarf, the average failure load in tension is 489 kN and, in bending, is 34 kN. The results are weakly dispersed. Taking into account the steel part of the specimens (50 mm wide x 20 mm thickness), it is possible to calculate an equivalent stress in the steel for a reinforced sheet. This value is 490 MPa for an ultimate capacity of 489 kN, this corresponds to more than the double of what is recommended by Bureau Véritas design rules (490 MPa versus 225 MPa).

Tests on specimens with a long scarf show greater failure load in tension, in the order of 787 kN on average (+60% compared to specimens with a short scarf) and similar forces (slightly lower) in the case of bending. For the studied specimen geometries, these results tend to demonstrate that the impact of the scarf length in bending is very limited, whereas in tension, it allows a clear improvement in the maximum resistance of the bonded patch. These results are related to the different strain profiles depending of the different solicitations. The three points bending test being more loaded on the center position of the patch (smaller strain gradient at the border than for tension test), failure load are less dependent of the scarf angles. The experimental results were compared with the results obtained for a bonded steel sheet solution having similar geometries as the composite specimen [START_REF] Sourisseau | Adhesively Bonded FRP Reinforcement of Steel Structures: Surface Preparation Analysis and Influence of the Primer[END_REF]. These results are summarized in Table 2. They highlight a clear gain with respect to the forces at break in the case of a repair by bonded composite patch compared to a similar repair (equivalent stiffness) using a steel sheet (6 mm thick). These results therefore indicate that for a real application, the choice of the large scarf will allow better performance of the bonded composite patch with a safety factor of approximately 3.5 (790 MPa vs 225 MPa) on the admissible breaking stresses in the steel before patch debonding (NI611). Figure 6 shows the obtained fracture surfaces after the tensile tests for specimens with a long scarf. A multi-interfacial rupture is observed between the steel and the resin, the first ply of glass fibers and the resin, as well as the beginning of delamination between the first two plies of glass fibers (white area on the patch). Similar fracture surfaces were obtained for the two types of scarfs, as well as for the two types of tests (tension and bending), showing a similar failure mode. The low dispersion of the ultimate forces, combined with similar fracture surfaces, is yet a guarantee of repeatability and confidence in the overall behavior of the patch.

EFFECT OF THE PATCH DESIGN ON INTERNAL STRAINS Bending Test

As exposed before, to obtain more information on the mechanical state of the patch and to validate that the stress concentration at the border of the patch is limited by the design, distributed strain measurements have been recorded during the tests. A high-definition optical fiber sensing system (based on the Rayleigh backscattering) with sub-millimeter sampling resolution was used for the measurements. This system has a maximum sampling rate of approximately 20 Hz and, for the postprocessing of data, the gauge length and spacing were fixed to be equal to 1 mm. The Figure 7 presents the obtained strains measurement along the optical fiber for one of the bending test with a specimen with small scarfs.

Figure 7: Bending test of small scarf samples optical fiber surface strains measurement. Figure 8 presents an example of the strain measurement obtained by the distributed optical fiber sensor during the bending test for a specimen with long scarfs. For all the figures, the abscise represent the relative position of the optical fiber on the patch (1.4m length patch). Embedded fiber measurements for small scarf samples are not provided, because the fibers were broken during the water jet cutting of the samples. The left part of the curves shows the surface measurement and right part of the curves the embedded one. For all the described results, the time t4 corresponds to the last strains measurement before the failure of the patch and time t1, t2 and t3 correspond to time during the loading of the patch. For the bending test (figures 7 and 8), the observation of strains profile on the surface of the patches shows that no strains concentrations are visible at the border of the patch (whether it be for the small scarfs or the long scarfs samples). In the case of the long scarf sample with embedded fiber, the direct effect of the patch on the steel surface strains is visible. It can be seen that they remain really low, especially in the center section of the patch. It indicates that the patch help to reduce stress in the steel surface where it is supposed to be corroded

Tension Test

The figure 9 presents the strains measurement obtained along the patch for one of the small scarfs specimens tested in tension. While, figure 10 presents the measured distributed strains during the tension test for a long scarfs sample. The left part of the curves shows the surface measurement and right part of the curves, the embedded one. For the tension test, two high strain peaks are clearly visible between 5 and 7 cm from the border of the patch (figure 9 and figure 10). These locations correspond to the position of the border of the first carbon plies. When comparing the small scarf surface results (figure 9) and long scarf surface (figure 10), the strain transition length (distance of the effect of scarf from the border of the patch) is much longer for the long scarf. It allows to obtain locally, higher strain at failure. From the results of the embedded optical fiber, it can be seen than, compare to the short scarf results, the strain gradient is much lower at failure. It indicates that the longer scarf allows to have a much smoother strain transition from the steel plate to the patch. Also, these results indicates that despite the capacity of the patch to sustain equivalent strain in the steel plate of around 787MPa for the long scarf, ultimate properties could be increased by further modification of the design (example: change in the layup to reduce the strain peak at the patch border). These results also prove that the patch performances (much higher than the standard requirement) are directly linked to the patch design. The tension test seems to be more critical because of the much higher strain gradient near the patch borders. This conclusion as led to the choice to limit the fatigue test campaign (described in the next chapter) to only tension tests.

Composites patch fatigue behavior assessment

To assess the behavior of the composite patch in fatigue, 10 tensile tests were carried out. From the results of the static tests on specimens with a long scarf, different load levels in traction, with a load ratio R=σmax/σmin = 0.1 have been chosen for the tests. The number of cycles at failure vary with applied load, between 50,000 and 5 million of cycles. Figure 11 shows the results of these tests in terms of service life, for different amplitudes of force. The orange squares correspond to the test results (at break), and the blue arrows to the tests which have not broken for a number of cycles corresponding to the base of the arrow. From these points of measurements, the fatigue curve is plotted in the figure (black straight line). For comparison, the fatigue curve of a reference FPSO unit calculated from the NI611 (2020) standard is also shown in the figure. It can thus be seen that the service life of the patch, obtained for different load amplitudes, is much greater than that of the reference histogram (minimum theoretical service life of the ship for each possible load level). Moreover, the number of cycles undergone during the life of a reference FPSO unit can be calculated from the formula given in Eq. 1. A target lifetime of 20 years corresponds to 63 million cycles. This value is reported in the figure 11 With Ncycles corresponding to the number of cycles at failure, Dlife the expected lifetime and Fwave to the average wave frequency, here fixed at 0.1Hz.

These results therefore predict that the lifetime of the patch, in real conditions of use and without external damage, will greatly exceed the lifetime of the ship. The high safety factor (difference between the theoretical and experimental lifespan) provides a very good level of confidence in the behavior of the bonded patch in real conditions. The Figure 12 shows the obtained fracture surfaces after the fatigue tensile tests A multi-interfacial failure similar the ones obtained for the monotonic test has been observed. Similar fracture surfaces were obtained for all the load level tested. It is concluded that when a fatigue crack is initiated in the patch, the failure of the patch occurs in the same way as in the monotonic test and therefore, no real fatigue crack propagation happened. This assumption has been validated by the witnessing of the violented debonding of the patch during fatigue tests.

Conclusion

An adhesively bonded composite patch was developed during the SBO project and was detailed. It consists in an infused composite patch (ply-stacking) associated with a dedicated surface preparation and a post-cure cycle feasible on site. To assess the performance of the developed patch, full-scale investigations were realized and are presented. Those consisted in evaluating the resistance of the bonded patch for several types of monotonous loading (traction and bending). These tests have shown the very good mechanical performance of the patch designed in the SBO project, being two to three times higher (depending on the angle of the scarf) than the values recommended by the standards. In addition, a specific monitoring strategy (use of continuous optical fiber) was used to better understand the importance of the edge treatment on the obtained results. Good repeatability and similar failure modes were obtained indicating the robustness of the developed protocol and the consistency of a dedicated design approach. In addition, the results of the fatigue test campaign have shown that the lifetimes under fatigue loading are much higher than the design loadings of an FPSO unit. These results are very promising for the use of bonded composite patches as a means of reinforcing corroded sheets in an offshore environment. Additional developments are under progress to propose an equivalent interfacial approach suitable to be used for the design of such patches. Yet, these results do not take into account the possible external degradation of the patch caused by humidity or the possible damage following an impact. The loss of mechanical performance resulting from these various degradations will further be studied to guarantee the proper functioning of the bonded composite patch as a durable reinforcement for the FPSO unit.

Figure 2 :

 2 Figure 2: Plies stacking before infusion with embedded optical fibers in the patch.

Figure 3 :

 3 Figure 3: Instrumentation, optical fiber position and sample size, long scarf sample example.

Figure 4 :

 4 Figure 4: Samples after water jet cutting.

Figure 5 :

 5 Figure 5: Traction (a) and three points bending (b) tests of composite to steel bonded assembly patch.

Figure 6 :

 6 Figure 6: Fracture surfaces of tested samples in tension with long scarf.

Figure 8 .

 8 Figure 8. Bending test of long scarf samples optical fiber outside (left) and inside (right) strains measurement.

Figure 9 :

 9 Figure 9: Tension test of small scarf sample optical fiber surface strain measurement.

Figure 10 :

 10 Figure 10: Tension test of long scarf sample, optical fiber inside (left) and outide (right) strainsmeasurement. For the tension test, two high strain peaks are clearly visible between 5 and 7 cm from the border of the patch (figure9and figure10). These locations correspond to the position of the border of the first carbon plies. When comparing the small scarf surface results (figure9) and long scarf surface (figure10), the strain transition length (distance of the effect of scarf from the border of the patch) is much longer for the long scarf. It allows to obtain locally, higher strain at failure. From the results of the embedded optical fiber, it can be seen than, compare to the short scarf results, the strain gradient is much lower at failure. It indicates that the longer scarf allows to have a much smoother strain transition from the steel plate to the patch. Also, these results indicates that despite the capacity of the patch to sustain equivalent strain in the steel plate of around 787MPa for the long scarf, ultimate properties could be increased by further modification of the design (example: change in the layup to reduce the strain peak at the patch border). These results also prove that the patch performances (much higher than the standard requirement) are directly linked to the patch design. The tension test seems to be more critical because

  (vertical blue line).

Figure 11 .

 11 Figure 11. Results obtained from the fatigue test campaign in tension on long scarf samples.𝑁𝑁 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 = 𝐷𝐷 𝑐𝑐𝑙𝑙𝑙𝑙𝑐𝑐 𝐹𝐹 𝑤𝑤𝑤𝑤𝑤𝑤𝑐𝑐Eq. 1

Figure 12 .

 12 Figure 12. Fracture surfaces of the fatigue test samples in tension.

Table 1 :

 1 Failure loads obtained for the samples with long and short scarf.

		Long scarf	Small scarf
	Failure load	Tension	Bending	Tension	Bending
		(kN)	(kN)	(kN)	(kN)
	Test 1	840	32	477	35
	Test 2	790	29	500	31
	Test 3	795	30	491	36
	Test 4	740	29
	Test 5	769
	Average	787	30	489	34
	Standard deviation/average	3%	3%	2%	8%

Table 2 :

 2 Average stress in steel at failure for three different bonded repair configurations of an equivalent thickness.

	Type of bonded reinforcement	Equivalent stress in steel
		(MPa, in tension)
	Short scarf composite patch	495
	Long scarf composite patch	787
	Steel patch	250

ACKNOWLEDGEMENTS

Acknowledgments to project partners StrengthBond Offshore (Bureau Veritas, Total, Petrobras, Naval Group, Siemens, ColdPad et Infracore Compagny) who funded this work.

DATA AVAILABILITY

Data on which this paper is based is available from the authors upon reasonable request.

CONFLICT OF INTEREST

The authors declare that they have no conflicts of interest associated with the work presented in this paper.


Lucie Pinasseau
email: lucie.pinasseau@univ-lyon1.fr

Florian Mermillod-Blondin

Aurélie Fildier

François Fourel

Félix Vallier

Ludovic Guillard

Laure Wiest

Laurence Volatier

Determination of groundwater origins and vulnerability based on multi-tracer investigations: New contributions from passive sampling and suspect screening approach

Keywords: chemical fingerprint, contaminants of emerging concern, groundwater recharge, passive sampling, hydrochemical tracer, isotopic tracer Conceptualization, Formal analysis, Writing -original draft, Writing Supervision, Conceptualization, Writing - Investigation, Resources Investigation, Resources. Laure Wiest: Conceptualization, Validation Supervision, Conceptualization, Writing -

Knowledge about groundwater origins and their interactions with surface water is fundamental to assess their vulnerability. In this context, hydrochemical and isotopic tracers are useful tools to investigate water origins and mixing. More recent studies examined the relevance of contaminants of emerging concern (CECs) as co-tracers to distinguish sources contributing to groundwater bodies. However, these studies focused on known and targeted CECs a priori selected regarding their origin and/or concentrations. This study aimed to improve these multi-tracer approaches using passive sampling and qualitative suspect screening by exploring a larger variety of historical and emerging concern contaminants in combination with hydrochemistry and water molecule isotopes. With this objective, an in-situ study was conducted in a drinking water catchment area located in an alluvial aquifer recharged by several water sources (both surface and groundwater sources). CECs determined by passive sampling and suspect screening allowed to provide in-depth chemical fingerprints of groundwater bodies by enabling the investigation of more than 2500 compounds with an increased analytical sensitivity. Obtained cocktails of CECs were discriminating enough to be used as chemical tracer in combination with hydrochemical and isotopic tracers. In addition, the occurrence and type of CECs contributed to a better understanding of groundwater-surface water interactions and highlighted short-time hydrological processes. Furthermore, the use of passive sampling with suspect screening analysis of CECs lead to a more realistic assessment and mapping of groundwater vulnerability.

Introduction

In many countries, shallow alluvial aquifers which are hydraulically connected to large rivers are often exploited by wellfields for drinking water supply [START_REF] Bourg | Biogeochemical processes during the infiltration of river water into an alluvial aquifer[END_REF][START_REF] Texier | Numerical Assessment of Groundwater Flowpaths below a Streambed in Alluvial Plains Impacted by a Pumping Field[END_REF]. These unconfined alluvial aquifers are highly vulnerable to contaminations by river water as groundwater extraction accelerates the rate of aquifer recharge with river waters [START_REF] Shamsudduha | The impact of intensive groundwater abstraction on recharge to a shallow regional aquifer system: evidence from Bangladesh[END_REF]. Due to these increased recharge rates, the time for selfpurification processes occurring in river banks is reduced and then, the vulnerability of the aquifer to contaminations from surface waters increases [START_REF] Kralik | Using 18 O/ 2 H, 3 H/ 3 He, 85 Kr and CFCs to determine mean residence times and water origin in the Grazer and Leibnitzer Feld groundwater bodies (Austria)[END_REF]. Under these conditions, knowledge about water origins and movements is fundamental for developing efficient monitoring tools and appropriate groundwater protection strategies [START_REF] Dillon | Future management of aquifer recharge[END_REF].

Various tracers are commonly used to collect information on subsurface processes such as age, travel time, stratification and temporal changes of the flow system. Tracers can be dye, heat, dissolved gases, trace elements and rare earth elements [START_REF] Benischke | Review: Advances in the methodology and application of tracing in karst aquifers[END_REF][START_REF] Díaz-Puga | Groundwater flow and residence time in a karst aquifer using ion and isotope characterization[END_REF][START_REF] Kurukulasuriya | Selecting Environmental Water Tracers to Understand Groundwater around Mines: Opportunities and Limitations[END_REF][START_REF] Kurylyk | Theory, tools, and multidisciplinary applications for tracing groundwater fluxes from temperature profiles[END_REF][START_REF] Moeck | Characterization of a managed aquifer recharge system using multiple tracers[END_REF][START_REF] Newman | Natural and Anthropogenic Geochemical Tracers to Investigate Residence Times and Groundwater-Surface-Water Interactions in an Urban Alluvial Aquifer[END_REF][START_REF] Potot | Groundwater and river baseline quality using major, trace elements, organic carbon and Sr-Pb-O isotopes in a Mediterranean catchment: The case of the Lower Var Valley (south-eastern France)[END_REF]. To estimate the origin of water bodies contributing to groundwater recharge, natural tracers like conservative solutes (i.e. major ions and silica) or stable isotopes of the water molecule (i.e. δ 2 H and δ 18 O) were identified as suitable tools [START_REF] Blumstock | Baseflow dynamics: Multi-tracer surveys to assess variable groundwater contributions to montane streams under low flows[END_REF][START_REF] Díaz-Puga | Groundwater flow and residence time in a karst aquifer using ion and isotope characterization[END_REF][START_REF] Innocent | A multi-isotopic study of the groundwaters from the Lower Triassic Sandstones aquifer of northeastern France: Groundwater origin, mixing and flowing velocity[END_REF][START_REF] Kurukulasuriya | Selecting Environmental Water Tracers to Understand Groundwater around Mines: Opportunities and Limitations[END_REF][START_REF] Moeck | Characterization of a managed aquifer recharge system using multiple tracers[END_REF][START_REF] Oyarzún | Chemical and isotopic assessment of surface water-shallow groundwater interaction in the arid Grande river basin, North-Central Chile[END_REF][START_REF] Poulain | Enhanced pumping test using physicochemical tracers to determine surface-water/groundwater interactions in an alluvial island aquifer, river Rhône, France[END_REF]. In addition, anthropogenic contaminants such as historical and emerging concern contaminants are increasingly used in groundwater studies to trace water sources. Contaminants of emerging concern (CECs) are anthropogenic contaminants not considered until the recent development of improved analytical method allowing their detection [START_REF] Richardson | Water Analysis: Emerging Contaminants and Current Issues[END_REF]. [START_REF] Banzhaf | Using selected pharmaceutical compounds as indicators for surface water and groundwater interaction in the hyporheic zone of a low permeability riverbank: SELECTED PHARMACEUTICALS AS INDICATORS J o u r n a l P r e -p r o o f Journal Pre-proof IN A LOW PERMEABILITY RIVERBANK[END_REF] and [START_REF] Müller | Pharmaceuticals as indictors of sewage-influenced groundwater[END_REF] proved that pharmaceuticals (i.e. carbamazepine, sulfamethazine, and sulfamethoxazole) could be used as anthropogenic J o u r n a l P r e -p r o o f potentially below the detection limits of most analytical methods, and targeted analyses typically cover a few dozen to a few hundred contaminants [START_REF] Erostate | Coupling isotope hydrology, geochemical tracers and emerging compounds to evaluate mixing J o u r n a l P r e -p r o o f Journal Pre-proof processes and groundwater dependence of a highly anthropized coastal hydrosystem[END_REF][START_REF] Newman | Natural and Anthropogenic Geochemical Tracers to Investigate Residence Times and Groundwater-Surface-Water Interactions in an Urban Alluvial Aquifer[END_REF], sometimes up to 1000 [START_REF] Lapworth | Persistent and emerging micro-organic contaminants in Chalk groundwater of England and France[END_REF][START_REF] Stuart | Fingerprinting groundwater pollution in catchments with contrasting contaminant sources using microorganic compounds[END_REF]. As a result, resolution may not be high enough to establish an in-depth chemical fingerprint of groundwater bodies and to discriminate water bodies with low contrasts. In this context, passive samplers such as solid phase extraction (SPE) disk-based samplers can be useful tools as contaminants accumulate on a receiving phase over several days or weeks [START_REF] Page | Environmental monitoring of selected pesticides and organic chemicals in urban stormwater recycling systems using passive sampling techniques[END_REF][START_REF] Petrie | In Situ Calibration of a New Chemcatcher Configuration for the Determination of Polar Organic Micropollutants in Wastewater Effluent[END_REF]Pinasseau et al., 2020a;[START_REF] Shaw | Time Integrative Passive Sampling: How Well Do Chemcatchers Integrate Fluctuating Pollutant Concentrations?[END_REF][START_REF] Vermeirssen | Uptake and release kinetics of 22 polar organic chemicals in the Chemcatcher passive sampler[END_REF][START_REF] Vrana | Passive sampling techniques for monitoring pollutants in water[END_REF]. Therefore, the analyte pre-concentration allows for an increase analytical sensitivity of the procedure and a more accurate assessment of groundwater contaminants [START_REF] Brack | Towards the review of the European Union Water Framework Directive: Recommendations for more efficient assessment and management of chemical contamination in European surface water resources[END_REF][START_REF] Jones | Emerging priority substances in the aquatic environment: a role for passive sampling in supporting WFD monitoring and compliance[END_REF][START_REF] Miège | Position paper on passive sampling techniques for the monitoring of contaminants in the aquatic environment -Achievements to date and perspectives[END_REF][START_REF] Mills | Measurement of environmental pollutants using passive sampling devicesan updated commentary on the current state of the art[END_REF]. In addition, among the number of analytical methods developed for the measurement of historical contaminants and CECs in water [START_REF] Richardson | Water Analysis: Emerging Contaminants and Current Issues[END_REF], it has been proven that high resolution mass spectrometry (HRMS) coupled with a suspect screening approach allows the detection of a large number of compounds (i.e. several thousand) without reference standards or pre-selection and facilitates comprehensive screening of contaminants [START_REF] Leendert | Trends in liquid chromatography coupled to high-resolution mass spectrometry for multi-residue analysis of organic micropollutants in aquatic environments[END_REF][START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF][START_REF] Taylor | Passive sampling with suspect screening of polar pesticides and multivariate analysis in river catchments: Informing environmental risk assessments and designing future monitoring programmes[END_REF]. This qualitative approach has several advantages over the quantitative approach: calibration to determine the sampling rate of compounds is not required and an extended list of compounds can be investigated.

Therefore, combining passive sampling with suspect screening can be a powerful method to accurately characterize groundwater bodies.

The aim of the present study is to explore the benefits of passive sampling and suspect screening for historical and emerging concern contaminants (both called hereafter CECs for clarity sake) in combination with hydrochemical (NO 3 -, Cl -, SiO 2 ) and isotopic (δ 18 O and δ 2 H) tracers to characterize water bodies contributing to alluvial aquifer recharge and the J o u r n a l P r e -p r o o f potential threat for groundwater quality. Nitrate, chloride and silica were monitored as they act as an agricultural practice tracer [START_REF] Böhlke | Groundwater recharge and agricultural contamination[END_REF][START_REF] Menció | Nitrate as a tracer of groundwater flow in a fractured multilayered aquifer[END_REF], a conservative tracer [START_REF] Hem | Study and interpretation of the Chemical Characteristics of Natural Water[END_REF] and an indicator of groundwater residence time [START_REF] Marçais | Dating groundwater with dissolved silica and CFC concentrations in crystalline aquifers[END_REF], respectively. Concerning CECs, a focus was made on pesticides and pharmaceuticals, which are usually small, polar and mobile molecules that are likely to be found in groundwater [START_REF] Demir | A new screening index for pesticides leachability to groundwater[END_REF][START_REF] Dabrowski | Prioritizing agricultural pesticides used in South Africa based on their environmental mobility and potential human health effects[END_REF][START_REF] Postigo | Synthetic organic compounds and their transformation products in groundwater: Occurrence, fate and mitigation[END_REF]. The study site is an alluvial aquifer used for the drinking water production of the Lyon metropolitan area (more than 1 million inhabitants) which is recharged by mixtures of surface and groundwater sources varying both spatially and temporally [START_REF] Refloch | Compréhension expérimentale et numérique des chemins de l"eau sur l"ensemble du champ captant de la Métropole de Lyon[END_REF]. In this context, coupling hydrochemical and isotopic tracers with CECs analyses was expected as an efficient procedure to determine the contributions of several water sources to the alluvial aquifer and to point out potential zones of vulnerability for groundwater quality.

Material and Methods

Study area

The wellfield of Crépieux-Charmy is located immediately upstream of the Lyon metropolitan area (France) in the alluvial plain of the Rhône (Figure 1). The Rhône alluvial aquifer is composed of gravel layers and sand lenses, its depth is comprised between 1 and 10 m below the soil surface and its thickness between 10 and 30 m. The hydraulic conductivity at saturation is about 10 -3 to 5.10 -2 m s -1 and groundwater globally flows from east to west. The substratum is delimited by a low permeable sandy-clay layer dating from the Miocene age [START_REF] Loizeau | Water infiltration in an aquifer recharge basin affected by temperature and air entrapment[END_REF]. The natural recharge of the Rhône alluvial aquifer comes mainly from river-groundwater exchanges as well as from underground flows from the fluvio-glacial corridors of Meyzieu and Décines (Est-Lyonnais aquifer) (Figures 1 andS1). At the Crépieux-Charmy site (375 ha), the Rhône alluvial aquifer is strongly influenced by pumping for drinking water production (114 pumping wells for an average pumping rate of 240 000 m 3 J o u r n a l P r e -p r o o f per day). This groundwater extraction accelerates the recharge rate of the alluvial aquifer with several potential sources like surface waters (Miribel channel, Vieux Rhône river, and Jonage channel, Figure 1) and other groundwater sources (Est-Lyonnais aquifer, Dombes aquifer, Figure 1).

Experimental design and sampling

Two campaigns of fourteen days were performed to match the mean duration of the linear uptake regime of the majority of polar pesticides and pharmaceuticals on passive samplers [START_REF] Gunold | Calibration of the Chemcatcher® passive sampler for monitoring selected polar and semi-polar pesticides in surface water[END_REF][START_REF] Moschet | Evaluation of in-situ calibration of Chemcatcher passive samplers for 322 micropollutants in agricultural and urban affected rivers[END_REF]Pinasseau et al., 2020a;[START_REF] Vermeirssen | Passive sampling combined with ecotoxicological and chemical analysis of pharmaceuticals and biocidesevaluation of three Chemcatcher TM configurations[END_REF].

One campaign took place during summer (from August 3 rd to August 17 th 2021) and the other in autumn (from October 26 th to November 9 th 2021) to evaluate a potential seasonal effect.

Ten sampling locations were selected: three dealing with surface water samples (i.e. rivers surrounding the wellfield: Jonage channel, Miribel channel and Vieux-Rhône river) and seven dealing with groundwater samples from the 7 wells indicated in Figure 1. Sampling locations were selected based on potential vulnerability areas identified by [START_REF] Refloch | Compréhension expérimentale et numérique des chemins de l"eau sur l"ensemble du champ captant de la Métropole de Lyon[END_REF] using hydro-thermal flow modelling. Minimum distance from the nearest upstream riverbank are given for each groundwater sampling location in Table S1. The wells were built in either polyvinyl chloride or stainless steel (with a minimum internal diameter of 60 mm) perforated along their entire length.

Groundwater was collected in wells with a submerged pump (PP36 inox, SDEC, Reignac sur-Indre, France). The first 50 L pumped were used to rinse the sampling equipment and were discarded. Then, the following 6 L of pumped water were used for physico-chemical analyses. Groundwater and surface water physico-chemical analyses performed were electrical conductivity, temperature (T), pH and dissolved oxygen (DO) using portable electrical conductivity and DO meter probes (HQ20, HACH, Dusseldorf, Germany). Samples

J o u r n a l P r e -p r o o f

Journal Pre-proof of the 10 sampling locations were collected in 1 L polyethylene bottles previously washed with sampling water and brought back to the laboratory in an isotherm box at 4 °C for hydrochemical and isotopic analyses. Bottles were filled to avoid headspace and water-air equilibration prior to isotopic analyses. In addition, continuous measurements of electrical conductivity (LTC Levelogger® Junior, Solinst, Canada), DO and temperature (HOBO® U26, Onset, USA and Ponsel, Aqualabo, France), and piezometric levels (OTT Orpheus Mini, OTT HydroMet SARL, France) were monitored during the studied periods (depths of probes in piezometers are given in Table S1, mean values for each sampling location and field campaign are reported on Table S2 and evolutions of piezometric level, DO and temperature are displayed on Figure S2).

Hydrochemical analyses

Water samples dedicated to physico-chemical analyses were filtered (0.7 µm pore size Whatman™ GF/F filters, GE, Healthcare, Boston, MA, USA) to remove particles and stored at 4°C until analyses. Nitrate and nitrite (called N-NO 3 -thereafter because N-NO 2 concentrations were negligible compared with N-NO 3 -concentrations), chloride (Cl -) and silica (SiO 2 ) concentrations were measured following standard colorimetric methods, using an automatic analyzer (Smartchem 200, AMS Alliance, Frépillon, France).

Isotopic analyses

Samples for isotopic analyses were transferred in glass tubes with screw caps to prevent evaporation during storage. The tubes were filled to avoid headspace and water-air equilibration prior to analyses. Oxygen isotope (δ 18 O) of the water molecule were measured on samples stored at 4°C using a continuous flow CO 2 equilibration technique (Epstein and Mayeda's 1953;Horita et al., 1989;[START_REF] Mccarthy | Geochemistry of Champagne Hot Springs shallow hydrothermal vent field and associated sediments, Dominica, Lesser Antilles[END_REF]. The analyses were carried out using an isoFLOW automated system (Elementar UK Ltd -Cheadle Hulme UK) configured for at least 5 hours [START_REF] Lécuyer | Oxygen isotope fractionation and equilibration kinetics between CO2 and H2O as a function of salinity of aqueous solutions[END_REF]. Once equilibrated, the CO 2 gas was then transferred to the mass spectrometer via the centrION interface. Monitoring gas was a calibrated CO 2 gas. In order to anchor the results to the VSLAP/VSMOW scale, calibrated waters were analysed in the same batches as the water samples. The water working standards were calibrated against the WICO calibrated waters from the WICO intercalibration program [START_REF] Wassenaar | Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry[END_REF]. The working standard used were Apollo ( 18 O VSMOW = -10. Although the SI units to report isotopic ratios is the Urey (Ur), the traditional "‰" (permil)

notation with 1‰ = 1mUr was used for commodity. Typical external precision for 18 O analyses from water samples is 0.05‰. Samples were systematically run in triplicate.

Deuterium isotope (δ 2 H) method analysis was based on water reduction using a chromiumbased reactor following the protocol described by [START_REF] Morrison | On-Line High-Precision Stable Hydrogen Isotopic Analyses on Nanoliter Water Samples[END_REF]. Analyses were performed with a EuroEA3028-HTTM elemental analyser from Eurovector SpA (Milan-Italy). This elemental analyser was configured with a EuroAS300 series liquid autosampler

J o u r n a l P r e -p r o o f

Journal Pre-proof with a heated injector port equipped with a 1 µL 1BR-5 SGE syringe. The elemental analyser was connected online in continuous flow mode to an IsoPrime Isotopic Ratio Mass Spectrometer from Elementar UK Ltd (Cheadle Hulme-UK). The mass spectrometer was equipped with an electrostatic filter to prevent from helium interferences on hydrogen mass 3 beams. The H 3 + factor was calculated every day and was usually below 5 ppm/nA. The duration for each analytical run is approximately 300 s. Water samples collected were pipetted into 13x32 mm vials with butyl/Teflon sealed caps. Five injections were performed from each water sample. Hydrogen isotope ratios were reported relative to VSMOW in the ‰ unit, after scaling the raw data to the isotopic ratios of calibrated waters from the WICO inter calibration program [START_REF] Wassenaar | Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry[END_REF]. Drift correction was evaluated using the working standard water EE1 ( 2 H VSMOW = +12.5 ‰). Typical external precision for  2 H analyses from water samples is 0.5‰.

Suspect screening of contaminants of emerging concern (CECs)

Passive samplers were deployed during 14 days to sequester CECs like polar pesticides and pharmaceuticals from groundwater and surface water of the 10 sampling locations. Passive samplers were based on polystyrene divinylbenzene (SDB-XC) AttractSPE® disks (47 mm diameter, 12 mm particle size, 0.5 mm thick) purchased from Affinisep (Le Houlme, France).

SDB-XC SPE disks are suitable to sequester organic chemical with octanol/water partition coefficient at pH = 7.4 (logD OW ) ≤ 4 [START_REF] Burgeap ; French Charriau | Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler[END_REF]. Deployment rigs were designed to fit into piezometer dimensions (see details in [START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF]. They were placed inside piezometers one meter below the lowest groundwater level recorded since 2016 (Table S1). Each rig held 8 individual SPE disks to obtain duplicated analyses per rig (each SPE disk being extracted independently). Details of SPE disks preparation before deployment in the field and extraction after retrieval are given in [START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF]. A blank sampler For quality assurance/quality control (QA/QC), mass accuracy of the detector was monitored at the beginning of each run with a calibrant. A quality control was injected every 14 analyses to check for retention times and sensitivity during data acquisition. This quality control was a mix of standard solution of 53 compounds at 40 μg L -1 in water/methanol (90/10, v/v). These compounds were also used to correct the database retention times. Background signals were identified by analysis of blanks (solvent blank and procedural blank). Solvent blanks were also injected to monitor column carryover.

J o u r n a l P r e -p r o o f

Data process was performed using suspect screening strategy. Briefly, experimental sample data were compared with theoretical data from databases for each compound. Criteria used for evaluation of precursor and product ions were retention time, mass-to-charge (m/z) ratio and isotopic pattern. Deviations between experimental and theoretical data were scored 1 (high confidence score), 2 (medium confidence score) or 3 (low confidence score) according to tolerance thresholds set for each of the three criteria (see details in [START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF].

Additionally, the detection of at least one product ion for each precursor ion was mandatory and manual verification of chromatographic peak shapes, Δm/z and signal-to-noise (S/N) ratios was carried out in order to reduce false positives. The compounds detected in solvent blank and procedural blank were removed from the final list of detected CECs if they were ubiquitous and/or if the peak area of compounds detected in blanks was higher than 1/3 of the peak area of the same compounds in the field exposed samplers.

Statistical analysis

To characterize the hydrochemical conditions of sampling points, a Principal Component Analysis (PCA) was performed on hydrochemical and isotopic tracers and electrical conductivity using the R package FactoMineR [START_REF] Lê | FactoMineR : An R Package for Multivariate Analysis[END_REF], followed by a Hierarchical

Clustering on PCA scores (Ward method based on Euclidean distances) to discriminate sample clusters based on hydrochemistry. The mean of each hydrochemical tracer, isotopic tracer and electrical conductivity was then compared among clusters through ANOVA tests.

When significant differences were detected, Tukey"s HSD post-hoc tests (p < 0.05) were performed to determine which clusters differed. The Shapiro-Wilk"s test and the Bartlett"s test were used to verify the statistical assumptions of normality and homoscedasticity respectively. When these assumptions were not verified, values of hydrochemical tracers, isotopic tracers and electrical conductivity were compared among clusters using Kruskal-J o u r n a l P r e -p r o o f

Wallis" tests (p < 0.05). When significant differences were detected, Wilcoxon"s tests (p < 0.05) were performed to determine which clusters differed.

A correspondence analysis (CA) was performed on the presence/absence of the detected CECs to visualize and compare the seven groundwater and the three surface water sampling locations for the two sampling campaigns. A Hierarchical Clustering on CA scores (Ward method based on Euclidean distances) was then performed to discriminate sample clusters.

This method allowed to qualitatively regroup the sampling locations characterized by comparable CECs fingerprints.

All statistical analyses were carried out using R version 4.1.2 software (R Development Core

Team, 2017).

Results and discussion

Hydrochemical and isotopic tracers as well as electrical conductivity were used in combination with CECs to better understand the influence of groundwater bodies (Est-Lyonnais and Dombes aquifers) and surface water bodies (Jonage river, Miribel channel and

Vieux-Rhône river) on the Rhône alluvial aquifer used for drinking water production on the Crépieux-Charmy catchment area. CECs were also used for mapping groundwater vulnerability.

Wellfield groundwater bodies: evidence from hydrochemical and isotopic tracers

PCA was performed using chloride, nitrate and silica concentrations, δ 18 O and δ 2 H values and electrical conductivity of the seven groundwater and the three surface water sampling locations for the two sampling campaigns (Figure 2). Dimensions 1 and 2 of the PCA explained 92% of the variability contained in the data matrix, with 73% on the first axis J o u r n a l P r e -p r o o f

(Figure 2a). The correlation circle indicates which tracers had the same distributions among samples. For example, chlorides and silica presented the same distribution among samples with the highest concentrations obtained for samples having a positive score on the dimension 1 and a negative score on the dimension 2 like the samples done in W7 for the two campaigns (Figure 2b).

Hierarchical Clustering on PCA scores allowed to classify the 10 sampling locations into 3 clusters characterized by different concentrations in chloride, nitrate and silica (Kruskal-Wallis" tests, p < 0.05 for the three tracers), different water signatures in 18 O and 2 H (one-way ANOVAs, p < 0.05 for the two isotopic tracers), and different electrical conductivities (Kruskal-Wallis" test, p < 0.05).

The cluster 1 is composed of all samples collected in surface water (i.e. Jonage river, Miribel channel and Vieux-Rhône river) and almost all samples collected in groundwater sampling locations (i.e. W1, W2, W3, W4 and W5) (Figure 2b). For these samples, chlorides, nitrate and silica concentrations were comparable (i.e. about 10, 4 and 3 mg L -1 respectively; Table 1) as well as δ 18 O and δ 2 H values (i.e. about -10 and -72 ‰ respectively; Figure 3, Table S3)

and electrical conductivity (i.e. about 374 µS cm -1 ; Table S2). The comparable hydrochemical and isotopic values of surface water and groundwater suggest a rapid transfer of water from surface to the alluvial aquifer [START_REF] Marçais | Dating groundwater with dissolved silica and CFC concentrations in crystalline aquifers[END_REF]. Consequently, it can be hypothesized that, at the Crépieux-Charmy wellfield, the Rhône alluvial aquifer is mainly recharged by the Rhône surface water, with short hydrological transfers due to an intensive recharge by bank filtration.

The cluster 2 comprises only samples from W7 location (Figure 2b). These samples were characterized by significantly higher chloride and silica concentrations (i.e. about 32 and 18 mg L -1 respectively; Table 1) and significantly lower nitrate concentrations (i.e. about 0.5 mg J o u r n a l P r e -p r o o f L -1 ; Table 1) than samples from cluster 1 (Wilcoxon"s tests, p < 0.05 for the 3 parameters).

These samples were also enriched in 18 O and 2 H in comparison with samples from cluster 1 (i.e. about -9 and -63 ‰ respectively; Figure 3, Table S3) and presented significantly higher electrical conductivity (i.e. about 1400 µS cm -1 ; Table S2) than samples from cluster 1 (Tukey"s HSD post-hoc tests, p < 0.01 for 18 O and 2 H; Wilcoxon, p < 0.05 for electrical conductivity). These results highlight that the W7 sampling point is located in a different water body than samples from the cluster 1. Since W7 is located on the right riverbank of the Miribel channel, just outside the wellfield, it can be assumed that the Dombes aquifer was detected at this sampling point (Figure 1). Indeed, the watershed associated with the Dombes aquifer extends to a lower average altitude than the Rhône alluvial aquifer [START_REF] Burgeap ; French Charriau | Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler[END_REF], explaining the enrichment of water in δ 18 O VSMOW and δ 2 H VSMOW compared with samples collected in the alluvial aquifer of the Rhône River (Figure 3, Table S3).

The cluster 3 is only associated with samples collected in W6 (Figure 2b). W6 samples were characterized by significantly higher nitrate, chloride and silica concentrations (i.e. about 13, 18 and 9 mg L -1 respectively; Table 1) than samples from cluster 1 as well as significantly higher electrical conductivity (i.e. about 591 µS cm -1 ; Table S2) (Wilcoxon"s tests, p < 0.05 for the 4 parameters). The higher nitrate concentrations and electrical conductivity measured in W6 samples in comparison with samples from cluster 1 could be due to the presence of a groundwater flow coming to the studied site from the Est-Lyonnais aquifer by the south (Figure 1) via the fluvio-glacial corridors of Meyzieu and Décines (Figure S1). Indeed, nitrate concentrations of the Est-Lyonnais aquifer have been reported to be comprised between 22 and 89 mg L -1 with an average concentration of 44 mg L -1 and electrical conductivities were reported between 550 and 750 µS cm -1 (Mermillod- Blondin et al., 2019;[START_REF] Voisin | Aquifer recharge with stormwater runoff in urban areas: Influence of vadose zone thickness on nutrient and bacterial transfers from the surface of infiltration basins to groundwater[END_REF].

Therefore, groundwater collected at the W6 sampling location probably corresponded to a mixing of waters from the Rhône alluvial and the Est-Lyonnais aquifers.

J o u r n a l P r e -p r o o f

Overall, no significant seasonal effects were observed with similar hydrochemical tracer concentrations between the summer and autumn campaigns for the three clusters.

Insights from contaminants of emerging concerns (CECs)

The application of passive sampling in combination with the suspect screening allowed the detection of 125 contaminants among the 2500 pesticides and pharmaceuticals in the database. One hundred and nine CECS were detected in surface water samples and 51 in groundwater samples. Compound class, formula, theoretical exact masses, theoretical retention times, detection rates for the two sampling campaigns as well as global confidence scores are details in Table S4. From the 51 CECs detected in groundwater, 40 were detected with a global confidence score 1 or 2 (i.e. high or medium), including 22 pesticides and related transformation products (TPs), 15 pharmaceuticals and related TPs and 3 pharmaceutical-like products (Table 2). Octanol/water partition coefficient at pH = 7.4

(logD OW ) and soil adsorption coefficient (K OC ) are parameters used to predict the behaviour and occurrence of molecules in groundwater. In our case, all detected CECs have logD OW comprised between -3.1 and 3.2, indicating that they are likely to move easily in water due to their high polarity. Similarly, K OC values ranged between 1 (highly mobile) and 1337 mL g -1 (slightly mobile) with a median value of 34 mL g -1 , showing that most detected CECs were mobile. Several CECs corresponded to historical contaminants commonly reported in the literature like atrazine and TPs, caffeine, carbamazepine, carbendazim, simazine and sulfamethoxazole [START_REF] Bunting | Emerging organic compounds in European groundwater[END_REF][START_REF] Lapworth | Emerging organic contaminants in groundwater: A review of sources, fate and occurrence[END_REF][START_REF] Loos | Pan-European survey on the occurrence of selected polar organic persistent pollutants in ground water[END_REF][START_REF] Lopez | Screening of French groundwater for regulated and emerging contaminants[END_REF]. In addition, emerging contaminants, which have never been or rarely reported in the literature were also identified such as amidosulfuron, coumachlor, tritosulfuron, lamotrigine and warfarin (see Table S4 for compound class). Moreover, no differences were detected between the two campaigns as CECs detected during the summer campaign were generally detected during the autumn campaign (Table 2).

J o u r n a l P r e -p r o o f

A correspondence analysis (CA) was performed on CECs detected from the seven groundwater and the three surface water sampling locations for the two sampling campaigns (Figure 4). Dimensions 1 and 2 of the CA explained 53% of the variability contained in the data matrix, with 27% on the first axis. Hierarchical Clustering on CA scores allowed to classify the 10 sampling locations into 3 clusters (Figure 4a).

The cluster A includes the samples collected in the three Rhône surface water locations (i.e.

Jonage river, Miribel channel and Vieux-Rhône river) (Figure 4a). Detected CECs in these samples were historical (e.g. atenolol, diclofenac, terbuthylazine, tramadol) [START_REF] Mathon | Polar organic chemical integrative samplers as an effective tool for chemical monitoring of surface waters -Results from one-year monitoring in France[END_REF][START_REF] Tröger | What"s in the water? -Target and suspect screening of contaminants of emerging concern in raw water and drinking water from Europe and Asia[END_REF]Wilkinson et al., 2022) and emerging concern contaminants (e.g. amfepramone, lacosamide, niflumic acid) (Figure 4b and Table S4).

The cluster B comprises most of the groundwater samples collected in the Rhône alluvial aquifer (i.e. W1, W2, W3, W4, W5, W6). It is characterized by the detection of historic groundwater contaminants such as atrazine and related TPs, carbendazim, carbamazepine and related TPs, simazine and sulfamethoxazole (Figure 4b and Table 2), which have been reported in French and European groundwater for years [START_REF] Bunting | Emerging organic compounds in European groundwater[END_REF][START_REF] Lapworth | Emerging organic contaminants in groundwater: A review of sources, fate and occurrence[END_REF][START_REF] Loos | Pan-European survey on the occurrence of selected polar organic persistent pollutants in ground water[END_REF][START_REF] Lopez | Screening of French groundwater for regulated and emerging contaminants[END_REF]. However, some more unusual contaminants were also associated with cluster B such as lamotrigine, nicosulfuron and thiazafluron (see Table S4 for compound class). It is worth considering that W6 samples belonged to cluster B as samples located on the Rhône alluvial aquifer whereas they were clearly distinct on the PCA analysis based on hydrochemical and isotopic tracers (Figure 2b). The few detected CECs (13) in W6 samples were the same as those detected in the Rhône alluvial aquifer samples (Table 2). Besides, most CECs detected in locations belonging to cluster B were also found in samples of cluster A. However, clusters A and B were discriminated because surface water samples of cluster A were characterized by specific CECs not detected in groundwater locations. This is also due to the fact that more CECs were accumulated in passive samplers J o u r n a l P r e -p r o o f located in surface water than in groundwater sampling point given that CECs uptake is flow dependent [START_REF] Burgeap ; French Charriau | Overview of the Chemcatcher® for the passive sampling of various pollutants in aquatic environments Part A: Principles, calibration, preparation and analysis of the sampler[END_REF][START_REF] Vrana | Calibration of the Chemcatcher passive sampler for the monitoring of priority organic pollutants in water[END_REF].

The cluster C was associated with samples collected in W7 (Figure 4a) which were contaminated by pharmaceuticals of emerging concern such as methylephedrine, tolbutamide and warfarin (see Table S4 for compound class) (Figure 4b and Table 2), which have never been reported in the groundwater literature. Likewise, the rodenticide coumachlor detected in the W7 sampling point has never been documented in any aquatic environment. These results on CECs were consistent with hydrochemistry analyses demonstrating that W7 sampling point was located in a different groundwater body than the Rhône alluvial aquifer. In addition, the acidic pH and anoxic conditions measured in W7 (Table S2) could also explain why the CECs collected at this location were different from those associated with the Rhône alluvial aquifer. As it has been reported before, pH and redox conditions likely have an influence on CECs biodegradation and adsorption/desorption processes in soils [START_REF] Greskowiak | The uncertainty of biodegradation rate constants of emerging organic compounds in soil and groundwater -A compilation of literature values for 82 substances[END_REF][START_REF] Luo | Influence of different redox conditions and dissolved organic matter on pesticide biodegradation in simulated groundwater systems[END_REF][START_REF] Valhondo | Evaluation of EOC removal processes during artificial recharge through a reactive barrier[END_REF].

Complementarity of hydrochemistry and CECs for characterizing water bodies

Overall, groundwater bodies identified with hydrochemical and isotopic tracers (Figure 2)

were also pointed out with the CECs (Figure 4). Rhône river samples (cluster A) were distinguished from Rhône alluvial aquifer samples (cluster B) as more CECs were detected in surface waters than in groundwater (Figure 4). The fact that W7 sampling location (cluster C) was clearly isolated from other clusters on the correspondence analysis on CECs also demonstrates the ability of CECs to distinguish water bodies by providing a chemical fingerprint of groundwater. Such interpretation corroborates the study of [START_REF] Stuart | Fingerprinting groundwater pollution in catchments with contrasting contaminant sources using microorganic compounds[END_REF] who argued that a cocktail of micropollutants could be used to characterize groundwater bodies. Nevertheless, to be suitable as groundwater tracers to establish chemical fingerprint,

J o u r n a l P r e -p r o o f

Journal Pre-proof

CECs have to be persistent in the subsurface environment and thus, the attenuation of contaminants have to be taken into consideration [START_REF] Currell | Novel molecular tracers for the assessment of groundwater pollution[END_REF][START_REF] Mccance | Contaminants of Emerging Concern as novel groundwater tracers for delineating wastewater impacts in urban and peri-urban areas[END_REF][START_REF] Stuart | Fingerprinting groundwater pollution in catchments with contrasting contaminant sources using microorganic compounds[END_REF]. In the present study, contaminant attenuations likely occurred and were largely expected from data obtained from W6. Indeed, when considering CECs, groundwater collected from W6 had the signature of the Rhône alluvial aquifer (Figure 4). In contrast, when considering hydrochemical and isotopic tracers, its chemistry was distinct from the other sampling points, highlighting a mixing of waters from the Rhône alluvial aquifer and the Est-Lyonnais aquifer (Figure 2). This discrepancy between CECs data and hydrochemical analyses could have been due to the adsorption, the degradation and/or the dilution of the CECs commonly measured in the Est-Lyonnais aquifer during their transfer to the W6 sampling location. Effectively, analyses done in the Est-Lyonnais aquifer with the same methodology detected ubiquitous contaminants such as hexazinone and metolachlor (Pinasseau et al., 2020b[START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF], that were not detected in the present study. Hence, it supports the statement of [START_REF] Gasser | Calculation of wastewater effluent leakage to pristine water sources by the weighted average of multiple tracer approach[END_REF] and [START_REF] Massmann | Investigation of groundwater residence times during bank filtration in Berlin: a multitracer approach[END_REF] who underlined that the application of several tracers is necessary to avoid missing crucial information on subsurface processes. As specified by [START_REF] Moeck | Characterization of a managed aquifer recharge system using multiple tracers[END_REF], the use of multiple tracers also permits to minimize uncertainties in water body characterization when the chemical characteristics of water sources are not strongly contrasted.

The persistence of CECs also provides useful information on groundwater residence time and self-purification capacities. For instance, the presence of caffeine (Table 2), a marker of recent anthropogenic contamination due to its rapid degradation in the environment, is an evidence of a rapid transfer of water from surface (where contamination occurred) to groundwater [START_REF] Koroša | Estimating the transport parameters of propyphenazone, caffeine and carbamazepine by means of a tracer experiment in a coarse-gravel unsaturated zone[END_REF][START_REF] Lapworth | Deep urban groundwater vulnerability in India revealed through the use of emerging organic contaminants and residence time tracers[END_REF]. In contrast, the occurrence of persistent CECs such as carbamazepine and sulfamethoxazole (Table 2) can reflect the low self-purification capacities of the aquifer [START_REF] Fram | Occurrence and concentrations of pharmaceutical compounds in groundwater used for public drinking-water supply in California[END_REF]. The application of passive J o u r n a l P r e -p r o o f sampling in combination with suspect screening enabled a more accurate assessment of groundwater chemical fingerprint. It allowed the detection of CECs usually found at very low concentration and/or usually not investigated [START_REF] Godlewska | Pollutant analysis using passive samplers: principles, sorbents, calibration and applications. A review[END_REF][START_REF] Leendert | Trends in liquid chromatography coupled to high-resolution mass spectrometry for multi-residue analysis of organic micropollutants in aquatic environments[END_REF][START_REF] Taylor | Passive sampling with suspect screening of polar pesticides and multivariate analysis in river catchments: Informing environmental risk assessments and designing future monitoring programmes[END_REF]. For instance, CECs only detected at the W7 sampling location (i.e.

methylephedrine, tolbutamide and warfarin) would not have been detected and/or investigated with conventional spot sampling and target analysis method.

Groundwater-surface water interactions and assessment of potential vulnerability areas

The mean number of detected CECs during the two campaigns for each groundwater sampling location are shown in Figure 5. The greatest number of detected CECs were found at W3, W2 and W1 sampling locations (from 24 to 31 CECs), with the majority of the detected CECs shared with surface water (81 ± 1, 81 ± 1 and 91 ± 2 % for W3, W2 and W1 respectively). It is worth noting that these three sampling locations are the closest to the upstream riverbanks (i.e. ≤ 50 m) (Table S1). Moreover, hourly monitoring of groundwater table levels, DO concentrations and temperatures in W3 and W1 during the experiment followed the fluctuations of the same variables in surface water (Figure S2). These results clearly highlighted that W3 and W1 locations were highly connected to surface water bodies.

In comparison with samples collected from these sampling locations (W1, W2, W3), W7 and W5 contained slightly fewer CECs. All CECs detected in W5 were also present in surface waters and were probably less abundant than in W1 and W3 because this location was less connected to water surface bodies (Figure 5). In comparison, the lowest number of CECs shared with surface water (56 ± 1 %) were detected in W7 because, as underlined by hydrochemical, isotopic tracers and CECs, this sampling point was located in a different water body (i.e. Dombes aquifer; Figures 2 and4) than the other sampling locations. Indeed, J o u r n a l P r e -p r o o f several pharmaceuticals were only detected in W7 (Table 2 and Figure 4). The lack of water treatment plant or hospital in the vicinity of W7 that could explain the occurrence of these pharmaceuticals suggests a sewage leakage (as observed by [START_REF] Gaston | Prioritization Approaches for Substances of Emerging Concern in Groundwater: A Critical Review[END_REF]. This observation reveals the usefulness of the methodology based on passive sampling and suspect screening to detect unexpected sources of contamination.

Sampling locations W6 and W4 which were the farthest from upstream riverbanks (i.e. ≥ 200 m) (Table S1) exhibited the lowest numbers of detected CECs (Figure 5). We could expect to detect higher numbers of CECs in W6 given that this sampling location was influenced by the Est-Lyonnais aquifer (Figure 2) that is contaminated with around 70 pesticides and pharmaceuticals [START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF] with median concentrations of about 10 ng L -1 [START_REF] Marmonier | The use of crustaceans as sentinel organisms to evaluate groundwater ecological quality[END_REF]Pinasseau et al., 2020a). However, very few CECs were detected in W6 samples and all of them were also detected in surface waters (Table 2 and Figure 5). We can thus expect that the transfer of groundwater from the East-Lyonnais aquifer to W6 location in the wellfield site was long enough to allow the degradation and/or adsorption of contaminants [START_REF] Greskowiak | The uncertainty of biodegradation rate constants of emerging organic compounds in soil and groundwater -A compilation of literature values for 82 substances[END_REF][START_REF] Pitt | Groundwater contamination potential from stormwater in®ltration practices[END_REF][START_REF] Vystavna | Removal efficiency of pharmaceuticals in a full scale constructed wetland in East Ukraine[END_REF]. Overall, the number of detected CECs at a location appeared to be primarily related to the proximity of this location to rivers (i.e. distance from the nearest upstream riverbanks).

Conclusions

This study was the first to combine CECs determined by passive sampling and suspect screening with hydrochemical and isotopic tracer data. This approach allowed improving the determination of groundwater origins and vulnerability. By increasing the sensitivity of the analytical method and the number of CECs that can be investigated, passive sampling and suspect screening provided an in-depth chemical fingerprint of groundwater bodies. This is essential when CECs are used as anthropogenic markers and / or tracers of groundwater

  05‰), EE1 ( 18 O VSMOW = +6.44 ‰), LKD2 ( 18 O VSMOW = -20.95 ‰) and LKD3 ( 18 O VSMOW = -26.03 ‰). Aliquots of Apollo water were placed at the beginning and at the end of each analytical batch to check for potential instrumental drift with time. No significant drift was noticed during the experiments. Delta values are expressed with respect to VSMOW.

J

  o u r n a l P r e -p r o o f (procedural blank) was prepared using the same procedure to account for any contamination during each operation. Passive sampler adsorption kinetics are given inPinasseau et al. (2020a).Extracts were analysed using an Ultimate 3000 UHPLC system (Thermo Scientific®, MA, USA) equipped with a binary pump and reversed-phase analytical column, coupled to a quadrupole time-of-flight mass spectrometer (Q-ToF) (Maxis Plus, Bruker Daltonics®, Bremen, Germany). Data Analysis® 4.4 and Target Analysis for Screening and Quantitation (TASQ)® 1.4 (Bruker Daltonics®) were used for data processing. TASQ® 1.4 includes two databases (PesticideScreener 2.1 and ToxScreener 2.1) of about 2500 pesticide and pharmaceutical compounds. Separations were carried out using an Acclaim RSLC C18 column (2.1 × 100 mm, 2.2 μm particles, Thermo Fischer Scientific) maintained at 30 °C; the injection volume was 5 μL. The mobile phases consisted of: (A) water/methanol (90/10, v/v); and (B) methanol; with 5 mM ammonium formate and 0.01% formic acid in both phases for positive ionization mode. The analysis were performed in DIA mode (Data Independent Analysis) over the mass range of 80-1000 Da (see[START_REF] Pinasseau | Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff[END_REF] for details on the gradient elution and mass spectrometer parameters).

J

  o u r n a l P r e -p r o o fwhere they occur at very low concentrations, such as wellfield aquifers. Cocktails of CECs combined with hydrochemical and isotopic tracer data were proven to be useful to differentiate water bodies. In addition, occurrence and type of CECs contributed to a better understanding of short-time hydrological processes and groundwater-surface water interactions. Finally, passive sampling and suspect screening improved identification of potential vulnerability areas by allowing the investigation and detection of usually understudied contaminants. In the future, it would be relevant to assess the influence of hydrological and hydrogeological factors (e.g. river water levels, wellfield exploitation) on the findings of this study. Moreover, it would be of great interest to quantify some CECs after their accumulation on passive sampler to improve the understanding of the water flow as undertaken by[START_REF] Erostate | Coupling isotope hydrology, geochemical tracers and emerging compounds to evaluate mixing J o u r n a l P r e -p r o o f Journal Pre-proof processes and groundwater dependence of a highly anthropized coastal hydrosystem[END_REF] and[START_REF] Moeck | Characterization of a managed aquifer recharge system using multiple tracers[END_REF], and for groundwater quality assessment purposes.

Fig. 1 .Fig. 2 .Fig. 4 .Fig. 5 .

 1245 Fig. 1. (a) Location of the study area with a simplified representation of the Rhône alluvial

Table 1 .

 1 Mean hydrochemical tracer values ± standard deviation measured during the 2 campaigns for the 10 sampling locations.

	Sampling location	Cl -(mg L -1 )	NO 3 (mg L -1 ) -	SiO 2 (mg L -1 )
	Summer campaign
	Groundwater
	W1	14.93 ± 1.27 3.31 ± 0.94	4.21 ± 0.28
	W2	8.70 ± 0.36 3.46 ± 1.11	4.65 ± 0.41
	W3	9.53 ± 0.04 3.40 ± 0.09	4.85 ± 0.06
	W4	9.41 ± 1.68 3.36 ± 0.08	3.32 ± 0.01
	W5	7.09 ± 2.07 3.47 ± 0.30	2.61 ± 0.09
	W6 W7 Surface water Jonage channel Miribel channel Vieux-Rhône river Autumn campaign Groundwater W1 W2 W3 W4 W5 W6 W7 Surface water Jonage channel Miribel channel Vieux-Rhône river J o u r n a l P r e -p r o o f 18.22 ± 0.44 12.79 ± 0.11 8.56 ± 0.11 29.78 ± 2.47 0.70 ± 0.01 17.67 ± 0.82 9.55 ± 0.18 3.44 ± 0.31 1.42 ± 0.40 10.93 ± 1.58 4.27 ± 1.03 1.76 ± 0.82 8.11 ± 0.29 0.58 ± 0.02 1.20 ± 0.04 12.51 ± 1.64 4.51 ± 0.36 4.28 ± 0.22 10.36 ± 0.51 6.02 ± 0.21 4.14 ± 0.28 11.84 ± 0.15 4.80 ± 0.09 5.25 ± 0.04 10.59 ± 0.64 5.76 ± 0.65 3.71 ± 0.01 10.92 ± 1.93 5.50 ± 0.23 2.38 ± 0.10 17.62 ± 0.26 12.40 ± 0.47 8.86 ± 0.12 33.77 ± 0.47 0.30 ± 0.05 19.14 ± 1.01 9.12 ± 0.46 5.66 ± 0.016 2.60 ± 1.11 9.79 ± 1.46 6.10 ± 0.01 2.87 ± 1.07 10.15 ± 0.86 5.24 ± 0.01 2.59 ± 0.70

Table 2 .

 2 General data and physico-chemical information properties of compounds of emerging concern (CECs) (in alphabetical order) detected with a global confidence score 1 or 2, during the 2 campaigns for the 7 groundwater sampling locations (W1 to W7).

			Journal Pre-proof
	CEC	CAS	Formula	Molecula	logD OW	Koc	W	W	W	W	W	W	W
		No.		r weight	(pH=7.4	(m	1	2	3	4	5	6	7
				(g mol -1 ) c	) c	L g -
						1 ) c
	Pesticides
	2-	66753-	C 9 H 17 N 5 O	211.26	-2.1	1	X b X	X	X	X a ,
	hydroxyterbutylazin	07-9
	e*
	Amidosulfuron	120923	C 9 H 15 N 5 O 7 S 2 369.41	-1.4	1			X a
		-37-7
	Atrazine Atrazine 2-Hydroxy* Atrazine-desethyl* Atrazine-desisopropyl* Carbendazim + benomyl TP Chlorotoluron Coumachlor DEET Dichlorobenzamide * Diuron Ethidimuron Ethoxysulfuron Fluometuron Imidacloprid Metolachlor Nicosulfuron	1912-24-9 2163-68-0 6190-65-4 1007-28-9 10605-21-7 15545-48-9 81-82-3 134-62-3 2008-58-4 330-54-1 30043-49-3 126801 -58-9 2164-17-2 138261 -41-3 51218-45-2 111991 J o u r n a l P r e -p r o o f C 8 H 14 ClN 5 215.68 2.7 671 X X C 8 H 15 N 5 O 197.24 -0.7 9.7 X X C 6 H 10 ClN 5 187.63 1.5 164 X X C 5 H 8 ClN 5 173.60 1.3 116 X X C 9 H 9 N 3 O 2 191.19 1.6 175 X X C 10 H 13 ClN 2 O 212.68 2.5 530 X b X b X X X X X X C 19 H 15 ClO 4 342.77 0.8 4 C 12 H 17 NO 191.27 2.2 392 C 7 H 5 Cl 2 NO 190.02 1.3 118 X X C 9 H 10 Cl 2 N 2 O 233.10 0.1 2 X b X b X C 7 H 12 N 4 O 3 S 2 264.33 -0.01 23 X b X X C 15 H 18 N 4 O 7 S 398.39 -0.7 1 X C 10 H 11 F 3 N 2 O 232.20 2.4 455 X C 9 H 10 ClN 5 O 2 255.66 -0.21 18 X b C 15 H 22 ClNO C 15 H 18 N 6 O 6 S 410.41 -2.3 1 X X X 2 283.79 3.2 133 7 X a	X b X X X a , X a X b X X X X X X b X X X b X X X b	X X b X X
		-09-4
	Simazine	122-	C 7 H 12 ClN 5	201.66	2.3	422 X	X	X	X	X	X
		34-9
	Terbuthylazine	5915-	C 9 H 16 ClN 5	229.71	3.0	101	X b X b X
		41-3				0
	Thiazafluron	25366-	C 6 H 7 F 3 N 4 OS 240.21	1.6	183 X	X	X	X	X	X
		23-8
	Tritosulfuron	142469	C 13 H 9 F 6 N 5 O 4	445.30	1.1	12	X b X	X
		-14-5	S
	Pharmaceuticals
	4-	83-15-	C 13 H 15 N 3 O 2	245.28	0.08	26							X
	acetamidoantipyrine	8
	*
	Carbamazepine	298-	C 15 H 12 N 2 O	236.27	2.3	415 X	X	X	X	X		X
		46-4
	Carbamazepine-	36507-C 15 H 12 N 2 O 2	252.27	1.3	124 X	X	X	X	X	X b

J o u r n a l P r e -p r o o f

Acknowledgements

This work was supported by Métropole de Lyon. The authors thank the Greater Lyon Water Agency, the Rhone Mediterranean Corsica Water Agency and the Auvergne Rhône Alpes Region for logistic and financial support. We also acknowledge Yohan Lebon and Simon Navel for assisting with the field work. The 18 O/ 16 O measurements from water samples were done at the "Plateforme d"Ecologie Isotopique" (CNRS-UMR5023-LEHNA) member of the RéGEF network in Lyon (www.regef.fr/spectrometre-stables).