M.-P Turpault

S Rihs

L Mareschal

F Chabaux

D Lemarchand

Probing silicate weathering reactions in soils with B isotopes

Keywords: Boron isotopes, Breuil-Chenue, weathering, soil minerals Multiple sclerosis, Walking speed, Gait, Urination, Lower urinary tract symptoms

The determination of the mechanisms and extent of soil mineral weathering can be challenging, and the caveats reside in 1) difficulty identifying minerals that are actually involved in weathering reactions, 2) non-stoichiometric release of cations during weathering processes due to coupled dissolution, precipitation and transformation reactions and, 3) impact of vegetation activity on elemental cycles in upper soil horizons.

To better characterize mechanisms controlling mineral weathering in soils and trace the evolution of B concentration and isotope ratios during chemical weathering, quantitative mineralogical analyses were coupled to B isotopes in a group of minerals (biotite, muscovite, K-feldspar and albite). Samples were selected along an Alocrisol (Alumic Cambisol, WRB FAO) soil profile from the bedrock (at 130 cm depth) up to 20 cm depth, developed on granitic bedrock in the Breuil-Chenue forest (France).

The samples consist of residual primary minerals associated with weathering secondary phases (vermiculite, kaolinite…) in varying proportions.

The B isotopic compositions of the most pristine minerals span a very narrow range of values (around -31‰), whereas all secondary phases point to a much heavier value (around -16‰), regardless of mineralogy. Our results also show a mineral-dependent evolution of B concentration or isotopic composition as weathering progresses: no variation is observed during dissolution of K-feldspars; B behaves like a very mobile element in micas (biotite and muscovite), whereas it concentrates in weathered products derived from albite. However, rates of B concentrations and changes in isotopic compositions appear to be much faster than those inferred from mineralogy or major element concentrations determined by XRD and bulk chemical analyses, respectively. These results indicate that B is involved in very early weathering reactions and raises the question of its actual location in the structure of the various soil minerals as well as its pathway to solution.

sec at SDV versus 10.77 (3.8) sec at PV (p=0.004). No predictors of greater impairment of walking speed at SDV were identified.

Conclusion.

This study suggests a clinical impact of bladder sensation on walking speed in IwMS and urinary disorders. None of the individual characteristics could predict greater decrease in gait velocity at SDV.

Introduction

The generation of weathered particles and dissolved elements in soils and rivers is a complex process involving a combination of physicochemical and biological mechanisms. Usually, major or trace elements are used as proxies to assess the main parameters controlling weathering. These tracers have been used to determine weathering rates from soil profiles to continental scale watersheds [START_REF] Augustin | Evaluation of three methods for estimating the weathering rates of base cations in forested catchments[END_REF][START_REF] Bastian | Abrupt response of chemical weathering to Late Quaternary hydroclimate changes in northeast Africa[END_REF][START_REF] Maffre | Mountain ranges, climate and weathering. Do orogens strengthen or weaken the silicate weathering carbon sink?[END_REF][START_REF] Millot | The global control of silicate weathering rates and the coupling with physical erosion: new insights from rivers of the Canadian Shield[END_REF][START_REF] Rasmussen | Strong climate and tectonic control on plagioclase weathering in granitic terrain[END_REF][START_REF] Riebe | Controls on deep critical zone architecture: a historical review and four testable hypotheses[END_REF][START_REF] Turner | Effects of temperature on silicate weathering: Solute fluxes and chemical weathering in a temperate rain forest watershed, Jamieson Creek, British Columbia[END_REF][START_REF] Viers | Chemical composition of suspended sediments in World Rivers: New insights from a new database[END_REF][START_REF] Viville | Erosion and weathering fluxes in granitic basins: The example of the Strengbach catchment (Vosges massif, eastern France)[END_REF][START_REF] White | Quantitative Approaches to Characterizing Natural Chemical Weathering Rates[END_REF].

Determining continental weathering fluxes based on elemental mass balances from soil solutions or river chemistry may often lead to ambiguous interpretation, especially under the influence of the biota [START_REF] Ganor | Organics in Water-Rock Interactions[END_REF][START_REF] Kelly | The Effect of Plants on Mineral Weathering[END_REF][START_REF] Maher | Reactive Transport Processes that Drive Chemical Weathering: From Making Space for Water to Dismantling Continents[END_REF][START_REF] Wild | In-situ dissolution rates of silicate minerals and associated bacterial communities in the critical zone (Strengbach catchment, France)[END_REF]. Only in rare cases, when biological and lithological processes are spatially disconnected, can the distinction between bio-related mechanisms and water/rock interaction be made [START_REF] White | Chemical weathering rates of a soil chronosequence on granitic alluvium: III. Hydrochemical evolution and contemporary solute fluxes and rates[END_REF].

Boron behaves as a very incompatible element during magmatic processes [START_REF] Tonarini | Melt/biotite 11B/ 10B isotopic fractionation and the boron local environment in the structure of volcanic glasses[END_REF] and is incorporated into silicate minerals in either trigonal or tetrahedral crystallographic sites [START_REF] Anovitz | Mineralogy, petrology and geochemistry of boron; an introduction[END_REF]. In phyllosilicates such as biotite, muscovite, smectite and illite, B is either located in tetrahedral sites in substitution for Si [START_REF] Hålenius | Coordination of boron in nominally boron-free rock forming silicates: Evidence for incorporation of BO3 groups in clinopyroxene[END_REF][START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF][START_REF] Williams | Lithium and boron isotopes in illite-smectite: The importance of crystal size[END_REF] or forms surface complexes on minerals and interlayer sites [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF][START_REF] Williams | Boron isotope geochemistry during diagenesis. Part I. Experimental determination of fractionation during illitization of smectite[END_REF]. Boron can also substitute for aluminum in feldspar minerals, in trigonal sites in plagioclases [START_REF] Geisinger | Thermochemistry and structure of glasses along the join NaAlSi3O8-NaBSi3O8[END_REF][START_REF] Icenhower | Experimentally determined dissolution kinetics of Na-rich borosilicate glass at far from equilibrium conditions: Implications for Transition State Theory[END_REF][START_REF] Martens | Structural groups and their mixing in borosilicate glasses of various compositions – an NMR study[END_REF] or tetrahedral sites in K-feldspars [START_REF] Krzhizhanovskaya | A new borosilicate feldspar, KBSi3O8: synthesis, crystal structure and thermal behavior[END_REF]. The distribution of B isotopes between trigonal and tetrahedral sites is controlled by the crystallographic structure as well as the temperature of the fluid [START_REF] Gaillardet | Boron in the Weathering Environment[END_REF][START_REF] Marschall | Experimental boron isotope fractionation between tourmaline and fluid: confirmation from in situ analyses by secondary ion mass spectrometry and from Rayleigh fractionation modelling[END_REF][START_REF] Sanchez-Valle | Boron isotopic fractionation between minerals and fluids: New insights from in situ high pressure-high temperature vibrational spectroscopic data[END_REF][START_REF] Tonarini | Melt/biotite 11B/ 10B isotopic fractionation and the boron local environment in the structure of volcanic glasses[END_REF].

Therefore, the B isotopic composition of the various crystallographic sites within a same mineral can span a large range of values, with differences of about 40‰ observed between interlayer and tetrahedral sites in illite-smectite interlayered minerals [START_REF] Williams | Exploring intra-crystalline B-isotope variations in mixed-layer illite-smectite[END_REF] or up to 80‰ between interlayer and structural sites in biotite minerals (e.g., from the Bancroft ON, Canada pegmatite; [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF]. These intra-mineral heterogeneities give B the potential to be a suitable tracer of various weathering mechanisms such as phyllosilicate dissolution versus transformation [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF].

In this study, we analyzed the chemical composition as well as the B concentration and isotope ratios in a series of granite-forming minerals (biotite, muscovite, albite and K-feldspar) and their associated weathering products. Primary/secondary mineral assemblages were handpicked along a soil weathering profile. The main goal was to assess the evolution of B concentration and isotope ratios during chemical weathering of the most common granite-forming minerals, and to evaluate the potential of B as a proxy for silicate weathering reactions in soils.

Site and sampling

Site and soil

The Breuil-Chenue experimental forest site, created in 1976 by the INRA BEF team belongs to the ANAEE and SOERE F-ORE-T network. The site is located in the Morvan region (47°18' N, 4°5' E), in the northeastern part of Massif Central Mountains, on a plateau at an altitude of 638 m with a slight northwestern facing slope. The average yearly air temperature and precipitation are 9°C and 1280 mm, respectively. The bedrock comprises a two-micas granite, showing small variations in the size of the mineral grains, from 0.1 to 1 mm [START_REF] Mareschal | Effect of granite crystal grain size on soil properties and pedogenic processes along a lithosequence[END_REF]. The main mineral phases in the bedrock granite are quartz (34 to 35%), K-feldspar (23.8 to 24.2%), albite (30.3 to 31.2%), muscovite/white mica (8.1 to 8.9%), and biotite (1.2 to 2.2%) as well as some accessory minerals such as apatite and zircon [START_REF] Mareschal | Impact of common European tree species on the chemical and physicochemical properties of fine earth: An unusual pattern[END_REF][START_REF] Mareschal | Relationship between the weathering of clay minerals and the nitrification rate: a rapid tree species effect[END_REF]. K-feldspar and some albite crystallized as perthite [START_REF] Mareschal | Effect of granite crystal grain size on soil properties and pedogenic processes along a lithosequence[END_REF], and is referred to here as simply K-Feldspar.

Although this granite shows very few signs of hydrothermal alteration, some scattered evidence of later hydrothermal fluid circulation has been identified through precipitation of hematite as well as the destabilization of albite and biotite into white mica and chlorite, respectively [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF][START_REF] Mareschal | Effect of granite crystal grain size on soil properties and pedogenic processes along a lithosequence[END_REF]. Signs of hydrothermal activity are more pronounced at the boundary with the underlying unit, where aplites and pegmatites have been described with increased presence of Sn and W-rich phases (cassiterite and scheelite, respectively), some 2 km to the southwest of the study site [START_REF] Carrat | Evolution de la granitisation et du volcanisme dans le Morvan[END_REF][START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF].

The soil is classified as an Alocrisol (AFES, 1995) or Alumic Cambisol (WRB FAO) [START_REF] Mareschal | Impact of common European tree species on the chemical and physicochemical properties of fine earth: An unusual pattern[END_REF][START_REF] Mareschal | Relationship between the weathering of clay minerals and the nitrification rate: a rapid tree species effect[END_REF]. Two main mineral transformation reactions have been identified in this soil: 1) transformation of micas (muscovite and biotite) to 2:1 and hydroxy-interlayered phyllosilicates (vermiculite or smectite) in the upper soil horizon (20-30 cm), and 2) destabilization of biotite and albite into kaolinite and gibbsite in the deeper soil horizons (>1 m) (Figure 1, [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF].

Chemical compositions of primary and associated weathering minerals have been determined in an earlier study via thin sections microprobe analysis at Lorraine University in Nancy [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF].

Results are reported in Table 1. The cationic exchange capacity (CEC) is very low in the lower soil horizon (2.7-5.8 cmol.kg -1 ), but increases in the shallower horizon (9 cmol.kg -1 at 0-5 cm) due to higher organic matter content. The pH of the soil solutions range from 5.0 in the 100-140 cm soil horizon down to 3.8 in the shallowest soil horizon [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF].

Mineral separation

About 100 to 200 mg of primary granite-forming minerals (biotite, muscovite, albite and K-feldspar, Figure 1) were handpicked under a binocular microscope from bulk soil samples and from unaltered crushed bedrock. Quartz was not considered due to its very low B concentration (usually lower than 1 µg.g-1 , [START_REF] Anovitz | Mineralogy, petrology and geochemistry of boron; an introduction[END_REF][START_REF] Christ | Handbook of Geochemistry Chapter 5 -Boron[END_REF][START_REF] Yamaoka | Boron and oxygen isotope systematics for a complete section of oceanic crustal rocks in the Oman ophiolite[END_REF].

Each sample consists of a mixture of residual parent mineral and secondary/replacement phases that have precipitated within parent mineral as a result of dissolution or transformation. Because of the mineral separation procedure, possible traces of accessory minerals may remain in the handpicked mineral fraction.

Three unaltered granite samples (noted 1, 0a and 0b) were collected at three different locations within the sampling trench (30 m long, 1.4 m deep, Figure 1). The edges of the blocks were trimmed to remove the layer of regolith, and the remaining material was crushed into millimeter-sized grains before mineral separation. The bedrock exhibits traces of very localized hydrothermal alteration, with veins of quartz and hematite. Granite block #1 was collected at a depth of 0.8 to 1m in the soil (Figure 1) and shows evidence of weathering, such as precipitation of iron oxides in veins. Granite blocks #0a and #0b were sampled at a depth of about 1.4 m, at the interface between the bedrock and the soil, from which only biotite minerals were separated and analysed (samples B0a, B0b, Figure 1). Samples were collected through the soil profile: 20-30 cm, as well as 110-120 cm, 120-130 cm and 130-140 cm, corresponding to the soil horizons B1 and C, respectively (Figure 1, [START_REF] Gontier | Lack of bedrock grain size influence on the soil production rate[END_REF][START_REF] Mareschal | Impact of common European tree species on the chemical and physicochemical properties of fine earth: An unusual pattern[END_REF]. Soil sampling intervals were selected to target specific weathering reactions described in section 2.1. As such, only biotites were collected from the shallowest soil horizon (20-30 cm). Further, a distinction was made between coarse biotite grains (> 200 µm, separated from the 0.2-2 mm sieved bulk soil) and finer grains (50-200 µm) to assess the influence of grain size on B isotopes and weathering reactions. Biotite minerals were handpicked from the bulk soil matrix before being processed through a magnetic sector and vibrator (AA DYNA-MITE Electric vibrator 230V 50Hz, 10VA) for further separation from other mineral phases. Traces of accessory minerals were likely in the separated mineral phases, especially from those extracted from unaltered granite bedrock.

Of all albite samples, one sample collected between 1.3 and 1.4 m depth was showing mineralogical evidence of hydrothermal alteration (traces of hematite) and is hereafter referred to as AH.

Soil solution extraction

Pore and bound soil solutions were collected in soil horizons from which mineral samples were collected (20-30 cm and 120-140 cm, Figure 1). Water was extracted from the soil samples via centrifugation (Jouan KR422 centrifuge) using double-bottomed polycarbonate containers, precleaned with 0.5N HCl to minimize potential B contamination. Centrifugation was performed in two steps, starting with 20 min at 1000 rpm (acceleration of ≈ 180 G, pF = 3.25) followed by 20 min at 3000 rpm (≈ 2750 G, pF = 4.2) in order to extract pore and bound water, respectively [START_REF] Turpault | Influence of mature Douglas fir roots on the solid soil phase of the rhizosphere and its solution chemistry[END_REF]. A total volume of about 250 mL of water was extracted for each depth, corresponding to a mass of soil of ≈11 kg for the 20-30 cm horizon and ≈ 25 kg in the deepest horizon (Table 2). No pore water was extracted in the deepest soil horizon (120-140cm).

Analytical methods

Differential thermal analyses

Differential thermal analyses were used to directly quantify the amount of gibbsite and kaolinite in the samples. These analyses were conducted on about 10 mg of solid sample [START_REF] Caner | Accumulation of organo-metallic complexes in laterites and the formation of Aluandic Andosols in the Nilgiri Hills (southern India): similarities and differences with Umbric Podzols[END_REF] using a TA Instrument SDT Q600 at the Laboratoire Hydrasa (Université de Poitiers). During the procedure, the temperature was gradually increased at a rate of 10°C/min from 25 to 1000°C, while precisely monitoring the mass of the sample [START_REF] Kissinger | Reaction Kinetics in Differential Thermal Analysis[END_REF]. The mass loss between 250 and 285°C allows direct quantification of gibbsite from sample as follows:

= ∆ ∆ (eq. 1)
where is the fraction of gibbsite in the solid sample, ∆ and ∆ correspond to the relative weight loss between 250 and 285°C of the sample and the pure gibbsite, respectively (∆ = 31.2 %) [START_REF] Dejou | Évolution superficielle des roches cristallines et cristallophylliennes dans les régions tempérées[END_REF]. Similarly, the relative amount of kaolinite can be determined from the relative mass loss between 440 and 550°C (∆ = 13.6%) [START_REF] Dejou | Évolution superficielle des roches cristallines et cristallophylliennes dans les régions tempérées[END_REF].

X-ray diffraction

Identification of major mineral phases was performed by X-ray diffraction analyses on powdered samples at the Laboratoire de Biogéochimie des Ecosystèmes Forestiers (BEF, INRA, Champenoux) using a Siemens D5000 diffractometer fitted with a graphite monochromator with selected Cu-Kα radiation (30 mA/40 kV). X-ray diffraction data were collected from 1.5° to 70.2° with a 0.01° increment and 6 seconds acquisition time. In order to distinguish chlorite from vermiculite and hydroxyl-interlayered-vermiculite in biotite samples, additional X-ray diffraction analyses were performed on K-saturated oriented samples heated at 110, 330, 440, 550 and 650°C. For these analyses, diffracted rays were collected from 2° to 20° with an increment of 0.01° and 3 seconds acquisition time.

Scanning electron microscopy

Scanning electron microscopy (SEM) was used to confirm the presence of mineral phases identified by X-ray diffraction. A Tescan Vega II microscope equipped with an Edax Pegasus X-ray analysis device was used at the Laboratoire d'Hydrogéologie et de Géochimie de Strasbourg (LHyGeS).

Samples were deposited on glass slides and carbon coated. Both secondary electron and backscattered electron detectors were used.

Major element concentrations

Samples were dried at 110°C before calcination at 1000°C to determine water content and loss on ignition, respectively. After alkaline fusion with lithium tetraborate, concentrations of major elements were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES)

and inductively-coupled plasma mass spectrometry (ICP-MS). Fifty (50) mg of calcinated samples were mixed with lithium tetraborate with a sample/flux ratio of 7.5 and placed in an oven under controlled Ar atmosphere at 1000°C for 30 minutes. The fusion residue was then dissolved in a nitric acid/glycerin solution [START_REF] Besnus | Une methode d'analyse des roches au spectrometre d'arc à lecture directe par un dispositif d'électrode rotative[END_REF][START_REF] Samuel | Analyse multiélémentaire standardisée des matériaux géologiques en spectrométrie d'émission par plasma à couplage inductif = Geological materials standardized multi-analysis with inductively-coupled plasma emission spectrometry[END_REF]. The overall analytical uncertainty is < 3 % (±2σ) for major element concentrations.

Quantitative mineralogy

X-ray diffraction data (see annex Figure A1) and SEM observations were combined to identify significant mineral phases in each sample (Table 3). Based on differential thermal analyses, the contributions of kaolinite and gibbsite to the bulk chemical composition were subtracted, and the relative proportion of each remaining mineral phase was ascertained by solving the following system of equations, similarly to normative mineralogy of igneous rocks [START_REF] Ezzaïm | Quantification of weathering processes in an acid brown soil developed from tuff (Beaujolais, France) Part II. Soil formation[END_REF]Fichter et al., 1998a;Fichter et al., 1998b;[START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF][START_REF] Turpault | Elements in soils: total and extractable contents, solid phase speciation[END_REF]:

!"# $ = ∑ × !"# $ '( $ # ) = ∑ × '( $ # ) *+# = ∑ × *+# ,-# = ∑ × ,-# . $ # = ∑ × . $ # /0 $ # = ∑ × /0 $ # (eq. 2)
where !"# $ , '( $ # ) , *+# , ,-# , . $ # , /0 $ # refer to concentrations of different cations in the mineral assemblage; is the mass fraction of the mineral i and !"# $ , '( $ # ) , *+# , ,-# , . $ # , /0 $ # correspond of the cation concentration in each mineral. The composition of primary and secondary mineral phases (Table 1) and major element concentrations (Table 4) were used to solve the system of equations.

Boron concentrations and isotopic compositions

Boron was extracted from solid samples using K2CO3 alkaline fusion [START_REF] Lemarchand | Boron isotopes in different grain size fractions: Exploring past and present water'Äìrock interactions from two soil profiles (Strengbach, Vosges Mountains)[END_REF]. Fifty (50) mg of sample was analysed for both B concentration and isotopic composition. A 1:5 sample/flux ratio was used, and the mixture was placed in Pt-Au crucibles before heating at 950°C for 15 min in a muffle furnace [START_REF] Cividini | From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)[END_REF]. Boron was then extracted from the fusion residue by 3 successive leaching steps using 1mL of ultra-pure water [START_REF] Cividini | From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)[END_REF]. Boron concentrations were determined by Quadrupole ICPMS at LHyGeS on an aliquot of recovered leaching solution after a 10x dilution [START_REF] Lemarchand | Boron isotopes in different grain size fractions: Exploring past and present water'Äìrock interactions from two soil profiles (Strengbach, Vosges Mountains)[END_REF]. The long-term reproducibility of the method is 6% (±2SD).

Following a chemical purification using the B-specific resin Amberlite IRA-743 [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF], B isotopic compositions were subsequently determined by multi-collector ICP-MS (Thermo-Finnigan Neptune). The total procedural contamination is about 15 ng B and originates primarily from the muffle furnace and flux [START_REF] Prigent | Transfer of subduction fluids into the deforming mantle wedge during nascent subduction: Evidence from trace elements and boron isotopes (Semail ophiolite, Oman)[END_REF]. This contamination typically represents less than a few percents of the total B analysed and has a B isotopic composition (about -10 ‰) that is close to some of the samples that were measured, thus leading to limited potential isotopic shift. Boron isotopic compositions are expressed as the deviation in ‰-units from the NIST SRM 951 B isotopes standard processed though the same procedure as the samples: -1> × 1000 (eq. 3)

1 = 2
The long-term reproducibility of the entire B isotope analysis procedure is 0.6 ‰ (±2σ, n = 19) [START_REF] Cividini | From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)[END_REF][START_REF] Lemarchand | Boron isotopes in different grain size fractions: Exploring past and present water'Äìrock interactions from two soil profiles (Strengbach, Vosges Mountains)[END_REF]. Chemical compositions (major elements) as well as B concentrations and isotopic compositions of the samples are reported in Table 4.

Results

The mineral phases identified by XRD and SEM in each sample are reported in Table 3. Results from the quantitative mineralogy calculations, as well as B concentrations and isotopic compositions are illustrated in Figures 2 and3, respectively. Results for the differential thermal and X-ray diffraction analyses are provided in annex Figures A1 andA2.

K-feldspar

The combination of XRD, chemical and differential thermal analyses show no evidence of secondary phases in K-feldspar samples (Figures 2 andA1, Table 3). Although chemical analyses of K-feldspars show slight increase of the Na2O/K2O ratio with depth, suggesting a preferential dissolution of the albite end-member, both B concentrations and isotopic compositions in handpicked K-feldspars remain relatively constant along the soil profile, from 6.2 to 11.6 µg.g -1 and -33.2 to -30.3 ‰, respectively (Figure 3a).

Muscovite

Biotite

Quantitative mineralogy calculations performed on biotite collected in the deeper soil horizons (B1, B2, B3 and B4) exhibit a gradual decrease of the proportion of biotite with decreasing depth, from 90 to 60 %, while vermiculite and kaolinite proportions increase at shallower depths (Figure 2).

Overall, B concentrations in biotite samples cover a large range of values from 0.9 to 80 µg.g -1 and tend to decrease as the proportion of secondary phases increases. In parallel, δ 11 B values increase with the proportion of secondary phases, from about -30‰ in the non-weathered biotite to about -16 ‰ in the most weathered samples (Figures 2 and3c). Biotite samples picked from unaltered granite (samples B0a and B0b) exhibit variable B concentrations (21 and 74 µg.g -1 , respectively) and (-31.1 ‰ and -26.8 ‰, respectively) but show small variations in their mineralogical composition (Figures 2 and3c).

δ 11 B values
In the shallowest soil horizon (20-30 cm), the coarse-grained biotite (B5a, B5b, > 200 µm) shows mineralogical compositions that are intermediate between those from non-weathered granite (B0a and B0b) and the biotite samples picked in the deeper soil horizons (B2 and B3), with small amounts of vermiculite and kaolinite and high proportion of biotite (>60 %) (Figure 2). Samples B5a and B5b also contain small amounts of chlorite, and exhibit slightly higher isotopic compositions (-23.5 and -23‰, respectively) together with higher B concentrations (up to 80 µg.g -1 ) than biotite sampled in unaltered granite.

Finer grained samples collected from the same soil horizon (20-30cm, 50-200 µm fraction) are more weathered and exhibit much lower amounts of residual parent biotite -between 19 % and 26 % for samples B6b and B6a, respectively -associated with higher proportions of vermiculite (32-33 %) and kaolinite (around 24-25 %).

All samples contain approximately 10% quartz, including biotite grains sampled within the granite (samples B0a, B0b and B1), and likely result from the mineral separation process. Traces of Ti oxides (around 1 to 2 % in most samples) are also found, as well as up to 0.8% chlorite in samples B0b, B5a, B5b and B6a, with no direct correlation with B concentration or isotopic composition.

Albite

Albite picked from seemingly pristine looking granite (A1) contains about 15%. In albite collected within the saprolite (samples A2, A3 and A4), the parent albite minerals have almost entirely been replaced with kaolinite. SEM analyses of sample A2 (130 -140 cm) reveal a highly altered sponge-like structure (Figure 4) composed primarily of kaolinite, with only traces of residual albite.

Traces of quartz, muscovite as well as traces of gibbsite (< 2 %) are found in all albite samples.

Sample AH contain a significant amount of hematite (about 3%) likely resulting from hydrothermal alteration.

In contrast to biotite, B concentrations increase in weathered albite when δ 11 B values increase from -24.7 ‰ (A1) to -15.4 ‰ (A4). Compared with other albite samples, sample AH, shows evidence of hydrothermal alteration, and is characterized by a much higher B concentration (472 µg.g -1 ) and a lower B isotopic composition (-27.9 ‰).

Soil solutions

The extraction method used doesn't access water trapped within the phyllosilicate interlayers.

Accessing this water would require a specific technique such as ion exchange, followed by neutron diffraction (OECD, 2000;[START_REF] Powell | Interlayer water structure in Na-and Li-montmorillonite clays[END_REF][START_REF] Skipper | The structure of interlayer water in vermiculite[END_REF]. Pore waters could only be collected from the uppermost soil layer (20-30 cm), as deeper soil samples from the 110 -140 cm horizon were dry. Boron concentration and isotopic composition of shallow pore waters are 12 ng.mL -1 and +30.3 ‰, respectively (Table 2). The shallow bound water shows a slightly lower B concentration (8.4 ng.mL -1 ) and lower B isotopic composition (+22.3 ‰). The deeper bound water (110-140 cm) is characterized by a higher B concentration (12.5 ng.mL -1 ) and slightly lower B isotopic composition (+18.9 ‰).

Discussion

Influence of sorting residues

Most samples contain between 0 and 20 % of accessory minerals, that couldn't be separated during the mineral selection process. These include: quartz in biotite and albite, K-feldspar in muscovite and muscovite in albite (except for albite sample AH which exhibits a quartz proportion of about 35%, Figure 2). These are hereafter referred to as sorting residues.

Given that quartz in granitic rocks is usually characterized by very low B concentrations below 1 µg.g -1 [START_REF] Anovitz | Mineralogy, petrology and geochemistry of boron; an introduction[END_REF][START_REF] Christ | Handbook of Geochemistry Chapter 5 -Boron[END_REF][START_REF] Yamaoka | Boron and oxygen isotope systematics for a complete section of oceanic crustal rocks in the Oman ophiolite[END_REF], the presence of quartz in the samples only affects B concentration through dilution, but is not expected to impact the δ 11 B value. K-feldspar samples don't show any evidence of accessory minerals and can therefore be considered as pure. ‰. This contribution is not negligible and is greater than the analytical precision (about 0.6‰) but remains small compared to the observed range of B isotopes variation in albite samples (≈ 15 ‰).

Boron in primary non-weathered minerals

With the exception of albite sampled in seemingly unaltered granite (A1), which shows evidence of early weathering (presence of kaolinite), all δ 11 B values in non-weathered minerals span a very narrow range of values at -31 ± 3‰ (Figure 3). These values are lower than the continental crust inferred from B isotope analyses in tourmaline (-7 ‰, Chaussidon and Albarède, 1992) but are consistent with published analyses of soil profiles developed on granite bedrock, like values from the Strengbach catchment [START_REF] Cividini | From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)[END_REF][START_REF] Lemarchand | Boron isotopes in different grain size fractions: Exploring past and present water'Äìrock interactions from two soil profiles (Strengbach, Vosges Mountains)[END_REF] or the Guyana Shield [START_REF] Spivack | The sedimentary cycle of the boron isotopes[END_REF]. These low values suggest cogenetic minerals in plutonic rocks have similar δ 11 B values.

This is probably a result of the relatively small B isotopic fractionation coefficient (α = 1.005) observed during crystallisation of silicate melts, as well as to the fact that B occupies similar crystallographic sites in silicate minerals, substituting for Si or Al [START_REF] Marschall | Experimental boron isotope fractionation between tourmaline and fluid: confirmation from in situ analyses by secondary ion mass spectrometry and from Rayleigh fractionation modelling[END_REF][START_REF] Tonarini | Melt/biotite 11B/ 10B isotopic fractionation and the boron local environment in the structure of volcanic glasses[END_REF] 3c and3d).

In addition, the biotite samples B0b and B5a contain traces of chlorite (about 0.4%) and sample AH contains traces of hematite. This seems to point towards a potential hydrothermal or supergene alteration fluid imprint on B isotopic composition, as chlorite and hematite have been identified as indicators of hydrothermal fluid interaction in the study site [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF]. High B concentrations reaching several hundreds of µg.mL -1 have been observed in hydrothermal fluids, and exchange of B between host minerals and hydrothermal fluids is possible [START_REF] Aggarwal | Fractionation of boron isotopes in Icelandic hydrothermal systems[END_REF][START_REF] Boschi | Boron isotope systematic of marine hydrothermal fluids: New insights from the Lost City Hydrothermal System[END_REF][START_REF] Yamaoka | Boron isotope geochemistry of vent fluids from arc/back-arc seafloor hydrothermal systems in the western Pacific[END_REF][START_REF] Zeng | Boron isotope compositions of fluids and plumes from the Kueishantao hydrothermal field off northeastern Taiwan: Implications for fluid origin and hydrothermal processes[END_REF].

Boron in weathered minerals

Samples showing the highest proportions of secondary minerals (biotite B6a, B6b, B3, B4, and albite A2, A3, A4, Figures 2 and5) have similar δ 11 B values around -18.5‰ ± 1.5‰. Sample M4 exhibits a similar δ 11 B value, yet exhibits no chemical and XRD evidence of mineralogical alteration.

Possible explanations for this homogeneous B isotopic composition in all weathered minerals may involve either 1) B exchange between pore waters and all phases found in the mineral habits, which has been observed in high temperature systems but not at surface conditions [START_REF] Bobos | Boron, lithium and nitrogen isotope geochemistry of NH4-illite clays in the fossil hydrothermal system of Harghita Bãi, East Carpathians, Romania[END_REF][START_REF] Clauer | Illitization decrypted by B and Li isotope geochemistry of nanometer-sized illite crystals from bentonite beds, East Slovak Basin[END_REF][START_REF] Tonarini | Melt/biotite 11B/ 10B isotopic fractionation and the boron local environment in the structure of volcanic glasses[END_REF]; 2) a preferential release of B from different crystallographic sites (i.e., structural or water-accessible sites), each characterized by distinct δ 11 B signatures [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF][START_REF] Williams | Boron isotope geochemistry during diagenesis. Part I. Experimental determination of fractionation during illitization of smectite[END_REF] or 3) a difference in the weathering rate of at least two generations of parent minerals characterized by distinct δ 11 B values.

All weathered minerals span a very restricted range of δ 11 B values despite the large variety of mineral phases observed, with varying amounts of primary mineral residues associated with secondary minerals like vermiculite, kaolinite or gibbsite (Figure 5). A common δ 11 B signature in different minerals suggests similar mechanisms controlling the incorporation of B into mineral weathering products. The observed isotopic fractionation (∆ 11 Bsolid-solution) is therefore not mineral specific, but instead reflects similar crystallographic environment, with 10 B enriched tetrahedral B(OH)4 -being preferentially adsorbed onto the mineral surfaces [START_REF] Gaillardet | Boron in the Weathering Environment[END_REF][START_REF] Lemarchand | How surface complexes impact boron isotope fractionation: Evidence from Fe and Mn oxides sorption experiments[END_REF][START_REF] Muttik | Boron isotope composition of secondary smectite in suevites at the Ries crater, Germany: Boron fractionation in weathering and hydrothermal processes[END_REF][START_REF] Spivack | The sedimentary cycle of the boron isotopes[END_REF][START_REF] Williams | Boron isotope geochemistry during diagenesis. Part I. Experimental determination of fractionation during illitization of smectite[END_REF].

Considering that trapped pore water have a δ 11 B value around +20‰ (Table 2), and that the typical B isotopic fractionation generally observed between solids and solution at low temperature (∆solidsolution) is close to -35‰ [START_REF] Gaillardet | Boron in the Weathering Environment[END_REF]Lemarchand et al., 2012 and discussion therein;[START_REF] Lemarchand | How surface complexes impact boron isotope fractionation: Evidence from Fe and Mn oxides sorption experiments[END_REF][START_REF] Muttik | Boron isotope composition of secondary smectite in suevites at the Ries crater, Germany: Boron fractionation in weathering and hydrothermal processes[END_REF][START_REF] Spivack | The sedimentary cycle of the boron isotopes[END_REF], minerals in isotopic equilibrium with the pore water would have δ 11 B values close to -15‰, consistent with minerals analyzed in this study. Similar observations were made on the evolution of B in the clay-size fractions collected from the Strengbach watershed [START_REF] Lemarchand | Boron isotopes in different grain size fractions: Exploring past and present water'Äìrock interactions from two soil profiles (Strengbach, Vosges Mountains)[END_REF]. However, the pore water value measured in this study only is a snapshot of the hydrogeochemical conditions at a given instant in time (July 2012), that can't be extrapolated to the several thousands of years required for the soil to develop [START_REF] Moore | Crust Formation Effects on Soil Erosion Processes[END_REF][START_REF] Stevens | The Chronosequence Concept and Soil Formation[END_REF].

Interestingly, some samples show only minor changes in their mineralogical and chemical composition (muscovite samples M2, M3 and M4), yet exhibit δ 11 B values similar to those observed in the most weathered products (δ 11 B ≈ -16 ‰ for sample M4) (Figures 2 and5). This observation infers a large proportion of B in the bulk mineral can potentially exchange with the surrounding environment without evidence of alteration of mineralogical or crystallographic properties. Thus, a large proportion of B in these minerals is in exchangeable sites, such as reactive surfaces like those found in the interlayers, grain boudaries or crystal defects. The transfer of B to solution appears much faster than major elements, which is in agreement with previous laboratory dissolution experiments [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF][START_REF] Williams | Boron isotope geochemistry during diagenesis. Part I. Experimental determination of fractionation during illitization of smectite[END_REF]. In both micas, the relatively rapid transfer of similarly to what has been observed in laboratory studies [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF][START_REF] Williams | Exploring intra-crystalline B-isotope variations in mixed-layer illite-smectite[END_REF]. While facilitated matter transport is expected in phyllosilicates where interfoliar spaces can be efficient water pathways, it challenges our understanding of water and element transport across a crystallized lattice as found in albite.

Boron: a proxy of weathering regime?

The similarity in B isotopic composition between cogenetic silicate minerals can potentially be used to trace the source(s) of parent materials as well as to give information about the weathering regime, provided that 1) the signature of unaltered parent material can be recovered from samples and 2)

there is an observable difference between the B isotopic composition of weathered products and parent minerals. This difference can be magnified by two conditions: 1) in systems dominated by dissolution reactions leading to a relatively small rate of B incorporation into secondary phases, and

2) in systems where vegetation cover, which represents an isotopically fractionated B pool, is dense enough to control the B isotopic composition of solutions which precipitate secondary products (e.g. [START_REF] Cividini | From biological to lithological control of the B geochemical cycle in a forest watershed (Strengbach, Vosges)[END_REF].

From this study, analyses of B isotopes in K-feldspar demonstrate that their dissolution in soils occurs without observable isotopic fractionation. The B isotopic composition of these minerals therefore remains unchanged during the development of the weathering profile and can be potentially used as a reference to compare against weathering products. Similarly, the homogeneity of B isotopic compositions observed in different weathering products reflects the signature of the local weathering regime, which can be described as the ratio between dissolution and precipitation rates, including a potential contribution of organic matter and atmospheric B inputs. The results of this study therefore indicate that the comparison of B isotopes between pristine primary minerals (i.e. Kfeldspars) and secondary products (i.e., clay minerals) could potentially be used in various natural environments to resolve processes of source mixing and secondary mineral formation or transformation of primary mineral phases, similarly to what has been shown in laboratory experiments [START_REF] Voinot | Experimental dissolution vs. transformation of micas under acidic soil conditions: Clues from boron isotopes[END_REF] or observed in natural systems [START_REF] Ercolani | Insights on catchment-wide weathering regimes from boron isotopes in riverine material[END_REF].

The results herein also demonstrate that the discrepancy between the evolution of the mineral assemblage (inferred from X-ray diffraction and major element composition) and B isotopes is mineral dependent (Figures 5 and6). This property can potentially be used to determine the extent of weathering reactions with more refinement than major element or traditional mineralogical methods, or to identify the earliest stages of weathering reactions in soils. For example, if the δ 11 B values measured in biotite minerals are close to the ones measured in muscovites and in K-Feldspars, this would indicate a very early stage of weathering. In other cases, the progression of the weathering reactions would differentially affect each mineral assemblage (Figures 5 and6).

Boron concentration variations in weathered albite crystals differ from micas. Almost all albite crystals show a near complete loss of the primary albite form by kaolinite mass (about 75%).

However, contrary to what can be observed in micas, the B concentration progressively increases with the extent of weathering of the parent material, reaching up to 185 µg.g -1 , about twice the value of the least weathered albite sample A1. Such an increase of the B concentration together with the evolution of B isotopes may be explained by two different processes:

1) the presence of a low-solubility B-rich phase with a B isotopic composition close to -15‰ that progressively controls the B mass balance as the weathering reaction progresses. In order to explain B behaviour in all the samples, this accessory phase should be found in both micas and albite but not in K-feldspar. This phase should only be found at trace level in micas, as the B concentration in weathered products almost decreases to the analytical detection limit, but be in much larger proportion in albite to explain the increase in B concentration. Tourmaline might be a potential candidate for such an accessory mineral phase, but it has not been observed in our samples and so far, none of our observations can support this hypothesis.

2) the development of a very large reactive water/rock interface allowing a large amount of B to be incorporated in secondary products. Like other elements, such as U and Mo, specific chemical conditions can lead to very strong affinity with clay minerals and can show adsorbed concentrations of several hundreds of µg.g -1 [START_REF] Davey | Adsorption of Uranium on Clay Minerals[END_REF][START_REF] Li | Study on Adsorption of Uranium in Wastewater by Clay[END_REF][START_REF] Sikalidis | Adsorption of uranium and thorium from aqueous solutions by the clay minerals montmorillonite and vermiculite[END_REF][START_REF] Tournassat | Modeling uranium(VI) adsorption onto montmorillonite under varying carbonate concentrations: A surface complexation model accounting for the spillover effect on surface potential[END_REF][START_REF] Xu | A Review of Molybdenum Adsorption in Soils/Bed Sediments: Speciation, Mechanism, and Model Applications[END_REF]. It may be hypothesized that the development of a very small and dense porous network as the albite minerals are being weathered could generate such a large reactive surface. This hypothesis is supported by SEM analyses of the weathered albite samples (Figure 4) that clearly show a sponge-like porous structure. This is a well-known evolution of albite minerals for which the surface of water-rock interaction can increase by a factor of two during weathering [START_REF] White | Differential rates of feldspar weathering in granitic regoliths[END_REF]. Similar to the B-specific resin (Amberlite IRA 743), where the spongy structure leads to apparent huge partitioning coefficient [START_REF] Lemarchand | An optimized procedure for boron separation and mass spectrometry analysis for river samples[END_REF], it can be hypothesized that the formation or activation of nano-channels may considerably increase the reactive surface of the mineral and lead to an accumulation of B in the weathered albite product. This hypothesis, which seems to best fit our data, also points to a very different description of the weathering reactions than those used in classic numerical models. Precipitation of secondary products would not be controlled by supersaturation of the bulk solution with respect to secondary phases after dissolution of the primary ones, but would be controlled by the mineralogy of the mineral parent. For biotite, the low B concentration would indicate an efficient transport of water, thus draining mobile elements. For albite, the development of a nano-to micro-porous network would drastically increase the reactive surface while slowing down the velocity of water (high porosity, but low permeability), thus leading to an enhanced incorporation of soluble elements.

Conclusion

Investigation of B concentration and isotopic composition in weathered silicate minerals (biotite, muscovite, albite and K-feldspar) with associated secondary phases (gibbsite, kaolinite, vermiculite)

clearly emphasizes B sensitivity to water-rock processes. The homogenous B isotopic signature in the initial primary minerals on one hand and secondary weathering products on the other can greatly help understanding weathering conditions. In particular, combining B isotope analyses in minerals with varying weathering rates could help identify the primary mineral source of B and bring quantitative information on the soil forming mechanisms.

Among the minerals analyzed in this study, combined analyses of K-feldspar and muscovite minerals appear to be an ideal way to investigate weathering processes in soils, as these minerals show This study points to unresolved questions that require further investigations. In particular, it remains unclear if the B isotopic composition of secondary phases reflects isotopic equilibrium with the surrounding solution or a preferential disruption of specific B-bearing sites. In addition, B shows a very high mobility B in minerals showing no evidence of crystallographic transformation.

Once the mechanisms controlling the B distribution in weathered silicate minerals will be better understood, combined B analyses in soil or rivers detrital mineral grains would certainly provide strong information on weathering controls and help understanding sedimentary records.

Introduction

Multiple sclerosis (MS) causes demyelinating lesions and could be responsible for a number of symptoms, including motor or sensitivity disorders, cognitive impairment, visual disturbances, and urinary and bowel disorders. Gait difficulties are the most visible disability, and about 70% of patients report a psychological impact due to their walking impairment [START_REF] Larocca | Impact of walking impairment in multiple sclerosis: perspectives of patients and care partners[END_REF].

Different neurological presentations can be observed in different individuals: spastic, ataxic, cerebellar, and pyramidal forms, depending on the topography of the cerebral or medullar lesions. Lower urinary tract symptoms (LUTSs) are also very common, with a prevalence of 32% to 86% [START_REF] De Sèze | The neurogenic bladder in multiple sclerosis: review of the literature and proposal of management guidelines[END_REF]. Overactive bladder with urgency, increased bladder frequency and urgency urinary incontinence is the most common symptoms. Obstructive symptoms are also frequent and may coexist with storage symptoms. Detrusor overactivity is the most frequent urodynamic profile, but the correlation between clinical symptoms and urodynamics data is not perfect. Other urodynamic profiles exist: bladder oversensitivity, detrusor-sphincter dyssynergia, and neurogenic detrusor underactivity, but urodynamics can be normal for 1% to 34% of patients with LUTSs [START_REF] De Sèze | The neurogenic bladder in multiple sclerosis: review of the literature and proposal of management guidelines[END_REF][START_REF] Fragalà | Association Between the Neurogenic Bladder Symptom Score and Urodynamic Examination in Multiple Sclerosis Patients With Lower Urinary Tract Dysfunction[END_REF]. Despite a correlation between frequency and severity of LUTSs and severity of incapacity assessed by Expanded Disability Status Scale (EDSS) [START_REF] Koldewijn | Relationship between lower urinary tract abnormalities and disease-related parameters in multiple sclerosis[END_REF] or with number of falls [START_REF] Sung | Bladder function and falls in individuals with multiple sclerosis[END_REF], no strict relationship can be demonstrated between type of LUTS, urodynamics profile and type of neurological presentation (pyramidal, with or without major spasticity, cerebellar etc.) [START_REF] Koldewijn | Relationship between lower urinary tract abnormalities and disease-related parameters in multiple sclerosis[END_REF][START_REF] Giannantoni | Lower urinary tract dysfunction and disability status in patients with multiple sclerosis[END_REF].

The role of bladder filling and need to void on gait has been poorly studied and only in healthy populations. Yet, some hypotheses could support a link between these 2 parameters.

The need to void is a sensory stimulus, integrated in different cerebral areas, including insula, periaqueductal gray, cingulate cortex, hypothalamus and prefrontal area [START_REF] Athwal | Brain responses to changes in bladder volume and urge to void in healthy men[END_REF][START_REF] Khavari | Functional Magnetic Resonance Imaging with Concurrent Urodynamic Testing Identifies Brain Structures Involved in Micturition Cycle in Patients with Multiple Sclerosis[END_REF]. A modification in gait velocity with emotions was demonstrated. Jousse et al. showed a decrease in attentional skills with a strong desire to void (SDV) [START_REF] Jousse | Need to void and attentional process interrelationships[END_REF]. These 2 studies may suggest a possible impact of the need to void on gait velocity, as a new sensory phenomenon to integrate and modulate, as a function of the locomotion task.

At the medullar stage, a modification of the H-reflex was demonstrated at SDV in healthy individuals [START_REF] Inghilleri | Bladder filling inhibits somatic spinal motoneurones[END_REF]. The H-reflex is considered to reflect motoneuronal excitability. The impact of motoneuronal excitability on gait is not clearly established, but some studies revealed a modification of the H-reflex with gait velocity [START_REF] Simonsen | Amplitude of the human soleus H reflex during walking and running[END_REF][START_REF] Hodapp | Modulation of soleus H-reflexes during gait in healthy children[END_REF]. The H-reflex is also used as an indirect measure of spasticity, but its expression is not correlated with spasticity severity [START_REF] Voerman | Neurophysiological methods for the assessment of spasticity: the Hoffmann reflex, the tendon reflex, and the stretch reflex[END_REF]. The modulation of the medullar reflex with bladder sensation, and perhaps with bladder filling or detrusor overactivity, with a possible impact on gait may explain a link between gait and the need to void.

The consequences of the need to void on other tasks have been little studied and only in healthy populations; however, alterations in attentional condition [START_REF] Jousse | Need to void and attentional process interrelationships[END_REF], gait velocity [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF] and balance [START_REF] Smith | Is balance different in women with and without stress urinary incontinence?[END_REF] performance were shown. Assessing the effect of the need to void in a neurologic population with frequent gait disorders and LUTSs could be pertinent to better understand the pathophysiological mechanisms and evaluate whether an intervention for one condition may improve the other, with the hypothesis that an appropriate management of LUTSs could lead to an improvement in some locomotor parameters.

The primary aim of this study was to assess the effect of an SDV on gait in individuals with multiple sclerosis (IwMS) and LUTSs. The secondary aim was to identify clinical or urodynamic factors (EDSS, symptom severity, detrusor overactivity, cystometric capacity) associated with greater gait impairment.

Material and methods

Participants

Individuals over age 18 who were consulting for LUTSs linked with MS in the neuro-urology department of a university hospital between February 2017 and March 2017 were invited to participate in this observational study. Individuals who agreed to participate were included where they were admitted for a consultation or urodynamic assessment, and all tests were performed on the same day.

Inclusion criteria were MS with EDSS score 1 to 6. The primary outcome was gait velocity assessed by a 10-m walk test (10MWT) [START_REF] Paltamaa | Reliability of physical functioning measures in ambulatory subjects with MS[END_REF]. Three trials were recorded, as per Booth et al. [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF]. Individuals were instructed to walk the 10 m at a comfortable speed. Maximum speed was not recorded to limit the impact of fatigue on test repetition, because maximal speed improves energetic cost. Only the 6 intermediate meters (meters 2 to 8) were recorded, to limit the effect of acceleration and deceleration. Tests were recorded with a manual chronometer by the same examiner for each individual, with 30 sec of rest at most between each trial.

Secondary outcomes were time on the Timed Up and Go Test (TUG) [START_REF] Sebastião | Validity of the Timed Up and Go Test as a Measure of Functional Mobility in Persons With Multiple Sclerosis[END_REF][START_REF] Valet | Timed up-and-go and 2minute walk test in patients with multiple sclerosis with mild disability: reliability, responsiveness and link with perceived fatigue[END_REF] and gait variability assessed by the coefficient of variation (CoV) of the 3 trials of 10MWT. The trial began with a non-recorded TUG to understand instructions and to limit the learning effect, but only one trial was recorded to limit the test duration and fatigue induced by the get up exertion.

Medical history, treatment, and anthropometric data were collected. An MMSE was administered to identify memory impairment. Urinary symptoms were assessed by the questionnaire Urinary Symptom Profile (USP) with 3 aspects: "stress urinary incontinence" (/9), "overactive bladder" (/21) and "low stream" (/9) [START_REF] Haab | Comprehensive evaluation of bladder and urethral dysfunction symptoms: development and psychometric validation of the Urinary Symptom Profile (USP) questionnaire[END_REF]. Data for the last cystometry were collected (retrospectively if cystometry was not planned on the day of inclusion): detrusor overactivity, volume at first detrusor contraction, SDV during filling, and cystometric capacity. MS severity was assessed by the EDSS, a score based on measures of impairment in 8 functional systems, and on walking ability [START_REF] Kurtzke | Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS)[END_REF]. Individuals with an EDSS score > 4 complained of gait difficulties. Each participant was asked if they had urine leakage during the tests. PV residual volume was measured with a mobile transabdominal ultrasound apparatus (Bladder Scan®); 3 measures were taken, and the highest was recorded. Secondary analyses were planned to identify clinical or urodynamic factors associated with greater gait impairment: age, EDSS score, need for a walking device, severity of overactive bladder on USP score, spontaneous void or self-catheterization, cognitive impairment assessed by the MMSE, detrusor overactivity during the last cystometry, and PV residual volume.

Ethics approval

The study protocol and data collection were conducted in accordance with the ethical standards of the national research committee and the Declaration of Helsinki. This study was approved by the local ethics committee (registration no. 2015-A00125-44). All participants gave their consent to participate. This study was registered on ClinicalTrials.gov:

NCT03204747.

Statistical analysis

Statistical tests were performed with R for Windows (Rx64 3.2.3). In a previous study of healthy individuals, the only one assessing the effect of the need to void on gait, Booth et al. [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF] showed a mean difference on gait velocity of 0.05 m.s -1 between SDV and PV. In IwMS, we expected a slightly greater mean difference between the 2 conditions. Thus, based on this previous study, for an expected mean difference of 0.06 m.s -1 , a standard deviation of 0.17 The impact of clinical and urodynamic parameters on the mean difference between TM10 at SDV and PV were analyzed by Student t test for qualitative variables and Spearman correlation for quantitative variables. Significance was considered at p < 0.05. Missing data were not replaced.

Results

We included 72 individuals (mean [SD] age 50.6 [11.6] years; 46 [64%] females).

Characteristics are summarized in Table 1. Three individuals performed only 2 trials of the 10MWT for each condition because of physical tiredness. The mean speed for 10MWT was 1.00 (0.31) m.s -1 at SDV and 1.07 (0.30) m.s -1 at PV (p<0.0001; effect size 0.79). Maximal improvement on mean 10MWT was 0.34 m.s -1 (5.03 s). Only 10 (14%) participants had a lower performance at PV than SDV. These 10 participants and the others did not differ in EDSS score, use of a walking device, existence of detrusor overactivity, or age. The Secondary analysis did not identify any predictors of greater impairment of walking speed at SDV among the features explored (Tables 2 and3).

Discussion

The results of this study showed an increase in gait velocity after voiding as compared with velocity during an SDV in lwMS and urinary disorders. This finding suggests a negative impact of an urgent need to void on walking speed in IwMS and urinary disorders. No clinical or urodynamic factors were found to predict greater reduction in gait performance.

In their study, Booth et al. [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF] proposed that "the experience represents a dual task or divided attention situation" to explain the difference in the SDV and PV situation in healthy individuals. The authors introduced for the first time bladder sensation as a divided attention situation. The role of dual tasks is well established, particularly in older adults and with a risk of falling. The effect of dual tasks, in particular in gait, has been widely studied and demonstrated in IwMS. In a recent review, the presence of cognitive motor interference appeared more frequent in IwMS than in healthy individuals during gait analysis [START_REF] Postigo-Alonso | Cognitive-motor interference during gait in patients with Multiple Sclerosis: a mixed methods Systematic Review[END_REF].

Individuals with mild cognitive impairment seemed more sensitive to the influence of a cognitive task on walking speed [START_REF] Lee | Effects of a priority-based dual task on gait velocity and variability in older adults with mild cognitive impairment[END_REF]. Moreover, emotional perception of the need to void could also influence gait velocity.

Functional MRI shows activation of different areas during bladder filling (insula, periaqueductal gray, cingulate cortex, hypothalamus and prefrontal area, amygdala). Most of these cerebral areas are implicated in emotional control, and functional MRI studies found less activation or deactivation of some of these areas in individuals with overactive bladder as compared with healthy individuals, which suggests a lack of control of this unpleasant sensation [START_REF] Griffiths | Bladder control, urgency, and urge incontinence: Evidence from functional brain imaging[END_REF]. A modification of gait velocity has been found correlated with emotion in healthy individuals [START_REF] Kang | The effect of emotion on movement smoothness during gait in healthy young adults[END_REF]. In IwMS, only the fear of falling has been studied, but other emotions could also affect gait. We found no relationship between severity of symptoms and greater difference between the 2 conditions. However, the proportion of individuals with regular leaks was higher (no statistical analysis) in individuals with a difference of > 0.1 m/s between SDV and PV, which supports a possible distractible effect of the urge to void and the role of emotional control.

A second explanation is the effect of bladder sensation on motoneuronal excitability. Previous studies of individuals with spinal cord injury evoked a gait spinal central pattern generator [START_REF] Calancie | Involuntary stepping after chronic spinal cord injury. Evidence for a central rhythm generator for locomotion in man[END_REF][START_REF] Bussel | Evidence for a spinal stepping generator in man[END_REF]. Furthermore, the H-reflex, which is a spinal motoneuronal response to electrical stimulation, is considered to reflect motoneuronal excitability. Variation in H-reflex amplitude reflects modified spinal cell excitability [START_REF] Petersen | The effect of transcranial magnetic stimulation on the soleus H reflex during human walking[END_REF]. During gait, some studies showed an increase in H-reflex amplitude, which suggests an increase in motoneuronal excitability, with variation in function of gait cycle. A proportional increase in the amplitude of the H-reflex as a function of walking speed has been demonstrated [START_REF] Simonsen | Amplitude of the human soleus H reflex during walking and running[END_REF][START_REF] Hodapp | Modulation of soleus H-reflexes during gait in healthy children[END_REF]. Thus, a role of motoneuronal excitability in gait velocity can be supposed, and a decrease in motoneuronal excitability could affect walking speed. A decrease in H-reflex in the soleus muscle occurs at SDV in healthy individuals [START_REF] Inghilleri | Bladder filling inhibits somatic spinal motoneurones[END_REF]. However, no study has examined the impact of the need to void on motoneuronal excitability in IwMS, whereas in individuals with spinal cord injury, bladder filling tends to increase H-reflex amplitude [START_REF] Inghilleri | Bladder filling inhibits somatic spinal motoneurones[END_REF]. Application of these findings in IwMS is difficult, as far as lesion localizations at cerebral or medullar level could affect H-reflex variability, and a specific study would be necessary.

Another possible explanation is that pelvic and trunk muscle activation is modified by bladder filling: the activation of pelvic floor muscles decreases when the bladder is moderately full, and the obliquus internus abdominis and rectus abdominis activation is increased. Bladder fullness also influences balance: an increase in center-of-pressure motions on a force plate was demonstrated when the bladder was full in healthy individuals [START_REF] Smith | Is balance different in women with and without stress urinary incontinence?[END_REF]. These 2 parameters could participate in gait velocity decrease at SDV.

Our results agree with the Booth et al. [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF] study of healthy individuals (continent, International Prostate Symptom Score 0-7). The authors used a GAITRite® walkway and showed an impairment of 0.05 m.s -1 at SDV as compared with PV. Results in our study were obtained with clinical (not instrumental) tests. A potential limitation of the primary outcome is that fast speed usually has better reliability in 10MWT than comfortable speed, but energetic cost is improved at maximal speed. We chose not to record this measure to limit the impact of fatigue on the different tests.

Several measures were established to limit bias in recording walking tests. Participants underwent 3 trials for the 10MWT under each condition, to limit intra-individual variability and to observe whether this variability is modified by SDV, as previously described [START_REF] Booth | The relationship between urinary bladder control and gait in women[END_REF]. To prevent inter-judge variation, all tests were recorded by the same examiner using a standardized protocol and the same time-measuring tool. A recent study did not find a significant difference between 3 consecutive short walk tests (Timed 25-Foot Walk) [START_REF] Meyer | Repeated assessment of key clinical walking measures can induce confounding practice effects[END_REF],

which suggests no spontaneous improved performance with repeated tests. Thus, to reduce the impact of tiredness on recording, we did not randomize by order of condition, and clinical tests at PV were always performed after those at SDV. This minimization of bias is also a potential limitation for highlighting a greater difference between the 2 conditions, because fatigue induced by the first tests can affect subsequent performance with a limited rest time between the 2 conditions. Individuals could also take a rest between the tests to reduce this bias. Our results did not reveal a progressive improvement in performance with the repetition of tests during the same condition. This suggests that the difference shown between SDV and PV is not related to a spontaneous improvement due to the repetition of the same exercise. For the TUG test, the learning effect was limited by a first non-recorded trial to verify comprehension of instructions. Instructions were repeated before each trial to facilitate their memorization.

Our study has several limitations. Clinical tests are less precise than instrumental tests, and some gait parameters such as stride length, swing time, and duration of single support could not be studied. The examiner was not blinded to condition (PV or SDV), but participants did not know the expected results and were not informed of the time performed in each test. The sequence of the test after urination can have a negative impact on performance, by the fatigue induced by the first tests and by the fatigue induced by urination, with the different stages of undressing, sitting, etc. This could influence the identification of factors associated with a greater impact of the need to void on walking speed. Moreover, because of the design of the study, the negative impact of the urgent need to void is derived from the interpretation of the increase in speed after urination. An evaluation without the need to void but away from urination could have been interesting to free oneself from possible neurological reflexes induced by micturition, especially in individuals with detrusor overactivity. In secondary analyses, an evaluation of executive functions would have allowed a more specific analysis, in the hypothesis of "dual task" impact, because the MMSE does not properly evaluate these functions.

The difference between SDV and PV we found is less than the minimally clinical relevant differences described in the literature, but these have been defined with small numbers of participants with high EDSS score or using a modification of EDSS score as a relevant clinical change, but the EDSS score is not sensitive to minor change [START_REF] De Groot | The usefulness of evaluative outcome measures in patients with multiple sclerosis[END_REF][START_REF] Vaney | Assessing mobility in multiple sclerosis using the Rivermead Mobility Index and gait speed[END_REF][START_REF] Learmonth | Reliability and clinical significance of mobility and balance assessments in multiple sclerosis[END_REF]. Thus, the observed difference in our study can be difficult to interpret; we did not expect a clinical state change as a modification of the EDSS score between SDV and PV, and the comparison of our results with the mentioned thresholds is not wholly adapted (median EDSS or condition to realize the 10MWT differed from those of our study). Therefore, clinical interpretation of this PV improvement is subtle, and our data cannot lead to specific clinical recommendations.

There are many different perspectives from this study. First, a new study of the specific population within IwMS could improve the accuracy of results and clinical relevance. The role of detrusor overactivity was not shown, but there was likely a lack of power in secondary analysis, and owing to the study design, 27 of the 62 urodynamic data measurements available were older than 3 months. Also, all individuals did not have urodynamics data, and some measurements were prior to the inclusion date, which limits their interpretation. Further research is necessary to judge the influence on spasticity. Several conditions modify spasticity: urinary tract infections, ingrown nails, lithiasis, temperature [START_REF] Chiara | Cold effect on oxygen uptake, perceived exertion, and spasticity in patients with multiple sclerosis[END_REF]. Yet, the possibility of spasticity exacerbation during detrusor uninhibited contraction has never been considered. Moreover, considering the impact of the need to void as a dual task requires a comparison with cognitive tasks during gait evaluation, especially since an impact on attention skills has been demonstrated [START_REF] Jousse | Need to void and attentional process interrelationships[END_REF]. 1: Composition of primary and secondary minerals from well-preserved and weathered granite samples determined by microprobe analyses on granite or soil thin sections [START_REF] Mareschal | Effet des substitutions d'essences forestières sur l'évolution des sols et de leur minéralogie : bilan après 28 ans dans le site expérimental de Breuil (Morvan)[END_REF][START_REF] Mareschal | Effect of granite crystal grain size on soil properties and pedogenic processes along a lithosequence[END_REF]. Gibbsite and hematite are taken from Deer et al., 1996. SiO2 Al2O3 FeO Detection limit for all elements (except for boron isotopic composition where measurement external reproducibility is given). Loss on ignition Unaltered granite

% mineral phases

  Chemical, XRD and SEM analyses show no evidence of weathering of the muscovite. Traces of K-Feldspar and quartz are found in muscovite samples (Figure2) and are the result of the mineral separation procedure. In contrast to the apparent lack of alteration and secondary mineral phases of the handpicked muscovite samples, B concentrations and δ 11 B values cover a relatively large range of values, from 22.5 to 89.5 µg.g -1 and from -30.7 to -19.4 ‰, respectively (Figure3b). Samples M1, M2 and M3 show variable δ 11 B values, ranging from -30.7 to -21.4‰, but have similar relatively high -B concentrations between 76.1 and 89.5 µg.g -1 . The muscovite sample picked at the shallowest depth (M4) shows the lowest B concentration at 22.5 µg.g -1 and the highest δ11 B value (-19.4 ‰).

B

  without destruction of the crystal structure, as demonstrated by XRD analyses, may likely be facilitated by interfoliar spaces. The present study cannot firmly identify the exact mechanism(s) controlling B isotopic evolution during weathering of micas (surface interactions or structural breakdown of B-bearing sites). Further investigations at the crystallographic scale should help answer this question. But it's clear that B behaves like a very mobile element during the weathering of micas,

  contrasted B behaviour while still showing little to no mineralogical change with weathering, thus limiting complicated interpretations caused by presence of secondary phases. The second advance made by this study is to recognize different B behaviour during weathering, indicating distinct weathering mechanisms. B appears to behave like a very mobile element in micas from a chemical point of view but accumulates in the weathering products of albite.

  5 and LUTSs secondary to MS (storage or voiding symptoms). Participants had to be able to walk 50 m without human help and to hold urine for 5 min, the time required to perform the tests. They could be taking medication for MS or LUTSs. All types of MS were accepted. We excluded individuals with urinary tract infections, relapse of MS in the last 7 days, or severe cognitive impairment (Mini Mental State Examination [MMSE] score < 10). Measures and procedure Gait was assessed by 2 clinical tests approved for MS. The same tests were performed under 2 conditions: first when the individual felt an SDV, and then immediately after micturition, spontaneously or with self-catheterization (post-void [PV]).

(

  SD 0.18 to 0.19 in theBooth et al. study) and 80% power, we needed 65 participants. Mean gait velocity at SDV and PV were calculated for the 3 trials of 10MWT. Variability of the 3 trials was assessed by the CoV (standard deviation/average). The temporal parameters of gait for 10MWT, TUG and CoV data were normally distributed. Thus, these were analyzed by Student's t test for paired samples. The effect size was calculated with Cohen's d formula.

  distribution of gait velocity change between SDV and PV is presented in the Figure.The individual variability of the 3 trials of 10MWT, assessed by the CoV, was significant (mean [SD] 5.2%[3.9] vs 4.2%[3.6], p=0.048). Between the first and second try, 47% of participants showed improved gait velocity at SDV and 40% at PV. Between the second and third try, 68% of participants showed improved gait velocity at SDV and 63% at PV. Mean time for TUG was also increased when individuals felt SDV: 11.53 (4.6) sec at SDV versus10.77 (3.8) sec at PV (p=0.004, effect size 0.35). Only one participant reported a leak during the test.

Finally, our study

  Figure 1

  Figure 2

  Figure 4

  underestimation of their B concentrations but no impact on B isotope compositions. In albite samples, contribution of the traces of muscovite on the bulk B budget is less than 12 µg.g -1 , which represents 7.5 to 15% of the total analyzed B. Given the range of δ 11 B values measured in the various muscovite (from -30.7‰ to -19.4‰) and albite samples(-31.1‰ to -16.1‰), the expected maximum shift in B isotope values resulting from muscovite traces in albite samples is less than 2.2

	Traces of K-feldspar are found in muscovite samples (< 5%), with the exception of sample M2 where
	the K-feldspar proportion is about 20%. Because B concentration and isotope ratios in K-feldspar
	span a narrow range of values (from 6.2 to 11.6 µg.g -1 and -33.2 to -30.3 ‰, respectively), it's
	possible to correct the sample concentration and isotopic composition from the contribution of the
	K-feldspar sorting residue. Only the B concentration in sample M2 is affected beyond analytical

errors by the presence K-feldspar, and a corrected M2 concentration of about 64 µg.g -1 is therefore reported in Figure

3b

(sample M2*). All biotite samples contain about 10 to 15% quartz, thus leading to a slight

  . Biotite samples that show no chemical or mineralogical evidence of alteration (B0a, B0b) exhibit a significantly larger range of B concentrations (21 to 74 µg.g -1 ) and δ 11 B values (-26.8‰ to -31.1‰). Sample B0a shows a δ 11 B value similar to unaltered muscovite and K-feldspar samples, while sample B0b shows higher B concentration with a δ 11 B value similar to sample AH.

Samples B0b, B5a and AH have similar δ 11 B values, ranging from -27.9 to -23.5‰ (Figures

Table

		84		86	88	90	92	80 Weight loss (% wt) 82 84 94 96 98 100	86	88	90	92	94	96	98	100	figure A2
			A4	A2										B6a	B6b	B2	B3	B4	B5b	B5a
			Gibbsite								Gibbsite
			Kaolinite												Kaolinite
	Temperature (°C)	98.0	98.2	98.4	98.6	98.8	99.0	99.2	99.4	99.6	99.8 c	100	93		94	95		96	97	98	99 a	100
			F1	F3										M2	M1	M3	M4
			Gibbsite								Gibbsite
			Kaolinite												Kaolinite
												d									b

1 CaO MgO K2O Na2O MnO TiO2 Total

  Muscovites 46.0 32.2 2.45 <DL 2 1.03 10.4 0.70 <DL 2 0.12 93.0 K-feldspar 64.3 18.1 <DL 2 <DL 2 <DL 2 15.5 0.88 <DL 2 <DL 2 99.0 Albite 66.4 20.7 <DL 2 1.38 <DL 2 0.57 10.5 <DL 2 <DL 2 99.6 Kaolinite 45.0 39.5 1.00 <DL 2 0.06 0.08 0.10 <DL 2 0.20 86.6 Vermiculite 49.0 33.6 1.70 <DL 2 1.09 1.47 0.08 0.11 0.14 87.2

	Biotites	34.9 18.4 22.2 <DL 2 3.8	9.2 0.25 0.62 3.5 93.2
	STD (1 σ)	0.7	1.5	0.7		0.3	0.3	0.07	0.15	1.1	-
	STD (1 σ)	1.3	1.6	0.56		0.32	0.4	0.19		0.09	-
	STD (1 σ)	0.4	0.4				0.96	0.59			-
	STD (1 σ)	0.4	0.3		0.23		0.17	0.3			-
	STD (1 σ)	1.1	0.99	0.02		0.01	0.02	0.01		0.02	-
	STD (1 σ)	1.1	0.8	0.02		0.02	0.76	0.01	0.01	0.02	-
	Hematite	-	-	96.0	-	-	-	-	-	-	96.0
	STD (1 σ)	-	-	-	-	-	-	-	-	-	-
	Gibbsite	-	65.4	-	-	-	-	-	-	-	65.4
	STD (1 σ)	-	-	-	-	-	-	-	-	-	-

1

Total Fe (FeO + Fe2O3)

2

Below detection microprobe limit (DL)

Table 2 :

 2 Boron concentration and isotopic composition of pore and bound waters.

[B]

(ng B/ mL) δ 11 B (‰) Water/rock ratio (L/kg) 20-30 cm horizon pore water

		12.0	30.3	0.003
	20-30 cm horizon bound water	8.4	22.3	0.025
	110-140 cm horizon pore water	-	-	0
	110-140 cm horizon bound water	12.5	18.9	0.013

Table 3 :

 3 Mineral phases identified in each sample using a combination of XRD, SEM and differential thermal analyses (FigureA1). These phases were then used for quantitative mineralogy calculations(Eq. 3 in text)

	Samples	Identified mineral phases
	Biotite	Biotite, kaolinite, vermiculite, titanium oxides,
		quartz, gibbsite, chlorite 1
	Muscovites	Muscovite, K-feldspar, quartz
	K-feldspar	K-feldspar
	Albite	Albite, kaolinite, gibbsite, muscovite, quartz,
		hematite 2
	1 Samples B0b, B5a, B5b and B6a only
	2 Sample AH only

Table 4 :

 4 Major elements, B concentration and B isotopic composition in all studied samples (see table 3 for abbreviations).

	Primary	Depth
	mineral	(cm)	SiO2	Al2O3	MgO	CaO	Fe2O3	MnO	TiO2	Na2O	K2O	δ 11 B

(‰) B (µg.g -1 ) 1

			110-
	B4		120	41.1	19.9	5.5	<DL	18.7	0.5	3.3	0.3	5	-16.1	3.4
	B5a		20-30	43.3	19.9	4.1	0.1	18.1	0.5	2.5	0.6	6.3	-23.5	81
	B5b		20-30	43.5	20.8	4.1	0.1	17.1	0.5	2.7	0.4	5.4	-23	34.5
	B6a		20-30	34.8	21.7	5.7	0.1	22.7	0.7	1.4	0.2	2.6	-16.3	1.3
	B6b		20-30	39.5	20.8	3.4	0.1	19	0.8	1.3	0.5	2.4	-16.2	0.9
	F1		G.B. 3	64.6	18.2	<DL	0.2	0.2	<DL	<DL	3.3	11.4	-30.2	6.3
			130-
	F2		140	64.7	18.2	0.1	0.1	0.2	<DL	<DL	2.7	12.1	-30.8	10.7
		K-Felsdpar	120-
	F3		130	64	18.3	0.1	0.1	0.3	<DL	<DL	2.6	12.2	-31.2	11.5
			110-
	F4		120	62.7	18.4	0.1	0.1	0.5	<DL	<DL	2.1	12.7	-33.1	10.2
	M1		G.B. 3 .	44.8	31.3	1.3	0.1	3.4	0.1	0.1	0.9	9.5	-30.7	76.1
			130-
	M2		140	44.3	31.2	1.4	<DL	3	0.1	0.1	1	9.5	-21.4	78.3
		Muscovite	120-
	M3		130	45.3	31.4	1.4	<DL	3.1	0.1	0.1	0.8	9.4	-23.8	89.5
			110-
	M4		120	45.7	32.1	1.3	<DL	3.1	0.1	0.1	0.7	9.7	-19.4	22.5
	DL 1			0.009	0.002 0.0007	0.002	0.002	0.003	0.00003	0.01 0.004 +/-0.6	0.7
	A1		G.B. 3	67.1	18.7	0.7	0.3	0.1	0.02	0.01	5.8	0.2	-24.7	86.2
			130-
	A2		140	48.9	33.8	0.4	<DL	0.6	<DL	<DL	0.2	2.1	-16.1	108.6
			120-
	A3	Albite	130	47.2	35	0.4	<DL	0.6	<DL	<DL	0.2	1.9	-17.2	160
			110-
	A4		120	47.8	35.1	0.5	0.1	0.6	<DL	0.1	0.1	2	-15.4	185.2
			130-
	AH		140	43.8	33.6	0.6	<DL	5.7	0.1	<DL	0.8	1.6	-27.9	471.8
	B0a		G.B. 3	42.4	19.7	7.1	<DL	16.9	0.3	1.8	1.2	5.4	-31.1	21
	B0b		G.B. 3	43	18.9	4.2	0.1	19	0.5	2.4	0.7	7.2	-26.8	74.2
	B1	Biotite	G.B. 3 130-	41.7	21.4	4.3	0.1	15.3	0.5	2.2	0.6	5.5	-19.4	17.5
	B2		140	42.3	20.2	4.8	<DL	15.5	0.4	2.9	0.3	4.2	-16.4	7.2
			120-
	B3		130	44.1	20.2	4.8	<DL	16.1	0.5	2.6	0.3	4.4	-21.5	7.7

Acknowledgements

This work was supported by the INSU French National funding program (EC2CO, Cycles hydrobiogéochimiques, Transferts et Impacts écotoXicologiques, CYTRIX) and funding coming from both Alsace and Lorraine regions. The ISOSIL ANR, thanks to Nathalie Vigier, has provided funding to support mineral sorting from bulk soil matrices as well as rock grinding (done by Bruno Simon).

We would also like to thank A. Legout (Breuil forest site scientific supervisor) and C. Calvaruso for the help with the soil sampling, and K. Durocher for the manuscript proofreading.

Funding. Dr. Hentzen reports grants from SIFUD-PP (the francophone society of urodynamics) and from LILIAL-GREEN GRC-01 UPMC (Group of clinical REsEarch in Neurourology), during the conduct of the study.

Effect of a strong desire to void on walking speed in individuals with multiple sclerosis and urinary disorders Abstract Background. Lower urinary tract symptoms, especially overactive bladder, are frequent and disabling in individuals with multiple sclerosis (IwMS). An association with gait disorders is common, which could aggravate continence difficulties and affect quality of life. The association between the need to void and walking has never been studied in this population.

Objective. The primary aim of this study was to assess the effect of a strong desire to void (SDV) on walking speed in IwMS and lower urinary tract symptoms. The secondary aim was to identify clinical or urodynamic factors associated with walking speed impairment at SDV in this population.

Methods. We included IwMS with urinary disorders and Expanded Disability Status Scale score < 7 in this observational study. Individuals underwent 3 10-m walk tests (10MWT) and one Timed Up and Go (TUG) test at SDV and at post-void (PV).

Results. Among the 72 IwMS included (mean [SD] age 50.6 [11.6]