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Directeurs de Thèse : Dr. S. MOUNIER Université du Sud Toulon Var – PROTEE

« Mise au point d’une systématique de caractérisation des interactions Matière Organique Naturelle Dissoute (MOND) – Contaminants métalliques ». Thèse de Doctorat soutenue par: M. Yoann LOUIS En vue d’obtenir le titre de Docteur de l’Université du Sud Toulon-Var. Directeurs de Thèse :

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Directeurs de Thèse : Dr. S. MOUNIER Université du Sud Toulon Var – PROTEE

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  1. « Mise au point d’une systématique de caractérisation des interactions Matière Organique Naturelle Dissoute (MOND) – Contaminants métalliques » Thèse de Doctorat soutenue par: M. Yoann LOUIS En vue d’obtenir le titre de Docteur de l’Université du Sud Toulon-Var Directeurs de Thèse : Dr. S. MOUNIER Université du Sud Toulon Var – PROTEE (PROcessus de Transferts et d'Echanges dans l'Environnement) Dr. D.OMANOVIĆ Institut Ruđer Bošković – LPCT (Laboratory for Physical Chemistry of Traces) Université du Sud Toulon Var 21 novembre 2008 Subvention N° 03/1214910/T Matière Organique NAturelle en miLIeu SAlé

  2. SUMMARY • Introduction • Analytical protocol improvements • Concentrated Marine DNOM study • Natural Estuarine ecosystem study • Conclusions & perspectives Introduction – Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  3. Introduction Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  4. ATMOSPHERE Metals Metals AQUATIC ENVIRONMENT (Coastal and estuarine system) SOILS Trace metals in the environment Metals Metals WATER SEDIMENTS Anthropogenic origin Natural origin Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  5. Trace metals in the environment Toxic metals: not needed Pb, Hg, Cd, … Toxicity ≠ Total concentration When metal became toxic ?  depend on its speciation Concentration increase “Oligoelements”: necessary for metabolism Cu, Fe, F, Mg, Mn, Zn, … Metals Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  6. Filtration (0.45µm) Inorganic Ligands Cl-, NO3-, SO42-… OH- Organic Ligands M M EDTA, DNOM… M M Dissolved metal speciation “Not” or less bioavailable Particulate > 0.45 µm Dissolved < 0.45 µm Could be bioavailable Micro-organisms (bacteria, virus,…) M M bioavailable M Water column M n+ Organic and Inorganic Particules Trace metals speciation in the water column “Not” or lessbioavailable Generally toxic for biota Metal trap: Less toxic [MTOTAL] ≠ [MTOXIC] Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  7. Heterogeneous origins  heterogeneous and complex structure Anthropogenic activities Humification& Polymerization  DNOM modifications Plants, animals, µorganisms decomposition River input DNOM Origin? Photosynthesis Bacterial activity degradation Phytoplankton activity Representation of a simplified NOM Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  8. “Analytical speciation” “Mechanistical speciation” • Interactions characterization • ISE • Voltammetry • Fluorescence Quenching • … • Results usable in speciation codes for prediction (for example MOCO from IFREMER) No Functional characterization • “structural” determination • separation and analysis • Dialysis, UF GFAAS • CFFFF, HPSEC ICP-MS • HPLC, GC CV-AFS • C18, Chelex Voltammetry • … ... • Specific components determination Less usable for metal behavior prediction DNOM speciation Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  9. H+ H+ M M M DNOM DNOM Comp Comp L L DNOM-Metal interaction study Used to describe the DNOM reactivity kM1 KMthermo + kM-1 + KHthermo + KCompthermo DNOM speciation • Continuous model: NICA-Donnan • Discrete model: WHAM For 1 DNOM: All K and [LiT] determined = “Chimiotype”  For Metal-DNOM interaction study: Need a technique to measure only or Assuming a kinetic of 1st order Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  10. L M M DNOM M M M M M M M M M M M M M M 3 electrodes system: Counter electrode (Pt) Reference electrode (Ag/AgCl/KClsat) Working electrode (Hg) Stirrer Purging (N2) Metal addition Metal-Ligand Complex Direct measurement of free & inoganic copper fraction = electrolabile fraction (= bioavailable fraction) Escan Edep Edep After tdep = 5 min Escan Voltamogram Analytical tool used to measure trace metal: DPASV Oxydation step Reduction Step e- I=f([M]) Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  11. pCuT pCuLab Discrete fitting of experimental data with PROSECE program (Speciation calculus + optimization) Determination ofKequilibrium, [LT] Determination ofk1, k-1, [LT]  New characterization of the DNOM: reactivity [Metal added]: From nM to µM Data at equilibrium Kequilibrium, [LT] Kinetick1, k-1, [LT] Metal logarithmic scale titration (Garnier et al., 2004, Env. Technol. 25, 589-599) For each point: 2h of equilibrium Measurements every 6 min. Metal complexed by DNOM Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  12. Intensity (nA) Intensity (nA) Scanning potential (V) Deposition potential (V) Deposition potential (V) Measured if: UV, pH=2, Edep << Edep for CC Labile fraction = Free + inorganic fraction : bioavailable Dissociable organic fraction: Probably not bioavailable Not measured fraction = electroinactive in the Edep range used Voltammograms Pseudopolarogram Edep for CC measurements Direct ML complex reduction Pseudopolarography measurements (Nicolau et al., 2008, ACA 618, 35-42) Labile fraction Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  13. Goals of the study Analytical protocol determination adapted to low [DOC] and [Metal] Real complex natural ecosystem study • Improvements: • Technical • Analytical • Mathematical “Model DNOM” definition Based on the concentrated sample from GDR MONALISA Introduction– Analytical protocol – Marine DNOM study – Estuarine DNOM Study - Conclusion

  14. Analytical Protocol determination Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  15. Technical and mathematical improvements • Limit adsorption (Teflon use) • Precise metal additions (automatic pumps 500µl) • Avoid pollution with additions (tubing separation) • Avoid evaporation (N2 wetpurging) • Mathematical baseline and peak definition • Multi-PROSECE (more optimization loop & confidence interval calculus) Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  16. Edep Escan e- e- M M M M M M SAS SAS I  [Cu]meas  [LT] Distorded shape -0.45V with SAS Escan Analytical improvement: Surface Active Substances (SAS) interferences(Louis et al., 2008, ACA 606, 37-44) -0.45V without SAS Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  17. Additional experiment A.C Voltametry (Phase angle: 90° measure of capacitive current) Max. Ads. At pzc Classical used tdep Edep = -0.6V Classical Edep used for Cu Eacc= -0.45 V + 3sec at -1.6V Eacc= -1.6 V Eacc= -0.45 V - + Edep = -0.6V + 3s at -1.6V Analytical process to get rid of SAS interferences during the stripping step Edep = -1.6V ΔI ↑ = Itcap- It0cap = SAS quantity ↑ Full circles Edep=60 s Dotted circles Edep=60 s + 1s at -1.6V Triangles Edep =60s (After UV) High influence of SAS at tdep = 300 s and Edep ≈ - 0.5 V Only 1% of the total deposition time (297s) Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  18. Without 3sec [LT]= 335 nM logK=6.17 With 3sec [LT]= 160 nM logK=6.47 Influence of these SAS on the apparent [LT] Ruzić linearization [LT] change from 335 nM to 160 nM  Artificially « Hidden Metal » by SAS  bad speciation determination  toxicity Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  19. Raw sample Log addition window determination : Add1= 10% Mini Final conc.: 1mgC/L  1µM 10 mgC/L  10µM Potentiometry (Chelex) (4) (1) DOC (3) Filtration at 0.45µm (8) (5) PseudoEdep (2) UV at pH2 Salinity or majors ions by IonicChromatography (6) (9) Total Metal (Optional) H+ , Ca2+competition (After Chelex) (7) (10) Log additions at Edep, Kinetic experiment (11) PROSECE For concentrated samples Analytical protocol for DNOM study “Chimiotype” Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  20. Study of a natural seawater sample (MONALISA project)(Article submitted to Marine Environmental Research) Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  21. Sampling site: Balaguier Bay Military port > 100 nM ~ 15 nM ~ 5 nM Site interest: Coastal Semi-Closed Area under anthropogenic influences Goal: Give standard DNOM usable in metal speciation/transport program 1000L seawater sampling (online filtration and nanofiltration and reverse osmosis concentration byGDR MONALISA, ISM-LPTC: E. Parlanti, PhD of Arnaud Huguet). Concentrated from 1000 L to ~10 L, [DOC]final= 30.4 mg/L Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  22. Carboxylic-like Phenolic-like /2.7 60% 40% 30% 70% 165.3 Potentiometry on Concentrated DNOM (Garnier et al., 2004, Water Research, 38, 3685-3692) Lu and Allen (2002) : Suwanee River (also concentrated by RO) (Letizia and Gnudi, 1999) PROSECE Fitting for 4 types of acidic sites (DOC=1.2mmolC.L-1). Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  23. Edep = -0.5V 2nd site saturation 1st site saturation Exploratory experiment: Pseudopolarography coupled with logarithmic addition Estimation of a [1st site]: 90% x 2.5µM = 2.25 µM (= 1.87meq/molC) Estimation of a[2nd site]: 50% x 25µM - [1st site]:= 10.25 µM (= 8.54 meq/molC) Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  24. ≈ 2µM of Cu bound to specific sites Strong affinity toward proton  phenolic-like sites Strong affinity of copper for the studied DNOM % Cu lab Model Marine DNOM complexing parameters = DNOM “Chimiotype” (Comparable to standards OM used in NICA-Donnan /WHAM models, obtained for soil/river extracted OM) % Cu lab [LM1] = 0.03 meq/molC Ca additions pH [Cu]T = 12.5µM, pH = 8.2  [Cu]T= 4µM. Edep = -0.5V, pH = 8.2, DOC = 1.2mmolC.L-1. Log addition and Cu2+ competition with H+ and Ca2+ Hight calcium competition effect Strong complexing site specific to copper Comparison of 2 different Edep (-0.5V and -1.5V). Total metal binding site density LMT 12 Total acidic sites density 446 Closed to values estimated with pseudo coupled with log add. ~3% of (= Buffle, 1988) Phenolic-like sites Complexing parameters determined after simultaneous fitting by PROSECE of the 3 experiments Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  25. Experimental points DNOM simulated by Mineql adjusting only [DOC] Difference between modeled DNOM and experimental points MINEQL simulation of natural DNOM according to determined model marine DNOM <<5% seawater sample treated with Chelex (DOC = 0.09 mmolC.L-1); pH = 8.2, Salinity 37. • Correct simulation validating the characterization protocol • DNOM reactivity is not strongly modified by concentration step • Model DNOM determined usable Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  26. Condition: Majors ions for salinity of 38, DOC = 0.09 mmolC.L-1, Cutot = 14.8nM • 80% of total copper complexed as organic forms • >90% found in several paper: Influence of SAS ? • specific behavior of the studied DNOM and high copper content Simulation of copper speciation for the studied marine environment Natural marine water conditions 7.5 8.3 Introduction – Analytical protocol –Marine DNOM study– Estuarine DNOM Study - Conclusion

  27. Estuarine DNOM Study(Article submitted to Marine Chemistry) Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  28. Sampling in the water column:  gradient of salinity Brackish FSI layer Seawater • Low tide on Adriatic sea  stratified estuary • Pristine watershed Sampling site: Krka, Croatia(2007&2008) • Potential anthropogenic inputs in estuary • On site measurements in nearby laboratory • Challenge is to give data on speciation and kinetic in this natural area Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  29. Raw sample Log addition window determination : Add1= 10% Mini Final conc.: 1mgC/L  1µM 10 mgC/L  10µM Potentiometry (Chelex) (4) (1) DOC (3) Filtration at 0.45µm (8) (5) PseudoEdep (2) UV at pH2 Salinity or majors ions by IonicChromatography (6) (9) Total Metal (Optional) H+ , Ca2+competition (After Chelex) (7) (10) Log additions at Edep, Kinetic experiment (11) PROSECE Simplified protocol used No concentration step and no use of Chelex Introduction –Analytical protocol– Marine DNOM study – Estuarine DNOM Study - Conclusion

  30. (Elbaz-Poulichet F. et al., 1991) 1.78 in may 1988 Salinity, DOC and Copper profiles • Same curve shape for 2007 & 2008  • Oligotrophic freshwater  Very few carbon content, DOC est. < DOC sea  low anthrop. inputs • Non conservative behavior: Bigger amount of metal & DOC in the FSI  “special layer” • Additional source of DOC in the FSI: can be due to an exacerbated biological activity (Svensen et al, 2006) • Increase of copper in the FSI: particulate/dissolved metal exchange due to salinity increase Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  31. Data obtained for only 1 sample: Example from Salinity 11, April 2007 Log K at Equilibrium Log Kkinetic AverageofLog K kinetic AverageofLT kinetic LTkinetic LT at Equilibrium Fitting at Equilibrium Data at Equilibrium AverageofLog k1 kinetic Comparison of the kinetic and at Equilibrium approach Log k1 kinetic Good agreement between the constants obtainedat equilibriumand with thekineticapproach Fitted Kinetic data Kinetic data Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  32. Comparison of the kinetic and at Equilibrium approach k1 2007 (,) and 2008 (,). Good agreement between constants determinedat equilibriumor kinetic At equ: Higher M/L ratio  better [L] determination Kinet.: more points after each addition less equilibrium dependent, kinetic parameters determined • Apparent overestimation of Kinetically determined logK (or underestimation of the at equ. approach) due to: • kinetic first point estimation of Culab at t0 • Is the solution at equilibrium with the at equ. Approach • Both approaches are complementary k-1 Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  33. & In MINEQL: 83% Complexing parameters results Expected variation with salinity Organic Cu 90 to 99% Observed variation strong (,) and weak (,) ligands, 2007 (,) and 2008 (,), In dotted line in inset: toxicity limit of 10 pM (Sunda et al., 1987). Difference  Autochthonous DNOM production in the estuary Higher affinity for ligands from seawater origin In the FSI: Higher inorganic and free copper content (up to 20pM) in spite of [ligands] increase Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  34. Omanović et al., 2006 2006 Used for prediction time t50% t99% 2008 2008 2006 ≈ 2h30 ≈ 4h30 Simulation of DNOM reactivity under a Cu contamination • Higher [Metal] in summer due to traffic of touristic boats • Calculated free copper concentration potentially toxic for µorganisms at the surface in summer • Lower reactivity of the FSI DNOM • Compared to hydrodynamics variations tequ. are quite long  system probably not at equilibrium in the estuary Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  35. Determined with the simplified protocol Comparison of the measured DNOM vs. the model DNOM simulated from model marine DNOM Higher free [Cu] with the use of model DNOM > toxicity limit Bigger difference for marine sample  ≠ DNOM behavior between Toulon & Šibenik Model DNOM not sufficient, even if DNOM is from same origin  This ≠ show the necessity to study samples representatives of the studied system Introduction – Analytical protocol – Marine DNOM study –Estuarine DNOM Study- Conclusion

  36. Conclusion Introduction – Analytical protocol – Marine DNOM study – Estuarine DNOM Study -Conclusion

  37. Conclusions and perspectives • NEW use of “3sec” for DNOM analysis remove SAS interferences • Determined protocol  NEWdirect analysis of coastal natural samples at low [DOC] and [M] •  complexing parameters determination + NEWKinetic parameters (reactivity prediction) • model DNOM usable in environmental contaminant speciation/transport programs • Standard DNOM hardly usable to model DNOM behavior of a complex environment • Use of the determined protocol for specific ecosystem understanding • Main improvement needed: Voltammograms automatic fitting • Deeper analysis of pseudopolarograms, • On site measurements (DGT) and comparison of data • Actually protocol applied on a depth profile from Dycomed (Dyfamed site) … Introduction – Analytical protocol – Marine DNOM study – Estuarine DNOM Study -Conclusion

  38. 5 nM Application of the method to an “oceanic” depth profile • First results shows: • At natural [Cu]: Cufree under toxicity limit • until simulated total [Cu] up to 5nM • Surface DNOM is less complexant • Still analyzing samples (Dycomed 15) and need to treat all kinetics data… • Need to make a connection with on site measurments (Chlorophyll, COT, fluorescence … ) Introduction – Analytical protocol – Marine DNOM study – Estuarine DNOM Study -Conclusion

  39. Balaguier Bay (Toulon, France) Martinska (Šibenik, Croatia) Merci à tous de votre attention ! Special thanks to my Directors: Dr. Mounier S. Dr. Omanović D. To the Jury’s members: Prof. Marmier N. Prof. Riso R. D.R. Elbaz-Poulichet F. D.R. Cossa D. Dr. Garnier C. And members from PROTEE (USTV) and LPCT (RBI) labs

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