AIX MARSEILLE UNIVERSITÉ École doctorale des sciences de l’environnement Laboratoire Chimie Environnement – UMR CNRS 7376 – Équipe TRAME Centre de Recherche et d’Enseignement de Géosciences de l’Environnement UMR CNRS UMR CNRS 7330, UMR IRD 161, Collège de France THÈSE DE DOCTORAT Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ D’AIX-MARSEILLE Discipline : Science de l’Environnement Spécialité : Chimie de l’environnement Présentée par Kevin MBUSNUM GWETH Le 08 octobre 2020 Évaluation des Contaminants Organiques Hydrophobes dans deux Environnements Aquatiques en Afrique Centrale, Cameroun : Lac Barombi et Mangrove de l‘Estuaire du Wouri Composition du Jury : Mme Catherine GONZALEZ École des mines d’Ales Rapporteure M. Baghdad OUDDANE Professeur, Université de Lille Rapporteur Mme Guillemette MENOT Professeur, ENS de Lyon Examinatrice M. Jacques ETAME Professeur, IUT Université de Douala Examinateur Mme Aurore ZALOUK-VERGNOUX MCF, HDR Université de Nantes Examinatrice Mme Laure MALLERET MCF, Aix Marseille Université Co-directrice de thèse M. Pierre DESCHAMPS Chargé de Recherche, Aix Marseille Université Co-directeur de thèse M. Pierre DOUMENQ Professeur, Aix Marseille Université Directeur de thèse M. Jean-Jacques BRAUN Directeur de Recherche, IRD Membre invité M. Olivier DHONT Professeur des Universités, Université de Membre invité Paris1 Panthéon-Sorbonne Acknowledgements This thesis has been one of the most challenging and best life changing experiences in my life so far. Beyond the rich academic experience, I learned so much about human relationships and self-awareness. In this adventure I met many wonderful people that have contributed in making me a better version of myself and this is an experience I am ready and to relive in order to acquire all this knowledge. I will first thank the Almighty God for keeping in good health, safe and the journey mercies granted to me throughout this thesis. I express my gratitude to the members of jury; Pr. Catherine Gonzalez and Pr. Bagdhad Ouddane as rapporteur for the validation of this work and the consideration giving to it. Your comments and observations helped to improve its quality. I was honoured to have you; Pr. Guillemette Menot as jury chair. I lack words to express my gratitude for your unconditional and endless support from the beginning of this adventure. Thank you for your valuable comments, advices and constant motivation. You have been there for me in happy and tough times. I endlessly say thank you! I thank Dr. Aurore Zalouk-Vergnoux for taking part in the evaluation of this work and your valuable comments and suggestions. I thank Pr. Jacques Etame for the examination of this work, your interest and consideration for this work. I greatly appreciate your comments, observations and suggestions. I would like to express my sincere gratitude to my thesis supervisors. Working with three supervisors was challenging but very beneficial. To Pr. Pierre Doumenq, thank you Sir, for giving me this exceptional opportunity to learn by your side. Despite your heavy schedule, I greatly appreciate every effort to make time for us to carry this work forward. At the beginning, it wasn’t quite easy, but I gradually adapted to suit your way of working. Your great advices and words of encouragement kept me going. You are an inspiration to hard work and achievement; you have my deepest admiration and respect. To Dr. Pierre Deschamps without whom this thesis would not have been possible. I equally lack words to express my gratitude. Thank you for trusting me, it was a great boost of confidence and energy to overcome the encountered challenges. I appreciate your academic rigor and the relevance in your comments. You always did what was necessary to make things and your openness made me feel at ease. I have learned so much from your mentorship throughout these years. I endlessly say thank you! To Dr. Laure Malleret, I express my profound gratitude for your huge support and kindness. I greatly appreciate your listening ability, understanding and pedagogic approach in our discussions. Somehow difficult for me at the beginning, despite your busy schedule, you made time to clarify the questions, worries and doubts I had concerning certain aspects of this work. I had a sense of satisfaction at the end of every working session. Also, with time I discovered you have a great sense of humanity. I am very grateful to Dr. Jean-Jacques Braun for the multidimensional support from the beginning and future prospects related to this work. I am thankful to Pr. Olivier Dhont for the interest you have shown to this subject matter, the valuable advices and unforgettable moments during the Lake Barombi sampling campaign. Special thanks to Dr. Pascal Prudent for being part of my thesis committee and her active contribution to the realization of trace metal analyses which unfortunately does not appear in this thesis. This work is valorized in the article entitled “Assessment of organochlorinated pesticides, polyaromatic hydrocarbons and trace metals in water, soil and sediments of Lake Barombi watershed, Southwest Region of ii Cameroon. Special thanks to Dr. Yannick Garcin who open my way to this adventure. Thank you for giving me this great opportunity since 2015 to join the amazing team of researchers for the Lake Barombi sampling campaign. Thanks for your valuable advices and support from the beginning to the end of this thesis. I am grateful to Dr. Frank Torre, for giving me the opportunity through the MedNet Program of excellence that enabled my immersion in this rewarding journey. Thanks to Laurent Vassalo, for his training and assistance on the measurement TOC in soil and sediments samples. Thanks to Dr. Raphael Onguene, for the warm welcome at the University of Douala and JEAI-RELIFORME laboratory. Thanks to Pr. Henri Wortham (LCE Director) for welcoming me into LCE as a master’s intern and PhD student. This thesis was supported by the Institute of Recherche for Development (IRD), Service de Coopération et d’Action Culturelle (SCAC) of the French Embassy in Cameroon and Ecosystèmes Continentaux et Risques Environnementaux (ECCOREV). I express my profound gratitude to all the staff of Aix-Marseille University (AMU) in Laboratoire de Chimie de l’Environment (LCE), the IRA and TRAME teams. I am very grateful to Pr. Pascal Wong-Wah-Chung, an exceptional person. Every morning we greeted each other, It was a boost of energy and motivation for the day. I learned from you that self-discipline and organization are essential for achieving set objectives. Thanks for your valuable advices, great sense of humour and comprehension of cultural diversity. To Dr. Laurence Asia (Loloe) and Stephanie Lebarillier (Steph) thanks for your warm welcome at LCE and training on various analytical technics and equipments (ASE, SPE, GC-MS, HPLC etc…). You were always ready and available to help when I needed assistance. Thanks for your daily encouragements and attention. Thanks to Dr. Anne Piram and Dr. Stephanie Rossignol for the interesting discussions we had on various topics, your encouragements and moment we shared. Thanks to Cecile Langlois for her promptness and precious help for administrative procedures. I wish you a quick recovery. Thanks to Max Bresson and Jean François Barbion for your assistance when needed, wish you recover as soon as possible. Thanks to Pr. Gilbert Mille for his encouragement and discussion on polyaromatic hydrocarbons, may your Soul Rest in Peace. Thanks to Frederique, Lionel and Sylvain for the interesting discussions and encouragement. I express my sincere gratitude to my PhD colleagues at LCE, I wish you’ll the very best for the completion of your thesis. To Nuning Vita Hidayati my sister from Indonesia, thanks for your encouragements and support in various forms. We shared joyful and painful moments together, you are exceptional. All the best for the end of your thesis, you will make it. Clementine Côte, you were always available to help and supported me from the beginning to the end. You have done a great job in your thesis, all the best for the end of your thesis and future career. Houssein Louati, your kindness and respect are overwhelming. You were always willing to help. Stay as you are my friend. Imen, for your outstanding work on pesticides for the Wouri Estuary Mangrove during you master’s internship which is part of this thesis. I am grateful for your concern and unforgettable moments we shared. El Mountassir El Mouchtari, my brother from Morocco. I am thankful for your support in many forms and joke cracking moments. You have a great heart, stay as you are! Mathilde Godéré, an exceptional person with a great heart. I greatly appreciate the time you made out of your busy schedule to help me. I also thank you for the trips to and from the laboratory when it was possible. Maria iii Masry, you were able to put a smile on my face during hard times. Thanks for your kindness, you were always there for me, you are an amazing person. Mathilde Chantreux, a wonderful person with a great sense of humanity and comprehension of cultural diversity, I enjoyed the interesting philosophical discussions we had and was touched by your kindness. Carole Abdel-Nour, a lovely and caring person with a great heart. Thanks for your concern, the delicious banana cakes, and the breathing exercises. Dr. Perrine Branchet, we have known each other for a while but I was touched by your kindness. Thanks for the huge support you brought to me and the time you dedicated to help me. Dr. Camille Grandclément and Dr. Fanny Desbiolles, thank you for the interesting discussions we had and the encouragements. I am grateful to the former and present staff and PHD students of Aix-Marseille University in CEREGE; Pr.