By

ACKNOWLEDGMENTS I would like to sincerely appreciate my advisor Dr. Valsaraj for giving me this opportunity to pursue this degree and to do this project. I am also grateful to Drs. Valsaraj, Reible, and Thibodaux for their guidance during my research. I would like to thank Dr. Ravikrishna for his help and beneficial discussions. I also appreciate Dr. Willson for his guidance to digitalize the sediment tomography images with BLOB3D and T3D softwares. I wish to recognize the efforts of Joel Leger, a student worker who performed the extractions of some water samples. Special acknowledgments are extended to Dr. Constant and Dr. Rouse for being my committee members. I am indebted to my parents, my brothers and my sister for being always there for me whenever I needed them. I would like to thank my wife Jinhui Liu and my daughter Yunan Yuan for their love and encouragement. Without their encouragement and understanding, my researc