The properties of humic substances in plants, soils and sediments regulate the environment and affect all aspects of life, yet they are nature's least understood materials. Current work in this field in the late-1990s applies front-line instruments and techniques to solve the 200-year old mystery of humic substance structures and their relationships to macro- and microscopic properties. This book highlights environmental processes from a molecular viewpoint, focusing on the use of chemical and physical methodology to explain this complex subject matter and emphasizing up-to-date research. It covers aspects of biology, chemistry, physics and physiology of humic substance macromolecules, includes the very latest in high level molecular modelling and teaches techniques of particular relevance to agriculture and agronomy.