This second edition of Microplastic Contamination in Aquatic Environments: An Emerging Matter of Environmental Urgency presents 14 chapters, through which a team of global, expert contributors cover a full range of microplastic research. The first chapter describes the general patterns for sources, occurrence, and transport of microplastics to lead off the book. The next batch of chapters covers sampling analytical methods for quantifying microplastics in the environment, followed by chapters addressing the association of chemicals with microplastics. A large cluster of chapters focus on the fate and transport of microplastics in wastewater treatment plants, freshwater systems, marine environment, terrestrial settings, and riverine runoff that connects terrestrial and marine systems. The next few chapters examine biotransport and effects of microplastics in organisms. The last two chapters are dedicated to two emerging research areas: nanoplastics in the environment and management strategies for global plastic pollution. Outlooks for future research to better understand the situation and further improvements of microplastic research are also covered. In the 6 years since the previous edition published, this fast-moving area has evolved, and the contents of this revision reflect that. There are numerous brand-new chapters, chapters that have been revised, and chapters that have been completely refocused. This book provides an overview of microplastics research. It is a guide for researchers to better understand the occurrence of microplastics. Ideally, this book provides basic background knowledge of microplastics for oceanographers, ecologists, and climatologists.