This Dictionary of Environmental Sciences has been compiled as an easily accessible reference book for students and other sections of people alike. Every aspect of its conception and layout has been planned to help the reader to find information he/she needs with minimum difficulty. This Dictionary has been written to fulfill the needs in a single volume on the measure aspects of Environmental Sciences and its impact on mankind. It is also hoped that the book will prove useful to teachers as an aid in conducting discussions on environmental problems in existing courses, and to others as a scientific introduction to pollution and its control. We are deeply indebted to all our friends and relatives for their valuable help extended in the preparation of this book.