The critical importance of environmental preservation is apparent to everyone.  The issues facing us today, be they global warming, the depleting ozone layer, the controversy over nuclear power, or the continuing problems of water pollution and solid waste disposal, are headline news.  Environmental Science: Systems and Solutions, Fourth Edition, offers the basic principles necessary to understand and address these multi-faceted and often very complex current environmental concerns.  The book provides a comprehensive overview and synthesis of environmental science and provides the basic factual data necessary to understand the environment as it is today.  It is important that students understand how various aspects of the natural environment interconnect with each other and with human society. Using a systems approach, the authors have organized complex information in a way that highlights these connections in a fair and unbiased fashion.   A Study Guide is incorporated at the end of each chapter to help reinforce concepts and provide a clear overview of material.