This comprehensive text will provide upper level undergraduate students a look at heterogeneous natural systems in the environment. The links between and within the various environmental components --air, water, soil -- are emphasized. There has been insufficient material of this type in existence that supplies both the depth of chemistry needed to explain natural processes and the breadth of material that would present a well rounded introduction to such systems. While the text focuses on basic knowledge and general principles, examples are taken from around the world. The book describes the chemistry of natural environmental systems, their composition and the processes and reactions that operate within and between the various components. Without focusing specifically on pollution, it also discusses ways in which these systems respond to peturbations, either those that are natural or those that are caused by humans. Background material from subjects such as atmospheric science, limnology, and social science is provided in order to establish a setting for a description of relevant chemistry. Because issues of the environment related to every society, care has been taken to relate the subject material to situations in urban and rural areas in both highly industrialized and low-income countries.