Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source. It can be defined as the study of the sources, reactions, transport, effects, and fates of chemical species in the air, soil, and water environments; and the effect of human activity on these. Environmental chemistry is an interdisciplinary science that includes atmospheric, aquatic and soil chemistry, as well as heavily relying on analytical chemistry and being related to environmental and other areas of science. This book describes the chemistry of natural environmental systems, their composition and the processes and reactions that operate within and between the various components. It aims to apply knowledge of chemistry to understand environmental issues. The goal is to provide the readers the knowledge of how to do a chemist's share in improving environmental quality.