The field of environmental chemistry is broad and multidisciplinary, with ill-defined boundaries. The Handbook of Environmental Chemistry series is a useful compilation that has attempted, through several parts of three volumes, to meet the needs of the diverse environmental science community by presenting reviews of topics directly germane to the discipline as well as topics situated along disciplinary borders. The objectives of the series are to present a uniform view of the chemistry of the environment, to discuss the distribution of chemical reactions and the equilibrium between environmental compartments, to aid in the understanding and development of tests and models to predict the fate of new chemicals, and to present the properties of selected important compounds. Volume 1 deals with characteristics of the natural environment and the biogeochemical cycles. Part D, reviewed here, is divided into four chapters: the cycles of copper, silver, and gold; modeling the global carbon cycle; chemical limnology; and environmental microbiology. The apparent disparity among these subjects is not surprising when viewed in relation to parts A–C, which address more traditional and general subjects.