The study of the environment includes interactions among the physical, chemical and biological components of the environment. The introduction of contaminants into the environment that cause instability, disorder, harm or discomfort to the physical systems or living organisms is a major concern that is addressed in this book. A simple field sampling / preconcentration strategy for determination and speciation of Cr(III) and Cr(VI) in seawater is described. Advantages of green methodologies over traditional techniques to extract pesticides from the environment are also presented. Also included in the book is a review of the most important sources of Hg into the environment and an evaluation of the use of different animal species as bioindicators of human mercury exposure. A variety of regional air pollution issues including the toxicity of smoke and the harmful effects of high surface ozone concentrations effects on human's health and crop production are examined.