What is Environmental Chemistry?

 Environmental chemistry is traditionally defined as

 “the study of the sources, reactions, transport, effects and fates of chemical species, in water, soil, and air environments, and the effect of human activity on these” . 

This definition implies a major focus on the measurement of pollutants in the various environments. However, a more precise definition would be the study of chemistry in natural systems and how this chemistry changes when perturbed by anthropogenic activities and/or the release of chemicals into the environment which changes their natural background levels. Environmental chemistry is not simply the measurement of air, water, or soil pollutants. It is a multidisciplinary subject that requires the environmental chemist to have a solid background in all areas of chemistry, including analytical, physical, organic, inorganic, and simple biochemistry. It is also a discipline that requires studies  across boundaries between the different fields of chemistry, physics, biology, ecology, meteorology, and others involved in the various environmental systems, which include the atmosphere, hydrosphere, geosphere, and biosphere. Understanding how these different systems interact allows the environmental chemist to give an accurate assessment of the impacts of chemical species on the environment as a whole.

Thus, the scope of environmental chemistry covers all of the Earth’s systems and their interactions with each other. Future environmental chemists need to recognize these interactions and include them when predicting how energy and chemical usage will affect each of the various systems. Traditionally, environmental chemistry is taught in a compartmentalized manner, treating the chemistries of the air, water, soil, and biota separately. Although this is done in an effort to simplify the treatment of these complicated systems, it does not address the interactions between the different systems or the connections between the physics and chemistry of each system. Therefore, a major focus of this text will be on the connections between the various environmental compartments, with special attention given to the fundamental chemistry that is common to all of the various systems. Environmental chemistry should not be confused with “green chemistry.” The goal of green chemistry is the development of chemical processes that use smaller amounts of safer chemicals with less energy use in order to lower their environmental impacts. The goal of environmental chemistry is the understanding of the chemical reactions and processes that control the environmental systems and how these are impacted by the addition of anthropogenic chemicals.

This approach allows environmental chemistry to be proactive instead of reactive. In the past, environmental chemistry has had a more reactive approach, identifying problems after the occurrence of a tragedy or a clearly obvious impact on the environment with loss of life, damage to plants and animals, or radical changes in environmental conditions – such as the loss of visibility in air and water systems or the depletion of the stratospheric ozone layer. Some of these past incidents will be examined in this text as examples of events that have taught us the potential impacts of anthropogenic pollution on the environment and the importance of understanding how the different environmental systems are linked. The lessons learned from these events have helped us to understand how the whole Earth system works and how the separate environmental systems interact. So, this book will stress how the various chemistries of the natural systems in the atmosphere, geosphere, hydrosphere, and biosphere interact with each other, sometimes enhancing environmental impacts and sometimes mitigating those impacts.