Preface

This book was written as an introduction to the occurrence, geochemistry, and the treatment of high-fluoride groundwater. Dissolved fluoride is like several other elements which have been shown to be beneficial to human health but only at relatively low concentrations and detrimental to human health at higher concentrations. It is not essential to human health such as Se or Zn or Co or vitamin C, but it substantially decreases the occurrence of dental caries, particularly for the development of children’s teeth.

Because groundwater is being extracted at ever increasing rates, there is an increasing burden on society to regularly monitor groundwater quality to avoid ingesting injurious amounts of dissolved constituents. Public supply wells in developed countries are usually monitored for compliance with regulatory standards. However, water quality of private wells is often not required to be tested and deleterious concentrations of inorganic or organic constituents can affect the health of livestock, crops and humans. This book was written partly to inform the public that even though groundwater is naturally occurring, it can contain concentrations of several chemical elements that should not be consumed or used for cooking or used for plants and animals without treatment. Furthermore, excessive pumping of an aquifer can change the groundwater composition from an acceptable to an unacceptable designation in short periods of time. How climate change affects groundwater quality is another potential danger that we are only just beginning to appreciate.

The authors have studied many aspects of groundwater chemistry and have seen the results of communities that have been unknowingly exposed to high concentrations of fluoride and arsenic. They have joined with many others worldwide to sample and analyze groundwaters in different environments and interpret the processes that give rise to unhealthy concentrations of major, minor, and trace elements. From such studies, scientists can gradually reach conclusions of a general nature that make it easier to suggest whether a particular aquifer subject to a particular climate is likely to contain groundwater with natural contaminants that must be treated before using. It is only from the substantial work of so many scientists who came before us that we can contribute further to this body of accumulated knowledge we call hydrogeochemistry.