Preface

Groundwater microbiology is the study of the microscopic organisms that inhabit subsurface groundwater systems. For many years, it was generally assumed that the geological materials beneath our feet were repositories of long-dead organisms rather than habitats for living ones. Recent discoveries over the last few decades have demonstrated the existence of a diverse world of microorganisms living in the subsurface, independent of sunlight and oxygen and often thriving under extreme physical environmental conditions and nutrient limitations.

Groundwater systems are particularly favorable environments for microorganisms, with relatively stable temperatures, nutrients supplied by flowing groundwater, and abundant mineral and fracture surfaces to colonize. Any consideration of groundwater systems must therefore address the microorganisms that live there – for they are not passive inhabitants. Rather, the unique metabolic capabilities of microbes implicate them as key agents in the flow of energy and the processing of organic and inorganic compounds in subsurface environments, affecting the chemical composition of groundwater as well as the physical properties of the sediments and rock formations through which these hidden waters move.

This book introduces the principals of groundwater microbiology, from aspects of cell structure and growth, to the bioenergetics and metabolism of subsurface microorganisms, to the geochemical and physical influences of widespread microbial activity on groundwater systems and water quality. As summarized in the later sections of the book, the coupling of microorganisms with their geological surroundings – a bond established billions of years ago as life took hold on our planet – is of particular value in bioremediation and microbially induced mineral precipitation applications, such as the clean-up of contaminated groundwater systems and reduction of aquifer permeability.

As revealed in this book, microbiology has a central role in determining the patterns of groundwater chemistry. Studies of groundwater contamination and its remediation that do not incorporate microbiological insight are likely to overlook opportunities to understand the important processes governing conditions at the site and thus, fail to recognize alternative treatment options. Therefore, we recommend inclusion of a team member with microbiology expertise in every major investigation of groundwater contamination and remediation.