Early concepts of the role of microorganisms in hydrogeology

Hydrogeologists and geochemists have made great progress in the past few decades in understanding the water/rock interaction that are major controls on the chemical character of ground water. We also recognize that, for many reactions, we do not understand the specific mechanisms generating these reactions, such as those involved in the generation of gases, dissolution of some minerals, and some aspects of isotopic fractionation. Additional understanding will be gained only by study of the interaction of organic material, minerals, and microorganisms in the water and in the pore space of the aquifer material.