ABSTRACT
Heterogeneity dominates the microbiology of a subsurface system if inclusions are highly reactive or the predominant source of electron donor, electron acceptor, or nutrients. Environmental microbiology has historically been focused on isolating microorganisms and defining and understanding the various microbial processes in pure culture and in the environment. Indicator variograms are one of the geostatistical method of studying spatial continuity that have potential in the study of subsurface microbiology. The great majority of efforts to characterize subsurface microbiology have focused on variability between geologic strata, at scales ranging from meters to tens and hundreds of meters, in part because differences in chemical and physical properties are readily apparent and sampling is relatively easy. The subsurface environment can exhibit very pronounced spatial heterogeneity of physical properties as a result of the stratified nature of the deposits and the actions of geochemical processes over geologic time periods.
