Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/2005
Publication Date: 8/16/2005
Citation: Lehman, R.M. 2005. Aquifer microbiology: perfecting the view. The Joint International Symposium for Subsurface Microbiology (ISSM 2005) and Environmental Biogeochemistry (ISEB XVII), Jackson Hole, WY, August 14-19, 2005. Interpretive Summary: This paper considers the understanding of aquifer microbiology as determined from studying different types of samples: core, groundwater, and substratum incubated within wells.
Technical Abstract: Collection and examination of field samples are required to understand existing aquifer microbiology and predict the consequences of aquifer manipulations. Groundwater samples have been, and still are, the sources of a great deal of information regarding aquifer microorganisms. Samples of the geologic media, rock or sediment, have been increasingly studied through the 1980s and 1990s. A number of reports support the contention that the majority of aquifer biomass is attached and the cores should be the primary unit of study. However, a recent survey of the literature shows increasing reports of microorganisms that are unique to the groundwater. In two field studies of fractured rock aquifers, we found more biomass associated with groundwater compared to the rock, although fracture faces were not specifically studied. In another field study of an unconsolidated, sandy aquifer, we found an overwhelming percent of the overall activity was associated with the groundwater compared to the sandy sediments that comprised the shallow aquifer. Further, this distribution reversed with the addition of carbon to the aquifer. Other authors have suggested the opposite: that aquifer eutrophication enhances distribution of biomass to the groundwater. Given the cost and difficulty with acquiring core samples, some investigators have studied substrata that have been colonized during incubation in the aquifer. Studies of communities colonizing these substrata suggest that while the results are not the equivalent of core or groundwater samples, there may be greater access to the overall diversity of aquifer microorganisms.