Role of physical heterogeneity in the interpretation of small-scale laboratory and field observations of bacteria, microbial-sized microsphere, and bromide transport through aquifer sediments

Water Resources Research
By: , and 

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Abstract

The effect of physical variability upon the relative transport behavior of microbial-sized microspheres, indigenous bacteria, and bromide was examined in field and flow-through column studies for a layered, but relatively well sorted, sandy glaciofluvial aquifer. These investigations involved repacked, sieved, and undisturbed aquifer sediments. In the field, peak abundance of labeled bacteria traveling laterally with groundwater flow 6 m downgradient from point of injection was coincident with the retarded peak of carboxylated microspheres (retardation factor, RF = 1.7) at the 8.8 m depth, but preceded the bromide peak and the retarded microsphere peak (RF = 1.5) at the 9.0 m depth. At the 9.5 m depth, the bacterial peak was coincident with both the bromide and the microsphere peaks. Although sorption appeared to be a predominant mechanism responsible for immobilization of microbial-sized microspheres in the aquifer, straining appeared to be primarily responsible for their removal in 0.6-m-long columns of repacked, unsieved aquifer sediments. The manner in which the columns were packed also affected optimal size for microsphere transport, which in one experiment was near the size of the small (∼2 μm) groundwater protozoa (flagellates). These data suggest that variability in aquifer sediment structure can be important in interpretation of both small-scale field and laboratory experiments examining microbial transport behavior.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Role of physical heterogeneity in the interpretation of small-scale laboratory and field observations of bacteria, microbial-sized microsphere, and bromide transport through aquifer sediments
Series title Water Resources Research
DOI 10.1029/93WR00963
Volume 29
Issue 8
Year Published 1993
Language English
Publisher American Geophysical Union
Contributing office(s) Toxic Substances Hydrology Program
Description 9 p.
First page 2713
Last page 2721