Transport of indigenous bacteria through sandy aquifer sediments was investigated in forced- and natural-gradient tracer teste. A diverse population of bacteria was collected and concentrated from groundwater at the site, stained with a DNA-specific fluorochrome, and injected back into the aquifer. Included with the injectate were a conservative tracer (Br- or Cl-) and bacteria-sized (0.2-1.3-??m) microspheres having carboxylated, carbonyl, or neutral surfaces. Transport of stained bacteria and all types and size classes of microspheres was evident. In the natural-gradient test, both surface characteristics and size of microspheres affected attenuation. Surface characteristics had the greatest effect upon retardation. Peak break-through of DAPI-stained bacteria (forced-gradient experiment) occurred well in advance of bromide at the more distal sampler. Transport behavior of bacteria was substantially different from that of carboxylated microspheres of comparable size. ?? 1988 American Chemical Society.
Additional publication details
Transport of microspheres and indigenous bacteria through a sandy aquifer: Results of natural- and forced-gradient tracer experiments