Differential Effects of Dissolved Organic Carbon upon Re-Entrainment and Surface Properties of Groundwater Bacteria and Bacteria-Sized Microspheres during Transport through a Contaminated, Sandy Aquifer

Injection-and-recovery studies involving a contaminated, sandy aquifer (Cape Cod, Massachusetts) were conducted to assess the relative susceptibility for in situ re-entrainment of attached groundwater bacteria (Pseudomonas stuzeri ML2, and uncultured, native bacteria) and carboxylate-modified microspheres (0.2 and 1.0 ?m diameters). Different patterns of re-entrainment were evident for the two colloids in response to subsequent injections of groundwater (hydrodynamic perturbation), deionized water (ionic strength alteration), 77 ?M linear alkylbenzene sulfonates (LAS, anionic surfactant), and 76 ?M Tween 80 (polyoxyethylene sorbitan monooleate, a very hydrophobic nonionic surfactant). An injection of deionized water was more effective [...]