Extended tailing of bacteria following breakthrough at the Narrow Channel Focus Area, Oyster, Virginia

Abstract

Abstract. Extended tailing of low bacterial concentrations following breakthrough at the Narrow Channel focus area was observed for 4 months. Bacterial attachment and detachment kinetics associated with breakthrough and extended tailing were determined by fitting a one-dimensional transport model to the field breakthrough-tailing data. Spatial variations in attachment rate coefficient (k f) were observed under forced gradient conditions (i.e., kf decreased as travel distance increased), possibly because of decreased bacterial adhesion with increased transport distance. When pore water velocity decreased by an order of magnitude at 9 days following injection, apparent bacterial attachment rate coefficients did not decrease with velocity as expected from filtration theory, but, instead, increased greatly for most of the wells. The coincidence of the increase in apparent attachment rate coefficient with the occurrence of protist blooms suggested that the loss of bacteria from the aqueous phase during the protist blooms was not governed by filtration but rather was governed by predation. Simulations were performed to examine the transport distances achieved with and without detachment, using attachment and detachment rate coefficients similar to those obtained in this field study. Simulations that included detachment showed that transport distances of bacteria may significantly increase because of detachment under the conditions examined. The relationship between the attachment rate and pore wa-2687 Introduction Bacterial transport in the subsurface is influenced by advec-

Processes in Microbial Transport in the Natural Subsurface

“…However, slow release of attached bacteria at low concentrations over long periods of time may contribute significantly to transport over longer distances. At the South Oyster site (NC flow cell), inferred detachment rate coefficients were similar in magnitude to attachment rate coefficients [139]. This contrasts to laboratory experimental results reported in the literature, in which estimated detachment rate coefficients are one to three orders of magnitude smaller than attachment rate coefficients [139, Table 2].…”

Simultaneous Transport of Two Bacterial Strains in Intact Cores from Oyster, Virginia: Biological Effects and Numerical Modeling

“…Recent modeling . A particle-based model (T. D. Scheibe, submitted for publication) is capable of incorporating these complexities into the model formulation and yielding a robust fit for both effluent breakthrough and the profile of attached bacteria in sediment (51). Differential advection.…”

Processes in microbial transport in the natural subsurface

“…At South Oyster, a dramatic increase in protozoan populations was observed in response to the injection of bacteria [20]. Although the total effect is difficult to quantify because of limited observations of attached protozoan populations, it was shown that an apparent increase in attachment rate coincided with the timing of the protozoan bloom at a time when a decrease in attachment rate would have been expected based on other factors [139].…”

“…Note that pore exclusion is also termed specifically ''size exclusion'' by some authors [98], as well as various other terms such as ''volume exclusion'' [4], ''pore size exclusion'' [116], or ''size exclusion chromatography'' [50]. The term ''differential advection'' has also been introduced [138,139] to generally describe the phenomenon of earlier breakthrough of colloids relative to a solute tracer without specific regard to the mechanism. The mechanics and modeling of pore exclusion has been recently debated [44,98].…”