Colloid transport through fractured and unfractured laboratory sand columns

Toran, Laura; Palumbo, Anthony V.

doi:10.1016/0169-7722(92)90009-4

Cited by 83 publications

(36 citation statements)

References 26 publications

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“…This response demonstrates that particles traveling through the epikarst may be delivered to the water table at faster rates and have shorter overall residence times than non-reactive solutes derived from the same source. Such particle behavior, due to spatial variations in hydraulic conductivity and associated differences in pore aperture, has already been reported from porous aquifers (Toran and Palumbo 1992;Flynn 2003), and fractured media (Champ and Schroeter 1988;McKay et al 2000).…”

Section: Discussionsupporting

confidence: 66%

Use of particulate surrogates for assessing microbial mobility in subsurface ecosystems

Sinreich

Flynn²,

Zopfi

2008

Hydrogeol J

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Mass fluxes from the ground surface can play a vital role in influencing groundwater ecosystems. Rates of delivery may influence intact ecosystem composition, while fluxes of substances associated with anthropogenic activity may critically alter the functioning of associated microbial assemblages. Field-based tracing experiments offer a valuable means of understanding mass transport rates and mechanisms, particularly in complex heterogeneous epikarst systems overlying vulnerable fissured aquifers. A short-term tracer experiment monitoring solute and particle tracer concentrations after they passed through a 10-m-thick sequence of limestone, capped by a thin soil, revealed rapid travel times and variable attenuation rates for the substances employed. Results demonstrated that particle tracers have shorter average travel times and can reach the subsurface in higher concentrations and over shorter times than non-reactive solutes. High recovery rates for the bacterial tracer Ralstonia eutropha H16 contrasted strongly with those of similarly sized fluorescent polystyrene microspheres, highlighting the importance of physico-chemical surface characteristics of particle tracers. Complementary laboratory batch experiments examined the role played by organic and inorganic soil/rock surfaces on particle tracer attenuation. Findings suggest that biofilms may significantly promote transport of particulate material below ground, i.e., the delivery of allochthonous microorganisms to karst groundwater.

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Section: Discussionsupporting

confidence: 66%

Use of particulate surrogates for assessing microbial mobility in subsurface ecosystems

Sinreich

Flynn²,

Zopfi

2008

Hydrogeol J

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“…Differential advection. Early breakthrough of microorganisms compared to the breakthrough of a conservative tracer has been observed in several studies (1,37,44), and the primary mechanisms include (i) volume size exclusion (exclusion of colloids from smaller pores due to the inability of the colloids to fit into the pores), (ii) preferential flow path through high-conductivity regions, and (iii) hydrodynamic retardation (or chromatography) (exclusion of colloids from the lowervelocity regions of a pore throat due to the size of the colloids) (T. R. 1983-1984, 2000). It is likely that one or more of these mechanisms are operative, and our data provide a basis for a mechanistic interpretation.…”

Section: Discussionmentioning

confidence: 92%

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

Dong

Rothmel

Onstott

et al. 2002

Appl Environ Microbiol

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The transport characteristics of two adhesion-deficient, indigenous groundwater strains, Comamonas sp. strain DA001 and Erwinia herbicola OYS2-A, were studied by using intact sediment cores (7 by 50 cm) from Oyster, Va. Both strains are gram-negative rods (1.10 by 0.56 and 1.56 by 0.46 m, respectively) with strongly hydrophilic membranes and a slightly negative surface charge. The two strains exhibited markedly different behaviors when they were transported through granular porous sediment. To eliminate any effects of physical and chemical heterogeneity on bacterial transport and thus isolate the biological effect, the two strains were simultaneously injected into the same core. DA001 cells were metabolically labeled with 35 S and tagged with a vital fluorescent stain, while OYS2-A cells were metabolically labeled with 14 C. The fast decay of 35 S allowed deconvolution of the two isotopes (and therefore the two strains). Dramatic differences in the transport behaviors were observed. The breakthrough of DA001 and the breakthrough of OYS2-A both occurred before the breakthrough of a conservative tracer (termed differential advection), with effluent recoveries of 55 and 30%, respectively. The retained bacterial concentration of OYS2-A in the sediment was twofold higher than that of DA001. Among the cell properties analyzed, the statistically significant differences between the two strains were cell length and diameter. The shorter, larger-diameter DA001 cells displayed a higher effluent recovery than the longer, smaller-diameter OYS2-A cells. CXTFIT modeling results indicated that compared to the DA001 cells, the OYS2-A cells experienced lower pore velocity, higher porosity, a higher attachment rate, and a lower detachment rate. All these factors may contribute to the observed differences in transport.Understanding bacterial transport in porous media is of great importance for successful implementation of bioremediation strategies in subsurface environments. One vital requirement for successful implementation of bioaugmentation, the injection of bacteria with degradative capabilities into the subsurface to remediate a contaminated aquifer (30,36,43), is the delivery of selected bacteria to and through the contaminated zone of an aquifer. In most bacterial transport studies, bacterial attachment to mineral grains significantly impairs effective dispersion of the introduced bacteria throughout the aquifer (8,23,25). Bacterial attachment to mineral grain surfaces is influenced by biological factors associated with the bacterial cells and by physical and chemical factors associated with a granular aquifer (12,17,22,34).The physical, chemical, and biological effects are typically grouped into two probabilities, as described in filtration theory: the probability of bacterial collision with a sediment grain collector upon approach (collector efficiency) and the probability of bacterial attachment to the collector upon collision (collision efficiency). The collector efficiency accounts for the physical factors (interceptio...

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“…For nonperiodic or heterogeneous porous media, where REV selection Previous studies have suggested that colloid transport in porous media is significantly affected by particle size [Fontes et al, 1991, Gannon et al, 1991. Early breakthrough of colloids and biocolloids as compared to that of conservative tracers has been observed in several studies [Bales et al, 1989;Toran and Palumbo, 1992;Powelson et al, 1993;Grindrod et al, 1996;Dong et al, 2002;Keller et al, 2004;Vasiliadou and Chrysikopoulos, 2011;Sinton et al, 2012;Syngouna and Chrysikopoulos, 2013;Chrysikopoulos and Syngouna, 2014]. Colloid early breakthrough can be attributed to effective porosity reduction (colloids cannot penetrate smaller pores due to their inability to fit into them), preferential flow paths through high-conductivity regions, and exclusion from the lower-velocity regions [Chrysikopoulos and Abdel-Salam, 1997;Dong et al, 2002;Ginn, 2002;Ahfir et al, 2009], which can also be viewed as a reduction of the effective porosity of the porous medium [Morley et al, 1998].…”

Section: Introductionmentioning

confidence: 99%

Colloid particle size‐dependent dispersivity

Chrysikopoulos,

Katzourakis

2015

Water Resources Research

130

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Laboratory and field studies have demonstrated that dispersion coefficients evaluated by fitting advection-dispersion transport models to nonreactive tracer breakthrough curves do not adequately describe colloid transport under the same flow field conditions. Here an extensive laboratory study was undertaken to assess whether the dispersivity, which traditionally has been considered to be a property of the porous medium, is dependent on colloid particle size and interstitial velocity. A total of 48 colloid transport experiments were performed in columns packed with glass beads under chemically unfavorable colloid attachment conditions. Nine different colloid diameters and various flow velocities were examined. The breakthrough curves were successfully simulated with a mathematical model describing colloid transport in homogeneous, water-saturated porous media. The experimental data set collected in this study demonstrated that the dispersivity is positively correlated with colloid particle size, and increases with increasing velocity. The dispersivity values determined in this laboratory study were compared with 380 dispersivity values from earlier laboratory and field-scale solute, colloid and biocolloid transport studies published in the literature.

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Colloid transport through fractured and unfractured laboratory sand columns

Cited by 83 publications

References 26 publications

Use of particulate surrogates for assessing microbial mobility in subsurface ecosystems

Use of particulate surrogates for assessing microbial mobility in subsurface ecosystems

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

Colloid particle size‐dependent dispersivity

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