A comparison of clay colloid and artificial microsphere transport in natural discrete fractures

Zvikelsky, Ori; Weisbrod, Noam; Dody, Avraham

doi:10.1016/j.jcis.2008.04.035

Cited by 29 publications

(21 citation statements)

References 44 publications

(79 reference statements)

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“…Bromide arrived at the center of mass (0.5 C/C 0 ) at 3.5 ± 0.4 fracture volumes, much earlier than Li + (6.4 ± 0.8 fracture volumes), although they exhibited similar early arrival times. These results concur with those reported by Zvikelsky and Weisbrod (2006) and Zvikelsky et al (2008) for a different fractured chalk core and imply a marked retardation of Li + vs. Br − transport (Fig. 3).…”

Section: Resultssupporting

confidence: 93%

“…3–8). Zeta potentials of montmorillonite and chalk in the tracer solution in this study were close to the values reported by Tang and Weisbrod (2009) and Zvikelsky et al (2008)…”

Section: Resultssupporting

confidence: 91%

“…5 and 6 (Table 2) was 0.7 ± 0.0 fracture volume, versus 1.1 ± 0.1 fracture volumes for Br − and 1.0 ± 0.0 fracture volume for Li + . Th is is in good agreement with the results of Zvikelsky et al (2008) on a chalk core with slightly diff erent physical dimensions and equivalent hydraulic aperture. Th e addition of HA in Exp.…”

Section: Transport Experimentssupporting

confidence: 87%

“…After the postexperiment flushing stages, most (92.8–99.5%) of the colloid(s) were recovered, with no significant differences between experiments (vs. 70.0–91.5% recovery at the BTC), probably due to the combination of neutral pH (about 7.5) and high flow rate of the flushing solution, which favored the dispersion, transport, and (re)mobilization of the colloid(s) (Table 2). In the absence of Cs, irreversible deposition (<19%) of montmorillonite inside naturally fractured chalk has also been reported by Zvikelsky et al (2008) and attributed to the internal fracture structure and channels.…”

Section: Resultsmentioning

confidence: 74%

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Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures

Tang

Weisbrod

2010

J of Env Quality

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Transport of cesium (Cs) was investigated in a saturated natural chalk fracture with an average equivalent hydraulic aperture of 129 microm. The results show that Cs (inflow concentration of 0.22 mmol L(-1)) can be transported in its dissolved form and in association with montmorillonite. Humic acid (HA) did not sorb Cs but enhanced colloid-associated Cs transport by 12.5% in terms of breakthrough curve (BTC) recovery. The BTCs clearly showed desorption of Cs from the fracture walls during the artificial rainwater (ARW)-injection period. Cesium transport associated with montmorillonite colloids was significant, with a maximum colloid-associated Cs C/C(0) (outflow-to-inflow concentration ratio) value of 16.6 +/- 1.1% during the tracer (colloids and LiBr)-injection period. However, the relative contribution of colloid-associated Cs transport to total Cs transport was relatively low, amounting to 10.3 +/- 0.7% and 14.5 +/- 0.7% with montmorillonite (500 mg L(-1)) and the montmorillonite-HA (10 mg L(-1)) mixture, respectively. Readsorption of Cs onto the colloids occurred immediately on switching from the tracer suspension to the background solution of ARW. The significant colloid-associated Cs transport, the stripping effect of Cs from colloids, and the slow desorption of Cs from fracture walls reported in this study have important implications for risk assessments of Cs mobility in fractured carbonatic rocks.

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Section: Resultssupporting

confidence: 93%

“…3–8). Zeta potentials of montmorillonite and chalk in the tracer solution in this study were close to the values reported by Tang and Weisbrod (2009) and Zvikelsky et al (2008)…”

Section: Resultssupporting

confidence: 91%

Section: Transport Experimentssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 74%

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Dissolved and Colloidal Transport of Cesium in Natural Discrete Fractures

Tang

Weisbrod

2010

J of Env Quality

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“…We showed that intermittent rainfall can mobilize microspheres, and the mobilization could be particularly high in soil with greater permeability because of the presence of macropores. However, the transport and mobilization of actual pathogens can vary from that of microspheres (Harvey et al, 1989), possibly due to differences in contact points (Harvey et al, 2011), shape (Aramrak et al, 2013), density (Zvikelsky et al, 2008), and surface properties (Weisbrod et al, 2013). Furthermore, pathogens could lose their virulence and, perhaps, their viability during desiccation; both factors could either decrease or increase the mobilization of viable, infectious pathogens.…”

Section: Discussionmentioning

confidence: 99%

Mobilization of Microspheres from a Fractured Soil during Intermittent Infiltration Events

Mohanty

Bulicek

Metge

et al. 2015

Vadose Zone Journal

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The vadose zone filters pathogenic microbes from infiltrating water and consequently protects the groundwater from possible contamination. In some cases, however, the deposited microbes may be mobilized during rainfall and migrate into the groundwater. We examined the mobilization of microspheres, surrogates for microbes, in an intact core of a fractured soil by intermittent simulated rainfall. Fluorescent polystyrene microspheres of two sizes (0.5 and 1.8 mm) and Br− were first applied to the core to deposit the microspheres, and then the core was subjected to three intermittent infiltration events to mobilize the deposited microspheres. Collecting effluent samples through a 19‐port sampler at the base of the core, we found that water flowed through only five ports, and the flow rates varied among the ports by a factor of 12. These results suggest that flow paths leading to the ports had different permeabilities, partly due to macropores. Although 40 to 69% of injected microspheres were retained in the core during their application, 12 to 30% of the retained microspheres were mobilized during three intermittent infiltration events. The extent of microsphere mobilization was greater in flow paths with greater permeability, which indicates that macropores could enhance colloid mobilization during intermittent infiltration events. In all ports, the 1.8‐mm microspheres were mobilized to a greater extent than the 0.5‐mm microspheres, suggesting that larger colloids are more likely to mobilize. These results are useful in assessing the potential of pathogen mobilization and colloid‐facilitated transport of contaminants in the subsurface under natural infiltration events.

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