Mobilization of Microspheres from a Fractured Soil during Intermittent Infiltration Events

Mohanty, Sanjay K.; Bulicek, Mark Charles David; Metge, David W.; Harvey, Ronald W.; Ryan, Joseph N.; Boehm, Alexandria B.

doi:10.2136/vzj2014.05.0058

Cited by 29 publications

(36 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These preferential flow paths vary by lengths and pore sizes and are distributed heterogeneously along with the soil matrix. 24 Water flux exceeded the rainfall application rate at some ports, whereas in other ports, water flux remained lower than the rainfall application rate. The spatial variation of flux at the bottom of the cores indicates that the flow paths feeding the active ports were characterized by different permeability.…”

Section: ■ Discussionmentioning

confidence: 94%

“…The experimental setup consisted of a rainfall reservoir, a soil core, a sampling grid, and sample collection tubes. 24 Rainfall was simulated by dripping an aqueous solution (0.1 mM NaCl) through 85 needles (25 gauge) from the rainfall reservoir. The intact core was placed under the rainfall reservoir (distance between the needle tip and core top was 25 cm) and on a 19 port sampling grid (see Figure S1 of the Supporting Information).…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

See 1 more Smart Citation

Colloid Mobilization in a Fractured Soil during Dry–Wet Cycles: Role of Drying Duration and Flow Path Permeability

Mohanty

Saiers

Ryan

2015

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

In subsurface soils, colloids are mobilized by infiltrating rainwater, but the source of colloids and the process by which colloids are generated between rainfalls are not clear. We examined the effect of drying duration and the spatial variation of soil permeability on the mobilization of in situ colloids in intact soil cores (fractured and heavily weathered saprolite) during dry-wet cycles. Measuring water flux at multiple sampling ports at the core base, we found that water drained through flow paths of different permeability. The duration of antecedent drying cycles affected the amount of mobilized colloids, particularly in high-flux ports that received water from soil regions with a large number of macro- and mesopores. In these ports, the amount of mobilized colloids increased with increased drying duration up to 2.5 days. For drying durations greater than 2.5 days, the amount of mobilized colloids decreased. In contrast, increasing drying duration had a limited effect on colloid mobilization in low-flux ports, which presumably received water from soil regions with fewer macro- and mesopores. On the basis of these results, we attribute this dependence of colloid mobilization upon drying duration to colloid generation from dry pore walls and distribution of colloids in flow paths, which appear to be sensitive to the moisture content of soil after drying and flow path permeability. The results are useful for improving the understanding of colloid mobilization during fluctuating weather conditions.

show abstract

Section: ■ Discussionmentioning

confidence: 94%

Section: ■ Experimental Detailsmentioning

confidence: 99%

Colloid Mobilization in a Fractured Soil during Dry–Wet Cycles: Role of Drying Duration and Flow Path Permeability

Mohanty

Saiers

Ryan

2015

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The capillary stress is generated at an air-water interface (AWI) and is the sum of the surface tension and pressure forces caused by the curvature of the AWI (Chatterjee et al 2012(Chatterjee et al , 2013. The matrix in contact with an AWI could experience a capillary stress and be deformed (such as cracking and shrink) (Majdalani et al 2008;Mohanty et al 2015a), and the deformation of the matrix is a kind of weakening process. This weakening effect on pore walls could generate mounts of colloidal particles (Aramrak et al 2011(Aramrak et al , 2014Michel et al 2010).…”

Section: Particle Mobilization and Transportmentioning

confidence: 99%

“…AWI usually plays a fundamental role in particle mobilization and transport (Chatterjee et al 2012;Michel et al 2010;Mohanty et al 2015a;Zhuang et al 2010). Particles attached to AWIs experience strong capillary forces, and these forces can exceed solid water adhesion forces by several orders of magnitude (Aramrak et al 2011;Chatterjee et al 2012).…”

Section: Particle Mobilization and Transportmentioning

confidence: 99%

Drying–wetting cycles facilitated mobilization and transport of metal-rich colloidal particles from exposed mine tailing into soil in a gold mining region along the Silk Road

2016

Environ Earth Sci

View full text Add to dashboard Cite

Exposed mine tailings could release substantial amounts of toxic metal-rich colloidal particles into soils during drying-wetting (D-W) cycles, but the mechanisms are still incompletely understood. In this study, two-layered (tailings above and soils below) packed columns were set to explore the effects of D-W cycles on tailing particle (TP) mobilization and transport in soil, and the mediating effect of TPs on the release and transport of heavy metals (Pb and Cu) was also examined. Results show that D-W cycles enhanced colloidal TP (approximately 190-712 nm) release from the column. The enhancing effect depends on duration of drying period, being slight for short-term drying (1, 3, 7, and 14 days) and significant for long-term drying (30, 60, and 90 days). The most interesting observation is the concentration valley of the effluent TPs during wetting event after 7-and 14-day drying. Based on these results, the dependence of TP mobilization and transport upon drying duration can be attributed to a combined action of different particle generation mechanisms during different drying periods, which appears to be relevant to the pore water content. The release and transport of Pb and Cu from the tailings into soil were dominantly mediated by the TPs and significantly enhanced by D-W cycles. These findings improve the understanding of TPs mobilization and transport in soil under fluctuating weather conditions.

show abstract

“…This was expected as disturbances (mechanical, acoustic, etc.) are known to enhance colloid mobilization (Mohanty et al, 2015;Roberts and Abdel-Fattah, 2009). There was not; however, a corresponding pulse of Am.…”

Section: Column Breakthrough Experimentsmentioning

confidence: 99%

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

Dittrich

Boukhalfa

Ware

et al. 2015

Journal of Environmental Radioactivity

View full text Add to dashboard Cite

Understanding the parameters that control colloid-mediated transport of radionuclides is important for the safe disposal of used nuclear fuel. We report an experimental and reactive transport modeling examination of americium transport in a groundwater-bentonite-fracture fill material system. A series of batch sorption and column transport experiments were conducted to determine the role of desorption kinetics from bentonite colloids in the transport of americium through fracture materials. We used fracture fill material from a shear zone in altered granodiorite collected from the Grimsel Test Site (GTS) in Switzerland and colloidal suspensions generated from FEBEX bentonite, a potential repository backfill material. The colloidal suspension (100 mg L(-1)) was prepared in synthetic groundwater that matched the natural water chemistry at GTS and was spiked with 5.5 × 10(-10) M (241)Am. Batch characterizations indicated that 97% of the americium in the stock suspension was adsorbed to the colloids. Breakthrough experiments conducted by injecting the americium colloidal suspension through three identical columns in series, each with mean residence times of 6 h, show that more than 95% of the bentonite colloids were transported through each of the columns, with modeled colloid filtration rates (k(f)) of 0.01-0.02 h(-1). Am recoveries in each column were 55-60%, and Am desorption rate constants from the colloids, determined from 1-D transport modeling, were 0.96, 0.98, and 0.91 h(-1) in the three columns, respectively. The consistency in Am recoveries and desorption rate constants in each column indicates that the Am was not associated with binding sites of widely-varying strengths on the colloids, as one binding site with fast kinetics represented the system accurately for all three sequential columns. Our data suggest that colloid-mediated transport of Am in a bentonite-fracture fill material system is unlikely to result in transport over long distance scales because of the ability of the fracture materials to rapidly strip Am from the bentonite colloids and the apparent lack of a strong binding site that would keep a fraction of the Am strongly-associated with the colloids.

show abstract

Mobilization of Microspheres from a Fractured Soil during Intermittent Infiltration Events

Cited by 29 publications

References 62 publications

Colloid Mobilization in a Fractured Soil during Dry–Wet Cycles: Role of Drying Duration and Flow Path Permeability

Colloid Mobilization in a Fractured Soil during Dry–Wet Cycles: Role of Drying Duration and Flow Path Permeability

Drying–wetting cycles facilitated mobilization and transport of metal-rich colloidal particles from exposed mine tailing into soil in a gold mining region along the Silk Road

Laboratory investigation of the role of desorption kinetics on americium transport associated with bentonite colloids

Contact Info

Product

Resources

About