Ionic-strength effects on colloid transport and interfacial reactions in partially saturated porous media
نویسندگان
چکیده
[1] Contaminant migration through the vadose zone may be influenced by the presence of mineral colloids that are mobilized during infiltration events. In this work, we report model calculations and experimental data on the role of pore water ionic strength in the transport of silica colloids through water-saturated and unsaturated porous media. The transport model solves the advection-dispersion equation, together with kinetics equations for straining, air-water interface capture, and mineral-grain attachment. Parameters for airwater and solid-water interfacial area required by the transport model are derived through the application of a published liquid-vapor configuration model that accounts for dualphase (i.e., air and water) occupancy of pore spaces. Comparison of experimental and modeled results reveals that the dominant colloid-immobilization mechanism transitions from straining, to air-water interface capture, and finally, to mineral-grain attachment as the ionic strength increases from 2 10 4 M to 0.2 M. The results of this research provide a basic framework for interpreting how interactions between moisture content and pore water chemistry affect colloid mobility in the vadose zone.
منابع مشابه
Transport of Silica Colloid through Saturated Porous Media under Different Hydrogeochemical and Hydrodynamic Conditions Considering Managed Aquifer Recharge
Colloids may have an important role in regulating the structure and function of groundwater ecosystems, and may influence the migration of low solubility contaminants in groundwater. There is, however, a degree of uncertainty about how colloids behave under the variable hydrogeochemical and hydrodynamic conditions that occur during managed aquifer recharge. We used an online monitoring system t...
متن کاملColloid transport with wetting fronts: interactive effects of solution surface tension and ionic strength.
Transport of colloids with transient wetting fronts represents an important mechanism of contaminant migration in the vadose zone. The work presented here used steady-state saturated and transient unsaturated flow columns to evaluate the transport of a fluorescent latex microsphere (980 nm in diameter) with capillary wetting fronts of different solution surface tensions and ionic strengths. The...
متن کاملReview on subsurface colloids and colloid-associated contaminant transport in saturated porous media.
In this review article, the authors present up-to-date developments on experimental, modeling and field studies on the role of subsurface colloidal fines on contaminant transport in saturated porous media. It is a complex phenomenon in porous media involving several basic processes such as colloidal fines release, dispersion stabilization, migration and fines entrapment/plugging at the pore con...
متن کاملEffects of pH and ionic strength on sulfamethoxazole and ciprofloxacin transport in saturated porous media.
Many antibiotics regarded as emerging contaminants have been frequently detected in soils and groundwater; however, their transport behaviors in soils remain largely unknown. This study examined the transport of two antibiotics, sulfamethoxazole (SMZ) and ciprofloxacin (CIP), in saturated porous media. Laboratory columns packed with quartz sand was used to test the effects of solution pH and io...
متن کاملHysteresis of colloid retention and release in saturated porous media during transients in solution chemistry.
Saturated packed column and micromodel transport studies were conducted to gain insight on mechanisms of colloid retention and release under unfavorable attachment conditions. The initial deposition of colloids in porous media was found to be a strongly coupled process that depended on solution chemistry and pore space geometry. During steady state chemical conditions, colloid deposition was no...
متن کامل