Open AccessColloid Mobilization from a Variably Saturated, Intact Soil Core
Author(s) -
Levin Janna M.,
Herman Janet S.,
Hornberger George M.,
Saiers James E.
Publication year - 2006
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2005.0102
Subject(s) - colloid , soil water , infiltration (hvac) , chemistry , capillary action , mobilization , pore water pressure , vadose zone , flux (metallurgy) , soil science , geology , geotechnical engineering , materials science , composite material , archaeology , organic chemistry , history
Colloids may transport contaminants through unsaturated soils to the groundwater, and colloid mobilization is associated with transient hydrological events and sustained, steady flow. We examined mechanisms of colloid mobilization from an intact, unsaturated soil core during relatively steady flow. We collected the core from a site where soils contain 26% clay and infiltration occurs only at capillary‐pressure heads above −20 cm. We measured the colloid‐mass flux during consecutive, 1.5‐mo periods ( P 1 , P 2 , and P 3 ) distinguished by capillary‐pressure heads (Ψ B ) of −18.5, −11.5, and −18.5 cm, respectively. Mean mass flux values were 0.0886, 0.197, and 0.171 mg h −1 for P 1 , P 2 , and P 3 , respectively. Intervention analysis showed a significant increase in the mass flux of 0.079 mg h −1 as Ψ B became less negative. Results indicate that the number of soil pores through which water flows has a greater influence on colloid mobilization than do shear forces associated with elevated pore water velocities. Thus, colloid mobilization most likely is affected by a diffusion‐limited, colloid‐supply mechanism dependent on the number of pores contributing to flow.