Abstract:
Until recently, natural soils were
believed to constitute two mobile phases: soil
moisture and soil air. However, research
revealed later the presence of another mobile
phase, which is now referred as the colloidal
phase, with a strong potential to facilitate the
transport of toxic contaminants and various
nutrients to groundwater, leading to significant
health concerns. Colloids, consisting of soil
particles of nano and micrometer scale, are
highly reactive in subsurface and sensitive to
the physico-chemical properties of soil,
including soil pH. This study investigated the
effect of pH on colloid transport using soil
samples collected from two agricultural lands
in Medawachchiya and Horowpathana in
North Central Province of Sri Lanka, which
were recognized as high-CKDu endemic and
low-CKDu endemic areas, respectively.
Stability of the colloids extracted from the two
soil was investigated by varying the pH as 3, 5,
6, 7, 8, 11 in room temperature. According to
the results, enhance colloid stability at higher
pH values was observed for both soil types.
Furthermore, colloid turbidity change with
time was numerically characterized and
parameterized with an exponential parametric
function. These findings could be used
effectively on controlling groundwater
contamination via colloid-facilitated transport
in subsurface in contaminated soils.
