Page 20 - GreenMaster Winter 2025

Figure 2. Upper left: an alkyl block polymer (ABP; A); upper right: a polyoxyalkylene polymer (PoAP; B); lower left:
water (C); and lower right: an untreated control (D).
Following each simulated
irrigation events, leachates were
collected and their volume, and
organic carbon were detected in the
forms of dissolved (DOC) and
particulate organic carbon (POC)
were detected. These two forms of
organic carbons, one in liquid form
and one as fine particles suspended
in the leachates, are the evidence of
organic compounds that could
potentially be replaced and removed
from the hydrophobic sands by
wetting agent application and
following irrigation events.
At the end of the experiment,
sands were destructively sampled
and their solid phase organic carbon
(SOC), which reflects the number of
organic coatings left on the sand
surfaces, was detected, along with
soil hydrophobicity, which was
assessed by the molarity of ethanol
droplet (MED) test.
The experimental design was a
complete randomized design with
three replications, and the entire
experiment was repeated once.
Detailed experimental design and
statistical analysis can be found in
the article by Song et al. (2021).
WETTING AGENT PERFORMANCE
IN HYDROPHOBIC SANDS
Both wetting agents improved the
wettability of the hydrophobic sands
immediately following the first
wetting agent application. However,
after the first simulated irrigation
event, the ABP-treated sands
resulted in nearly 3-fold more water
in the leachates than PoAP-treated
sands, suggesting better facilitation
of water movement through the sand
columns. PoAP-treated sands
retained excessive water initially,
although these differences
diminished after multiple washes and
repeated treatment applications.
Dissolved organic carbon
detected in the leachates were
comparable between treatments
applied to fresh vs. hydrophobic
sand columns. Since both wetting
agents were applied in liquid form,
the DOC detected in leachates likely
reflected, in part, the organic
compounds introduced to the sand
systems by wetting agent
applications. However, POC detected
in the leachates varied substantially
among the treatments. Compared to
PoAP, application of ABP removed
1.7 times more POC from hydrophobic
sand columns.
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• CGSA • GreenMaster