Supplemental Information
Impacts of environmental colloids on the transport of 17 β-estradiol in intact soil cores
Jacob R. Prater, Robert Horton, and Michael L. Thompson
Figure 1. Clarion soil core with deposited soil colloids lining macropores. The darkened
areas where colloids have been deposited along the interior of soil macropores are noted by
red arrows.
0.1
1
0.08
0.8
BrE2
E1
0.6
0.4
0.06
0.04
0.02
0.2
0
0
0
5
10
15
20
25
Mass Fraction E2 and E1
Mass Fraction Br-
1.2
Pore Volumes
Figure 2. Mass fractions transported in Clarion with Br– and E2 added mass fraction E2
transported.
Mass Fraction
1.2
1
0.8
BrE2
E1
0.6
0.4
0.2
0
0
2
4
6
8
10
12
Pore Volume
Figure 3. Mass fractions transported in Clarion with Br–, E2, and soil water-dispersible
colloids (WDCs) added mass fraction E2 transported.
Mass Fraction
1.2
BrE2
E1
E2 WDC
1
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
12
Pore Volume
Figure 4. Mass fractions transported in Clarion with Br–, E2, and swine manure waterdispersible colloids (WDCs) added mass fraction E2 transported.
Mass Fraction
1.2
1
0.8
BrE2
E1
0.6
0.4
0.2
0
0
10
20
30
40
50
60
Pore Volume
Figure 5. Mass fractions transported in Hanlon with Br– and E2 added mass fraction E2
transported.
Mass Fraction
1.2
1
BrE2
E1
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
60
Pore Volume
Figure 6. Mass fractions transported in Hanlon with Br–, E2, and soil water-dispersible
colloids (WDCs) added mass fraction E2 transported.
Mass Fraction
1.2
1
0.8
0.6
BrE1
0.4
0.2
0
0
10
20
30
40
50
60
Pore Volume
Figure 7. Mass fractions transported in Hanlon with Br–, E2, and swine manure waterdispersible colloids (WDCs) added mass fraction E2 transported.
Mass Fraction
1.2
1
0.8
BrE2
E1
0.6
0.4
0.2
0
0
2
4
6
8
10
12
Pore Volume
Figure 8. Mass fractions transported in Zook with Br– and E2 added mass fraction E2
transported.
Mass Fraction
1.2
1
0.8
BrE2
E1
E2 WDC
0.6
0.4
0.2
0
0
2
4
6
8
10
12
Pore Volume
Figure 9. Mass fractions transported in Zook with Br–, E2, and soil water-dispersible
colloids (WDCs) added mass fraction E2 transported.
Mass Fraction
1.2
1
0.8
BrE2
E1
E2 WDC
0.6
0.4
0.2
0
0
2
4
6
8
10
12
Pore Volume
Figure 10. Mass fractions transported in Zook with Br–, E2, and swine manure waterdispersible colloids (WDCs) added mass fraction E2 transported.
Empirical Definition of Colloidal Materials
The particle size distributions of the colloidal materials of this study were measured using laser
scattering (Cilas, model 990, Orleans, France) with mean particle sizes and percentage in size
classes found in Table 1.
Table 1. Soil and swine manure water-dispersible colloid (WDC) size distributions
from laser scattering measurements.
Zook
Hanlon WDC
Clarion WDC
Manure WDC
WDC
---------------------------------------- µm ----------------------------------------4
4
3
21
Mean diameter
32
39
51
4
% < 2 (µm)
70
70
86
14
% < 5 (µm)
100
100
100
70
% < 25 (µm)
100
100
100
91
% < 50 (µm)
According to laser diffraction particle size measurements, the water-dispersible colloids (WDCs)
fractionated from soil and swine manure were larger than the intended size of < 1-µm (Table 1).
The calculated mean particle diameter of swine manure colloids (21 µm) was larger than that of
colloids derived from soil (3-4 µm).
The discrepancy between the calculated maximum diameters and the mean diameters measured
by laser diffraction is explained by the assumptions each method makes. Stokes’ Law of
sedimentation and laser diffraction both assume that particles are spheres, but this assumption
leads to different kinds of errors. In Stokes’ Law sedimentation, this means that non-spherical
(e.g., platy) particles of larger size may behave as if they were smaller spheres. Thus, some
particles > 1µm were included in the fractionated material.
The assumption of spherical particles in the laser scattering experiments can lead to imperfect
results as well. The orientation of an individual particle can lead to its size measurement being
different. For example, an oblong particle with its long axis parallel to the laser will appear
smaller than when its long axis is normal to the laser. Assumptions about the density of swine
manure colloids may also have led to part of the discrepancy.
The materials that we isolated from soil and from swine mature in this study had the “effective”
size of colloidal materials, and they had a profound impact on transport of estrogen molecules in
well-structured undisturbed soil cores.