Table 2. Bulk soil densities for various test samples.
groundwater. The vapor fortification solutions
were prepared by adding small volumes (0.1 L to
Air
% Moisture (initial)
0.5 mL) of six different VOCs to 2.0 mL or more of
20% Sat'd†
dried*
5%
10%
reagent-grade tetraethylene glycol dimethyl ether
CRREL surface
1.24**
1.46
1.57
1.76
(tetraglyme). The VOCs chosen for this study,
(silty/sand-loam) 0.06
0.04
0.04
0.09
trans-1,2-dichloroethene (TDCE), trichloroethene
CRREL deep
1.62
1.64
1.89
2.06
(TCE), tetrachloroethene (PCE), benzene (Ben),
0.05
0.06
0.04
0.07
(sandy/silt)
toluene (Tol), para-xylene (p-Xyl), were also
Wisconsin
1.56
1.65
1.72
2.01
reagent grade. The second 20-mL bottle contain-
0.04
0.03
0.04
0.03
(sand)
ing 10 mL of groundwater served as a source of
* <1% moisture
moisture to the chamber.
† Water saturated
Three soils were used, a silty/sand (CR-S), a
** Density (g/cm3)
sandy/silt (CR-D), and a coarse sand from Wis-
consin (Wis). The first two soils were collected at
ble 2). After filling a vial with soil, the rim was
the Cold Regions Research and Engineering Lab-
wiped clean and the weight of the contents deter-
oratory (CRREL) and the Wis soil from Shawano
mined. Following this second weighing, the cap
County, Wisconsin. The CR-S soil was obtained
and hydrophobic membrane were secured onto
from the topsoil (1030 cm), and the CR-D soil,
the vial and a third weight was taken. In addition,
from depths greater than 30 m below the surface,
two vials were half filled (1 mL) with ground-
and the Wis soil was a clean sand taken from a
water, covered with the hydrophobic membrane,
depth of 60 cm. All three soils were air dried,
and weighed.
passed through a 30-mesh sieve, and thoroughly
Once all the membrane-covered soil and
mixed. Portions of these air-dried soils (<1% mois-
water-containing vials had been placed into a
ture, ASTM D2216-66) were transferred to plastic
chamber, a vapor fortification solution was pre-
bottles and wetted by adding a locally obtained
pared by adding neat VOCs to tetraglyme held in
groundwater, creating four moisture conditions
a 20-mL glass bottle. To prepare this organic cock-
tail solution with 0.1 L of each the six VOCs
for each. The moisture contents at the beginning
(Table 3), a 1-L microvolume syringe (SGE) was
of the exposure period, general soil classifications,
and organic carbon contents are listed in Table 1.
used. Neat analytes were added to the other cock-
tail solutions using 10-, 100-, and 500-L syringes
(Hamilton), respectively. The vapor fortification
Table 1. Soil moisture levels, general classifica-
solution and a 20-mL glass bottle containing 10
tion, and percentage of organic carbon.
mL of groundwater were the last two vessels
Air
% Moisture (initial) % Organic
added to the chamber. The bottle containing 10
dried* 5% 10% 20% Sat'd† carbon**
CRREL surface
Table 3. Samples, fortification solution com-
√
√
√
√
(silty/sand-loam)
0.88
position, and exposure period for each cham-
CRREL deep
ber experiment.
√
√
√
√
(sandy/silt)
0.10
Equilibration
Wisconsin
Expt.
period
Single or
Volume (mL)
√
√
√
√
(sand)
0.17
no.
(days)
duplicates
VOCs* Tetraglyme
* <1% moisture
1
27
A
0.0001
5
† Water saturated
2
22
B
0.001
5
** As determined by Leco CR-12 furnace analysis (Merry and
3
22
A
0.01
5
Spouncer 1988).
4
24
B
0.1
4.5
5
25
B
0.5
2
Procedure
6
50
B
0.01
5
By using a funnel, spatula, and metal rod, por-
7
49
B
0.1
5
tions of each of the three soil types at the preset
8
55
B
0.001
5
moisture conditions (3 soil types 4 moisture con-
ASingle sample of each soil type at four different mois-
tents) were transferred to the small (2-mL) pre-
ture contents and two groundwater samples.
BDuplicate samples of CRREL soils (except single sam-
weighed sample vials. These vials were filled to
ple for saturated condition) at various moisture con-
capacity, leaving very little (0.1- to 0.3-mL) head-
tents, single replicate of Wisconsin soil at four mois-
space, while creating fairly consistent and envi-
ture contents, and two groundwater samples.
ronmentally representative bulk soil densities (Ta-
* Volume of TDCE, Ben, TCE, Tol, PCE and P-Xyl added.
3
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