In this work, natural decontamination of ERF
dissolved in 20 mL of isooctane by shaking for two
sediments was investigated in three ways:
hours. For the P4 concentration in the extract to be
A laboratory evaluation of the effect of sedi-
within the linear range of the GC detector, these
ment temperature and moisture on the persis-
solutions had to be diluted by a factor of 5000.
tence of P4 particles in ERF sediments;
Such a large dilution factor can contribute to a sys-
A field investigation to determine if sediment
tematic error. The masses of the particles (Table 4),
moisture and temperature reach levels condu-
as determined by GC, were in the range of 7.88.4
cive to size reduction of P4 particles in Eagle
with a mean of 8.1 mg. The relative standard devi-
River Flats; and
Table 4. Masses (mg) of
A field investigation of the pattern of P4 con-
eight replicate white
tamination around previously tested sites in
phosphorus particles.*
an intermittent ponded area to determine if
Mass
Mass
ter exposure to air during the summer of 1993.
mean =
8.09
7.97
max =
8.39
8.33
min =
7.77
7.77
Incubation of P4 particles at constant
std. dev. =
0.26
8.35
temperature and moisture content
RSD (%) =
3.21
8.39
8.18
Methods
7.77
To determine the effect of sediment tempera-
7.97
ture and moisture content on the persistence of P4
* Found following dissolu-
particles in ERF sediments, P4 particles of known
tion in isooctane, dilution
with isooctane and gas chro-
diameter (approximately 2 mm) were placed at a
matographic analysis.
depth of 3 cm in wet ERF sediment and the sedi-
ment was incubated in an environmental chamber
at a constant temperature. Table 3 gives the exper-
ation (RSD) for these measurements was only
imental variables. The temperatures were selected
3.2%. Therefore, the measurements were very pre-
cise; however, the masses were higher than expect-
Table 3. Experimental parameters for the
ed. For a 1.8-mm particle, the mass should be
laboratory study on the effect of sediment
approximately 6 mg. Our calibration standard was
temperature and moisture on the persis-
checked against one prepared independently at
tence of white phosphorus particles.
the Waterways Experiment Station and was found
to have the same GC response within experimental
Treatments
error.
Temperatures: 4 , 15, 20C
Recovery from sediment at various moisture con-
Approximate degree of saturation: 0.4, 0.6, 0.8, 1, >1
tents. Triplicate sediment samples were prepared
to reflect sediment temperatures previously
at each of the five moisture contents used in this
measured in Eagle River Flats. The moisture
experiment. One P4 particle was placed in each
range was chosen to include unsaturated and sat-
sample, and then each sample was extracted with
urated conditions. The sediment was contained in
isooctane. The P4 mass found in each sample was
8- 8- 6-cm plastic dishes, with one particle per
determined by isooctane extraction and gas chro-
dish. At discrete time intervals, samples were tak-
matography and compared with the mass found
en to determine if the P4 particles had decreased in
in samples without sediment (Table 5). The aver-
size. Particle sizes were measured directly with a
age P4 mass found in the sediment samples was
micrometer, and gas chromatography (GC) was
7.99 mg, which yielded an average recovery of
used to determine particle masses as well as resid-
97.8%, based on the samples without sediment
ual P4 that may be sorbed to the sediment or dis-
(8.17 mg).
solved in the sediment moisture. Details of the
Physical appearance of particles following incuba-
methods used are given in Appendix A.
tion. Following incubation the physical appear-
ance was noted of each particle that could be locat-
Results
ed (Table 6). Initially the particles were spherical
Precision and accuracy of the measurement of parti-
and had a smooth surface and a lustrous, translu-
cle mass. Eight replicate particles produced in the
cent appearance. Following incubation the most
laboratory from molten white phosphorus were
noticeable change in those particles where there
9
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