Depending on the size of the sample and the ob-
were combined in a 500-mL jar. Each jar was filled
jective of the analysis, several subsamples were
to capacity. The second sampling method involved
taken.
scooping several samples of sediment into a wash
To detect WP particles, the aluminum pie pan
bucket equipped with a no. 30-mesh (0.59-mm)
with a thin smear of sample was placed on a
sieve and stirring the sample underwater. This
heated surface. In the field, we used a double burn-
procedure preconcentrated the sample by remov-
er propane camp stove (American Camper propane
ing most of the fine-grained silt particles. The
stove) and a cast iron pancake griddle (Wagner 's
material left on the sieve was placed in a 500-mL
1891 cast iron cookware) (Fig. 1a and 1b). In the
jar with enough water to cover the sample. Sam-
lab, we used a hot plate (Corning) set on the
ples collected by either method were cooled to
4C and stored in the dark until analyzed.
highest setting. The hot plate was placed in the
back of the fume hood and the shield of the fume
hood pulled down.
Detection of WP particles
The heat from the stove or hot plate evaporat-
ed the water from the sample and ignited WP
Field method
particles, if they were present. A positive test for a
Each sample was prepared for analysis by tak-
WP particle was indicated by a localized area of
ing an approximately 20- to 30-mL subsample
intense smoke and flame and the formation of a
and spreading it across the bottom of a 20-cm-
bright orange residue (Fig. 2). The orange residue,
diam. aluminum pie pan. The subsample was
a mixture of oxidation products of WP (Daasch et
spread in a thin layer (approx. 1 mm thick). High-
al. 1969), is hygroscopic and, if the residue was
ly organic, fibrous samples were pulled apart.
surrounded by sediment, the sediment also ap-
peared moist. The moist sediment was darker than
the light gray, dried ERF sediment, forming a
dark halo around the orange residue. The
orange residue also had a garlic-like odor, proba-
bly due to the production of P4O6.
Solid phase micro-extraction screening method
A 40-g wet sediment subsample, measured with
a field-portable balance (Ohaus model CT200),
was placed in a 120-mL jar equipped with a
septa-top. A 10-mL aliquot of reagent grade wa-
ter (MilliQ, Millipore) was added and the sample
was equilibrated at room temperature for one hour.
a. Preparation of samples for field test.
b. A thin smear of sediment is heated until all water
Figure 2. Positive test for a WP particle. This consists
evaporates.
of a localized area of intense smoke and flame, and the
formation of a bright orange residue (dark gray in this
Figure 1. Field test for the detection of white phospho-
black-and-white picture).
rus particles in sediment.
2
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