Table 3. Summary of pesticide study.
Bailer
Bladder pump system
Mean initial conc. Mean desorbed conc.
Mean initial conc.
Mean conc. after 24 hr Mean desorbed conc.
MDL
(g/L)* (S.D.)
(g/L)† (S.D.)
(g/L)* (S.D.)
(g/L)* (S.D.)
(g/L)† (S.D.)
(g/L)
Analyte
Lindane
525
(47)
LD
484
(32)
503 (31)
LD
0.74
Heptachlor
17.5
(3.4)
LD
13.0
(1.4)
6.83 (0.95)
LD
0.84
Aldrin
46.3
(5.7)
LD
37.9
(7.5)
20.5 (1.9)
LD
0.55
Dieldrin
58.0
(5.3)
LD
53.8
(3.9)
35.1 (2.0)
LD
0.85
*
Concentration of the well water
†
Concentration found in DI water from the "decontaminated" device
LD = Less than method detection limit
MDL= Method detection limit
S.D. = Standard deviation
means that the materials used in the bladder pump
CONCLUSIONS
sorbed these analytes as the sample was pumped
This research clearly shows that if groundwa-
through the system. The hot water wash proce-
ter sampling devices are not decontaminated, re-
dure was effective in removing these contami-
sidual contamination will be carried over into the
nants from both the bailer and bladder pump
next sample. A simple detergent cleaning proce-
system (Table 3).
dure (consisting of a hot tap water detergent wash,
hot tap water rinse, and DI water rinse) was effec-
Munitions study
tive in reducing residual pesticide concentrations
In this study, we see that washing was rela-
in DI water that was sampled with the decon-
tively effective for removing most of the muni-
taminated bailer and bladder pump. Concentra-
tions (Table 4, Table A8). Ultra-low concentra-
tions of munitions in DI water sampled with de-
tions (ppt) of two munitions were detected in
vices decontaminated with this procedure were
samples taken with the decontaminated bailer and
also reduced to either nondetectable or low-ppt
the pump. However, these concentrations were
levels. TCE, a volatile organic, proved to be the
well below the EPA's lifetime health advisory
limits of 2 g/L for TNT and 0.1 g/L for 2,4-
most recalcitrant contaminant. VOCs have been
shown to be readily absorbed by polymeric mate-
DNT (Gordon and Hartley 1989, Brower et al.
rials. We found that a hot detergent wash and hot
1992). Because these concentrations were well be-
water rinse followed by hot air drying (~70C
low the health advisory limits, we did not test the
initial temperature) was effective in removing TCE
efficiency of using an additional hot air treatment
from both the bailer and bladder pump but not
with these contaminants.
Table 4. Summary of munitions study.
Bailer
Bladder pump system
Mean initial conc.
Mean desorbed conc.
Mean desorbed conc.
EDL
(g/L)* (S.D.)
(g/L)† (S.D.)
(g/L)† (S.D.)
(g/L)
Analyte
HMX
168 (18)
LD
LD
0.0041
TNB
100 (21)
LD
LD
0.0066
DNB
108 (4)
<0.0057
LD
0.0036
TNT
2425 (7)
0.037 (0.004)
0.034 (0.006)
0.014
2,4-DNT
100 (14)
0.041 (0.013)
0.032 (0.006)
0.0092
*
Concentration of the well water
†
Concentration found in DI water from the "decontaminated" device
LD = Less than estimated detection limit
EDL = Estimated detection limit by method being developed by Walsh and Ranney (in
prep.)
S.D. = Standard deviation
11
Previous Page
