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The
Elimination of PCB Congener Interference in Organochlorine
Pesticide Analysis Using Mass Spectrometry
Jeff Grindstaff, Columbia Analytical Services, Inc.,
Kelso, WA
Degradation
of Chlorinated Pesticides Using Stabilized Nanoscale
Zero-Valent Iron Nanoparitcles under Aerobic and Anaerobic
Conditions
Sung Hee Joo, Auburn University, Auburn, AL
Anaerobic
Bioremediation of DDT and Toxaphene in Soils via
Simultaneous Stimulation of Anaerobic Oxidation and
Reduction Processes
Eric Hince, Geovation Technologies, Inc., Florida, NY
The
Elimination of PCB Congener Interference in Organochlorine
Pesticide Analysis Using Mass Spectrometry
Jeff
Grindstaff,
Columbia Analytical Services, Inc. 1317 S. 13th
Ave., Kelso, WA, 98632, Tel: 360-501-3283, Fax:
360-636-1068, Email: jgrindstaff@kelso.caslab.com
Julie Gish, Columbia Analytical Services, Inc. 1317 S. 13th
Ave., Kelso, WA, 98632, Tel: 360-501-3270, Fax:
360-636-1068, Email: jgish@kelso.caslab.com
Jim Smith, Columbia Analytical Services, Inc. 1317 S. 13th
Ave., Kelso, WA, 98632, Tel: 360-501-3372, Fax:
360-636-1068, Email: jsmith@kelso.caslab.com
Adam Bradbury, Columbia Analytical Services, Inc. 1317 S.
13th Ave., Kelso, WA, 98632, Tel: 360-501-3318,
Fax: 360-636-1068, Email: abradbury@kelso.caslab.com
The
analysis of organochlorine pesticides using traditional
EPA methodologies that employ electron capture detectors (ECD)
are often affected by PCB congener contamination causing
the overestimation of some compounds. High biased results
for oganochlorine pesticides can lead to an overall lack
of data confidence and unnecessary environmental actions.
To eliminate the congener interference two separate GC/MS
methods were developed and evaluated. A method using Large
Volume Injection (LVI) with GC/MS in the Selected Ion
Monitoring (SIM) mode was compared with an LVI Ion Trap
MS/MS method. Using standard extraction procedures
combined with large volume injection, both methods were
able to achieve detection levels equivalent to levels
typically observed by ECD detection. The GC/MS methods
were applied to water, soil/sediment and tissue matrices.
Ion trap GC/MS/MS provided an additional level of
selectivity over GC/MS SIM and showed advantages in
complex matrices by further reducing co-extractable
interferences.
The use of ion trap GC/MS/MS for chlorinated
pesticide analysis provides superior analyte selectivity
resulting in increased data defensibility.
Sung
Hee Joo,
Ph.D. Environmental Engineering Program, Department of
Civil Engineering, Auburn University, Auburn, AL 36832,
Tel: 334-844-1498, Fax: 334-844-6290, Email: joosung@auburn.edu
Dongye
Zhao, Ph.D. Environmental Engineering Program, Department
of Civil Engineering, Auburn University, Auburn, AL 36832,
Tel: 334-844-6277, Fax: 334-844-6290, Email: dzhao@eng.auburn.edu
Contamination
of soils and groundwater by chlorinated pesticides such as
lindane and atrazine has been a worldwide environmental
challenge, and cost effective remediation technologies
have been sought for decades. We have investigated the
treatability of these chlorinated pesticides and
herbicides in water using stabilized nanoscale zero-valent
iron particles (nZVI) and the reduction-oxidation
kinetics. While both lindane and atrazine were degraded by
the monometallic nZVI particles, the degradation
effectiveness was greatly enhanced by adding a small
fraction (0.1% of Fe) of Pd to the iron nanoparticles.
Complete degradation of lindane (1000-μg/L) using
nZVI (0.5g/L) was observed over 3-hours with the Fe-Pd
bimetallic nanoparticles under anaerobic condition. While
60% degradation was observed with the same amount of Fe-Pd
nanoparticles in the same reaction time under aerobic
condition. Complete removal of atrazine (1000-μg/L)
was also observed using a low dosage of iron (0.05g/L) and
Pd (0.1% of Fe) under anaerobic condition.
Again, the degradation of atrazine was more effective
under anaerobic condition than when the reactor was
exposed to air (a 20 difference at an iron dose of
0.02g/L) in the presence of the stabilizer. Interestingly,
the degradation efficiency of atrazine (5000-μg/L)
was enhanced to 40% in the absence of the stabilizer under
aerobic condition at the same dose of iron (0.1g/L).
For both lindane and atrazine, the aerobic
degradation kinetics was slower than that under anaerobic
condition, which suggests that radical release from nZVI
surface under aerobic condition is hindered by the
stabilizer (NaCMC). Research is ongoing to further
elucidate these observed phenomena.
Anaerobic
Bioremediation of DDT and Toxaphene in Soils via
Simultaneous Stimulation of Anaerobic Oxidation and
Reduction Processes
Robert
L. Zimmer, P.G., P.E., Eric C. Hince, P.G.,
Geovation Consultants, Inc.; 468 Route 17A, Florida, NY,
10921; Tel: 845-651-4141, Fax: 845-651-0040; Email: rzimmer@geovation.com,
echince@geovation.com
The
organochlorine pesticides DDT and toxaphene are among the
most recalcitrant man-made chemicals in the environment.
Whereas there is a substantial body of literature on the
partial biodegradation of chlorinated pesticides via the
creation of anaerobic and reducing conditions that dates
back to the 1960s (e.g., Guenzi and Beard, Science,
1967), more recent research suggests that certain
metabolites of these “parent” compounds are resistant
to further reductive dechlorination even under highly
reducing conditions.
For example, DDMu, a metabolite of the
DDT-breakdown product DDE, is known to be persistent in
marine sediments where anaerobic and reducing conditions
prevail. Additional
work has suggested that the reductive dechlorination of
toxaphene “stalls” at congeners that contain from six
to eight chlorine atoms.
Accordingly, a major objective of this project was
to overcome the shortcomings of prior approaches to
anaerobic bioremediation of pesticides that have focused
primarily on reductive dechlorination with a more
comprehensive treatment process that involved the
simultaneous stimulation of both anaerobic oxidation and
reduction processes.
Previously,
a case study describing a large-scale containment and
anaerobic bioremediation project for 29,000 tons of DDT
and toxaphene contaminated soils was reported (Hince et
al., U.Mass Soils 2005).
Subsequently, post-treatment data were collected
from the soils in the most highly contaminated layer
within the anaerobic biocell.
Briefly, soils were pre-treated with a patented
solid-chemical composition, BioGeoCheMix® (“BGC”)
that contains abundant plant materials, high-surface-area
native iron and manganese (IV) minerals among other
amendments. The manganese (IV) minerals in the BGC serve as both a
sacrificial oxidative catalyst to minimize biofouling of
the iron particles and as a relatively high-energy
electron acceptor for anaerobic oxidation processes.
The BGC also contained targeted co-substrates
designed to help stimulate the anaerobic oxidation of less
chlorinated toxaphene congeners and metabolites of DDT.
After “BGC” treatment and placement of the
soils in the biocell, the soils were subjected to a brief
but intensive period of repeated applications of a
patented liquid-chemical composition “N-Blend” to
provide nitrates as an additional source of high-energy
anaerobic electron acceptors along with complex phosphate
nutrients and a suite of micronutrients.
Post-treatment
soil sampling data collected within three months of
treatment documented, on average, 95.4% reductions in
toxaphene levels and 96.9% reductions in DDT
concentrations. DDE
levels changed only slightly whereas DDD reductions were
significant (56.9% on average) but lower than for DDT.
As DDD is produced by the first step in the
reductive dechlorination of DDT, it follows that the
decrease in DDD levels is less than that of DDT as
"new" DDD was being formed by the removal of one
chlorine from DDT. The proportions of DDT daughters (DDD +
DDE) increased from less than 30% before treatment to
greater than 87% after three months.
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