Pesticides in the Hudson River Basin analyzed by HRGC/HRMS: Results, Data Quality, and Implications
Victoria A. Pretti1,2, Simon L. Litten1, Dale Hoover3, Coreen Hamilton3, Jason Fagel1,2 and Larry T. Bailey1
INTRODUCTION
Organochlorine pesticide monitoring has undergone major changes during the past few decades (Nowell et al
1999, Larsen et al 1997). Today, organochlorine pesticides are still targeted for a number of reasons: listed as
priority pollutants by the USEPA, extremely persistent, and have a potential for long-range atmospheric
transport. Some pesticides can migrate from applied regions to surface waters where they have an affinity to
attach to fatty acids in biota, and colloidal particles, organic matter, and bed sediments.
Few intensive studies have been conducted that address the quality of pesticide results with respect to analyte
specific detection levels (Phillips and Bode 2002, Eckhardt et al. 2001) and the media in which the pesticide
resides. In the studies that have been reported, the analytical methods used were not capable of detecting target
analytes that are expected to be at concentrations below detection of conventional sampling and analytical
methodologies and did not analyze for organochlorines (OCs) of primary interest to the New York State
Department of Environmental Conservation (NYSDEC) (Table 1). The NYS Department of Health (1976)
conducted a study of the public water supply in the Hudson and Mohawk River basins of New York. Out of the
481 samples collected, only one sample had a positive result for an OC pesticide with respect to NYS drinking
water standards at that time.
After stricter deep-ocean disposal regulations for dredged sediments went into effect in 1997, NYSDEC began a
cooperative study, with New Jersey and a group of academic, private, and other government experts, called
Contaminant Assessment and Reduction Project (CARP), to examine the movement of a broad range of organic
pollutants and track down the sources of the pollutants discharged into the NY/NJ Harbor, southernmost part of
the Hudson River Basin (Figure 1). The Basin is about 78% forested land, 14% agricultural, and 8%
urban/residential land (USGS 1997).
Figure 1 The Hudson River Basin covers the eastern part of New York and includes the New York/New Jersey Harbor at the
southernmost extent of the Basin (near Long Island).
In this study, we focus on organochlorine pesticides, in particular, DDT-type and cyclodiene-type insecticides
and hexachlorocyclohexane (HCH) isomers and hexachlorobenzene (HCB) in the southernmost part of the
Basin. NYSDEC established high-resolution gas chromatography/high-resolution mass spectrometry
1
New York State Department of Environmental Conservation, 625 Broadway, Albany, NY 12233. vapretti@gw.dec.state.ny.us
New England Interstate Water Pollution Control Commission, Boott Mills S., 100 Foot of John St., Lowell, MA 01852.
3
Axys Analytical Services Ltd., 2045 Mills Road W., Sidney, BC, Canada V8L 3S8.
2
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(HRGC/HRMS) as a standard method to measure organic contaminants (NYSDEC method HRMS-2). This
method is extremely sensitive, providing results in the 0.1 to 2.0 ng/L range for analysis of 1 L aqueous
samples, in comparison to the low resolution EPA method 608, providing results in the 2-75 ng/L range for
analysis of 1 L aqueous samples (Guide to EAM 1998). Combining the highly sensitive method with the use of
large volume sampling can lead to part per quadrillion range detection limits in water samples. The HRMS
method also has a high degree of selectivity and permits positive detection at these levels for a variety of
samples. This paper summarizes the frequency of chlorinated pesticide detected in various environmental
medium by HRMS, classifies the detection of some of the CARP pesticides into a land use category, and relates
the concentrations of detected analytes in surface waters to NYS drinking water standards.
METHODS
Streambed sediments, sludge and aqueous samples such as surface water, baseflow and wastewater were
collected in the Hudson River Basin from 1998 to 2001. Plasma samples from Lake Erie cormorants were also
analyzed. Quality Control (QC) was maintained by collecting field blanks and equipment blanks for each type
of matrix. Aqueous samples were collected with a NYSDEC designed and manufactured Trace Organic
Platform Sampler (TOPS). The TOPS system processes large volumes of water (100s of liters) through
cartridge filters at a rate of 3200 ml/min and then through 45g or 65g XAD (a polymeric adsorbent resin)
columns at a maximum rate of 620 ml/min. Sediment sampling was accomplished by collecting ponar samples
from the bed sediments of the Arthur Kill situated between northeastern NJ and Staten Island. Approximately
38 liters of sediment were composited and homogenized in a plastic cement mixer. Sludge samples were taken
from 10 sites within the Basin as grab samples. Plasma samples were obtained from 3-week old cormorants
along the Lake Erie shoreline.
Aliquots of the media were routinely sent to NYSDEC contracted laboratories for analysis of primary organic
pollutants. The analytical labs used NYSDEC method HRMS-2, that is partly based on EPA Method 1668A
(1999) and technical literature (Van den Berg et al. 1998, AXYS 2002), for the extraction, concentration,
cleanup and determination of the organochlorine pesticides listed in Table 1.
Method HRMS-2 is a performance-based method. Sample preparation, extraction, and cleanup varied
depending on the matrix of the sample of interest, but essentially involved the following procedures. The
sample was spiked with a set of 20 carbon-13 labeled surrogate standards. Sample extraction was accomplished
with an SDS extractor and hexane extract. The extract was then concentrated for cleanup. Recovery standards
(e.g., 13C12-PCB52, 13C12-PCB138, and 13C12-PCB153) were added to the extracts just prior to instrumental
analysis to measure the recovery of labeled surrogate standards through the analytical process. Cleanup varied
and included the use of any or all of the following procedures to eliminate interfering compounds: gel
permeation chromatography and florisil and copper treatements. The final sample extract was concentrated to a
final volume of 20 to 500 l.
Samples and standards were analyzed by HRMS equipped with a HRGC. Mass resolution was at least 8000.
No fewer than 5 standards, ranging in concentration from 10 to 4000 ng/ml, were required for initial calibration.
Calibration verification was performed every 12 hours using the mid-level calibration standard. Method
performance was demonstrated through the analysis of laboratory procedural blanks and spiked reference
samples.
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RESULTS and DISCUSSION
Of the matrices sampled in the Hudson River Basin, only dieldrin had detectable frequencies greater than 70%
of the time in all 4 matrices. Chlorinated pesticide results are summarized in Table 1 with respect to 5 times the
analyte specific instrument detection levels (IDLs).
Table 1 Comparison of mean frequency of detection of chlorinated pesticides of interest in various media from the Hudson
River Basin that were detected greater than five times the analyte detection limit. Sludge (S); Arthur Kill bed sediment (B);
Cormorant plasma (P); and XAD (X). Cormorant results were from the Lake Erie coastline of NY.
Chlorinated Pesticide
ID
No.
100-91
Mean Percent Frequency of Detection
(> 5*DL)
90-81 80-71 70-61 60-51  50
Mean Concentration A
Plasma
Unit of Measure (NOTE: differed among the media tyoes.)
g/kg ww
2,4’-DDD
1
B,S
P
X
0.19
2,4’-DDE
2
B,S
P
0.17
2,4’-DDT
3
B,P,S,X
0.064
4,4’-DDD
4
B,S
X
P,X
0.79
4,4’-DDE
5
B,P,S
12
4,4’-DDT
6
B,S
P,X
0.34
Aldrin
7
P,S
B,X
0.14
8
X
B,P,S
0.013
-Hexachlorocyclohexane
9
B,P,S,X
0.072
-Hexachlorocyclohexane
10
X
B,P,S
0.052
-Hexachlorocyclohexane
Cis-chlordane
11
B,S
P
X
0.24
Trans-chlordane
12
B,S
P
X
0.10
Oxychlordane
13
P
B,S,X
1.3
Dieldrin
14
P,S
B
X
0.94
Endosulfan sulfate
15
S
B,P,X
0.11
16
P
B,S,X
0.14
-Endosulfan
17
B,P,S,X
0.0
-Endosulfan
Endrin
18
P
B,S,X
0.16
Endrin aldehyde
19
P
B,S,X
0.21
Endrin ketone
20
P
B,S,X
0.20
Heptachlor
21
B
P
S,X
0.17
Heptachlor epoxide
22
P,S
B,X
0.41
Hexachlorobenzene
23
P,S
X
B
0.28
Methoxychlor
24
P
B,S,X
0.18
Mirex
25
P,S
B,X
0.099
Cis-nonachlor
26
P,S
B
X
0.71
Trans-nonachlor
27
S
B
P
X
0.20
A. A value of 0.0 indicated that the value was not detected greater than 5 times the analyte specific detection limit.
Sludge
g/kg dw
13
2.5
1.0
30
65
7.7
0.32
0.0
0.0
0.039
55
52
0.11
26
0.60
0.0
0.0
0.061
0.0
0.0
0.0
3.9
7.1
0.0
5.3
8.1
27
Bed
Sediment
g/kg dw
93
71
150
260
170
140
0.066
0.22
0.062
0.044
12
15
0.29
3.8
0.0017
0.0
0.14
0.0
0.0029
0.0
6.0
0.0029
0.16
0.53
0.079
4.1
6.0
XAD
na/sample
14
1.7
2.2
38
14
6.7
0.42
46
11
170
16
12
4.7
35
11
1.8
3.2
3.0
0.17
2.6
2.0
12
27
8.6
23
5.1
19
Surface Waters and XAD
We examined 279 Hudson River Basin surface water samples. The samples were collected from landfill runoff,
minor and major Basin tributaries and wastewater facilities. The pesticides were eluted from a series of filters
and Teflon columns holding XAD that represented the suspended sediment and dissolved fraction, respectively.
The chlorinated pesticides most often detected 5 times the IDL in XAD samples by mean frequency were the 
isotope of HCH, (79%), dieldrin (74%) and 4,4’-DDD (71%). Hexachlorobenzene (HCB) was detected about
50% of the time, but only contributed about 6% to the mean total pesticide mass (Figure 1). Nearly 50% of the
total mean mass was from HCH isotopes in decreasing order of contribution: lindane (-HCH), -HCH and HCH. The mean total pesticide result contributed by each analyte ranged from 0.03 g for endrin aldehyde to
26 g for lindane.
Hexachlorobenzene was commonly detected in 29 field blanks (FBs) at 5 times the IDL (Figure 2). At the IDL,
HCB concentrations in 85% of the XAD samples exceeded the 90th percentile of FBs while the -HCH
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concentrations in 97% of the XAD samples exceeded the 90th percentile of FBs. Method blank (MB) results for
lindane never exceeded the sample results, and MB results for HCB only impinged on 2% of the sample results
for HCB.
Figure 2 Comparison of Organochlorine Pesticides detected in field blanks and XAD samples from the Hudson River Basin at
5 times the instrument detection limit. X-axis number corresponds to ID number in Table 1.
These pesticides results are affected by a series of sorption and partitioning interactions, bioaccumulation, and
transport and transformation. Lindane, a natural degradation product of -HCH, is very soluble in water (S >1),
indicating its high contribution to the total pesticide concentration in aqueous XAD samples. In contrast, HCB
is a synthetically produced fungicide unfamiliar to microorganisms, hydrophobic (S = 0.04), and recalcitrant
(Nowell et al. 1999, Larsen et al. 1997). Equipment blanks collected at the NYSDEC Hemlock Lab (Colonie,
NY) continually had detections greater than 5 times the IDL for HCB, and at times for endosulfan sulfate,
methoxychlor, and the HCH isomers.
Endosulfan, methoxychlor and HCH isomers are the least-hydrophobic insecticides of the 27 OCs of interest to
NYS and are currently used in agricultural areas in the United States. Concentrations of these pesticides are
known to be highest in areas with extensive agriculture or large residential populations near industry. The
Wallkill River at New Paltz and wastewater treatment plants (i.e., Hunts Point, Rockaway and Yonkers) were
the largest contributors of pesticides to the Lower Hudson River Basin (Figure 3, Table 2). New Paltz is at the
base of the eastern Catskill Mountains and has a population density of 3-711 persons/mi2; whereas, the
population density of Yonkers and Hunts Point is much greater (20,000+ persons/mi2) (U.S. Census 2000).
Highly contaminated samples collected from surface waters in agricultural and urban sites may be toxic to
microorganisms that are potential substrates. Therefore, samples high in HCB and the less hydrophobic
insecticides may have contaminated the sampling equipment and appeared in the QC blanks. Long-lived
pesticides are also more likely to be deposited by atmospheric deposition and in remote places. Eastern New
York, particularly the Catskills and Adirondacks, are known to be affected by atmospheric deposition of
pollutants derived from the Ohio and Tennessee Valleys. Significant depositional amounts of HCH isomers and
HCB were reported for the Great Lakes, South Atlantic and North Pacific (Larsen et al. 1997); thus,
atmospheric deposition may have contributed to the HCH and HCB levels detected in the Hudson River Basin.
NEW YORK STATE WATER QUALITY STANDARDS
According to EPA method 608, the lowest detection level for reagent waters and synthetic groundwater is
estimated at 1.5 ng/L for such analytes as cis- and trans-chlordane (Guide to EAM 1998). This level is not
applicable to NYS water quality standards (NYSWQS) that are very stringent. NYSDEC HRMS-2 was
successful at detecting CARP analytes of interest in the sub-ppt range. All sites exceeded NYSWQS for total
chlordane (Table 2). Three sites with the highest total concentration of pesticides and number of pesticides
detected above the NYSWQS were associated with stream watersheds draining urban/industrial settings near
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New York City (NYC) or agricultural valleys near the Catskills. The correlation between pesticides and land
use were seen in the concentrations, as well as, the types of pesticides detected. For example, insecticide
concentrations for total DDT and total dieldrin (aldrin+dieldrin) were highest in agriculturally fed watersheds
such as the Wallkill River at New Paltz (Figure 3). The synthetic fungicide HCB was highest in wastewater
influents from facilities near NYC. The elevated concentrations detected (greater than 10 times the IDL) in the
Wallkill River and wastewater treatment plants were at least 3 times higher than any NYSWQS (Table 2).
Table 2 Comparison of pesticide concentrations in tributary, wastewater and landfill samples from the Hudson River Basin
with New York State water quality standards for human fish consumption. Sample results are greater than 10 times the
instrument detection limit. Concentrations are in ng/L. Major tributaries are in red, and minor tributaries are in blue.
Figure 3 Comparison of XAD results from landfills, wastewater treatment plants, and major and minor tributary waters of
the Hudson River Basin. Concentrations reported are for those results that are 10 times the instrument detection limit.
For most of the OCs, the sorbed phase represents a significant portion of the total amount in the water column.
Aldrin and dieldrin, an aldrin by-product, sorb strongly to soil particles (high Koc). The XAD samples used in
this study represented whole-water samples. The lower total dieldrin concentrations and frequency of detection
may have been due to variations in suspended sediment concentrations at the time of sampling. As we will
demonstrate in the following sections, the analysis of bed sediment and sludge samples is a more appropriate
method of monitoring the occurrence of this OC in surface waters. Dieldrin is detected nearly all the time in
sludge and bed sediment samples.
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SLUDGE
Seventy-eight percent of the sludge data was detected at 5 times the IDL. Seven pesticides, in particular, were
detected 100% of the time at concentrations greater than 5 times the IDL (Figure 4). These pesticides include
DDD-type pesticides, 4,4’-DDE, cis- and trans-chlordane, dieldrin, and trans-nonachlor. As indicated by their
physical and chemical transformation properties, the pesticides have fairly low volatility (low Henry’s law
constants) and low water solubility (S <1). The total pesticide concentrations in sludge samples from the
urbanized Lower Basin averaged 4000  200 g/kg dry weight (dw). All of the sites indicated that the sum
result of 4,4’-DDE, and cis- and trans-chlordane contributed on average 56  4% to the mean total pesticide
result for the NY/NJ Harbor, while HCB only contributed ~2% to the mean total pesticide result.
Aldrin and dieldrin were used to kill soil-dwelling insects until 1972 and sorbed strongly to soil particles (high
Koc). Dieldrin has a longer residence time (1/2-life ~3yrs) in sediments than aldrin’s residence time in
sediments (1/2-life ~1yr) (Nowell et al. 1999). Dieldrin only contributed about 9% to the total pesticide mass
detected in the Harbor. Aldrin was never detected at 5 times the IDL, possibly indicating that all the aldrin had
degraded to dieldrin and its presence could be the result of atmospheric transport from areas in which pesticides
were applied or manufactured.
Figure 4 Frequency of detection of organochlorines greater than 5 times the instrument detection limit in 13 sludge samples
from 8 sites in the southern part of the Hudson River Basin (Y-axis). Mean total pesticide results in g/kg dry weight for
sludge samples from 8 sites within the Harbor (Y’-axis).
SEDIMENT
We examined 29 aliquots from the homogenized Arthur Kill bed sediments. Of the 27 pesticides for which the
aliquots were analyzed, 8 were detected greater than 90% of the time (Table 1, Figure 5). The pesticides
detected in the sediment samples are a specific class of insecticides that were used to control insect-borne
diseases on crop. DDT-type pesticides and its principle metabolites, DDE and DDD, biodegrade very slowly in
the environment. The half-life of DDT and its metabolites in soil has been estimated at 15 years (Agricultural
Research Center 2003). DDT is ~400 times more volatile than DDD and DDE, but has an analogously low
water solubility, and strong tendency to bioaccumulate (high Kow) and sorb to soil particles (high Koc) (Nowell
et al. 1999). The high frequency of detection for HCB and DDT is noteworthy. Input from this synthetic
fungicide in urban/residential watersheds is generally small, contributing to less than 1% of the mean total
pesticide concentration; whereas, total DDT (31%DDT+26%DDE+38%DDD) contributed the most to the mean
total pesticide mass (Figure 5). Total (cis- + trans- + oxy-) chlordane only contributed 3% to the mean total
mass. All other pesticides did not significantly contribute to the overall pesticide concentration, having mean
results at or near our quality criteria of 5 times the detection limit. The mean concentration of total DDT (884
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g/kg dw) correlated with the high population density of eastern NJ and Staten Island. In addition, the Arthur
Kill is flanked by many oil and fuel tank farms, receives run-off from sanitary landfills, and is heavily traveled
by commercial barges and tankers. These factors most likely contributed to the high concentration and
detection of total DDT in the Harbor.
Figure 5 Mean frequencies of pesticide detection (as a % between 0 and 100 (solid gray line)) and mean concentrations (in
g/kg dry weight) in Arthur Kill bed sediments. A mean concentration of zero indicated that the concentration was less than
or equal to 5 times the instrument detection limit. Frequency is represented by the shaded area and concentrations by vertical
bars.
PLASMA
The frequencies of detection of the plasma samples are included in Table 1, and the calculated mean results of
the plasma samples are shown in Figure 6. We analyzed 36 plasma samples from aquatic birds in the Lake Erie
region because some of the best understanding of pesticide inputs to surface waters comes from decades of
research of OCs in and around Lake Erie (Larsen et al. 1997, Murphy 1984). In considering the mean
concentration of OCs, 4,4’-DDE, a DDT metabolite, appeared to be the dominant contributor to Lake Erie
cormorants (~63%). The next largest contributor was total chlordane (~8%), followed equally by total (cis- +
trans-) nonachlor and total dieldrin (~6% each). The large inferred mass contribution from 4,4’-DDE was
influenced by its sorption and partitioning interactions. 4,4’-DDE and the other DD-type insecticides are
characterized by long half-lives and strong tendencies to sorb to particles and bioaccumulate (high Kow and
high Koc). 4,4’-DDE is unique because its water solubility is 10 to 1000 times higher than the other 4,4’insectides (Nowell et al. 1999).
Figure 6 Comparison of mean frequency of detection (as a % from 0 to 100) and mean concentrations of organochlorines (in
g/kg wet weight) of interest in plasma from Lake Erie aquatic birds. ). A mean concentration of zero indicated that the
concentration was less than or equal to 5 times the instrument detection limit. Vertical bars indicate frequencies and stars
represent concentrations.
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The results for the Lake Erie cormorants were consistent with results for NY Harbor cormorants. 4,4’-DDE was
found to be the largest contributor. Mean 4,4’-DDE values in Lake Erie and NY Harbor cormorants ranged
from 1.1 to 42 and 1.07 to 89 g/kg ww, respectively (Parsons 2003). Dieldrin was the second largest
contributor and had mean values of 950 pg/g ww for Lake Erie nestlings and 890 pg/g ww for NY Harbor
nestlings. Mean results of HCB were very similar for the two sites: Lake Erie HCB result was 284 pg/g ww and
NY Harbor HCB result was 291 pg/g ww. The pesticide contamination in the NY Harbor cormorants was
attributed to a pesticide manufacturing plant, operating for decades, in the Newark Bay (Parsons 2003).
SUMMARY
New York State’s high-resolution pesticide method was successful at detecting chlorinated pesticides at sub-ppt
levels in different types of media. Of the 27 organochlorine pesticides for which the samples were analyzed,
only dieldrin was detected at a frequency greater than 70% in all 4 matrices. Concentrations of dieldrin were
only detectable in appreciably amounts in sludge and XAD samples; whereas, 4,4’-DDE significantly impacted
sludge and streambed sediment samples. Hexachlorobenzene was detected at least 90% of the time in sludge,
sediment and plasma samples and at concentrations at or near 5 times instrument detection limits.
Concentrations of HCB were detected in XAD samples representative of whole surface waters 51-60% of the
time and showed up 100% of the time in QC blank samples. Patterns of HCB detections in XAD blanks
corresponded to patterns of use, longevity and atmospheric deposition. Highly contaminated sites had greater
concentrations of HCB than did sites known to be relatively “clean.” In general, the XAD method was adequate
at representing whole water samples with pesticides sorbed to suspended particles and in the dissolved phase.
Concentrations of 4 organochlorine compounds exceeded applicable state water quality standards. New York
State water quality criteria were exceeded at all sites for total chlordane. The state water quality standards,
based on human fish consumption, are very stringent and cannot be detected by conventional analytical methods
(EPA method 608). The number and concentration of detected pesticides exceeding the standards were
associated with stream watersheds dominated by woodlands and orchards or in watersheds dominated by urban,
industrialized areas.
Full interpretation of field and laboratory data also requires measuring accessory parameters like total
suspended solids, particulate organic carbon, and dissolved organic carbon. Recent studies are interested in
modeling the interactions between organic compounds and trace metals such as Zn, Cd, Pb and Fe (Gustafsson
and Pechova 2003, Liu et al. 2003). A possible future development for the Hudson River Basin is to assess the
quality of the CARP metal database and determine the major controls on and interactions between pesticide and
metal concentrations on a regional scale. But first, we must take great care in extrapolating the results of an
individual watershed study to regional metal and pesticide budgets.
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