Organochlorine Compounds and CurrentUse Pesticides in Snow and Lake 

Sediment in Rocky Mountain National 

Park, Colorado, and Glacier National Park, 

Montana, 2002–03

By M. Alisa Mast, William T. Foreman, and Serena V. Skaates

Prepared in cooperation with the

National Park Service

Scientific Investigations Report 2006–5119

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

Dirk Kempthorne, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Mast, M.A., Foreman, W.T., and Skaates, S.V., 2006, Organochlorine compounds and current-use pesticides in snow 

and lake sediment in Rocky Mountain National Park, Colorado, and Glacier National Park, Montana, 2002–03: 

U.S. Geological Survey Scientific Investigations Report 2006–5119, 54 p.
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Study Area Description........................................................................................................................3

Acknowledgments................................................................................................................................4

Sample Collection and Analytical Methods ..............................................................................................4

Collection of Snow and Lake-Sediment Samples ...........................................................................4

Analytical Methods...............................................................................................................................6

Snow ..............................................................................................................................................7

Lake Sediment............................................................................................................................17

Reporting Levels.........................................................................................................................17

Field Quality Control............................................................................................................................17

Laboratory Quality Control ................................................................................................................21

Snow ............................................................................................................................................21

Lake Sediment............................................................................................................................25

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment.................28

Snow .....................................................................................................................................................28

Lake Sediment.....................................................................................................................................40

Summary........................................................................................................................................................51

References Cited..........................................................................................................................................52

Figures

1–4. Maps showing:

 1. Rocky Mountain National Park in Colorado showing elevation ranges and 

major drainages.....................................................................................................................3

 2. Glacier National Park in Montana showing elevation ranges and major 

drainages ................................................................................................................................5

 3. Location of snow and lake sampling sites in Rocky Mountain National Park, 

Colorado..................................................................................................................................7

 4. Locations of snow and lake sampling sites in Glacier National Park, Montana ........8

5. Photographs showing (A) Transport of snow-sampling equipment and samples, 

(B) preparation of snowpits for sampling, and (C) collection of a sample from 

the snowpit face ...........................................................................................................................9

6. Photographs showing (A) Transport of sediment sampling gear to a lake in Glacier 

National Park, (B) crew working from an inflatable boat, and (C) collection of 

surface sediment from lake core .............................................................................................11

7–9. Graphs showing:

 7. Elevation and distance from Continental Divide of snow-sampling sites 

in Rocky Mountain National Park and Glacier National Park......................................30

 8. Concentration ranges of most frequently detected pesticides in snow 

collected in Rocky Mountain National Park and Glacier National Park ....................37

 9. Comparison of dacthal concentrations in snow between Rocky Mountain 

National Park and Glacier National Park ........................................................................37
iv

10. Maps showing usage of chlorothalonil, dacthal, and endosulfan in the Western 

United States during 1997..........................................................................................................39

11. Photographs showing character of lakes sampled for sediment during the study 

including (A) Akokala Lake and (B) Stoney Indian Lake in Glacier National Park 

and (C) Lone Pine Lake and (D) Sky Pond in Rocky Mountain National Park...................42

12. Graph showing range of DDD and DDE concentrations in surface sediments 

from lakes in Rocky Mountain National Park and Glacier National Park .........................45

13. Graph showing concentrations of DDD and DDE in a lake-sediment core from 

Mills Lake in Rocky Mountain National Park .........................................................................46

Tables

1. Description of snow-sampling sites in Rocky Mountain National Park and Glacier 

National Park and analytical methods used ............................................................................6

2. Description of lake-sediment sampling sites in Rocky Mountain National Park 

and Glacier National Park and analytical methods used.....................................................10

3. Pesticides and other organic compounds analyzed in snow and sediment samples 

collected during this study........................................................................................................12

4. Concentrations of current-use pesticides analyzed by gas chromatography/

electron-impact mass spectrometry in field blanks and replicate snow samples 

collected in 2002–03 ...................................................................................................................18

5. Concentrations of organohalogen compounds analyzed by gas chromatography/

electron-capture negative ion mass spectrometry in field blanks and replicate 

snow samples collected in 2003...............................................................................................20

6. Concentrations of organochlorine compounds analyzed by gas chromatography/

electron-capture detection in replicate sediment samples collected in 2003 .................21

7. Concentrations and percent recovery of current-use pesticides analyzed by gas 

chromatography/electron-impact mass spectrometry in laboratory blanks and 

reagent spikes analyzed with snow samples in 2002–03.....................................................22

8. Concentrations and percent recovery of organohalogen compounds analyzed 

by gas chromatography/electron-capture negative ion mass spectrometry in 

laboratory blanks and reagent spikes analyzed with snow samples in 2002–03.............24

9. Concentrations of organochlorine compounds analyzed by gas chromatography/

electron-capture detection in laboratory blanks and replicates analyzed with 

sediment samples in three analytical runs during 2002–03.................................................26

10. Percent recovery and analytical control limits of organochlorine compounds 

analyzed by gas chromatography/electron-capture detection in certified reference 

materials and laboratory reagent spikes analyzed with sediment samples in three 

analytical runs during 2002–03 .................................................................................................27

11. Concentrations and percent recovery of current-use pesticides analyzed by gas 

chromatography/electron-impact mass spectrometry in laboratory blanks and 

reagent spikes analyzed with sediment samples in 2003 ....................................................28

12. Concentrations and percent recovery of organohalogen compounds analyzed 

by gas chromatography/electron-capture negative ion mass spectrometry in 

laboratory blanks and reagent spikes analyzed with sediment samples in 2003 ............29

13. Concentrations of current-use pesticides analyzed by gas chromatography/

electron-impact mass spectrometry in snow samples collected in Rocky Mountain 

National Park in 2002–03 ...........................................................................................................31
14. Concentrations of current-use pesticides analyzed by gas chromatography/

electron-impact mass spectrometry in snow samples collected in Glacier National 

Park in 2002–03............................................................................................................................33

15. Concentrations of organohalogen compounds analyzed by gas chromatography/

electron-capture negative ion mass spectrometry in snow samples collected 

in Rocky Mountain National Park and Glacier National Park in 2002–03..........................35

16. Comparison of organic compound concentrations in snow and rain from remote 

mountainous regions..................................................................................................................41

17. Concentrations of organochlorine compounds analyzed by gas chromatography/

electron-capture detection in lake-sediment samples collected in Rocky Mountain 

National Park in 2002..................................................................................................................43

18. Concentrations of organochlorine compounds analyzed by gas chromatography/

electron-capture detection in lake-sediment samples collected in Glacier National 

Park in 2002–03............................................................................................................................44

19. Concentrations of current-use pesticides analyzed by gas chromatography/

electron-impact mass spectrometry in lake-sediment samples collected in Rocky 

Mountain National Park and Glacier National Park in 2003 ................................................47

20. Concentrations of organohalogen compounds analyzed by gas chromatography/

electron-capture negative ion mass spectrometry in lake-sediment samples 

collected in Rocky Mountain National Park and Glacier National Park in 2003 ..............49

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square meter (m2) 0.0002471 acre

hectare (ha) 2.471 acre

square kilometer (km2) 247.1 acre

square meter (m2) 10.76 square foot (ft2)

hectare (ha) 0.003861 square mile (mi2)

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 33.82 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

cubic meter (m3) 264.2 gallon (gal)

cubic meter (m3) 0.0008107 acre-foot (acre-ft)

Mass

milligram (mg) 0.03527 × 10–3 ounce, avoirdupois (oz)

gram (g) 0.03527 ounce, avoirdupois (oz)

microgram 0.03527 × 10–6 ounce, avoirdupois (oz)

kilogram (kg) 2.205 ounce, avoirdupois (lb)

nanogram (ng) 0.03527 × 10–9 ounce, avoirdupois (oz)

dalton 0.058 × 10–24 ounce, avoirdupois (oz)

Pressure

pascal (Pa) 9.869 atmosphere, standard (atm)
vi

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Abbreviations

cm, centimeter

km, kilometer

kPa, kilopascal

L, liter

m, meter

mL, milliliter

mm, millimeter

min, minutes

ng/L, nanogram per liter

μg/kg, microgram per kilogram

μg/L, microgram per liter

μg/m2, microgram per square meter

μm, micrometer

°C, degrees Celsius

Acronyms

α-HCH-d6, alpha-hexachlorocyclohexane-d6

CRM, certified reference material

CUP, current-use pesticides

DCM, dichloromethane

DDD, p,p’-dichlorodiphenyldichloroethane

DDE, p,p’-dichlorodiphenyldichoroethene

DDT, p,p’-dichlorodiphenyltrichloroethane

E, estimated concentration

GC, gas chromatography

GC/ECD, gas chromatography with electron-capture detection

GC/EIMS, gas chromatography with electron-impact mass spectrometry

GC/ECNIMS, gas chromatography with electron capture negative ion mass spectrometry

GLAC, Glacier National Park 

HCB, hexachlorobenzene

HCH, hexachlorocyclohexane

MRL, method reporting limit 
vii

NAWQA, National Water-Quality Assessment Program 

NPS, National Park Service

NWQL, National Water Quality Laboratory

OCC, organochlorine compounds

OHC, organohalogen compounds

PAH, polycyclic aromatic hydrocarbons

PCB, polychlorinated biphenyls

PBDE, polybrominated diphenyl ethers

PTFE, polytetrafluoroethylene 

RPD, relative percent difference

ROMO, Rocky Mountain National Park

SNOTEL, Snow Telemetry

USGS, U.S. Geological Survey

WACAP, Western Air Contaminants Assessment Project
Abstract

Organochlorine compounds and current-use pesticides 

were measured in snow and lake-sediment samples from 

Rocky Mountain National Park in Colorado and Glacier 

National Park in Montana to determine their occurrence 

and distribution in high-elevation aquatic ecosystems. The 

U.S. Geological Survey, in cooperation with the National 

Park Service, collected snow samples at eight sites in Rocky 

Mountain National Park and at eight sites in Glacier National 

Park during spring of 2002 and 2003 just prior to the start of 

snowmelt. Surface sediments were collected from 11 lakes 

in Rocky Mountain National Park and 10 lakes in Glacier 

National Park during summer months of 2002 and 2003. 

Samples were analyzed for organochlorine compounds by gas 

chromatography with electron-capture detection and currentuse pesticides by gas chromatography with electron-impact 

mass spectrometry. A subset of samples was reanalyzed using 

a third instrumental technique (gas chromatography with 

electron-capture negative ion mass spectrometry) to verify 

detected concentrations in the initial analysis and to investigate 

the presence of additional compounds.

For the snow samples, the pesticides most frequently 

detected were endosulfan, dacthal, and chlorothalonil, all of 

which are chlorinated pesticides that currently are registered 

for use in North America. Concentrations of these pesticides 

in snow were very low, ranging from 0.07 to 2.36 nanograms 

per liter. Of the historical-use pesticides, hexachlorobenzene, 

dieldrin, and trans-nonachlor were detected in snow but 

only in one sample each. Annual deposition rates of dacthal, 

endosulfan, and chlorothalonil were estimated at 0.7 to 

3.0 micrograms per square meter. These estimates are likely 

biased low because they do not account for pesticide deposition 

during summer months.

For the lake-sediment samples, DDE (p,p’-dichlorodiphenyldichoroethene) and DDD (p,p’-dichlorodiphenyldichoroethane) were the most frequently detected 

organochlorine compounds. DDE and DDD are degradation products of DDT (p,p’-dichlorodiphenyltrichloroethane), which is a well-documented, persistent organochlorine 

insecticide that has been banned from use in the United States 

since 1972. Detected concentrations were very low, ranging 

from 0.12 to 4.7 micrograms per kilogram, and probably pose 

little threat to aquatic organisms in park lakes. DDD and DDE 

concentrations in a sediment core from Mills Lake in Rocky 

Mountain National Park indicate that atmospheric deposition 

of DDT and possibly other banned organochlorine compounds 

to high-elevation parks has been in decline since the 1970s. 

Commonly detected current-use pesticides in lake sediments 

included dacthal and endosulfan sulfate, which ranged in 

concentrations from 0.11 to 0.26 micrograms per kilogram for 

dacthal and 0.12 to 1.2 micrograms per kilogram for endosulfan sulfate. Both compounds were found in nearly all the snow 

samples, confirming that some current-use pesticides entering high-elevation aquatic ecosystems through atmospheric 

deposition are accumulating in lake sediments and potentially 

in aquatic biota.

Introduction

A number of studies have documented the presence 

of organochlorine compounds in remote polar ecosystems 

(Simonich and Hites, 1995; Wania and Mackay, 1996; Blais, 

2005). These compounds are accumulating at high latitudes 

due to long-range atmospheric transport and the effects of 

cold condensation, a process which causes semivolatile 

organic compounds used at warmer temperate latitudes 

to accumulate in colder high-latitude regions (Simonich 

and Hites, 1995). Organochlorine compounds frequently 

detected in these environments include the pesticides DDT, 

hexachlorocyclohexanes (α- and γ-HCH), and hexachlorobenzene (HCB), and the industrially used polychlorinated 

Organochlorine Compounds and Current-Use Pesticides 

in Snow and Lake Sediment in Rocky Mountain National 

Park in Colorado and Glacier National Park in Montana, 

2002–03

By M. Alisa Mast, William T. Foreman, and Serena V. Skaates
biphenyls (PCB). Although usage of most of these compounds 

ceased in the 1970s and 1980s, they are still detected in the 

environment because of their resistance to natural degradation 

processes (Majewski and Capel, 1995). These compounds are 

of environmental concern because they tend to concentrate in 

aquatic organisms through bioconcentration and biomagnification and, for some, are known or suspected of disrupting 

the endocrine system of aquatic organisms. Several recent 

studies also have documented the accumulation of organochlorine compounds in high-elevation areas at temperate 

latitudes (Blais and others, 1998; Carrera and others, 2001; 

Grimalt and others, 2001; Blais, 2005; Daly and Wania, 

2005; Wilkinson and others, 2005). Blais and others (1998) 

detected organochlorine compounds in seasonal snowpacks 

in Canada and found that concentrations tended to increase 

with increasing elevation. Grimalt and others (2001) reported 

elevated concentrations of organochlorine compounds in lake 

sediment and fish tissue in mountainous areas of Europe. The 

authors hypothesized that low annual air temperature at high 

elevations was causing selective accumulation of organochlorine compounds in temperate mountain areas. Based on 

these results, it has been suggested that temperate mountains 

in the Western United States, such as the Rocky Mountains, 

Cascade Range, and Sierra Nevada, may be particularly 

susceptible to accumulation of organochlorine compounds 

because they have low annual air temperatures, relatively high 

rates of precipitation, and are close to agricultural and urban 

source areas.

Although the widespread occurrence of organochlorine 

compounds in the environment has been documented, much 

less is known about long-range atmospheric transport of 

current-use pesticides and the persistence of these compounds 

in aquatic environments, particularly in remote mountainous areas. A major class of current-use pesticides is organophosphate insecticides, which includes pesticides such as 

chlorpyrifos, malathion, and diazinon and accounts for about 

65 percent of insecticide usage in the United States (Majewski 

and Capel, 1995). The triazine and acetanilide herbicides, 

which include atrazine and metolachlor, account for about 

50 percent of herbicide usage in the United States (Majewski 

and Capel, 1995). Current-use pesticides have been detected 

in precipitation collected in remote areas of the United States 

indicating these compounds can be transported by air currents over substantial distances (Goolsby and others, 1995; 

Majewski and Capel, 1995; McConnell and others, 1998; 

Mast and others, 2003). McConnell and others (1998) detected 

several organophosphate insecticides in rain and snow samples 

collected at high elevations in the Sierra Nevada of California. 

Atmospheric transport of pesticides from California’s Central 

Valley, one of the heaviest pesticide-use areas in the United 

States, was considered the most likely source of the pesticides. 

These compounds also were detected in surface-water samples 

from two areas in the Sierra Nevada but not in frog tissue 

(Fellers and others, 2004), indicating the organophosphate 

insecticides may not be as easily accumulated in aquatic 

ecosystems as organochlorine compounds (Majewski and 

Capel, 1995). Mast and others (2003) detected the currentuse pesticides atrazine, carbaryl, and dacthal in rain samples 

collected at a high-elevation site in the Colorado Front Range. 

The authors suggested a likely source of these pesticides 

was urban and agricultural areas on the eastern plains of 

Colorado.

National Parks in mountainous areas of the Western 

United States have a large percentage of lakes and streams 

at high elevations that may be at risk from long-range 

transport and deposition of organochlorine compounds and 

current-use pesticides. To date only a few measurements 

have been made in high-elevation parks (Heit and others, 

1984; Tate and Heiny, 1996; Stephens and Deacon, 1997; 

Cubala and others, 1995; McConnell and others, 1998; Mast 

and others, 2003) so relatively little is known about deposition to and occurrence in these sensitive ecosystems. The 

U.S. Geological Survey (USGS), in cooperation with the 

National Park Service (NPS), conducted a study in 2002–03 

to provide baseline information on organic contaminants 

at two National Parks in the Rocky Mountain Region. This 

information is needed by park managers to protect and preserve park resources from damage by atmospheric contaminants as required by the Clean Air Act Amendments of 1977 

(http://www2.nature.nps.gov/air/regs/cleanAir.cfm, accessed 

January 2006).

Purpose and Scope

The purpose of this report is to describe the occurrence 

and distribution of selected organochlorine compounds and 

current-use pesticides in snow and lake-sediment samples 

collected in Rocky Mountain National Park (ROMO) in 

Colorado and Glacier National Park (GLAC) in Montana 

during 2002–03. This report also presents estimates of atmospheric deposition rates of selected pesticides to each park and 

compares the findings with concentrations reported in similar 

studies in remote mountainous regions. This information can 

be used to assess if current levels of organic contaminants 

pose a threat to aquatic organisms and to establish a baseline 

of information against which changes may be measured in the 

future. This report includes data for snow samples that were 

collected at eight sites in ROMO and eight sites in GLAC 

during spring of 2002 and 2003 and data for surface sediments that were collected at 11 lakes in ROMO and 10 lakes 

in GLAC during summer months of 2002 and 2003. Snow 

and sediment samples were analyzed for selected organochlorine compounds and current-use pesticides by three different 

instrumental techniques.

   Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Figure 1. Rocky Mountain National Park in Colorado showing elevation ranges and major drainages.

Introduction   

Study Area Description

ROMO is located in the Colorado Front Range in northcentral Colorado and is characterized by steep, mountainous 

terrain with elevations ranging from 2,500 m at the eastern 

park boundary to more than 4,000 m along the Continental 

Divide (fig. 1). Drainages on the east side of the park form the 

headwaters of the Big Thompson River and Saint Vrain Creek, 

and those on the west side drain into the Upper Colorado 

River system. The three major ecoregions in ROMO are alpine 

tundra, subalpine forest, and montane forest. Vegetation in 

ROMO is dominated by spruce-fir forests between 2,860 and 

3,300 m and alpine tundra communities at higher elevations 

(Baron, 1992). The area is characterized by a continental 

COLORADO

Elevation

EXPLANATION

40o15’ N 40o15’ N

40o30’ N 40o30’ N

105o45’ W

105o45’ W

2,250–2,750 meters

2,750–3,250 meters

3,250–3,750 meters

>3,750 meters

Big Thompson River

Fall River

0 6 12 MILES

0 6 12 KILOMETERS

Study area

Colora

do River

Continental 

Divide

Base from U.S. Geological Survey digital data

1927, 1:100,000

Universal transverse Mercator projection

Zone 13

Park

boundary

Saint Vrain Creek
climate with long, cold winters and a short growing season 

(1–3 months). Mean annual precipitation, which varies considerably with elevation, is about 100 cm at 3,150 m. More than 

one-half of the precipitation occurs as snow that accumulates 

in a seasonal snowpack between October and April. Winter 

precipitation is associated with synoptic weather systems 

with westerly airflow, and summer precipitation is associated 

with convective air masses originating primarily from the 

southwest and southeast (Baron and Denning, 1993). Approximately 95 percent of ROMO is designated or recommended 

as wilderness, and human activities are limited to tourism 

and recreation. Although the park is adjacent to large areas 

of undeveloped State and National Forest lands, it is situated 

less than 40 km to the west of the Front Range urban corridor, 

which contains the most concentrated population density in the 

Rocky Mountain region (Dennehy and others, 1993). The park 

also is situated directly west of large expanses of cropland 

and pasture on the plains of eastern Colorado. Agricultural 

pesticide use in this area exceeds 1.3 million kilograms per 

year and is used primarily to treat corn and hay (Kimbrough 

and Litke, 1997).

GLAC is located in the northern Rocky Mountains in 

northwestern Montana and is bounded to the north by the 

Canadian provinces of Alberta and British Columbia (fig. 2). 

The North and Middle Forks of the Flathead River border 

the park on the west and south, and the park is bisected by 

the Continental Divide. The glaciated landscape, which 

ranges in elevation from 949 to 3,180 m, is characterized 

by horn-shaped peaks, broad U-shaped valleys, numerous 

glacial lakes, and 36 active glaciers. Five large ecoregions 

are found in GLAC: alpine tundra, subalpine forest, montane forest, aspen parkland, and fescue grassland. Coniferous forests dominate much of the landscape with lodgepole 

pine, Douglas fir, and western larch growing on drier sites 

and western hemlock and western red cedar inhabiting wetter sites (White and others, 1998). The climate in GLAC is 

one of long, cold, snowy winters and relatively short, warm 

summers. The west side of the park is influenced by Pacific 

air masses, which result in a milder and moister climate; 

the east side is dominated by colder Continental air masses. 

Annual precipitation varies substantially between west-side 

and east-side locations in the park and ranges from as little as 

30 cm at low elevations on the east side to as much as 350 cm 

at higher elevations on the west side (Finklin, 1986). Most 

precipitation in winter falls as snow, which accumulates in a 

seasonal snowpack between November and April. Most of the 

park is designated wilderness, and human activities are very 

limited. GLAC is bounded by largely undeveloped National 

Forest land to the west and south and by the Blackfeet Indian 

Reservation to the east. Land-use activities in areas adjacent 

to GLAC include timber harvesting, low-density residential development, road networks, and ranching. Although 

there is some pesticide use in agricultural areas immediately adjacent to the park, the heaviest use in the region is 

in agricultural areas in central Washington and southern Idaho 

(http://ca.water.usgs.gov/pnsp/pesticide_use_maps_1997/, 

accessed December 2005) and to the northeast in Alberta, 

Canada.

Acknowledgments

Field assistance for the project was provided by 

Donald H. Campbell, David W. Clow, Karen Holzer, 

George P. Ingersoll, David J. Manthorne, Elisabeth A. 

Mast, Leora Nanus, Blase Reardon, and Jesse Winterringer. 

Analytical assistance was provided by James E. Madsen, 

Frank W. Wiebe, Jim Madsen, and Lisa Greaser. The 

authors appreciate the helpful review comments provided by Mary Kidd, Michael S. Majewski, and 

William A. Battaglin. Support for this project was provided by the USGS/NPS Water Quality Partnership 

Program (http://water.usgs.gov/nps_partnership/, accessed 

December 2005).

Sample Collection and Analytical 

Methods

Collection of Snow and Lake-Sediment Samples

Snow samples were collected at eight sites in ROMO 

and eight sites in GLAC during spring of 2002 and 2003. 

Snow-sampling sites in each park were established along 

elevation gradients and on both sides (east and west) of the 

Continental Divide (table 1, figs. 3–4). Snow samples were 

collected in late spring at maximum accumulation according 

to methods developed by Ingersoll and others (2001). Due to 

the remote location of the sites (fig. 5), all sampling equipment had to be transported on skis into the sampling sites. At 

each site, a snowpit was excavated and temperature measurements were made along the freshly exposed face to ensure that 

the snowpack was sampled prior to the onset of spring melt. 

This timing is important for obtaining a representative sample 

because some constituents are preferentially eluted from the 

snowpack during the initial stages of snowmelt (Ingersoll and 

others, 2001). Snow samples for pesticide analyses were collected from the clean snowpit face into two 20-L PTFE bags 

using a polycarbonate scoop and shovel. A complete vertical 

snow column was collected to obtain a sample representative 

of the entire snowpack. The shovel, scoop, and 20-L PTFE 

bags were precleaned at a USGS laboratory by washing with 

laboratory detergent followed by several rinses with tap water, 

deionized water, methanol, and dichloromethane (DCM). All 

organic solvents used in this study were pesticide-residue 

analysis quality. Once filled with snow, the PTFE bags were 

closed with plastic cable ties and wrapped in aluminum foil 

to exclude light and then placed in large polypropylene bags 

 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Figure 2. Glacier National Park in Montana showing elevation ranges and major drainages.

Sample Collection and Analytical Methods 

Continental 

Divide 

Base from U.S. Geological Survey digital data 

1983, 1:100,000 

Universal transverse Mercator projection 

Zone 12

Park 

boundary 

49o N 

48o30’ N 

114o W 48o30’ N 

114o W 

115o W 

0 10 20 KILOMETERS 

0 10 20 MILES 

EXPLANATION 

<1,275 meters

1,275–1,775 meters

1,775–2,225 meters

>2,225 meters

Elevation 

MONTANA 

Study area 

North

Fork Flathead River

Middle Fork Flathead

River

Lake McDonald 

St. Mary Lake 
to prevent puncture of the PTFE bags. Snow samples were 

transported on dry ice to the laboratory freezer where they 

were stored at –15°C for 2 to 3 months before processing 

and analysis at the USGS National Water Quality Laboratory 

(NWQL).

Surface sediments were collected at 11 lakes in ROMO 

and 10 lakes in GLAC during summer months of 2002 and 

2003 (table 2, figs. 3–4). Lakes that supported fish populations 

were selected from each side of the Continental Divide. Cores 

were collected from a small inflatable raft anchored near the 

deepest point in each lake by using a gravity benthos corer 

(fig. 6C). Due to the remote location of the lakes, all sampling 

equipment had to be backpacked into the sampling sites. The 

surface sediment (top 3 cm) of each core was extruded from 

the core tube and transferred into a baked glass jar using a 

precleaned metal spatula. Based on 210Pb dating of several 

sediment cores from each park, the top 3 cm of sediment generally represented lake sediments that were deposited over the 

past 10–15 years (M.A. Mast, U.S. Geological Survey, unpub. 

data, 2004). Due to the small diameter of the corer (6 cm), 

surface sediment from three to five cores had to be combined 

into one jar to acquire sufficient sample mass for the pesticide 

analyses. The samples were transported on ice to the laboratory where they were stored frozen (–5°C) until analysis at the 

NWQL.

Analytical Methods

This study initially was designed to determine organochlorine compounds (OCC) in snow and sediment from the 

two parks. In 2002, all samples were extracted and analyzed 

for selected organochlorine pesticides and PCB congeners 

by gas chromatography with electron-capture detection 

(GC/ECD); however, none of the OCCs were detected in the 

snow samples and only a few compounds were detected in the 

sediment samples. Based on the presence of several currentuse pesticides in previously collected snow and rain samples 

from ROMO (Mast and others, 2001; Mast and others, 2003), 

the method used for the 2003 snow samples was modified for 

the extraction and analysis of current-use pesticides (CUP) by 

gas chromatography with electron-impact mass spectrometry 

(GC/EIMS). The 2003 sediment samples were extracted and 

analyzed by both the OCC and CUP methods. Several of the 

snow and sediment extracts prepared by these two methods 

also were reanalyzed by gas chromatography with electroncapture negative ion mass spectrometry (GC/ECNIMS). This 

third instrumental analysis was used to verify detected concentrations in the initial analysis and to investigate the presence of 

additional organohalogen compounds (OHC). Methods used to 

prepare and analyze the snow and sediment samples are listed 

in tables 1 and 2 and analytes determined by each instrumental 

technique are listed in table 3.

Table 1. Description of snow-sampling sites in Rocky Mountain National Park and Glacier National Park and analytical methods used.

[No., number in figures 3 and 4; USGS, U.S. Geological Survey; ROMO, Rocky Mountain National Park; GLAC, Glacier National Park; Location, location of 

sampling site relative to the Continental Divide; Elev., elevation in meters; OCC, organochlorine compounds analyzed by gas chromatography/electron capture 

detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS); OHC, organohalogen 

compounds analyzed by gas chromatography/electron-capture negative ion mass spectrometry (GC/ECNIMS)]

No. USGS 

site number Site name Park Location Elev. 20021 20032

OCC CUP OHC CUP OHC

S1 401848105384200 Bear Lake ROMO East 2,934 x x -- x x

S2 401723105395701 Loch Vale Forest ROMO East 3,216 x x x x x

S3 401725105400001 Loch Vale Meadow ROMO East 3,215 -- -- -- x x

S4 401720105403400 Upper Andrews Tarn ROMO East 3,402 x x x -- --

S5 402350105505400 Phantom Valley ROMO West 2,752 x x -- x x

S6 402443105491600 Lake Irene Meadow ROMO West 3,237 -- -- -- x x

S7 402442105491000 Lake Irene Forest ROMO West 3,243 x -- -- -- --

S8 402530105482000 Forest Canyon Pass ROMO West 3,414 x x -- -- --

S9 484741113410800 Swiftcurrent Creek GLAC East 1,542 x x -- -- --

S10 484037113383800 E3 GLAC East 1,581 x x -- -- --

S11 484129113392800 E6 GLAC East 1,937 x x -- -- --

S12 484240113390500 Preston Park GLAC East 2,163 x x -- -- --

S13 484553113482100 W10 GLAC West 1,467 x x -- -- --

S14 483723113483600 Lower Snyder Lake GLAC West 1,585 -- -- -- x x

S15 484546113473400 W11 GLAC West 1,753 x x -- -- --

S16 484616113461300 Granite Park GLAC West 2,006 x x -- x x

1

2002 samples were prepared by OCC method and initially analyzed by GC/ECD. The same extracts were subsequently analyzed for CUPs by GC/EIMS 

and OHCs by GC/ECNIMS.

2

2003 samples were prepared by CUP method and initially analyzed by GC/EIMS. The same extracts were subsequently analyzed for OHCs by 

GC/ECNIMS.

 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Figure 3. Location of snow and lake sampling sites in Rocky Mountain National Park, Colorado.

Snow

Snow samples were melted in the sealed PTFE bags (two 

bags per sample) over a 24-hour period at the NWQL, which 

typically yielded 10 to 15 L of snowmelt. In 2002, 25 ng of 

organochlorine surrogate α-HCH-d6, isodrin, and PCB 207 

and 50 ng of organophosphorus surrogate isofenphos were 

added to each of the two bags to monitor recoveries from the 

sample preparation process. Pesticides in the snowmelt were 

extracted by adding 200 mL of DCM directly to the sample 

in the PTFE bag. The melted snow samples were not filtered, 

so both dissolved and particulate phases were extracted by the 

solvent, including organic debris (pine needles and immature 

cones) present in some samples. The DCM was mixed with 

the sample by using a shaker table, then the extracted water 

was pumped from the bag to a waste container and the DCM 

was pumped into a separatory funnel. An additional 50 mL 

of DCM was used to rinse each PTFE bag and added to the 

separatory funnel. The combined DCM extracts and bag rinses 

were drained from the separatory funnel into a baked 1-L glass 

Sample Collection and Analytical Methods 

105°45'W

105°45'W

40°30'N

40°15'N 40°15'N

COLORADO 

S1 

S4 

S8 

S6 & S7

S5 

L10 

L2 

L4 

L9 

L5 

L6 

L3 

L8 

L1 

L7 

L11 Big Thompson River

Fall River

EXPLANATION 

Lake sites (numbers in table 2) 

Bear Lake SNOTEL site

Snow sites (numbers in table 1) 

Continental 

Divide 

Park

boundary 

Study area 

0 6 12 MILES 

0 6 12 KILOMETERS

Base from U.S. Geological Survey digital data 

1927, 1:100,000 

Universal transverse Mercator projection 

Zone 13

Colorado

River

S2 & S3

S2 & S3

Saint Vrain Creek
Continental 

Divide 

114°W

114°W

115°W

48°30'N

49°N

Lake McDonald 

St. Mary Lake 

MONTANA 

Study area 

Park 

boundary 

Base from U.S. Geological Survey digital data 

1983, 1:100,000 

Universal transverse Mercator projection 

Zone 12

0 10 20 KILOMETERS 

0 10 20 MILES 

EXPLANATION 

Lake sites (numbers in table 2) 

Flattop Mountain SNOTEL site

Snow sites (numbers in table 1) 

North

Fork Flathead River

S15 

S16 

S14 

S13 

S9 

S12 

S11 

S10 

L15 

L13 

L21 

L20 

L17 

L18 

L19 

L16 

L14 

L12 

Middle Fork Flathead

River

Figure 4. Locations of snow and lake sampling sites in Glacier National Park, Montana.

 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
bottle and dried with sodium sulfate. The extract was reduced 

in volume and exchanged to hexane using Kuderna-Danish 

distillation and nitrogen gas evaporation to 1 mL. The extract 

was cleaned and fractionated using an alumina/silica column 

according to the method of Noriega and others (2004). The 

fractions were reduced in volume by micro-Kuderna-Danish 

distillation and nitrogen gas evaporation to 0.5 mL and transferred to a gas chromatography (GC) vial. Each fraction was 

analyzed for 16 organochlorine pesticides and degradates and 

27 PCB congeners by dual-capillary-column GC/ECD according to the method of Noriega and others (2004). This extraction procedure and instrumental analysis for organochlorine 

compounds is referred to as the “OCC” method in this report. 

No compounds were detected by the OCC method in any of 

the 2002 snow samples above the reporting levels listed in 

table 3 and will not be discussed further in this report.

C 

A 

B 

Figure 5. (A) Transport of snow-sampling equipment and samples, (B) preparation of snowpits for sampling, and (C) collection of a 

sample from the snowpit face.

Sample Collection and Analytical Methods 
In 2003, the method used to process snow samples 

was targeted toward analysis of current-use pesticides 

and is referred to as the “CUP” method in this report. The 

melted snow sample in each bag was fortified with 50 ng 

of α-HCH-d6 and diazinon-d10 surrogates and then poured 

through a coarse filter (to remove pine needles and other 

debris greater than 1 mm) into a 6-L separatory funnel. 

The samples were shake extracted using 200-mL aliquots 

of DCM per 5 L of meltwater plus 50 mL of DCM used to 

rinse the bag. The DCM extracts and bag rinses for each 

sample were combined in a baked 1-L glass bottle and dried 

with sodium sulfate. The extract was reduced in volume and 

exchanged to ethyl acetate using Kuderna-Danish distillation 

and nitrogen gas evaporation to 1 mL. The extract was passed 

through a graphitized carbon solid-phase extraction column 

(CarboPrep 90), and the analytes were eluted with 13 mL of 

a solution of 50 percent DCM in ethyl acetate. A procedural 

internal standard solution of three perdeuterated polycyclic 

aromatic hydrocarbons (PAH) was added to the extract before 

final solvent reduction and exchange to toluene using nitrogen 

gas evaporation. The extract was transferred to a GC vial 

with toluene rinse to 0.25-mL final volume and analyzed 

for 62 current-use pesticides by GC/EIMS operated in the 

selected-ion monitoring mode using conditions described in 

Zaugg and others (1995), Sandstrom and others (2001), and 

Madsen and others (2003). The 2002 snow extracts prepared by the OCC method also were analyzed for CUPs by 

GC/EIMS; however, only 18 of the 62 current-use pesticides 

were recovered from the alumina/silica cleanup procedure and 

could be quantified.

The 2002 snow extracts (prepared by the OCC method) 

and 2003 snow extracts (prepared by the CUP method) also 

were analyzed for a variety of organohalogen compounds 

by gas chromatography with electron-capture negative 

ion mass spectrometry (GC/ECNIMS), referred to as the 

“OHC” instrumental analysis in this report. The compounds 

determined by the OHC analysis include selected organochlorine and current-use pesticides (several of which also 

were analyzed by the OCC and CUP methods) and selected 

PCB congeners and PBDE flame retardants (table 3). 

Table 2. Description of lake-sediment sampling sites in Rocky Mountain National Park and Glacier National Park and analytical 

methods used.

[No., number in figures 3 and 4; USGS, U.S. Geological Survey; ROMO, Rocky Mountain National Park; GLAC, Glacier National Park; Location, location of 

sampling site relative to the Continental Divide; Elev., elevation in meters; OCC, organochlorine compounds analyzed by gas chromatography/electron capture 

detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS); OHC, organohalogen 

compounds analyzed by gas chromatography/electron-capture negative ion mass spectrometry (GC/ECNIMS)]

No. USGS site number Site name Park Location Elev. 2002 2003 

OCC OCC CUP OHC1

L1 401555105382700 Black Lake ROMO East 3,237 -- x x x

L2 402011105403801 Fern Lake ROMO East 2,903 x -- -- --

L3 401247105404400 Fifth Lake ROMO West 3,280 x -- -- --

L4 401817105394500 Lake Haiyaha ROMO East 3,115 -- x x x

L5 401523105430000 Lake Nanita ROMO West 3,267 x -- -- --

L6 401324105435400 Lone Pine Lake ROMO West 3,078 x -- -- --

L7 403215105415200 Mirror Lake ROMO East 3,359 x -- -- --

L8 401308105360500 Sandbeach Lake ROMO East 3,134 x -- -- --

L9 401643105400100 Sky Pond ROMO East 3,316 x -- -- --

L10 402227105474501 Timber Lake ROMO West 3,371 x -- -- --

L11 402636105394100 Ypsilon Lake ROMO East 3,200 -- x x x

L12 485230113503300 Atsina Lake GLAC East 1,757 -- x x x

L13 485244114115400 Akokala Lake GLAC West 1,463 x -- -- --

L14 485639113563600 Lake Janet GLAC East 1,512 -- x x x

L15 483736113481100 Lower Snyder Lake GLAC West 1,585 x -- -- --

L16 485254113485000 Mokowanis Lake GLAC East 1,524 -- x x x

L17 482844113265000 Noname Lake GLAC East 1,817 x -- -- --

L18 484746113422300 Redrock Lake GLAC East 1,536 x -- -- --

L19 485407113372500 Slide Lake GLAC East 1,838 -- x x x

L20 485309113515800 Stoney Indian Lake GLAC East 1,926 -- x x x

L21 484709113441900 Upper Bullhead Lake GLAC East 1,585 x -- -- --

1

Samples were prepared by CUP sediment method and initially analyzed by GC/EIMS. The same extracts were subsequently analyzed for OHCs by 

GC/ECNIMS.

10 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
A 

B 

C 

Figure 6. (A) Transport of sediment sampling gear to a lake in Glacier National Park, (B) crew working from an inflatable 

boat, and (C) collection of surface sediment from lake core.

Sample Collection and Analytical Methods 11
Table 3. Pesticides and other organic compounds analyzed in snow and sediment samples collected during this study.—Continued

[D, degradate; E, all concentrations for this compounds reported as estimated; F, fungicide; H, herbicide; I, insecticide; M, manufacturing or byproduct; R, flame retardant; TEC, threshold effect concentration; PEC, probable effect concentration; --, not analyzed or not available; μg/L, microgram per liter; μg/kg, microgram per kilogram; ng/L, nanogram per liter; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Chemical Abstract Service registry number Type of compound

Aquatic-life 

criterion, Water 

chronic1

(μg/L) 

Aquatic-life 

criterion, 

Sediment 

TEC (PEC)2

(μg/kg)

Determined 

for snow 

samples

Determined 

for sediment 

samples

Reporting 

limit for 

OCC snow 

method3

(ng/L)

Organochlorine compounds (OCC) analyzed by gas chromatography with electron-capture detection (GC/ECD)

Aldrin 309-00-2 I -- -- 2002 2002–03 1.9Chlordane, technical 57-74-9 I -- 3.24 (17.6) -- 2002–03 --cis-Chlordane 5103-71-9 I -- -- 2002 2003 2.4trans-Chlordane 5103-74-2 I -- -- 2002 2003 2.4p,p’-DDT 50-29-3 I -- 4.16 (62.9) 2002 2002–03 1.9	 p,p’-DDD 72-54-8

D -- 4.88 (28.0) 2002 2002–03 2.4

	 p,p’-DDE 72-55-9

D -- 3.16 (31.3) 2002 2002–03 1.9

Dieldrin 60-57-1 I 0.056 1.90 (61.8) 2002 2002–03 2.0Endosulfan I 959-98-8 I -- -- 2002 2002–03 2.1Endrin 72-20-8 I -- 2.22 (207) 2002 2002–03 1.9γ-HCH (Lindane) 58-89-9 I 0.01 2.37 (4.99) 2002 2002–03 2.0Heptachlor 76-44-8 I -- -- 2002 2002–03 1.5

Heptachlor epoxide 1024-57-3

D -- 2.47 (16.0) 2002 2002–03 2.6

p,p’-Methoxychlor 72-43-5 I -- -- 2002 2002–03 2.8Mirex 2385-85-5 I -- -- 2002 2002–03 2.4trans-Nonachlor 39765-80-5 I -- -- 2002 2003 2.4PCBs as Aroclor 1242 53469-21-9

M -- -- -- 2002–03 --

PCBs as Aroclor 1254 11097-69-1

M -- -- -- 2002–03 --

PCBs as Aroclor 1260 11097-69-1

M -- -- -- 2002–03 --

Toxaphene 8001-35-2 I -- -- 2002 2002–03 1,000

Current-use pesticides (CUP) analyzed by gas chromatography with electron-impact mass spectrometry (GC/EIMS)

Acetochlor 34256-82-1

H -- -- 2002–03 2003

Alachlor 15972-60-8

H -- -- 2002–03 2003

2-Chloro-2,6-diethylacetanilide 6967-29-9

D -- -- 2003 2003

2,6-Diethylaniline (E) 579-66-8

D -- -- 2002–03 2003

Atrazine 1912-24-9

H 1.8 -- 2003 2003

2-Chloro-4-isopropylamino6-amino-s-triazine 6190-65-4

D -- -- 2003 2003

Azinphos-methyl (E) 86-50-0 I 0.01 -- 2003 2003

Azinphos-methyl-oxon (E) 961-22-8

D -- -- 2003 2003

Benfluralin 1861-40-1

H -- -- 2002–03 2003

Carbaryl (E) 63-25-2 I 0.2 -- 2003 2003

1-Naphthol (E) 90-15-3

D -- -- 2003 2003

4-Chloro-2-methylphenol (E) 1570-64-5 D -- -- 2003 2003

12 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 3. Pesticides and other organic compounds analyzed in snow and sediment samples collected during this study.—Continued

[D, degradate; E, all concentrations for this compounds reported as estimated; F, fungicide; H, herbicide; I, insecticide; M, manufacturing or byproduct; R, flame retardant; TEC, threshold effect concentration; PEC, probable effect concentration; --, not analyzed or not available; μg/L, microgram per liter; μg/kg, microgram per kilogram; ng/L, nanogram per liter; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Chemical Abstract Service registry number Type of compound

Aquatic-life 

criterion, Water 

chronic1

(μg/L) 

Aquatic-life 

criterion, 

Sediment 

TEC (PEC)2

(μg/kg)

Determined 

for snow 

samples

Determined 

for sediment 

samples

Reporting 

limit for 

OCC snow 

method3

(ng/L)

Current-use pesticides (CUP) analyzed by gas chromatography with electron-impact mass spectrometry (GC/EIMS)—Continued

Chlorpyrifos 2921-88-2 I 0.041 -- 2002–03 2003

Chlorpyrifos, oxygen analog (E) 5598-15-2

D -- -- 2003 2003

Cyfluthrin (E) 68359-37-5 I -- -- 2003 2003Cypermethrin (E) 52315-07-8 I -- -- 2003 2003Dacthal 1861-32-1

H -- -- 2002–03 2003

Diazinon 333-41-5 I 0.08 -- 2002–03 2003

Diazinon, oxygen analog (E) 962-58-3

D -- -- 2002–03 2003

3,4-Dichloroaniline (E) 95-76-1 D -- -- 2003 2003Dichlorvos (E) 62-73-7 I -- -- 2003 2003Dicrotophos (E) 141-66-2 I -- -- 2003 2003Dieldrin 60-57-1 I 0.056 1.90 (61.8) 2002–03 2003Dimethoate 60-51-5 I -- -- 2003 2003Ethion 563-12-2 I -- -- 2002–03 2003

Ethion monoxon 17356-42-2

D -- -- 2003 2003

Fenamiphos (E) 22224-92-6 I -- -- 2003 2003

Fenamiphos sulfone (E) 31972-44-8

D -- -- 2003 2003

Fenamiphos sulfoxide (E) 31972-43-7

D -- -- 2003 2003

Fipronil (E) 120068-37-3 I -- -- 2003 2003

Fipronil sulfide (E) 120067-83-6

D -- -- 2003 2003

Fipronil sulfone 120068-36-2

D -- -- 2003 2003

Fipronil, desulfinyl

D -- -- 2003 2003

Fipronil amide, desulfinyl (E)

D -- -- 2003 2003

Fonofos 944-22-9 I -- -- 2002–03 2003Hexazinone 51235-04-2

H -- -- 2003 2003

Iprodione (E) 36734-19-7

F -- -- 2003 2003

Isofenphos 25311-71-1 I -- -- 2002–03 2003Malathion 121-75-5 I 0.1 -- 2003 2003

Malathion, oxygen analog (E) 1634-78-2

D -- -- 2003 2003

Metalaxyl 57837-19-1

F -- -- 2003 2003

Methidathion 950-37-8 I -- -- 2003 2003Metolachlor 51218-45-2

H 7.8 -- 2003 2003

2-Ethyl-6-methylaniline (E) 24549-06-2

D -- -- 2002–03 2003

Metribuzin 21087-64-9

H 1.0 -- 2003 2003

Myclobutanil (E) 88671-89-0

F -- -- 2003 2003

Sample Collection and Analytical Methods 13
Table 3. Pesticides and other organic compounds analyzed in snow and sediment samples collected during this study.—Continued

[D, degradate; E, all concentrations for this compounds reported as estimated; F, fungicide; H, herbicide; I, insecticide; M, manufacturing or byproduct; R, flame retardant; TEC, threshold effect concentration; PEC, probable effect concentration; --, not analyzed or not available; μg/L, microgram per liter; μg/kg, microgram per kilogram; ng/L, nanogram per liter; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Chemical Abstract Service registry number Type of compound

Aquatic-life 

criterion, Water 

chronic1

(μg/L) 

Aquatic-life 

criterion, 

Sediment 

TEC (PEC)2

(μg/kg)

Determined 

for snow 

samples

Determined 

for sediment 

samples

Reporting 

limit for 

OCC snow 

method3

(ng/L)

Current-use pesticides (CUP) analyzed by gas chromatography with electron-impact mass spectrometry (GC/EIMS)—Continued

Parathion-methyl 298-00-0 I 0.013 -- 2003 2003

Parathion-methyl. Oxygen analog (E) 950-35-6

D -- -- 2003 2003

Pendimethalin 40487-42-1

H -- -- 2002 2003

cis-Permethrin 54774-45-7 I -- -- 2002 2003Phorate (E) 298-02-2 I -- -- 2003 2003

Phorate, oxygen analog (E) 2600-69-3

D -- -- 2003 2003

Prometon (E) 1610-18-0

H -- -- 2003 2003

Prometryn 7287-19-6

H -- -- 2003 2003

Propyzamide 23950-58-5

H -- -- 2002–03 2003

Simazine 122-34-9

H 10 -- 2003 2003

Tebuthiuron (E) 34014-18-1

H -- -- 2003 2003

Terbufos 13071-79-9 I -- -- 2003 2003

Terbufos-oxygen analog sulfone (E) 56070-15-6

D -- -- 2003 2003

Terbuthylazine 5915-41-3

H -- -- 2003 2003

Trifluralin 1582-09-8

H 0.2 -- 2002–03 2003

Organohalogen compounds (OHC) analyzed by gas chromatography with electron-capture negative ion mass spectrometry (GC/ECNIMS)

Aldrin 309-00-2 I -- -- 2002–03 2003Benfluralin 1861-40-1

H -- -- 2002–03 2003

cis-Chlordane 5103-71-9 I -- -- 2002–03 2003trans-Chlordane 5103-74-2 I -- -- 2002–03 2003

Oxychlordane 27304-13-8 D -- -- 2002–03 2003

Chlorothalonil (E)

F 0.18 -- 2003 --

Dacthal (DCPA) 1861-32-1

H -- -- 2002–03 2003

o,p’-DDD 53-19-0

D -- -- 2002–03 2003

o,p’-DDE 3424-82-6

D -- -- 2002–03 2003

p,p’-DDE 72-55-9

D -- 3.16 (31.3) 2002–03 2003

Dieldrin 60-57-1 I 0.056 1.90 (61.8) 2002–03 2003Endosulfan I 959-98-8 I -- -- 2002–03 2003Endosulfan II 33213-65-9 I -- -- 2002–03 2003

Endosulfan sulfate 1031-07-8

D -- -- 2003 2003

14  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 3. Pesticides and other organic compounds analyzed in snow and sediment samples collected during this study.—Continued

[D, degradate; E, all concentrations for this compounds reported as estimated; F, fungicide; H, herbicide; I, insecticide; M, manufacturing or byproduct; R, flame retardant; TEC, threshold effect concentration; PEC, probable effect concentration; --, not analyzed or not available; μg/L, microgram per liter; μg/kg, microgram per kilogram; ng/L, nanogram per liter; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Chemical Abstract Service registry number Type of compound

Aquatic-life 

criterion, Water 

chronic1

(μg/L) 

Aquatic-life 

criterion, 

Sediment 

TEC (PEC)2

(μg/kg)

Determined 

for snow 

samples

Determined 

for sediment 

samples

Reporting 

limit for 

OCC snow 

method3

(ng/L)

Organohalogen compounds (OHC) analyzed by gas chromatography with electron-capture negative ion mass spectrometry (GC/ECNIMS)—Continued

Endrin 72-20-8 I -- 2.22 (207) 2002–03 2003

Endrin aldehyde (E) 7421-93-4 D -- -- 2003 2003Endrin ketone (E) 53494-70-5 D -- -- 2003 2003

Fipronil (E) 120068-37-3 I -- -- 2003 2003

Fipronil sulfide 120067-83-6 D -- -- 2003 2003Fipronil sulfone 120068-36-2 D -- -- 2003 2003Fipronil, desulfinyl -- D -- -- 2003 2003Fipronil amide, desulfinyl (E) -- D -- -- 2003 2003

Heptachlor 76-44-8 I -- -- 2002–03 2003

Heptachlor epoxide 1024-57-3 D -- 2.47 (16.0) 2002–03 2003

Hexachlorobenzene (HCB) 118-74-1 F, M -- -- 2002 2003α-HCH 319-84-6 I -- -- 2002–03 2003β-HCH 319-85-7 I -- -- -- 2003δ-HCH 319-86-8 I -- -- 2002–03 2003γ-HCH (Lindane) 58-89-9 I 0.01 2.37 (4.99) 2002–03 2003Isodrin 465-73-6 S, I -- -- 2002–03 2003Mirex 2385-85-5 I -- -- 2002–03 2003cis-Nonachlor 5103-73-1 I -- -- 2002–03 2003trans-Nonachlor 39765-80-5 I -- -- 2002–03 2003Octachlorostyrene (E) 29082-74-4 M -- -- 2003 2003Pentachloroanisole (PCA) 1825-21-4 D -- -- 2002–03 2003Trifluralin 1582-09-8 H 0.02 -- 2002–03 2003PCB congeners

PCB 70 32598-11-1 M -- -- 2002–03 2003PCB 101 37680-73-2 M -- -- 2002–03 2003PCB 110 38380-03-9 M -- -- 2002–03 2003PCB 118 31508-00-6 M -- -- 2002–03 2003PCB 138 35065-28-2 M -- -- 2002–03 2003PCB 146 51908-16-8 M -- -- 2002–03 2003PCB 149 38380-04-0 M -- -- 2002–03 2003

Sample Collection and Analytical Methods 15
Table 3. Pesticides and other organic compounds analyzed in snow and sediment samples collected during this study.—Continued

[D, degradate; E, all concentrations for this compounds reported as estimated; F, fungicide; H, herbicide; I, insecticide; M, manufacturing or byproduct; R, flame retardant; TEC, threshold effect concentration; PEC, probable effect concentration; --, not analyzed or not available; μg/L, microgram per liter; μg/kg, microgram per kilogram; ng/L, nanogram per liter; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Chemical Abstract Service registry number Type of compound

Aquatic-life 

criterion, Water 

chronic1

(μg/L) 

Aquatic-life 

criterion, 

Sediment 

TEC (PEC)2

(μg/kg)

Determined 

for snow 

samples

Determined 

for sediment 

samples

Reporting 

limit for 

OCC snow 

method3

(ng/L)

Organohalogen compounds (OHC) analyzed by gas chromatography with electron-capture negative ion mass spectrometry (GC/ECNIMS)—Continued

PCB congeners—Continued

PCB 151 52663-63-5

M -- -- 2002–03 2003

PCB 170 35065-30-6

M -- -- 2002–03 2003

PCB 174 38411-25-5

M -- -- 2002–03 2003

PCB 177 52663-70-4

M -- -- 2002–03 2003

PCB 180 35065-29-3

M -- -- 2002–03 2003

PCB 183 52663-69-1

M -- -- 2002–03 2003

PCB 187 52663-68-0

M -- -- 2002–03 2003

PCB 194 35694-08-7

M -- -- 2002–03 2003

PCB 206 40186-72-9

M -- -- 2002–03 2003

PBDE congeners

PBDE 47 66115-57-9

R -- -- 2002–03 2003

PBDE 99 81397-99-1

R -- -- 2002–03 2003

PBDE 100 97038-97-6

R -- -- 2002–03 2003

PBDE 153 59080-40-9

R -- -- 2002–03 2003

PBDE 154 36402-15-0

R -- -- 2002–03 2003

1Standards obtained at http://ca.water.usgs.gov/pnsp/anstrat/index.html#hdr3 (accessed December 2005).2Consensus-based standards from MacDonald and others (2000).3Reporting levels for other methods/matrices provided in data tables.

16  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Before OHC analysis, the 2002 OCC extracts were reduced 

in volume from 0.5 mL to about 0.15 mL using nitrogen 

evaporation. Only two of the 2002 snow samples were 

actually analyzed for OHCs because most of the samples 

were lost during this solvent-reduction step. All seven of 

the 2003 snow extracts were successfully analyzed by the 

OHC instrumental technique. For the analysis, 10 ng of 

dibromooctafluorobiphenyl was added to the extracts as an 

internal injection standard. Analytes were separated on a 

30-m by 0.25-mm-internal-diameter capillary column (Restek 

Rtx–5MS) with 0.25-μm film thickness using the following oven temperature program: 80 degrees Celsius (°C) for 

5 min, 10°C/min to 125°C, 1.5°C/min to 200°C, and 8°C/min 

to 325°C (hold for 20 min). Extract introduction to the gas 

chromatograph was by splitless injection at 285°C at a helium 

carrier gas flow rate of about 2 mL/min. Mass spectrometer 

source and analyzer temperatures were 160°C and 140°C, 

respectively. Mass spectrometer scan range was 50–600 daltons. Methane was used as the modifying gas at a source ion 

gage pressure of 0.027 pascal.

Lake Sediment

Lake sediments were prepared and analyzed for OCCs, 

including selected PCB congeners, by dual-capillary-column 

GC/ECD according to the method of Noriega and others 

(2004). Because PCB congeners were not detected in any of 

the 2002 samples, PCBs were not analyzed for in the 2003 

sediments. Separate aliquots of the lake sediments collected 

in 2003 also were prepared and analyzed for CUPs by the 

method described by Foreman and others (2005). Samples 

were centrifuged to remove excess water, homogenized, and 

analyzed for dry weight on a 1.5 to 3 g aliquot. A 5 to 44 g 

aliquot was mixed with Hydromatrix to disperse the sediment matrix and bind residual sediment moisture and was 

extracted with 25-percent acetone in DCM at 100°C under 

pressurized conditions (10,342 kPa) to isolate analytes in 

organic solvent. Resultant extracts were concentrated and 

cleaned up on a graphitized carbon, solid-phase extraction 

column as described above for the CUP snow method. The 

eluent was reduced using micro-Kuderna-Danish distillation 

and nitrogen gas evaporation to 2.5 mL. The analytes were 

further isolated from elemental sulfur and some additional 

unwanted coextractants by gel permeation chromatography 

on a portion of the extract using a 300-mm-long by 7.5-mminternal-diameter polystyrene divinylbenzene column (Polymer 

Laboratories, Ltd., PL gel column containing 5-μm-diameter 

particles with 50-angstrom pores) with ethyl acetate mobile 

phase at 1-mL/min flow rate. The 9-mL collected gel permeation chromatography fraction was reduced as a hexane/ethyl 

acetate azeotrope by micro-Kuderna-Danish distillation to 

1–2 mL. A procedural internal standard solution of perdeuterated PAHs was added to the extract before final solvent reduction and exchange to toluene using nitrogen gas evaporation. 

The extract was transferred to a GC vial with toluene rinse to 

0.5-mL final volume and analyzed for CUPs by GC/EIMS and 

then for OHCs by GC/ECNIMS, as described for the 2003 

snow samples.

Reporting Levels

Analyte concentrations are reported using the convention outlined in Childress and others (1999). The OCC snow 

and sediment methods use a minimum reporting level (MRL), 

which is the minimum concentration of a compound that can 

be reliably reported for an analytical method. No concentrations are reported less than the MRL for the OCC method. 

Reporting levels are preceded by a “<” symbol in the data 

tables (tables 4–9, 11–15, and 17–20, presented later in the 

report). The CUP sediment method used an interim reporting 

level (Sandstrom and others, 2001) comparable in scope to the 

laboratory reporting level described in Childress and others 

(1999). Reporting levels listed for CUPs and OHCs in snow 

and OHCs in sediment were estimated on the basis of sample 

volume, analyte recovery, and instrument detection capability 

for low-concentration calibration standards during the analysis 

periods. In some cases, reporting levels were raised because of 

interferences in samples or blank contamination. For all mass 

spectrometric analyses, concentrations of an analyte less than 

the reporting level or lowest calibration standard (whichever 

was higher) are reported as estimated (E) concentrations. In 

these cases, the presence of the pesticide has been verified, 

but the concentration is estimated because it falls below the 

range of the calibration standards. Some compounds (table 3) 

are always reported as estimated regardless of concentration 

because of recognized performance issues (Childress and 

others, 1999; Sandstrom and others, 2001). In the remainder 

of this report, estimated concentrations were treated as normal 

detected concentrations.

Field Quality Control

Field blanks were used to assess potential contamination of a sample from collection and processing procedures. 

For snow samples, one equipment blank and two field blanks 

were collected during the study. The equipment blank was 

processed in the laboratory using the same equipment used to 

collect snow samples whereas the field blanks were collected 

at the field site. Field blanks were not collected with any of 

the sediment samples due to the lack of a representative blank 

material. Snow-sample blanks were prepared by pouring commercially available pesticide-residue grade water over the sampling scoop and shovel into the PTFE bag. The blank samples 

were stored in the same freezer with the field samples and 

melted and processed along with the snow samples. No CUPs 

(table 4) or OHCs (table 5) were detected in the three snow 

blanks with the exception of two PCB congeners (PCB 118 

Sample Collection and Analytical Methods 17
and PCB 138), which were detected in the 2003 field blank 

(table 5). Because these congeners were not detected in the 

laboratory blanks or in any of the environmental samples, the 

results indicate that the reagent water used for this sample 

might have been contaminated. Aside from these two congeners, the blank results indicate the potential for contamination of snow samples from sample-collection and processing 

procedures was minimal.

Field replicate samples were used to provide information 

on the precision of concentration values and the consistency 

in identifying the compounds of interest in the environmental samples. Field replicates for snow were collected at two 

sites in 2002 and two sites in 2003. Results for CUPs in field 

replicates are presented in table 4, and results for OHCs are 

presented in table 5. Concentrations of CUPs in the snow 

replicates were below the estimated reporting levels for all of 

the target compounds except for dacthal (table 4). The relative 

percent difference (RPD) in dacthal concentrations, calculated 

as the difference in concentration between replicates divided 

by the average concentration, shows greater variability in 

the 2002 replicates (111 RPD for Bear Lake and 140 RPD 

for W10) compared to the 2003 replicates (70 RPD for Loch 

Vale and 54 RPD for Lake Irene). One possible explanation 

for the poor agreement between 2002 replicates is that these 

extracts were stored for nearly a year before being analyzed 

for CUPs. Another consideration is that some 2002 snow 

samples contained small but variable amounts of organic 

debris (needles and immature cones), which also might have 

contributed to concentration differences (Reischl and others, 

1987; Horstmann and McLaughlin, 1998). Larger (>1-mm 

diameter) plant debris was removed from 2003 snow samples 

prior to extraction to minimize their potential contribution. 

Five OHCs were detected in both replicate pairs indicating there was good reliability in identifying the target OHCs 

(table 5). Although dieldrin and trans-nonachlor were detected 

in the Lake Irene environmental sample but not the replicate 

sample, the concentrations were reported as estimated and 

were below the reporting level for both compounds. Relative 

Table 4. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in field blanks 

and replicate snow samples collected in 2002–03.—Continued

[Equip, equipment; Environ, environmental sample; Repl, replicate sample; <, less than; --, not determined; ns, not in spike or surrogate; %, percent; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds by gas chromatography/electron-capture detection 

(GC/ECD); CUP, current-use pesticides by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

20021

Blank

2003

Blank

20021

Bear Lake

20021

W10

2003

Loch Vale 

Forest

2003

Lake Irene 

Meadow

Equip Field Field Environ Repl Environ Repl Environ Repl Environ Repl

Acetochlor <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

Alachlor <13 <13 <8.0 <13 <13 <13 <13 <8.0 <8.0 <8.0 <8.0

Atrazine -- -- <1.5 -- -- -- -- <1.5 <1.5 <1.5 <1.5

Azinphos-methyl -- -- <5.0 -- -- -- -- <8.7 <5.0 <5.0 <5.0

Azinphos-methyl-oxygen analog -- -- <11 -- -- -- -- <11 <11 <11 <11

Benfluralin <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

Carbaryl -- -- <4.1 -- -- -- -- <4.1 <4.1 <4.1 <4.1

2-Chloro-2,6-diethylacetanilide -- -- <0.50 -- -- -- -- <0.50 <0.50 <0.50 <0.50

2-Chloro-4-isopropylamino6-amino-s-triazine -- -- <0.60 -- -- -- -- <0.60 <0.60 <0.60 <0.60

4-Chloro-2-methylphenol -- -- <0.56 -- -- -- -- <0.56 <0.56 <0.56 <0.56

Chlorpyrifos <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Chlorpyrifos, oxygen analog -- -- <5.6 -- -- -- -- <5.6 <5.6 <5.6 <5.6

Cyfluthrin -- -- <2.7 -- -- -- -- <2.7 <2.7 <2.7 <2.7

Cypermethrin -- -- <0.86 -- -- -- -- <0.86 <0.86 <0.86 <0.86

Dacthal <0.30 <0.30 <0.80 2.20 0.63 0.27 1.53 0.48 1.00 1.08 1.88

Diazinon <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Diazinon, oxygen analog <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

3,4-Dichloroaniline -- -- <0.45 -- -- -- -- <0.45 <0.45 <0.45 <0.45

Dichlorvos -- <1.2 <1.2 -- -- -- -- <1.2 <1.2 <1.2 <1.2

Dicrotophos -- <8.4 <8.4 -- -- -- -- <8.4 <8.4 <8.4 <8.4

Dieldrin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90

2,6-Diethylaniline <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

Dimethoate -- -- <0.61 -- -- -- -- <0.61 <0.61 <0.61 <0.61

18  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 4. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in field blanks 

and replicate snow samples collected in 2002–03.—Continued

[Equip, equipment; Environ, environmental sample; Repl, replicate sample; <, less than; --, not determined; ns, not in spike or surrogate; %, percent; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds by gas chromatography/electron-capture detection 

(GC/ECD); CUP, current-use pesticides by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

20021

Blank

2003

Blank

20021

Bear Lake

20021

W10

2003

Loch Vale 

Forest

2003

Lake Irene 

Meadow

Equip Field Field Environ Repl Environ Repl Environ Repl Environ Repl

Ethion <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

Ethion monoxon -- -- <0.20 -- -- -- -- <0.20 <0.20 <0.20 <0.20

2-Ethyl-6-methylaniline <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45

Fenamiphos -- -- <2.9 -- -- -- -- <2.9 <2.9 <2.9 <2.9

Fenamiphos sulfone -- -- <4.9 -- -- -- -- <4.9 <4.9 <4.9 <4.9

Fenamiphos sulfoxide -- -- <3.9 -- -- -- -- <3.9 <3.9 <3.9 <3.9

Fipronil -- -- <1.6 -- -- -- -- <1.6 <1.6 <1.6 <1.6

Fipronil sulfide -- -- <1.3 -- -- -- -- <1.3 <1.3 <1.3 <1.3

Fipronil sulfone -- -- <2.4 -- -- -- -- <2.4 <2.4 <2.4 <2.4

Fipronil, desulfinyl -- -- <1.2 -- -- -- -- <1.2 <1.2 <1.2 <1.2

Fipronil amide, desulfinyl -- -- <2.9 -- -- -- -- <2.9 <2.9 <2.9 <2.9

Fonofos <1.0 <1.0 <0.30 <1.0 <1.0 <1.0 <1.0 <0.30 <0.30 <0.30 <0.30

Hexazinone -- -- <50 -- -- -- -- <50 <50 <50 <50

Iprodione -- -- <54 -- -- -- -- <54 <54 <54 <54

Isofenphos2 -- -- <0.34 -- -- -- -- <0.34 <0.34 <0.34 <0.34

Malathion -- -- <2.7 -- -- -- -- <2.7 <2.7 <2.7 <2.7

Malathion, oxygen analog -- -- <3.0 -- -- -- -- <3.0 <3.0 <3.0 <3.0

Metalaxyl -- -- <2.9 -- -- -- -- <2.9 <2.9 <2.9 <2.9

Methidathion -- -- <0.58 -- -- -- -- <0.58 <0.58 <0.58 <0.58

Metolachlor -- -- <0.60 -- -- -- -- <0.60 <0.60 <0.60 <0.60

Metribuzin -- -- <2.6 -- -- -- -- <2.6 <2.6 <2.6 <2.6

Myclobutanil -- -- <0.80 -- -- -- -- <0.80 <0.80 <0.80 <0.80

1-Naphthol -- -- <8.8 -- -- -- -- <8.8 <8.8 <8.8 <8.8

Parathion-methyl -- -- <1.5 -- -- -- -- <1.5 <1.5 <1.5 <1.5

Parathion-methyl, oxygen analog -- -- <3.0 -- -- -- -- <3.0 <3.0 <3.0 <3.0

Pendimethalin <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <20 <20

cis-Permethrin <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <5.8 <0.60

Phorate -- -- <1.1 -- -- -- -- <1.1 <1.1 <1.1 <1.1

Phorate oxygen analog -- -- <11 -- -- -- -- <11 <11 <11 <11

Prometon -- -- <1.0 -- -- -- -- <1.0 <1.0 <1.0 <1.0

Prometryn -- -- <0.54 -- -- -- -- <0.54 <0.54 <0.54 <0.54

Propyzamide <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

Simazine -- -- <0.50 -- -- -- -- <0.50 <0.50 <0.50 <0.50

Tebuthiuron -- -- <1.6 -- -- -- -- <1.6 <1.6 <1.6 <1.6

Terbufos -- -- <1.7 -- -- -- -- <1.7 <1.7 <1.7 <1.7

Terbufos oxygen analog sulfone -- -- <6.8 -- -- -- -- <6.8 <6.8 <6.8 <6.8

Terbuthylazine -- -- <1.0 -- -- -- -- <1.0 <1.0 <1.0 <1.0

Trifluralin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90

α-HCH-d6 surrogate, % recovery 16 27 32 58 20 44 16 28 47 60 61

Diazinon-d10 surrogate, % recovery ns ns 55 ns ns ns ns 43 48 89 91

Isofenphos surrogate, % recovery2 25 28 ns 128 43 130 34 ns ns ns ns

Sample volume, liters 9.7 7.4 5.0 9.5 3.7 9.6 11.8 15.3 11.3 18.2 13.9

1

2002 samples initially prepared using OCC method and analyzed by GC/ECD. Extract subsequently analyzed for CUPs by GC/EIMS.

2

Isofenphos was a surrogate compound for 2002 samples but an analyte for 2003 sample.

Sample Collection and Analytical Methods 19
Table 5. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass 

spectrometry in field blanks and replicate snow samples collected in 2003.—Continued

[Environ, environmental sample; Repl, replicate sample; <, less than; E, estimated concentration; %, percent; concentrations in nanograms per liter; shaded cells 

denote detectable concentrations; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Blank Loch Vale Forest Lake Irene Meadow

Field Environ Repl Environ Repl

Aldrin <0.50 <0.50 <0.50 <0.50 <0.50

Chlorpyrifos <0.29 <0.10 <0.10 <0.081 <0.10

cis-Chlordane <0.13 <0.13 <0.13 <0.13 <0.13

trans-Chlordane <0.15 <0.15 <0.15 <0.15 <0.15

Chlorothalonil <1.0 E1.59 E2.56 E1.37 E1.44

Dacthal (DCPA) <0.34 0.68 1.60 1.58 2.54

o,p’-DDD <1.0 <1.0 <1.0 <1.0 <1.0

o,p’-DDE <0.50 <0.50 <0.50 <0.50 <0.50

p,p’-DDE <2.0 <2.0 <2.0 <2.0 <2.0

Dieldrin <0.40 <0.40 <0.40 E0.22 <0.40

Endosulfan I <0.07 0.27 0.75 0.79 0.80

Endosulfan II <0.07 0.13 0.31 0.19 0.26

Endosulfan sulfate <0.13 0.15 0.23 0.14 0.17

Endrin <0.50 <0.50 <0.50 <0.50 <0.50

Endrin aldehyde <0.50 <0.50 <0.50 <0.50 <0.50

Endrin ketone <2.0 <2.0 <2.0 <2.0 <2.0

Fipronil <0.07 <0.07 <0.07 <0.07 <0.07

Fipronil sulfide <0.03 <0.03 <0.03 <0.03 <0.03

Fipronil sulfone <0.07 <0.07 <0.07 <0.07 <0.07

Fipronil, desulfinyl <0.26 <0.12 <0.12 <0.07 <0.12

Fipronil amide, desulfinyl <0.31 <0.31 <0.31 <0.31 <0.31

α-HCH <0.50 <0.50 <0.50 <0.50 <0.50

δ-HCH <0.50 <0.50 <0.50 <0.50 <0.50

γ-HCH (Lindane) <0.25 <0.25 <0.25 <0.25 <0.25

Heptachlor <1.0 <1.0 <1.0 <1.0 <1.0

Heptachlor epoxide <0.13 <0.13 <0.13 <0.13 <0.13

Isodrin <0.50 <0.50 <0.50 <0.50 <0.50

Mirex <0.25 <0.25 <0.25 <0.25 <0.25

cis-Nonachlor <0.07 <0.07 <0.07 <0.07 <0.07

trans-Nonachlor <0.20 <0.20 <0.20 E0.14 <0.20

Octachlorostyrene <0.07 <0.07 <0.07 <0.07 <0.07

Oxychlordane <0.13 <0.13 <0.13 <0.13 <0.13

Pentachloroanisole (PCA) <0.07 <0.07 <0.07 <0.07 <0.07

Trifluralin <0.07 <0.07 <0.07 <0.07 <0.07

PCB congeners

PCB 70 <1.0 <1.0 <1.0 <1.0 <1.0

PCB 101 <0.50 <0.50 <0.50 <0.50 <0.50

PCB 110 <0.25 <0.25 <0.25 <0.25 <0.25

PCB 118 0.71 <0.07 <0.07 <0.07 <0.07

PCB 138 0.68 <0.07 <0.07 <0.07 <0.07

PCB 146 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 149 <0.50 <0.50 <0.50 <0.50 <0.50

PCB 151 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 170 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 174 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 177 <0.07 <0.07 <0.07 <0.07 <0.07

20 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
percent differences in concentrations for the five detected 

compounds ranged from 1 to 94 percent with an average of 

69 percent for the Loch Vale replicates and 21 percent for the 

Lake Irene replicates. The larger differences in concentrations 

between the Loch Vale replicates are partly explained by the 

larger difference in α-HCH-d6 surrogate recovery (67 RPD) 

between replicates compared to Lake Irene (16 RPD).

Field replicates were collected at two sites for lake sediment, and results for OCCs are presented in table 6. The only 

detected compound was DDE, which was detected in both replicate pairs. Ypsilon Lake replicates had excellent agreement. 

The difference between the Lake Haiyaha sediment replicates 

was fairly large (50 RPD); however, the concentrations were 

close to the reporting level of 0.5 μg/kg.

Laboratory Quality Control

Laboratory quality-control samples analyzed with the 

snow and sediment samples included reagent blanks, reagent 

spikes, and laboratory replicates. In addition, each environmental and quality-control sample was fortified with surrogate 

compounds before extraction to monitor performance of the 

sample-preparation process. Certified reference materials were 

included with sediments analyzed by the OCC method.

Snow

Snow-sample analyses from each year included laboratory reagent blanks and reagent spikes. In 2002, the reagent 

spike was fortified with OCC-method compounds, and in 2003 

Table 5. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass 

spectrometry in field blanks and replicate snow samples collected in 2003.—Continued

[Environ, environmental sample; Repl, replicate sample; <, less than; E, estimated concentration; %, percent; concentrations in nanograms per liter; shaded cells 

denote detectable concentrations; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound Blank Loch Vale Forest Lake Irene Meadow

Field Environ Repl Environ Repl

PCB congeners—Continued

PCB 180 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 183 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 187 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 194 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 206 <0.07 <0.07 <0.07 <0.07 <0.07

PBDE congeners

PBDE 47 <0.80 <0.80 <0.80 <0.80 <0.80

PBDE 99 <0.40 <0.40 <0.40 <0.40 <0.40

PBDE 100 <0.35 <0.35 <0.35 <0.35 <0.35

PBDE 153 <0.13 <0.13 <0.13 <0.13 <0.13

PBDE 154 <0.03 <0.03 <0.03 <0.03 <0.03

α-HCH-d6 surrogate, % recovery 76 29 59 107 92

Sample volume, liters 5.0 15.3 11.3 18.2 13.9

Table 6. Concentrations of organochlorine compounds analyzed 

by gas chromatography/electron-capture detection in replicate 

sediment samples collected in 2003.

[Environ, environmental sample; Repl, replicate sample; <, less than; E, estimated concentration; %, percent; concentrations in micrograms per kilogram 

of sediment (dry weight); shaded cells denote detectable concentrations]

Compound Lake Haiyaha Ypsilon Lake

Environ Repl Environ Repl

Aldrin <1.5 <2.0 <5.5 <8.5

Chlordane, technical <15 <20 <55 <85

p,p’-DDD <1.5 <2.0 <9.0 <8.5

p,p’-DDE E0.9 E1.5 E3.1 E3.1

p,p’-DDT <1.5 <2.0 <5.5 <8.5

Dieldrin <1.5 <2.0 <5.5 <8.5

Endosulfan I <1.5 <2.0 <5.5 <8.5

Endrin <1.5 <2.0 <5.5 <8.5

γ-HCH (Lindane) <1.5 <2.0 <5.5 <8.5

Heptachlor <1.5 <2.0 <5.5 <8.5

Heptachlor epoxide <1.5 <2.0 <5.5 <8.5

p,p’-Methoxychlor <6.0 <8.0 <22.0 <34

Mirex <1.5 <2.0 <5.5 <8.5

PCB Aroclor 1242 <15 <20 <55 <85

PCB Aroclor 1254 <15 <20 <55 <85

PCB Aroclor 1260 <15 <20 <55 <85

Toxaphene <150 <200 <550 <850

α−HCH-d6 surrogate, % recovery 73 103 76 100

Isodrin surrogate, % recovery 54 76 46 53

PCB 207 surrogate, % recovery 44 53 65 43

Sample Collection and Analytical Methods 21
one reagent spike was fortified with OCC-method compounds 

and a second was fortified with CUP-method compounds. 

Results for blanks and reagent spikes analyzed by the CUP 

method are shown in table 7 and by the OHC instrumental 

analysis are shown in table 8. No compounds were detected 

in the laboratory blanks for either analysis (CUP and OHC) 

except for one detection of PCB 206 (0.27 ng/L) in the 2002 

laboratory blank (table 8).

Recoveries of the 61 analytes fortified in the 2003 CUP 

spike that were determined by the CUP method ranged from 

30 to 150 percent with a median of 95 percent (table 7), 

with compounds exhibiting greatest bias typically those with 

known performance limitations (Zaugg and others, 1995; 

Sandstrom and others, 2001). The 2002 OCC reagent spike 

contained only dieldrin and two surrogates of the compounds 

determined by the CUP method. Only 28 percent of dieldrin in the reagent spike was detected by the CUP analysis 

(GC/EIMS) (table 7) compared to 81 percent recovery by 

Table 7. Concentrations and percent recovery of current-use pesticides analyzed by gas chromatography/electron-impact mass 

spectrometry in laboratory blanks and reagent spikes analyzed with snow samples in 2002–03.—Continued

[<, less than; E, estimated concentration; --, not determined; %, percent; ng/L, nanogram per liter; ns, not in spike or surrogate; OCC, organochlorine compounds analyzed by gas chromatography/electron capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact 

mass spectrometry (GC/EIMS)]

Compound

2002 2003

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Reagent

Spike2

(% recovery)

Acetochlor <0.60 ns <0.60 ns 104

Alachlor <13 ns <8.0 ns 92

Atrazine -- ns <1.5 ns 86

Azinphos-methyl -- ns <5.0 ns 109

Azinphos-methyl, oxygen analog -- ns <11 ns E44

Benfluralin <1.0 ns <1.0 ns 79

Carbaryl -- ns <4.1 ns E114

2-Chloro-2,6-diethylacetanilide -- ns <0.50 ns 104

2-Chloro-4-isopropylamino-6-amino-s-triazine -- ns <0.60 ns 34

4-Chloro-2-methylphenol -- ns <0.56 ns 36

Chlorpyrifos <0.50 ns <0.50 ns 95

Chlorpyrifos, oxygen analog -- ns <5.6 ns 51

Cyfluthrin -- ns <2.7 ns 149

Cypermethrin -- ns <0.86 ns 137

Dacthal <0.30 ns <0.30 ns 83

Diazinon <0.50 ns <0.50 ns 89

Diazinon, oxygen analog <0.60 ns <0.60 43 69

3,4-Dichloroaniline -- ns <0.45 ns 69

Dichlorvos -- ns <1.2 ns E62

Dicrotophos -- ns <8.4 ns E53

Dieldrin <0.90 28 <0.90 ns 69

2,6-Diethylaniline <0.60 ns <0.60 ns 40

Dimethoate -- ns <0.61 ns 71

Ethion <0.40 ns <0.40 ns 93

the OCC method (GC/ECD) used in 2002 (results for snow 

samples not shown in report) indicating recoveries for samples 

extracted using the OCC method but analyzed for CUPs by 

GC/EIMS may be low. Median surrogate recoveries for all 

2003 snow and quality-control samples determined by the 

CUP method (tables 4, 7, 13, 14) were 47 percent (range 

15–96) for α-HCH-d6 and 64 percent (range 27–123) for 

diazinon-d10. Recoveries of 16 compounds and 3 surrogates 

in the 2002 OCC spike that were subsequently determined 

by the OHC instrumental analysis (GC/ECNIMS) ranged 

from 15 to 94 percent with a median of 52 percent (table 8). 

Recoveries were considerably lower than the average acceptable recovery-limits range (60–120 percent) for several 

compounds, particularly dieldrin (15 percent) and the isodrin 

surrogate (26 percent). Recoveries of 18 compounds and 1 

surrogate in the 2003 OCC spike determined by the OHC 

instrumental analysis ranged from 21 to 122 percent with a 

median of 74 percent. Comparison of recoveries for the 2003 

22 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 7. Concentrations and percent recovery of current-use pesticides analyzed by gas chromatography/electron-impact mass 

spectrometry in laboratory blanks and reagent spikes analyzed with snow samples in 2002–03.—Continued

[<, less than; E, estimated concentration; --, not determined; %, percent; ng/L, nanogram per liter; ns, not in spike or surrogate; OCC, organochlorine compounds analyzed by gas chromatography/electron capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact 

mass spectrometry (GC/EIMS)]

Compound

2002 2003

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Reagent

Spike2

(% recovery)

Ethion monoxon -- ns <0.20 ns 131

2-Ethyl-6-methylaniline <0.45 ns <0.45 ns 30

Fenamiphos -- ns <2.9 ns E147

Fenamiphos sulfone -- ns <4.9 ns E124

Fenamiphos sulfoxide -- ns <3.9 ns E114

Fipronil -- ns <1.6 ns 124

Fipronil sulfide -- ns <1.3 ns 100

Fipronil sulfone -- ns <2.4 ns 91

Fipronil, desulfinyl -- ns <1.2 ns 86

Fipronil amide, desulfinyl -- ns <2.9 ns E120

Fonofos <1.0 ns <0.30 ns 74

Hexazinone -- ns <50 ns 110

Iprodione -- ns <54 ns 69

Isofenphos3 -- ns <0.34 ns 105

Malathion -- ns <2.7 ns 113

Malathion, oxygen analog -- ns <3.0 ns 113

Metalaxyl -- ns <2.9 ns 100

Methidathion -- ns <0.58 ns 85

Metolachlor -- ns <0.60 ns 98

Metribuzin -- ns <2.6 ns 111

Myclobutanil -- ns <0.80 ns 135

1-Naphthol -- ns <8.8 ns 78

Parathion-methyl -- ns <1.5 ns 93

Parathion-methyl, oxygen analog -- ns <3.0 ns 106

Pendimethalin <2.2 ns <2.2 ns 132

cis-Permethrin <0.60 ns <0.60 ns 132

Phorate -- ns <1.1 ns 68

Phorate, oxygen analog -- ns <11 ns E114

Prometon -- ns <1.0 ns 108

Prometryn -- ns <0.54 ns 107

Propyzamide <0.40 ns <0.40 ns 97

Simazine -- ns <0.50 ns 95

Tebuthiuron -- ns <1.6 ns E150

Terbufos -- ns <1.7 ns 80

Terbufos oxygen analog sulfone -- ns <6.8 ns 102

Terbuthylazine -- ns <1.0 ns 89

Trifluralin <0.90 ns <0.90 ns 91

α-HCH-d6 surrogate, % recovery 33 28 15 64 62

Diazinon-d10 surrogate, % recovery ns ns 27 98 92

Isofenphos surrogate, % recovery3 34 53 ns ns ns

1

Reagent spike fortified with OCC method compounds only.

2

Reagent spike fortified with CUP method compounds only.

3

Isofenphos was a surrogate compound for 2002 samples but an analyte for 2003 samples.

Sample Collection and Analytical Methods 23
Table 8. Concentrations and percent recovery of organohalogen compounds analyzed by gas chromatography/electron-capture 

negative ion mass spectrometry in laboratory blanks and reagent spikes analyzed with snow samples in 2002–03.—Continued

[<, less than; --, not determined; %, percent; ng/L, nanogram per liter; ns, not in spike or surrogate; shaded cells denote detectable concentrations; 

OCC, organochlorine compounds analyzed by gas chromatography/electron capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas 

chromatography/electron-impact mass spectrometry (GC/EIMS) ; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound

2002 2003

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Reagent

spike2

(% recovery)

Aldrin <0.25 51 <0.50 21 ns

Chlorpyrifos <0.03 ns <0.29 ns 148

cis-Chlordane <0.07 86 <0.13 81 ns

trans-Chlordane <0.15 88 <0.15 69 ns

Chlorothalonil <1.0 ns <1.0 ns ns

Dacthal (DCPA) <0.03 ns <0.34 ns 156

o,p’-DDD <0.50 ns <1.0 ns ns

o,p’-DDE <0.50 ns <0.50 ns ns

p,p’-DDE <0.50 94 <2.0 89 154

Dieldrin <0.25 15 <0.40 54 98

Endosulfan I <0.07 43 <0.07 80 180

Endosulfan II <0.07 43 <0.07 59 142

Endosulfan sulfate -- -- <0.13 58 147

Endrin <0.25 53 <0.50 82 ns

Endrin aldehyde -- -- <0.50 122 ns

Endrin ketone -- -- <2.0 44 ns

Fipronil -- ns <0.07 ns 60

Fipronil sulfide -- ns <0.03 ns 112

Fipronil sulfone -- ns <0.07 ns 94

Fipronil, desulfinyl -- ns <0.26 ns 160

Fipronil amide, desulfinyl -- ns <0.31 ns 57

α-HCH <0.25 68 <0.50 102 169

δ-HCH <0.50 81 <0.50 98 ns

γ-HCH (Lindane) <0.25 52 <0.25 82 177

Heptachlor <0.50 30 <1.0 37 ns

Heptachlor epoxide <0.13 25 <0.13 44 ns

Hexachlorobenzene (HCB) <0.17 30 -- -- --

Isodrin3 -- -- <0.50 ns ns

Mirex <0.25 84 <0.25 37 ns

cis-Nonachlor <0.07 ns <0.07 ns ns

trans-Nonachlor <0.18 78 <0.20 69 ns

Octachlorostyrene <0.07 ns <0.07 ns ns

Oxychlordane <0.13 ns <0.13 ns ns

Pentachloroanisole (PCA) <0.07 ns <0.07 ns ns

Trifluralin <0.07 ns <0.07 ns 77

PCB congeners

PCB 70 <0.50 ns <1.0 ns ns

PCB 101 <0.25 ns <0.50 ns ns

PCB 110 <0.25 ns <0.25 ns ns

PCB 118 <0.24 ns <0.07 ns ns

PCB 138 <0.07 ns <0.07 ns ns

PCB 146 <0.07 ns <0.07 ns ns

PCB 149 <0.25 ns <0.50 ns ns

24  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
CUP reagent spike determined by the CUP method (table 7) 

and the CUP reagent spike determined by the OHC instrumental analysis (table 8) reveals that recoveries by the CUP 

method (GC/EIMS) were closer to expected values and probably less biased than the OHC analysis (GC/ECNIMS). This 

result is not unexpected because the CUP method was used 

to extract and analyze the reagent spike. The ratio of recoveries between the two analyses suggests that concentrations 

from the OHC instrumental analysis for samples processed by 

the CUP method may be biased high by as much as a factor 

of 2 for some analytes. Recoveries for 16 compounds in the 

2003 CUP-method spike determined by the OHC instrumental analysis ranged from 57 to 180 percent with a median 

of 147 percent, with some recoveries nearly double those 

expected. Median surrogate recovery for all 2003 snow and 

quality-control samples determined by the OHC instrumental 

analysis (tables 8 and 15) was 59 percent (range 14–158) for 

α-HCH-d6 with lower recoveries resulting from preparation 

losses for several samples. The results presented in this section 

suggest that for compounds with low recovery percentages 

in reagent spikes or for snow samples with low surrogate 

recoveries, the detection frequencies presented in this report 

may be biased low. Reported concentrations in field samples 

are not corrected using surrogate or spike recoveries.

Lake Sediment

Sediment samples prepared by the OCC method were 

analyzed in three separate analytical runs including two in 

2002 and one in 2003. Table 9 shows results for laboratory 

blanks and replicates analyzed with the sediment samples. 

No compounds were detected in any of the three laboratory 

blanks. For the replicate samples, the only detected compound 

was DDE, which was detected in both the environmental 

sample and laboratory replicate in each of the three replicate 

pairs (table 9). Relative percent differences between the 

replicate pairs were small (8–13 percent), indicating there 

was good consistency in identifying and quantifying this compound. Table 10 shows results for certified reference materials 

and reagent spikes analyzed with the sediment samples by the 

OCC method. The three certified reference materials analyzed 

(CRM 1944, CRM 362, and CRM D035) were within the 

Table 8. Concentrations and percent recovery of organohalogen compounds analyzed by gas chromatography/electron-capture 

negative ion mass spectrometry in laboratory blanks and reagent spikes analyzed with snow samples in 2002–03.—Continued

[<, less than; --, not determined; %, percent; ng/L, nanogram per liter; ns, not in spike or surrogate; shaded cells denote detectable concentrations; 

OCC, organochlorine compounds analyzed by gas chromatography/electron capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas 

chromatography/electron-impact mass spectrometry (GC/EIMS) ; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound

2002 2003

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Laboratory

blank

(ng/L)

Reagent

spike1

(% recovery)

Reagent

spike2

(% recovery)

PCB congeners—Continued

PCB 151 <0.07 ns <0.07 ns ns

PCB 170 <0.07 ns <0.07 ns ns

PCB 174 <0.07 ns <0.07 ns ns

PCB 177 <0.07 ns <0.07 ns ns

PCB 180 <0.07 ns <0.07 ns ns

PCB 183 <0.07 ns <0.07 ns ns

PCB 187 <0.07 ns <0.07 ns ns

PCB 194 <0.07 ns <0.07 ns ns

PCB 206 0.27 ns <0.07 ns ns

PBDE congeners

PBDE 47 <0.32 ns <0.80 ns ns

PBDE 99 <0.17 ns <0.40 ns ns

PBDE 100 <0.14 ns <0.35 ns ns

PBDE 153 <0.13 ns <0.13 ns ns

PBDE 154 <0.03 ns <0.03 ns ns

α-HCH-d6 surrogate, % recovery 31 42 14 100 117

Isodrin surrogate, % recovery3 45 26 ns ns ns

PCB 207 surrogate, % recovery 21 82 ns ns ns

1

Reagent spike fortified with OCC-method compounds only.

2

Reagent spike fortified with CUP-method compounds only.

3

Isodrin was a surrogate compound for 2002 samples but an analyte for 2003 samples.

Sample Collection and Analytical Methods 25
acceptable control limits, with the exception of heptachlor 

in CRM 362, which was just outside (41 percent) the control limits of 42–146 percent. Reagent spike recoveries also 

were within the analytical control limits in all three analytical 

runs with the exception of heptachlor in the second 2002 run 

(18 percent), which, similar to CRM 362, was just below the 

lower control limit of 25 percent. Median recoveries for the 

three surrogates, which were added to each of the environmental and quality-control samples (tables 6, 9, 10, 17, 18), 

were 91 percent (range 40–110) for α-HCH-d6, 56 percent 

(range 40–90) for isodrin, and 69 percent (range 43–109) for 

PCB 207. All surrogate recoveries were within control limits 

with the exception of α-HCH-d6 in two of the replicate samples (table 9) that were slightly higher than the upper control 

limit of 102 percent for this surrogate.

Results for the laboratory blank and reagent spike for the 

CUP sediment method are shown in table 11 and for the OCH 

instrumental analysis are shown in table 12. No compounds 

were detected in the laboratory blanks for either analysis type 

(CUP and OHC). Median recovery of 63 compounds in the 

CUP reagent spike analyzed by the CUP method was 88 percent (range 11–156), with larger deviation from 100 percent 

expected for compounds with concentrations permanently 

reported as estimated (table 3; Foreman and others, 2005). 

Recoveries of the 10 compounds in the OCC-method reagent 

spike analyzed by the OHC instrumental analysis ranged 

from 54 to 80 percent (table 12). Recoveries for the six 

compounds in the CUP-method reagent spike were similar, 

ranging from 63 to 102 percent. Median surrogate recoveries in all sediments and quality-control samples analyzed by 

the CUP sediment method (tables 11 and 19) were 59 percent (range 50–133) for α-HCH-d6 and 115 percent (range 

75–124) for diazinon-d10, compared to the control limits 

of 28–121 percent for α-HCH-d6 and 37–142 percent for 

diazinon-d10. The median surrogate recovery in all samples 

analyzed by the OHC instrumental analysis (tables 12 and 20) 

was 60 percent (range 55–77) for α-HCH-d6.

Although recoveries for surrogates or analytes in reagent 

spikes or reference materials were less than 100 percent in 

many cases, they generally were within acceptable ranges for 

these samples and, therefore, do not necessarily indicate a 

low bias in detection frequencies and concentrations for the 

environmental sediment samples.

Table 9. Concentrations of organochlorine compounds analyzed by gas chromatography/electron-capture detection in laboratory 

blanks and replicates analyzed with sediment samples in three analytical runs during 2002–03.

[<, less than; E, estimated concentration; --, not determined; %, percent; concentrations in micrograms per kilogram of sediment (dry weight); shaded cells 

denote detectable concentrations]

Compound

2002 2002 2003

Mirror Lake Upper Bullhead Lake Mokowanis Lake

Blank Sample Replicate Blank Sample Replicate Blank Sample Replicate

Aldrin <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Chlordane, technical <5.0 <80 <80 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

cis-Chlordane -- -- -- -- -- -- <0.5 <0.5 <0.5

trans-Chlordane -- -- -- -- -- -- <0.5 <0.5 <0.5

p,p’-DDD <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

p,p’-DDE <0.5 E0.96 E1.1 <0.5 E0.34 E0.37 <0.5 0.88 E1.0

p,p’-DDT <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Dieldrin <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Endosulfan I <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Endrin <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

γ-HCH (Lindane) <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Heptachlor <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Heptachlor epoxide <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

p,p’-Methoxychlor <2.0 <32 <32 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0

Mirex <0.5 <8.0 <8.0 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

trans-Nonachlor -- -- -- -- -- -- <0.5 <0.5 <0.5

PCB Aroclor 1242 <5.0 <80 <80 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

PCB Aroclor 1254 <5.0 <80 <80 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

PCB Aroclor 1260 <5.0 <80 <80 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

Toxaphene <50 <800 <800 <50 <50 <50 <50 <50 <50

α−HCH-d6 surrogate, % recovery 78 72 78 104 102 110 78 101 105

Isodrin surrogate, % recovery 53 40 50 63 58 57 64 67 90

PCB 207 surrogate, % recovery 74 63 73 109 87 86 80 72 81

26  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 10. Percent recovery and analytical control limits of organochlorine compounds analyzed by gas chromatography/electron-capture detection in certified reference 

materials and laboratory reagent spikes analyzed with sediment samples in three analytical runs during 2002–03.[ns, not in spike or surrogate; --, not determined; %, percent; CRM, certified reference material; values in bold outside control limits]

Compound

2002 2002 2003

CRM

1944

Control

limits

Reagent

spike

Control

limits

CRM

362

Control

limits

Reagent

spike

Control

limits

CRM

D035

Control

limits

Reagent

spike

Control

limits

Aldrin ns 49 15–133 61 47–136 74 15–133 59 50–121 68 32–101Chlordane, technical ns ns ns ns ns nscis-Chlordane -- -- -- -- 59 43–123 72 45–81trans-Chlordane -- -- -- -- 62 46–122 67 46–84p,p’-DDD 52 22–158 56 22–158 63 44–148 54 22–158 61 57–126 86 29–105p,p’-DDE 44 34–140 79 34–140 69 51–133 92 34–140 64 49–126 90 51–120p,p’-DDT 86 15–150 56 15–150 72 44–123 82 15–150 65 46–133 79 32–101Dieldrin ns 55 15–150 60 49–139 64 15–150 62 50–125 68 35–101Endosulfan I ns 42 25–94 89 38–122 62 25–94 51 40–119 63 32–86Endrin ns 59 33–133 86 60–142 76 33–133 78 55–130 77 39–105γ-HCH (Lindane) ns 42 15–112 59 35–152 67 15–112 ns 54 29–81Heptachlor ns 45 25–109 41 42–146 18 25–109 62 53–120 75 24–91Heptachlor epoxide ns 56 15–155 59 53–127 64 15–155 67 58–137 66 35–93p,p’-Methoxychlor ns 67 15–150 72 34–146 53 15–150 75 37–141 84 27–118Mirex ns 52 32–120 ns 68 32–120 ns 74 46–93trans-Nonachlor -- -- -- -- ns 80 50–82PCB as Aroclor 1242 ns 68 17–145 ns ns ns 89 30–110PCB as Aroclor 1254 ns 114 53–150 ns ns ns 100 45–127PCB as Aroclor 1260 ns 109 33–150 ns ns ns 96 47–125Toxaphene ns ns ns ns ns nsα-HCH-d6 surrogate, % recovery 58 15–102 40 15–102 100 15–102 88 15–102 84 15–102 80 15–102Isodrin surrogate, % recovery 49 16–105 62 16–105 60 16–105 66 16–105 70 16–105 68 16–105PCB 207 surrogate, % recovery 52 15–124 74 15–124 91 15–124 94 15–124 76 15–124 80 15–124

Sample Collection and Analytical Methods 27
Organochlorine Compounds and 

Current-Use Pesticides in Snow 

and Lake Sediment

Snow

Because atmospheric deposition is the primary pathway 

by which pesticides enter remote high-elevation ecosystems in 

ROMO and GLAC, snow samples were collected to determine 

which pesticides are currently entering these systems and at 

what rates (loadings). Snow was selected as a sample medium 

because snowfall provides most of the annual precipitation in 

high-elevation areas. Snow sampling has an additional advantage in that a single full-depth snowpack sample collected at 

maximum accumulation represents the majority of the wet 

and dry deposition for the winter snowfall period. The snowsampling sites for this study were selected along elevation 

gradients on each side (east-west) of the Continental Divide 

(fig. 7). In ROMO, snow was collected at eight sites that 

spanned an elevation range of about 660 m. At the Loch Vale 

and Lake Irene sites, samples were collected in adjacent forested and open (meadow) areas in 2003 to assess the influence 

of the forest canopy on pesticide concentrations and loading 

(Horstmann and McLaughlin, 1998). In GLAC, snow was collected at eight sites that spanned an elevation range of about 

700 m. On average, the sites in ROMO were about 1,400 m 

higher than the sites in GLAC. Many of the sites sampled 

during this study are part of the Rocky Mountain snowpack 

network, which is a network of snowpack chemistry sites that 

have been monitored by the USGS since 1991 (Ingersoll and 

others, 2001).

Table 11. Concentrations and percent recovery of current-use 

pesticides analyzed by gas chromatography/electron-impact mass 

spectrometry in laboratory blanks and reagent spikes analyzed 

with sediment samples in 2003.

[<, less than; %, percent; μg/kg, microgram per kilogram of sediment (dry 

weight); OCC, organochlorine compounds analyzed by gas chromatography/

electron-capture detection (GC/ECD)]

Compound

Laboratory

blank

(μg/kg)

Reagent

spike1

(% recovery)

Acetochlor <1 97

Alachlor <1 87

Atrazine <1 104

Azinphos-methyl <5 120

Azinphos-methyl, oxygen analog <30 105

Benfluralin <1 65

Carbaryl <2 96

2-Chloro-2,6-diethylacetanilide <1 89

2-Chloro-4-isopropylamino6-amino-s-triazine<2 90

4-Chloro-2-methylphenol <10 55

Chlorpyrifos <1 86

Chlorpyrifos oxygen analog <30 73

Cyfluthrin <20 130

Cypermethrin <20 134

Dacthal <1.0 94

Diazinon <1 91

Diazinon, oxygen analog <5 73

3,4-Dichloroaniline <75 40

Dichlorvos <30 37

Dicrotophos <3 75

Dieldrin <2 99

2,6-Diethylaniline <30 37

Dimethoate <2 76

Ethion <2 87

Ethion monoxon <2 88

2-Ethyl-6-methylaniline <30 37

Fenamiphos <30 81

Fenamiphos sulfone <10 107

Fenamiphos sulfoxide <10 156

Fipronil <1 104

Fipronil sulfide <1 114

Fipronil sulfone <1 108

Fipronil, desulfinyl <1 96

Fipronil amide, desulfinyl <1 114

Fonofos <1 72

Fonofos oxygen analog <5 85

Hexazinone <44 113

Iprodione <10 52

Isofenphos <2 109

Malathion <2 71

Malathion, oxygen analog <5 56

Metalaxyl <1 102

Methidathion <2 101

Metolachlor <1 93

Metribuzin <4 82

Myclobutanil <10 86

1-Naphthol <10 11

Parathion-methyl <2 82

Compound

Laboratory

blank

(μg/kg)

Reagent

spike1

(% recovery)

Parathion-methyl, oxygen analog <5 76

Pendimethalin <1 95

Phorate <5 39

Phorate oxygen analog <7 50

Prometon <2 81

Prometryn <2 92

cis-Permethrin <5 142

trans-Permethrin <5 112

Propyzamide <2 77

Simazine <2 96

Tebuthiuron <3 74

Terbufos <3 64

Terbufos-o-analogue sulfone <5 93

Terbuthylazine <1 100

Trifluralin <1 69

α-HCH-d6 surrogate, % recovery 54 52

Diazinon-d10 surrogate, % recovery 75 83

1

Reagent spike fortified with OCC-method compounds only.

Table 11.—Continued

28  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
In 2002, snowfall was less than average in ROMO but 

greater than average in GLAC, and in 2003 snowfall was 

close to average in both parks. Maximum water content of 

the snowpack at the Bear Lake Snow Telemetry (SNOTEL) 

site in ROMO (fig. 3), which is operated by the Natural 

Resources Conservation Service, was 24 cm in 2002 and 

63 cm in 2003 compared to the long-term (1971–2000) average of 50 cm (http://www.wcc.nrcs.usda.gov/snow/, accessed 

December 2005). In GLAC, maximum annual water content 

at the Flattop Mountain SNOTEL site (fig. 4) was 153 cm 

in 2002 and 112 cm in 2003 compared to the long-term 

(1971–2000) average of 118 cm. Snow depths at the sampling sites increased with elevation in both parks. In ROMO, 

snow depths in 2002 ranged from 70 cm at Phantom Valley 

to 327 cm at Upper Andrews Tarn. Snowpacks were typically 

deeper in GLAC, ranging from 184 cm at E3 to 370 cm at 

Granite Park. In both parks, snow depths on the east and west 

sides of the Continental Divide were comparable for sites at 

similar elevations.

Concentrations of pesticides and other compounds 

detected in snow samples are shown in tables 13–15, and the 

most frequently detected pesticides are shown in figure 8. 

Of the 66 compounds determined by the CUP method, only 

carbaryl, chlorpyrifos, and dacthal were detected in snow 

(tables 13–14). Dacthal was detected in all 19 of the snow 

samples analyzed, but carbaryl and chlorpyrifos were detected 

Table 12. Concentrations and percent recovery of 

organohalogen compounds analyzed by gas chromatography/

electron-capture negative ion mass spectrometry in laboratory 

blanks and reagent spikes analyzed with sediment samples in 

2003.

[<, less than; %, percent; μg/kg, microgram per kilogram of sediment (dry 

weight); ns, not in spike or surrogate; OCC, organochlorine compounds 

analyzed by gas chromatography/electron-capture detection (GC/ECD); CUP, 

current-use pesticides analyzed by gas chromatography/electron-impact mass 

spectrometry (GC/EIMS); PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound

Laboratory

blank

(μg/kg)

Reagent

spike1

(% recovery)

Reagent

spike2

(% recovery)

Aldrin <0.8 68 ns

Benfluralin <0.1 ns 63

Chlorpyrifos <0.1 ns 91

cis-Chlordane <0.2 72 ns

trans-Chlordane <0.1 67 ns

Dacthal (DCPA) <0.27 nn 99

o,p’-DDD <1.6 ns ns

o,p’-DDE <1.6 ns ns

o,p’-DDT <6.4 ns ns

o,p’-DDD <15 ns ns

o,p’-DDE <4.0 ns ns

Dieldrin <0.8 68 86

Endosulfan I <0.1 63 ns

Endosulfan II <0.1 ns ns

Endosulfan sulfate <0.2 ns ns

Endrin <0.8 77 ns

Endrin aldehyde <0.8 ns ns

Endrin ketone <3.2 ns ns

Fipronil <0.4 ns 102

Fipronil sulfide <6.4 ns ns

Fipronil amide, desulfinyl <1.6 ns ns

α-HCH <0.8 ns ns

β-HCH <1.6 ns ns

δ-HCH <0.8 ns ns

γ-HCH (Lindane) <0.8 54 ns

Heptachlor epoxide <1.6 66 ns

Hexachlorobenzene (HCB) 4.7 ns ns

Mirex <0.8 74 ns

cis-Nonachlor <0.2 ns ns

trans-Nonachlor <0.2 80 ns

Octachlorostyrene <0.2 ns ns

Oxychlordane <1.6 ns ns

Pentachloroanisole (PCA) <0.1 ns ns

Trifluralin <0.1 ns 92

PCB congeners

PCB 70 <1.6 ns ns

PCB 101 <0.8 ns ns

PCB 110 <0.8 ns ns

PCB 118 <0.1 ns ns

Compound

Laboratory

blank

(μg/kg)

Reagent

spike1

(% recovery)

Reagent

spike2

(% recovery)

PCB congeners—Continued

PCB 138 <0.1 ns ns

PCB 146 <0.1 ns ns

PCB 149 <0.4 ns ns

PCB 151 <0.1 ns ns

PCB 170 <0.1 ns ns

PCB 174 <0.1 ns ns

PCB 177 <0.1 ns ns

PCB 180 <0.1 ns ns

PCB 183 <0.1 ns ns

PCB 187 <0.1 ns ns

PCB 194 <0.1 ns ns

PCB 206 <0.1 ns ns

PBDE congeners

PBDE 47 <3.2 ns ns

PBDE 99 <3.2 ns ns

PBDE 100 <3.2 ns ns

PBDE 153 <3.2 ns ns

PBDE 154 <3.2 ns ns

α-HCH-d6 surrogate, 

% recovery

59 -- 77

1

Reagent spike fortified with OCC-method compounds only.

2

Reagent spike fortified with CUP-method compounds only.

Table 12.—Continued

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 29
in only one sample each. Concentrations of all the detected 

compounds were very low, ranging from 0.27 to 2.2 ng/L. The 

concentrations of the detected pesticides in snow were not 

related to site elevation or location relative to the Continental 

Divide and were not notably different between meadow and 

forest sites, indicating that the presence of any fine canopy 

material in the 2003 samples had minimal or no influence 

on concentrations. Needles and other forest materials uptake 

organic contaminants (Reischl and others, 1987; Horstmann 

and McLaughlin, 1998), although their contribution, if any, 

to observed concentrations in 2002 snow samples cannot be 

distinguished. Concentrations were similar between the two 

parks with the exception of dacthal, which was slightly higher 

in ROMO compared to GLAC (fig. 9). For the organohalogen 

compounds, 10 of the 58 targeted compounds were detected in 

one or more snow samples including chlorpyrifos, chlorothalonil, dacthal, dieldrin, endosulfan I, endosulfan II, endosulfan 

sulfate, hexachlorobenzene (HCB), trans-nonachlor, and trifluralin (table 15). Three of these compounds—HCB, dieldrin, 

and trans-nonachlor—are organochlorine pesticides that have 

not been used commercially in the United States or Canada for 

several decades.

The pesticides most frequently detected in snow were 

endosulfan, dacthal, and chlorothalonil (fig. 8), which 

are all chlorinated pesticides that are registered for use in 

North America. Endosulfan, which consists of two isomers (endosulfan I and endosulfan II), is the only chlorinated cyclodiene insecticide that is still in use in the United 

States (National Pesticide Information Retrieval System, 

http://ppis.ceris.purdue.edu/htbin/epachem.com, accessed 

February 2006). It is used on cotton and tobacco and on a 

wide variety of fruits and vegetables, particularly potatoes and 

apples. Endosulfan is highly toxic to fish and aquatic invertebrates (Johnson and Finley, 1980). Endosulfans were detected 

in all nine of the snow samples analyzed by GC/ECNIMS 

(table 15). Concentrations ranged from 0.20 to 1.06 ng/L for 

endosulfan I and 0.07 to 1.18 ng/L for endosulfan II. The highest concentrations of endosulfans were measured at Granite 

Park on the west side of GLAC. Both isomers were detected in 

all the snow samples, although concentrations of endosulfan I 

were as much as four times higher than endosulfan II. Higher 

concentrations of endosulfan I may reflect the composition 

of the technical mixture applied in agricultural areas, which 

contains a 7:3 mixture of endosulfan I to endosulfan II, as 

well as differences in physical properties (Shen and Wania, 

2005). Endosulfan I is more volatile than endosulfan II and, 

thus, typically has higher atmospheric concentrations. However, endosulfan II has a lower Henry’s law constant which 

favors its removal from the atmosphere by wet deposition and 

air-water exchange (Rice and others, 1997). Isomer conversion 

Figure 7. Elevation and distance from Continental Divide of snow-sampling sites in Rocky 

Mountain National Park and Glacier National Park.

30 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03

(2) (2) 

1,000 

1,500 

2,000 

2,500 

3,000 

3,500 

6 4 2 0 2 4 6 8 

ELEVEATI

ON, IN METERS 

DISTANCE FROM CONTINENTAL DIVIDE, IN KILOMETERS 

Bear Lake 

Loch Vale 

Forest & Meadow 

Upper Andrews Tarn Forest Canyon Pass

Lake Irene

Forest & Meadow

Phantom Valley 

Preston Park 

E6 

E3 

Swiftcurrent 

Creek 

Granite Park 

W11 

W10 

Lower Snyder 

Lake 

Rocky Mountain National Park 

Glacier National Park 

West East 

EXPLANATION 

Continental Divide 
Table 13. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in snow samples collected in Rocky Mountain 

National Park in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds analyzed by gas chromatography/electron-capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

Bear

Lake1

04/03/2002

Loch Vale

Forest1

04/01/2002

Upper 

Andrews1

04/01/2002

Phantom

Valley1

03/07/2002

Forest

Canyon Pass1

03/29/2002

Loch Vale

Forest

04/08/2003

Loch Vale

Meadow

04/07/2003

BearLake

04/08/2003

Lake Irene

Forest

04/01/2003

Lake Irene

Meadow

04/01/2003

Acetochlor <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60Alachlor <10.0 <10.0 <10.0 <20 <13 <8.0 <8.0 <8.0 <8.0 <8.0Atrazine -- -- -- -- -- <1.5 <1.5 <1.5 <1.5 <1.5Azinphos-methyl -- -- -- -- -- <8.7 <5.0 <5.0 <5.0 <5.0Azinphos-methyl, oxygen analog -- -- -- -- -- <11 <11 <11 <11 <11Benfluralin <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0Carbaryl -- -- -- -- -- <4.1 0.82 <4.1 <4.1 <4.12-Chloro-2,6-diethylacetanilide -- -- -- -- -- <0.50 <0.50 <0.50 <0.50 <0.502-Chloro-4-isopropylamino-6-amino-s-triazine -- -- -- -- -- <0.60 <0.60 <0.60 <0.60 <0.604-Chloro-2-methylphenol -- -- -- -- -- <0.56 <0.56 <0.56 <0.56 <0.56Chlorpyrifos <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50Chlorpyrifos, oxygen analog -- -- -- -- -- <5.6 <5.6 <5.6 <5.6 <5.6Cyfluthrin -- -- -- -- -- <2.7 <2.7 <2.7 <2.7 <2.7Cypermethrin -- -- -- -- -- <0.86 <0.86 <0.86 <0.86 <0.86Dacthal 2.20 1.12 0.81 1.21 1.00 0.48 0.76 0.93 2.05 1.08Diazinon <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50Diazinon, oxygen analog <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.603,4-Dichloroaniline -- -- -- -- -- <0.45 <0.45 <0.45 <0.45 <0.45Dichlorvos -- -- -- -- -- <1.2 <1.2 <1.2 <1.2 <1.2Dicrotophos -- -- -- -- -- <8.4 <8.4 <8.4 <8.4 <8.4Dieldrin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.902,6-Diethylaniline <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60Dimethoate -- -- -- -- -- <0.61 <0.61 <0.61 <0.61 <0.61Ethion <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40Ethion monoxon -- -- -- -- -- <0.20 <0.20 <0.20 <0.20 <0.202-Ethyl-6-methylaniline <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45Fenamiphos -- -- -- -- -- <2.9 <2.9 <2.9 <2.9 <2.9Fenamiphos sulfone -- -- -- -- -- <4.9 <4.9 <4.9 <4.9 <4.9Fenamiphos sulfoxide -- -- -- -- -- <3.9 <3.9 <3.9 <3.9 <3.9Fipronil -- -- -- -- -- <1.6 <1.6 <1.6 <1.6 <1.6Fipronil sulfide -- -- -- -- -- <1.3 <1.3 <1.3 <1.3 <1.3Fipronil sulfone -- -- -- -- -- <2.4 <2.4 <2.4 <2.4 <2.4Fipronil, desulfinyl -- -- -- -- -- <1.2 <1.2 <1.2 <1.2 <1.2Fipronil amide, desulfinyl -- -- -- -- -- <2.9 <2.9 <2.9 <2.9 <2.9

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 31
Table 13. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in snow samples collected in Rocky Mountain 

National Park in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds analyzed by gas chromatography/electron-capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

Bear

Lake1

04/03/2002

Loch Vale

Forest1

04/01/2002

Upper 

Andrews1

04/01/2002

Phantom

Valley1

03/07/2002

Forest

Canyon Pass1

03/29/2002

Loch Vale

Forest

04/08/2003

Loch Vale

Meadow

04/07/2003

BearLake

04/08/2003

Lake Irene

Forest

04/01/2003

Lake Irene

Meadow

04/01/2003

Fonofos <1.0 <1.0 <1.0 <1.0 <1.0 <0.30 <0.30 <0.30 <0.30 <0.30Hexazinone -- -- -- -- -- <50 <50 <50 <50 <50Iprodione -- -- -- -- -- <54 <54 <54 <54 <54Isofenphos2 -- -- -- -- -- <0.34 <0.34 <12 <0.34 <0.34Malathion -- -- -- -- -- <2.7 <2.7 <2.7 <2.7 <2.7Malathion, oxygen analog -- -- -- -- -- <3.0 <3.0 <3.0 <3.0 <3.0Metalaxyl -- -- -- -- -- <2.9 <2.9 <2.9 <2.9 <2.9Methidathion -- -- -- -- -- <0.58 <0.58 <0.58 <0.58 <0.58Metolachlor -- -- -- -- -- <0.60 <0.60 <0.60 <0.60 <0.60Metribuzin -- -- -- -- -- <2.6 <2.6 <2.6 <2.6 <2.6Myclobutanil -- -- -- -- -- <0.80 <0.80 <0.80 <0.80 <0.801-Naphthol -- -- -- -- -- <8.8 <8.8 <8.8 <8.8 <8.8Parathion-methyl -- -- -- -- -- <1.5 <1.5 <1.5 <1.5 <1.5Parathion-methyl, oxygen analog -- -- -- -- -- <3.0 <3.0 <3.0 <3.0 <3.0Pendimethalin <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <20 <20cis-Permethrin <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <5.8Phorate -- -- -- -- -- <1.1 <1.1 <1.1 <1.1 <1.1Phorate oxygen analog -- -- -- -- -- <11 <11 <11 <11 <11Prometon -- -- -- -- -- <1.0 <1.0 <1.0 <1.0 <1.0Prometryn -- -- -- -- -- <0.54 <0.54 <0.54 <0.54 <0.54Propyzamide <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40Simazine -- -- -- -- -- <0.50 <0.50 <0.50 <0.50 <0.50Tebuthiuron -- -- -- -- -- <1.6 <1.6 <1.6 <1.6 <1.6Terbufos -- -- -- -- -- <1.7 <1.7 <1.7 <1.7 <1.7Terbufos oxygen analog sulfone -- -- -- -- -- <6.8 <6.8 <6.8 <6.8 <6.8Terbuthylazine -- -- -- -- -- <1.0 <1.0 <1.0 <1.0 <1.0Trifluralin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90α-HCH-d6 surrogate, % recovery 58 27 29 38 24 28 31 46 96 60Diazinon-d10 surrogate % recovery ns ns ns ns ns 43 57 71 123 89Isofenphos surrogate, % recovery2 128 72 55 133 62 ns ns ns ns nsSample volume, liters 9.5 10.3 11.4 6.3 10.6 15.3 13.4 14.9 16.8 18.2

12002 samples initially prepared using OCC method and analyzed by GC/ECD. Extract subsequently analyzed for current-use pesticides by GC/EIMS.2Isofenphos was a surrogate compound for 2002 samples but an analyte for 2003 samples.

32 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 14. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in snow samples collected in Glacier National Park 

in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds analyzed by gas chromatography/electron-capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

Swiftcurrent

Creek1

03/19/2002

E31

03/12/2002

E61

03/13/2002

Preston

Park1

03/13/2002

W101

03/12/2002

W111

03/13/2002

Granite

Park1

03/13/2002

Granite

Park

04/08/2003

Lower

Snyder

03/15/2003

Acetochlor <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

Alachlor <13 <13 <13 <13 <13 <13 <13 <8.0 <8.0

Atrazine -- -- -- -- -- -- -- <1.5 <1.5Azinphos-methyl -- -- -- -- -- -- -- <5.0 <5.0Azinphos-methyl, oxygen analog -- -- -- -- -- -- -- <11 <11Benfluralin <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

Carbaryl -- -- -- -- -- -- -- <4.1 <4.12-Chloro-2,6-diethylacetanilide -- -- -- -- -- -- -- <0.50 <0.502-Chloro-4-isopropylamino-6-amino-s-triazine -- -- -- -- -- -- -- <0.60 <0.604-Chloro-2-methylphenol -- -- -- -- -- -- -- <0.56 <0.56Chlorpyrifos <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 2.06 <0.50

Chlorpyrofos, oxygen analog -- -- -- -- -- -- -- E1.98 <5.6Cyfluthrin -- -- -- -- -- -- -- <2.7 <2.7Cypermethrin -- -- -- -- -- -- -- <0.86 <0.86Dacthal 0.82 1.05 0.55 0.69 0.27 0.35 0.40 0.95 0.33Diazinon <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Diazinon, oxygen analog <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

3,4-Dichloroaniline -- -- -- -- -- -- -- <0.45 <0.45Dichlorvos -- -- -- -- -- -- -- <1.2 <1.2Dicrotophos -- -- -- -- -- -- -- <8.4 <8.4Dieldrin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90

2,6-Diethylaniline <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

Dimethoate -- -- -- -- -- -- -- <0.61 <0.61Ethion <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

Ethion monoxon -- -- -- -- -- -- -- <0.20 <0.202-Ethyl-6-methylaniline <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45 <0.45

Fenamiphos -- -- -- -- -- -- -- <2.9 <2.9Fenamiphos sulfone -- -- -- -- -- -- -- <4.9 <4.9Fenamiphos sulfoxide -- -- -- -- -- -- -- <3.9 <3.9Fipronil -- -- -- -- -- -- -- <1.6 <1.6Fipronil sulfide -- -- -- -- -- -- -- <1.3 <1.3Fipronil sulfone -- -- -- -- -- -- -- <2.4 <2.4Fipronil, desulfinyl -- -- -- -- -- -- -- <1.2 <1.2

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 33
Table 14. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in snow samples collected in Glacier National Park 

in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations; OCC, organochlorine compounds analyzed by gas chromatography/electron-capture detection (GC/ECD); CUP, current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry (GC/EIMS)]

Compound

Swiftcurrent

Creek1

03/19/2002

E31

03/12/2002

E61

03/13/2002

Preston

Park1

03/13/2002

W101

03/12/2002

W111

03/13/2002

Granite

Park1

03/13/2002

Granite

Park

04/08/2003

Lower

Snyder

03/15/2003

Fipronil amide, desulfinyl -- -- -- -- -- -- -- <2.9 <2.9Fonofos <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <0.30 <0.30

Hexazinone -- -- -- -- -- -- -- <50 <50Iprodione -- -- -- -- -- -- -- <54 <54Isofenphos2 -- -- -- -- -- -- -- <0.34 <0.34Malathion -- -- -- -- -- -- -- <2.7 <2.7Malathion, oxygen analog -- -- -- -- -- -- -- <3.0 <3.0Metalaxyl -- -- -- -- -- -- -- <2.9 <2.9Methidathion -- -- -- -- -- -- -- <0.58 <0.58Metolachlor -- -- -- -- -- -- -- <0.60 <0.60Metribuzin -- -- -- -- -- -- -- <2.6 <2.6Myclobutanil -- -- -- -- -- -- -- <0.80 <0.801-Naphthol -- -- -- -- -- -- -- <8.8 <8.8Parathion-methyl, oxygen analog -- -- -- -- -- -- -- <3.0 <3.0Parathion-methyl -- -- -- -- -- -- -- <1.5 <1.5Pendimethalin <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2 <2.2

cis-Permethrin <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60 <0.60

Phorate -- -- -- -- -- -- -- <1.1 <1.1Phorate, oxygen analog -- -- -- -- -- -- -- <11 <11Prometon -- -- -- -- -- -- -- <1.0 <1.0Prometryn -- -- -- -- -- -- -- <0.54 <0.54Propyzamide <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

Simazine -- -- -- -- -- -- -- <0.50 <2.6Tebuthiuron -- -- -- -- -- -- -- <1.6 <1.6Terbufos -- -- -- -- -- -- -- <1.7 <1.7Terbufos oxygen analog sulfone -- -- -- -- -- -- -- <6.8 <6.8Terbuthylazine -- -- -- -- -- -- -- <1.0 <1.0Trifluralin <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90 <0.90α-HCH-d6 surrogate, % recovery 60 51 24 54 16 20 36 42 28Diazinon-d10 surrogate, % recovery ns ns ns ns ns ns ns 52 47Isofenphos surrogate, % recovery2 87 86 80 103 34 50 61 ns nsSample volume, liters 10.7 7.7 12.6 5.6 9.6 11.4 11.3 11.7 17.3

12002 samples initially prepared using OCC method and analyzed by GC/ECD. Extract subsequently analyzed for current-use pesticides by GC/EIMS.2Isofenphos was a surrogate compound for 2002 samples but an analyte for 2003 samples.

34  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 15. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass spectrometry in snow samples collected 

in Rocky Mountain National Park and Glacier National Park in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations]

Compound

Rocky Mountain National Park Glacier National Park

Loch Vale

Forest

04/01/2002

Upper

Andrews

04/01/2002

Loch Vale

Forest

04/08/2003

Loch Vale

Meadow

04/07/2003

BearLake

04/08/2003

Lake Irene

Forest

04/01/2003

Lake Irene

Meadow

04/01/2003

Granite

Park

04/08/2003

Lower

Snyder

03/15/2003

Aldrin <0.25 <0.25 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Chlorpyrifos <0.03 <0.03 <0.10 <0.10 <0.10 <0.10 <0.08 2.11 <0.10cis-Chlordane <0.07 <0.07 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13

trans-Chlordane <0.07 <0.07 <0.15 <0.15 <0.15 <0.15 <0.15 <0.15 <0.15

Chlorothalonil E0.58 E0.51 E1.59 E1.26 E1.85 E2.36 E1.37 <1.0 <1.0

Dacthal (DCPA) 0.52 0.46 0.68 1.19 1.05 3.48 1.58 1.39 0.41o,p’-DDD <0.50 <0.50 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

o,p’-DDE <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

p,p’-DDE <0.50 <0.50 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0

Dieldrin <0.10 <0.10 <0.40 <0.40 <0.40 <0.40 0.22 <0.40 <0.40

Endosulfan I 0.20 0.22 0.27 0.61 0.41 0.74 0.79 1.06 0.24Endosulfan II 0.14 0.07 0.13 0.18 0.18 0.21 0.19 1.18 0.27Endosulfan sulfate -- -- 0.15 0.15 0.16 0.21 0.14 0.21 0.18Endrin <0.25 <0.25 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Endrin aldehyde -- -- <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Endrin ketone -- -- <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0

Fipronil <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

Fipronil sulfide <0.13 <0.13 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03

Fipronil sulfone <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

Fipronil, desulfinyl <0.07 <0.07 <0.12 <0.10 <0.12 <0.12 <0.07 <0.12 <0.12

Fipronil amide, desulfinyl <0.20 <0.20 <0.31 <0.31 <0.31 <0.31 <0.31 <0.31 <0.31

α-HCH <0.25 <0.25 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

δ-HCH <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

γ-HCH (Lindane) <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25

Heptachlor <0.50 <0.50 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

Heptachlor epoxide <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13

Hexachlorobenzene (HCB) E0.08 <0.08 -- -- -- -- -- -- --Isodrin <3.4 <3.4 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

Mirex <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25

cis-Nonachlor <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

trans-Nonachlor <0.10 <0.10 <0.20 <0.20 <0.20 <0.20 E0.14 <0.20 <0.20

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 35
Table 15. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass spectrometry in snow samples collected 

in Rocky Mountain National Park and Glacier National Park in 2002–03.—Continued[<, less than; E, estimated concentration; --, not determined; %, percent; ns, not in spike or surrogate; concentrations in nanograms per liter; shaded cells denote detectable concentrations]

Compound

Rocky Mountain National Park Glacier National Park

Loch Vale

Forest

04/01/2002

Upper

Andrews

04/01/2002

Loch Vale

Forest

04/08/2003

Loch Vale

Meadow

04/07/2003

BearLake

04/08/2003

Lake Irene

Forest

04/01/2003

Lake Irene

Meadow

04/01/2003

Granite

Park

04/08/2003

Lower

Snyder

03/15/2003

Octachlorostyrene <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

Oxychlordane <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13

Pentachloroanisole (PCA) <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

Trifluralin E0.05 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB congeners

PCB 70 <0.50 <0.50 <0.50 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

PCB 101 <0.25 <0.25 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

PCB 110 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25

PCB 118 <0.10 <0.10 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 138 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 146 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 149 <0.25 <0.25 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50 <0.50

PCB 151 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 170 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 174 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 177 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 180 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 183 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 187 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 194 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PCB 206 <0.27 <0.13 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07 <0.07

PBDE Congeners

PBDE 47 <0.78 <0.32 <0.80 <0.80 <0.80 <0.80 <0.80 <0.80 <0.80

PBDE 99 <0.39 <0.17 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40 <0.40

PBDE 100 <0.34 <0.14 <0.35 <0.35 <0.35 <0.35 <0.35 <0.35 <0.35

PBDE 153 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13

PBDE 154 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03

α-HCH-d6 surrogate, % recovery 29 34 29 44 52 158 107 44 35Isodrin surrogate, % recovery 74 66 ns ns ns ns ns ns nsPCB207 surrogate, % recovery 67 43 ns ns ns ns ns ns nsSample volume, liters 10.3 11.4 15.3 13.4 14.9 16.8 18.2 11.7 17.3

36  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
from endosulfan II to I also can occur (Schmidt and others, 

2001). Endosulfan sulfate, which is a degradation product 

of endosulfan I and II, was detected in all seven of the 2003 

samples in concentrations ranging from 0.14 to 0.21 ng/L. 

Endosulfan sulfate was not analyzed for in the 2002 samples.

Dacthal, also known as DCPA, is a pre-emergence 

herbicide used primarily on onions and broccoli as well as on 

sod farms, golf courses, and residential lawns (Kimbrough 

and Litke, 1997). Dacthal is only slightly toxic to aquatic 

organisms (Johnson and Finley, 1980; U.S. Environmental 

Protection Agency, 1988), and currently there are no established water-quality guidelines for this compound. All 19 snow 

samples collected during the study were analyzed for dacthal 

by GC/EIMS (tables 13–14). Nine of the 19 samples also were 

analyzed for dacthal by GC/ECNIMS (table 15). Dacthal was 

detected in all 19 samples by GC/EIMS and all 9 samples by 

GC/ECNIMS. Comparison between the GC/ECNIMS and 

GC/EIMS concentrations showed good correlation (r2 = 0.95), 

although the GC/ECNIMS concentrations tended to be about 

30 percent higher than the GC/EIMS concentrations. Recovery 

of dacthal in the reagent spike by GC/EIMS was 83 percent 

(table 7), indicating the GC/EIMS values are reasonable. 

Recovery of dacthal in the reagent spike by GC/ECNIMs was 

156 percent, however, which may indicate the GC/ECNIMS 

concentrations are biased high (table 8). Dacthal concentrations in snow samples analyzed by GC/EIMS ranged from 

0.27 to 2.2 ng/L, and the highest concentration was measured 

at Bear Lake (2002) on the east side of ROMO (table 13–14). 

The mono- and di-acid degradates of dacthal were not determined by the methods used in this study.

Chlorothalonil is a broad-spectrum organochlorine fungicide that is used on a variety of fruit and vegetable crops but 

most commonly on potatoes and peanuts. It also has nonagricultural uses on golf courses and in nurseries and as a fungicide in paints, grouts, and other building products. Chlorothalonil is highly toxic to aquatic organisms in laboratory studies; 

however, it does not have the high degree of persistence in 

the environment that is typical of many other chlorinated 

pesticides (http:// www.epa.gov/oppfead1/endanger/effects/

#chlorothalonil, accessed December 2005). Chlorothalonil 

was detected in seven of the nine snow samples analyzed 

by GC/ECNIMS (table 15). The estimated concentrations 

ranged from 0.51 to 2.36 ng/L, which generally were higher 

than concentrations of other detected compounds in snow 

(fig. 8). Interestingly, only snow from ROMO had detectable 

concentrations of chlorothalonil, although only two samples 

from GLAC were analyzed for the compound so the results 

may not be representative. Concentrations of chlorothalonil in 

snow were 1–2 orders of magnitude lower than the freshwater 

aquatic-life criterion of 0.18 μg/L (table 3).

Because the snow-sampling sites are remote and pesticide usage in the parks is minimal, the most reasonable 

source for endosulfan, dacthal, and chlorothalonil is regional 

to long-range atmospheric transport and subsequent wet and 

Figure 8. Concentration ranges of most frequently detected 

pesticides in snow collected in Rocky Mountain National Park 

and Glacier National Park.

Figure 9. Comparison of dacthal concentrations in 

snow between Rocky Mountain National Park and Glacier 

National Park.

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 37

PESTICIDE CONCENTRATION, IN NANOGRAMS PER LITER

0

0.5

1.0

1.5

2.0

2.5

Chlorothalonil Dacthal Endosulfans

0

0.5

1.0

1.5

2.0

2.5

Rocky Mountain

National Park

Glacier 

National Park

DACTHAL CONCENTRATION, IN NANOGRAMS 

PER LITER
dry deposition to the snowpack. Based on air concentrations 

as measured by passive air samplers, Shen and others (2005) 

estimated that endosulfan I has a characteristic travel distance 

(or “half distance” analogous to half-life) of about 650 km or 

more in air. This travel distance indicates agricultural areas 

adjacent to ROMO and GLAC are the mostly likely source 

of endosulfans in snow. This is consistent with pesticide 

usage data, which shows heavy use of endosulfan in central 

Washington primarily for fruit, and moderate use in northeastern and south-central Colorado, primarily for potatoes 

(fig. 10). Observations of endosulfans in high arctic air and 

snow (Gregor and Gummer, 1989; Patton and others, 1989; 

Chernyak and others, 1996; Shen and others, 2005) indicate 

that some endosulfans might come from long-range transport 

to the parks.

Dacthal also has properties that give it the potential for 

long-range atmospheric transport (Muir and others, 2004). 

It has been detected in air and rain samples collected at sites 

along the Great Lakes (James and Hites, 1999; Foreman 

and others, 2000) and in a watershed in southern Manitoba, 

Canada, distant from sources (Rawn and Muir, 1999), as well 

as in air samples from Cheeka Peak Observatory in Oregon 

(Killin and others, 2004), indicating that dacthal can be transported by air currents over regional to long distances. On the 

basis of empirical models, Muir and others (2004) determined 

that dacthal had a significantly greater potential for long-range 

transport than other commonly used current-use pesticides. 

Similar to endosulfan, the most likely source of dacthal in 

ROMO is in eastern Colorado (fig. 10), where it is among 

the 10 most commonly used agricultural herbicides on irrigated land and primarily is used for the cultivation of onions 

(Kimbrough and Litke, 1997). Usage around GLAC is heaviest 

in agricultural areas of the Idaho panhandle and in southeastern Washington (fig. 10) where it also is used predominantly on onions (http://www.ncfap.org/database/default.htm,

accessed December 2005). As noted previously, dacthal 

concentrations in snow from ROMO were slightly higher than 

in snow from GLAC (fig. 9). This pattern may reflect closer 

proximity of agricultural areas in eastern Colorado to ROMO 

compared to agricultural areas in Washington and Idaho, 

which are located farther to the west and south of GLAC.

The long-range transport characteristics of chlorothalonil 

are not well understood, in part because its analytical determination is challenging (Mackay and others, 1997). Chernyak 

and others (1996) reported concentrations in fog and seawater 

samples collected in the Bering and Chukchi Seas, indicating long-range atmospheric transport. McConnell and others (1998) detected chlorothalonil in snow and rain samples 

collected in Sequoia National Park and the Lake Tahoe 

Basin. It also has been detected in air samples from sites on 

the Great Lakes (James and Hites, 1999), at Cheeka Peak, 

Oregon (Killin and others, 2004), and on the Chesapeake 

Bay (Harman-Fetcho and others, 2000). The presence of this 

compound in ROMO snow indicates that it is transported 

at least regionally in the atmosphere. Chlorothalonil was 

detected in all seven of the snow samples from ROMO and, 

similar to dacthal and endosulfan, probably was transported 

from agricultural and(or) urban areas in the eastern part of the 

State, likely from use during potato cultivation where loss to 

the atmosphere can be substantial (White and others, 2006). 

Chlorothalonil was not detected in the two snow samples from 

GLAC despite the fact that there is reported use of the pesticide in areas adjacent to the park (fig. 10).

Of the banned or historical-use pesticides, only dieldrin, hexachlorobenzene (HCB), and trans-nonachlor were 

detected and only in one sample each. Dieldrin was used as 

a termiticide and as an insecticide primarily for cotton, corn, 

and fruit and was banned from use in the United States in the 

1970s. HCB production, uses, and environmental fate and 

risk were recently reviewed by Jones (2005). HCB is a highly 

chlorinated compound that had varied applications. In agriculture, it was used as a fungicide as a seed dressing for onions, 

sorghum, and for crops such as wheat, barley, oats, and rye. It 

also was used as a wood preservative and in industrial applications, including production of chlorinated solvents, aromatics, 

and pesticides. In the United States, it has not been commercially produced since the late 1970s. However, HCB can be 

formed as a by-product in the production of some chlorinated 

compounds, including pesticides such as chlorothalonil, dacthal, and the chlorinated triazine herbicides including atrazine 

and simazine, which provides a continued, yet much reduced, 

source of HCB in North America (Jones, 2005). HCB has a 

very long residence time in the atmosphere that has allowed it 

to become widely distributed in the global atmosphere (Shen 

and others, 2005). HCB could not be determined in 2003 snow 

samples because it was not recovered from the graphitized carbon column used in the CUP method. trans-Nonachlor is one 

of the three major component congeners of technical chlordane, which was used as an insecticide and termiticide until 

the early 1980s when most of these uses were restricted in 

North America. Based on characteristic travel distances (Shen 

and others, 2005), sources of dieldrin and trans-nonachlor 

might be from regional or long-range transport. Limited 

detections of the banned compounds are possibly a reflection 

of decreasing atmospheric concentrations in North America 

(Cortes and others, 1998).

Atmospheric deposition rates of the most frequently 

detected pesticides were estimated for each park from snowpack concentrations and precipitation amount measured at the 

Bear Lake and Flattop Mountain SNOTEL sites. Average concentrations using data from both years for total endosulfans, 

dacthal, and chlorothalonil in ROMO were 0.78, 1.16, and 

1.36, ng/L, respectively. Average concentrations of total endosulfans and dacthal in GLAC were 1.57 and 0.6 ng/L, respectively. Because chlorothalonil was not detected in GLAC 

snowpack samples, the concentration in snow was estimated as 

0.5 ng/L, one-half the method reporting level. Using the longterm (1981–2005) annual (winter plus summer) precipitation 

amount at Bear Lake (89 cm) and assuming that average 

concentrations in snow are representative of precipitation over 

38  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Figure 10. Maps showing usage of chlorothalonil, dacthal, and endosulfan 

in the Western United States during 1997.

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment 39

Chlorothalonil

>0.83

0.14–0.83

0.027–0.13

0.005–0.026

<0.005

Kilograms per square kilometer

per county per year

Dacthal

>0.037

0.0055–0.037

0.0022–0.0054

0.0007–0.0021

<0.0007

Kilograms per square kilometer

per county per year

Endosulfan

>0.15

0.040–0.15

0.0089–0.039

0.0016–0.0088

<0.0016

Kilograms per square kilometer

per county per year

Glacier

Rocky Mountain

Source: http://ca.water.usgs.gov/pnsp

0 300 600 KILOMETERS

0 300 600 MILES
an entire year, annual deposition rates for total endosulfans, 

dacthal, and chlorothalonil in ROMO were estimated around 

0.7, 1.0, and 1.2 μg/m2, respectively. Using long-term precipitation data at Flattop Mountain (196 cm), annual deposition 

for endosulfan, dacthal, and chlorothalonil in GLAC was 

estimated to be around 3.0, 1.2, and 1.0 μg/m2, respectively. 

The higher rates in GLAC compared to ROMO are largely a 

function of greater precipitation amounts in GLAC. These estimates of annual deposition are likely biased low on the basis 

of results from a recent study in ROMO that found pesticide 

concentrations in summer rain were substantially higher than 

in snow (Mast and others, 2003). For example, if the annual 

deposition rate of dacthal (the only pesticide measured in 

both studies) is recalculated for ROMO by using the average concentration in rain (6.1 ng/L) for the summer months 

(May–October), annual deposition increases to 3.0 μg/m2 with 

0.6 μg/m2 deposited during winter and 2.4 μg/m2 deposited 

during summer. This estimate is three times higher than the 

estimate based on snowpack concentrations alone and emphasizes the importance of year-round monitoring of precipitation 

chemistry to improve estimates of pesticide deposition rates to 

high-elevation ecosystems.

To place the snowpack results in some perspective, concentrations of selected current-use pesticides in this study are 

compared to precipitation data from other studies conducted 

in remote mountainous regions (table 16). In similar studies in 

ROMO, pesticides were measured in snow samples that were 

collected in spring of 2001 from four sites (Mast and others, 

2001) and in rain samples collected near Bear Lake during 

summer of 2002 (Mast and others, 2003). Snow also was 

collected in ROMO in 2002–03 as part of the NPS Western 

Airborne Contaminants Assessment Project (WACAP). This 

program was initiated by the NPS to determine the risk to 

ecosystems and food webs in Western National Parks from the 

long-range transport of airborne contaminants (National Park 

Service, 2004). Concentrations of dacthal in snow were similar 

among the three studies in ROMO and varied by less than 

a factor of 4. By contrast, concentrations of dacthal in rain 

(3–9.3 ng/L) were as much as an order of magnitude higher 

than those measured in the snow (0.48–2.2 ng/L). Among the 

three ROMO studies, atrazine only was detected in snow collected during 2001 (Mast and others, 2001). Similar to dacthal, 

there were substantially higher atrazine concentrations in rain 

(14.7–60 ng/L) compared to snow (1.0–3.1 ng/L). Carbaryl 

was detected in nearly every rain sample in ROMO at concentrations as high as 95 ng/L but was detected in only one snow 

sample at a very low concentration (0.82 ng/L). The large 

difference in concentrations between snow and rain is not 

surprising considering that pesticide concentrations in air and 

precipitation generally are highest in spring and summer coinciding with pesticide application times and warmer temperatures that increase revolatilization from soil and plant surfaces 

(Majewski and Capel, 1995; Carrera and others, 2002; Carlson 

and others, 2004). The organophosphorus insecticides (chlorpyrifos, diazinon, and malathion) were the most frequently 

detected pesticides in rain and snow samples collected in the 

Sierra Nevada. This pattern is consistent with heavy usage of 

these pesticides in the Central Valley of California where pesticides are applied throughout the year (McConnell and others, 

1998; Majewski and others, 2005).

For the organochlorine pesticides, endosulfan I was the 

most commonly detected compound in rain and snow from 

remote mountainous areas (table 16). Concentrations of 

endosulfan I in snow were similar among the three studies 

in ROMO and were similar to those measured in snow from 

the Canadian Rockies (Blais and others, 1998) and from a 

high-elevation site (1,920 m) in the Sierra Nevada (McConnell 

and others, 1998). Lindane (γ-HCH) was detected in the 2001 

ROMO snow samples (0.6–1.1 ng/L) but not in any samples 

collected as part of the current study. Lindane also was 

detected in the 2002–03 samples collected as part of WACAP 

(National Park Service, 2005) but in concentrations nearly an 

order of magnitude lower than those measured in the 2001 

ROMO snow. Blais and others (1998) detected several organochlorine compounds in snow collected along an elevation gradient in western Canada including HCH, heptachlorepoxide, 

dieldrin, DDT, and chlordane. Although the concentrations 

were very low (less than 1 ng/L), concentrations of most compounds tended to increase with elevation due to the effects of 

cold-condensation. In a similar study in mountainous regions 

of Europe, several organochlorine compounds were detected 

in snow, also at very low concentrations. For example, PCBs 

ranged from 0.20 to 2.2 ng/L and γ-HCH ranged from 0.02 to 

1.1 ng/L (Carrera and others, 2001). Dieldrin, HCB, and transnonachlor were the only historical-use pesticides detected in 

snow samples collected as part of this study.

Lake Sediment

Because sediments are recognized as a primary reservoir of organic contaminants to fish, surface sediments were 

collected to investigate occurrence and distribution of these 

compounds in park lakes and to determine if current levels 

of these compounds in lake sediment might pose a risk to 

aquatic organisms. The lakes selected for this study were 

high-elevation, oligotrophic lakes (fig. 11, table 2) that supported trout populations. In ROMO, the lowest lake was Fern 

Lake at 2,903 m and the highest was Timber Lake at 3,371 m. 

The lakes in GLAC were lower in elevation, ranging from 

1,463 m at Akokala Lake to 1,926 m at Stoney Indian Lake. 

The smallest lake in ROMO was Fifth Lake at 1.8 ha, and the 

largest was Lake Nanita at 12.6 ha. The lakes in GLAC were 

slightly larger in area, ranging from 4.2 ha at Noname Lake to 

15.2 ha at Slide Lake. The shallowest lake was Lake Janet in 

GLAC at 2 m, and the deepest was Black Lake in ROMO at 

30 m.

All 11 surface-sediment samples from ROMO had low 

but detectable concentrations of DDE, which ranged from 

0.62 μg/kg (dry weight) in Fifth Lake to 15 μg/kg in Lake 

40 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 16. Comparison of organic compound concentrations in snow and rain from remote mountainous regions.

[nd, not detected; --, not analyzed or not reported; ROMO, Rocky Mountain National Park; GLAC, Glacier National Park; concentrations in nanograms per liter; NPS, National Park Service]

Site Type Atrazine Carbaryl Chloro- thalonil Chlor- pyrifos Dacthal Diazinon Endo- sulfan I HCB

α-HCH γ-HCH (Lindane) Mala- thion PCB Reference

ROMO Snow nd 0.821 0.51–2.36 nd 0.48–2.2 nd 0.27–.79 0.081 nd nd nd nd this studyROMO Snow 1.0–3.1 nd -- nd 0.8–1.1 nd 1.5–2.5 nd nd 0.6–1.1 nd -- Mast and others, 

2001

ROMO Snow -- -- -- 0.031 0.95–1.1 -- 0.92–1.3 0.0071 0.08–.14 0.07–.12 -- -- NPS, 2005ROMO Rain 14.7–60 7.9–95 -- nd 3–9.3 nd -- -- -- nd 661 -- Mast and others, 

2003

GLAC Snow nd nd nd 2.111 0.27–1.05 nd 0.24–1.06 nd nd nd nd nd this studySierra 

Nevada

Snow/rain -- -- 0.66–85 0.30–13 -- 3.7–19 0.93–6.5 -- -- 0.39–1.87 3.6–24 -- McConnell and 

others, 1998

Canadian 

Rockies

Snow -- -- -- -- -- -- 0.03–0.5 -- 0.06–0.78 0.05–0.35 -- 0.30–2.17 Blais and others, 

1998

Canadian 

Arctic2

Snow -- -- -- -- -- -- 0.09–1.3 -- 0.43–8.7 0.22–5.3 -- 0.02–1.8 Gregor and Gummer, 

1989

Europe Snow -- -- -- -- -- -- -- .025–0.22 -- 0.02–1.13 -- 0.2–2.2 Carrera and others, 

2001

Europe Snow/rain -- -- -- -- -- -- 0.03–45 0.03–0.22 0.30–0.48 1.5–5.6 -- 0.32–2.8 Carrera and others, 

2002

1Detected in only one sample.2Remote but nonmountainous area.3Sum of 

α-HCH and γ-HCH.

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment  41
Nanita (table 17). The relatively high concentration at Lake 

Nanita, however, is likely an analytical artifact related to the 

higher reporting levels for this sample, which resulted from 

a low sample dry weight. For this reason, the DDE value 

for Lake Nanita is not included in the following discussion. 

Surface sediment from 8 of the 11 lakes also had detectable 

DDD, but only Black Lake had a detectable concentration of 

DDT. In GLAC, 9 of the 10 lakes also had detectable concentrations of DDE in surface sediments. Only two lakes, Lake 

Janet and Stoney Indian Lake, had detectable concentrations 

of DDD and none of the sampled lakes had detectable DDT 

in surface sediment (table 18). The range of concentrations of 

DDD, which likely was formed in the anoxic lake sediments, 

was much narrower than DDE, which was formed either in 

oxidized surface sediments or was degraded before transport 

and burial. Sediment concentrations of DDE and DDD were 

not related to lake elevation, surface area or depth, or lake 

location relative to the Continental Divide. The only notable 

spatial pattern was higher DDE and DDD concentrations in 

ROMO compared to GLAC (fig. 12), which might reflect 

closer proximity of ROMO to urban and agricultural areas 

compared to GLAC. Alternatively, the pattern in surfacesediment concentrations could simply be due to differences in 

sediment accumulation rates between the two parks. This latter 

explanation is plausible considering that GLAC is underlain 

by sedimentary bedrock types that are more erodible than the 

granitic and gneissic bedrock that underlies ROMO, which 

would result in lower sediment concentrations in GLAC. DDE 

and DDD concentrations in surface sediments of all lakes were 

below the probable effect concentration (PEC) of 31.3 μg/kg 

for DDE and 28.0 μg/kg for DDD. The PEC represents sediment concentrations above which harmful effects for benthic 

A B

C D

Figure 11. Character of lakes sampled for sediment during the study including (A) Akokala Lake and (B) Stoney Indian Lake in Glacier 

National Park and (C) Lone Pine Lake and (D) Sky Pond in Rocky Mountain National Park.

42 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 17. Concentrations of organochlorine compounds analyzed by gas chromatography/electron-capture detection in lake-sediment samples collected in Rocky Mountain 

National Park in 2002.[<, less than; E, estimated concentration; --, not determined; %, percent; concentrations in micrograms per kilogram of sediment (dry weight); shaded cells denote detectable concentrations]

Compound

Black 

Lake

07/31/2003

Fern 

Lake

07/11/2002

Fifth 

Lake

08/13/2002

Lake 

Haiyaha

08/13/2003

Lake 

Nanita

08/14/2002

Lone Pine 

Lake

08/12/2002

Mirror 

Lake

08/2/2002

Sandbeach 

Lake

07/22/2002

Sky 

Pond

09/6/2002

Timber 

Lake

08/1/2002

Ypsilon 

Lake

07/24/2003

Aldrin <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Chlordane, technical <15 <25 <10 <15 <110 <35 <80 <15 <15 <40 <55

cis-Chlordane <1.5 -- -- <1.5 -- -- -- -- -- -- <5.5trans-Chlordane <1.5 -- -- <1.5 -- -- -- -- -- -- <5.5p,p’-DDD 2.20 E2.3 E0.60 <1.5 12 E2.3 <8.0 3.8 E0.80 E2.2 <9.0

p,p’-DDE 4.7 2.8 E0.62 E0.9 15 E3.1 E0.96 3.5 E 0.9 E3.5 E3.1

p,p’-DDT E0.9 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Dieldrin <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Endosulfan I <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Endrin <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

γ-HCH (Lindane) <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Heptachlor <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

Heptachlor epoxide <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

p,p’-Methoxychlor <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0

Mirex <1.5 <2.5 <1.0 <1.5 <11 <3.5 <8.0 <1.5 <1.5 <4.0 <5.5

trans-Nonachlor <1.5 -- -- <1.5 -- -- -- -- -- -- <5.5PCB Aroclor 1242 <15 <25 <10 <15 <110 <35 <80 <15 <15 <4.0 <55

PCB Aroclor 1254 <15 <25 <10 <15 <110 <35 <80 <15 <15 <4.0 <55

PCB Aroclor 1260 <15 <25 <10 <15 <110 <35 <80 <15 <15 <4.0 <55

Toxaphene <150 <250 <100 <150 <1100 <350 <800 <150 <150 <400 <550

α-HCH-d6 surrogate, % recovery 101 74 78 107 63 76 72 80 77 72 100Isodrin surrogate, % recovery 77 55 49 76 56 56 40 52 52 59 53PCB 207 surrogate, % recovery 52 73 66 53 46 76 63 56 72 54 43

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment  43
Table 18. Concentrations of organochlorine compounds analyzed by gas chromatography/electron-capture detection in lake-sediment samples collected in Glacier National 

Park in 2002–03.[<, less than; E, estimated concentration; --, not determined; %, percent; concentrations in micrograms per kilogram of sediment (dry weight); shaded cells denote detectable concentrations]

Compound

Akokala

Lake

09/20/2002

Atsina

Lake

09/11/2003

Lake

Janet

09/13/2003

Lower 

Snyder

Lake

09/19/2002

Mokowanis

Lake

09/10/2003

Noname

Lake

09/18/2002

Redrock

Lake

09/17/2002

Slide

Lake

09/9/2003

Stoney

Indian

Lake

09/12/2003

Upper 

Bullhead

Lake

09/17/2002

Aldrin <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Chlordane, technical <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10.0 <5.0 <5.0

cis-Chlordane -- <0.5 <0.5 -- <0.5 -- -- <1.0 <0.5 --trans-Chlordane -- <0.5 <0.5 -- <0.5 -- -- <1.0 <0.5 --p,p’-DDD <0.5 <0.5 E0.5 <0.5 <0.5 <0.5 <0.5 <1.0 E0.4 <0.5

p,p’-DDE E0.12 0.9 E0.7 E0.22 0.88 E0.23 E0.28 <1.0 0.8 E0.34

p,p’-DDT <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Dieldrin <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Endosulfan I <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Endrin <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

γ-HCH (Lindane) <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Heptachlor <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

Heptachlor epoxide <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

p,p’-Methoxychlor <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <2.0 <4.0 <2.0 <2.0

Mirex <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <1.0 <0.5 <0.5

trans-Nonachlor -- <0.5 <0.5 -- <0.5 -- -- <1.0 <0.5 --PCB Aroclor 1242 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10.0 <5.0 <5.0

PCB Aroclor 1254 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10.0 <5.0 <5.0

PCB Aroclor 1260 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <10.0 <5.0 <5.0

Toxaphene <50 <50 <50 <50 <50 <50 <50 <100 <50 <50

α-HCH-d6 surrogate, % recovery 73 108 96 90 101 92 89 91 98 102Isodrin surrogate, % recovery 52 82 67 56 67 48 47 82 81 56PCB 207 surrogate, % recovery 72 73 80 71 72 64 66 64 62 87

44  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
organisms are likely to be observed (MacDonald and others, 

2000). Discounting Lake Nanita, three ROMO sediments were 

above the threshold effect concentrations (TEC) of 3.16 μg/kg 

for DDE and no sediments exceeded the TEC of 4.88 μg/kg 

for DDD. The TEC represents concentrations below which 

harmful effects for benthic organisms are unlikely to be 

observed (MacDonald and others, 2000). The other 14 organochlorine pesticides and 3 PCB aroclors (tables 17–18) and the 

27 PCB congeners (2002 samples only, not shown in tables) 

analyzed by GC/ECD were not detected in any of the lakesediment samples collected during the study.

DDE and DDD are degradation products of DDT, which 

is a well-documented, persistent organochlorine insecticide 

that has been banned from use in the United States since 

1972. DDT and its degradates are of concern because they are 

endocrine-disrupting compounds that accumulate in the food 

chain and persist in the environment for long periods of time 

(Majewski and Capel, 1995; Tyler and others, 1998). Because 

the lakes in ROMO and GLAC are remote and there is no 

reported use of DDT in either park, the presence of DDE and 

DDD is likely the result of long-range atmospheric transport 

and subsequent wet and dry deposition to the lake and watershed. The source of these compounds in recent sediments (last 

10 to 15 years) is unknown particularly because they have not 

been used in the United States since 1972. Recent air-quality 

studies in North America indicate DDT in the atmosphere is 

from an aged source such as volatilization from agricultural 

or forest soils that were contaminated in the past (Shen and 

others, 2005). Another possibility is long-range transport 

from distant sources in Central America or Asia where some 

banned compounds are still in use (National Park Service, 

2005; Shen and others, 2005). Neither DDT nor its degradates 

were detected in any of the snow samples collected during this 

study. This may be because the analytical detection limits in 

this study were not low enough to detect these compounds in 

snow. In a similar study, Usenko and others (2005) also did not 

detect DDT or its degradates in snow collected in ROMO in 

2003, even though their detection limits were an order of magnitude lower than those in this study. The lack of detectable 

DDT in snow may indicate that atmospheric deposition of this 

compound may not be dominated by deposition to the snowpack. Other potential atmospheric inputs of DDT are from wet 

and dry deposition to the lake and watershed during summer 

months and gas exchange between the air and lake water during the ice-free season (Blais and others, 2001).

Although DDD and DDE were detected in most of the 

surface sediments analyzed, the concentrations were very 

low and probably pose little threat to aquatic organisms. It is 

possible, however, that concentrations of these compounds 

may increase with sediment depth (and age) due to greater use 

in the past. Van Metre and Mahler (2005) found significant 

declines in sediment DDT, DDE, and PCB concentrations 

between 1970 and 2001 in sediment cores collected from 

lakes across the United States, reflecting the discontinued 

use of these compounds in North America over the past 

3 decades. Although older sediments were not analyzed as 

Figure 12. Range of DDD and DDE concentrations in surface sediments from lakes in Rocky 

Mountain National Park and Glacier National Park.

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment  45

0 

1 

2 

3 

4 

5 

SURFACE SEDIMENT CONCENTRATION,

IN MICROGRAMS PER KILOGRA

M

DDE 

Rocky Mountain 

National Park 

Glacier 

National Park 

DDD DDE DDD 

n=10 

n=7 

n=9 

n=2 

6 

Outlier 

90th percentile

75th

50th (median)

25th

10th 

EXPLANATION 

DDD threshold effect concentration 

DDE threshold effect concentration 
part of this study, Mills Lake (2 km downstream from Black 

Lake in ROMO) was cored, dated, and analyzed for OCCs by 

the USGS in 1999 (P.C. Van Metre, U.S. Geological Survey, 

unpub. data, 2000). DDD and DDE concentrations in the 

Mills Lake sediment core show distinct increases with depth 

(fig. 13), and the highest concentrations were measured in 

sediments deposited during the 1970s (4.0 μg/kg DDE and 

9.7 μg/kg DDD), which correlates with its ban from usage in 

North America in 1972. The results at Mills Lake indicate that 

concentrations of some OCCs measured in this study likely are 

higher at greater depths in undisturbed bottom sediments of 

lakes. These results also indicate that atmospheric deposition 

of DDT and possibly other banned organochlorine compounds 

to ROMO and other high-elevation parks has been in decline 

since the 1970s.

Lakes sampled in 2003, which included Black Lake, 

Lake Haiyaha, and Ypsilon Lake in ROMO and Atsina Lake, 

Lake Janet, Mokowanis Lake, Slide Lake, and Stoney Indian 

Lake in GLAC, also were analyzed for CUPs by GC/EIMS 

and OHCs by GC/ECNIMS. Only one CUP, dacthal, was 

detected in the lake sediments by GC/EIMS (table 19). Nine 

OHCs were detected by GC/ECNIMS: trans-chlordane, 

dacthal, DDE, endosulfan sulfate, HCB, cis-nonachlor, transnonachlor, and PCB congeners 180 and 187 (table 20).

Of these compounds, endosulfan sulfate was detected 

most frequently and occurred in six of the eight sediments 

analyzed including two lakes in ROMO and four lakes in 

GLAC. The highest concentrations of endosulfan sulfate 

were measured in Black Lake (0.44 μg/kg) and Ypsilon Lake 

(1.2 μg/kg), both of which are on the east side of ROMO. 

Concentrations in the GLAC lakes were lower, ranging from 

0.12 to 0.15 μg/kg. These results are consistent with the 

snow samples in which endosulfans (endosulfan I, endosulfan II, and endosulfan sulfate) were detected in nearly all of 

the snow samples, indicating that atmospheric deposition is 

the primary source of this pesticide entering park lakes. In 

contrast to snow, only the degradation product endosulfan 

sulfate was detected in sediments, indicating that the isomers 

(endosulfan I and II) are metabolized to endosulfan sulfate in 

the aquatic environment. Endosulfan sulfate typically is more 

persistent in aqueous environments than either of the parent 

isomers due to its longer half-life in water and soil (Peterson 

and Batley, 1993). Endosulfan in bed sediment has been 

shown to be toxic to aquatic invertebrates (Leonard and others, 

2001), although currently there are no established sediment 

guidelines for aquatic life.

Dacthal was detected in four of the eight sediments 

analyzed by GC/ECNIMS: Black Lake in ROMO and Atsina 

Lake, Mokowanis Lake, and Stoney Indian Lake in GLAC 

(table 20). In three of these four samples, dacthal also was 

detected by GC/EIMS (table 19), confirming its presence in 

the sediments. Dacthal is considered a general hazard to fish, 

although there are no established guidelines for concentrations 

in sediment or surface water (Stephens and Deacon, 1997). 

As observed for endosulfans, dacthal was detected in nearly 

all of the snow samples, providing evidence that atmospheric 

deposition is the source of dacthal in lake sediments. Dacthal 

also was detected in summer precipitation samples collected 

on the east side of ROMO near Bear Lake (Mast and others, 

2003), although at concentrations substantially higher than 

those measured in snow. Other current-use pesticides commonly detected in snow (this study) and rain (Mast and others, 

2003) include atrazine, carbaryl, and chlorothalonil; however, 

none of these pesticides were detected in lake sediments. This 

pattern is reasonable because endosulfan and dacthal are more 

hydrophobic and persistent than many other current-use pesticides and therefore have a higher potential to accumulate in 

sediment and aquatic biota (Nowell and others, 1999).

Of the historical-use pesticides analyzed by GC/ECNIMS, 

components of chlordane (trans-chlordane, cis-nonachlor, 

trans-nonachlor) were detected most frequently, with at least 

one component occurring in four of the eight sediment samples 

analyzed. Technical chlordane was used as an insecticide and 

termiticide until the early 1980s when most of these uses were 

restricted in North America (http://www.epa.gov/pbt/pubs/

chlordane.htm, accessed June 2006). Chlordane use in agriculture, primarily on corn, was discontinued in 1978. Commercial 

use of chlordane was banned in 1988 where it primarily was 

used in urban areas for control of termites, although it was still 

permitted for use by homeowners after 1988. The concentrations of the chlordane components detected in the lake sediments (0.10–1.0 μg/kg) were well below the threshold effect 

level of 3.24 μg/kg for chlordane reported by MacDonald and 

others (2000). Of the chlordane components, trans-nonachlor 

Figure 13. Concentrations of DDD and DDE in a lake-sediment 

core from Mills Lake in Rocky Mountain National Park 

(unpublished data, P. Van Metre, USGS).

46  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03

0

5

10

15

20

SEDIMENT DEPTH, IN CENTIMETERS

0.0 5.0 10.0

CONCENTRATION,

IN MICROGRAMS PER KILOGRAM

1863

1891

1918

1946

1970

1990

SEDIMENT DATING AGE, BY YEAR

DDD

DDE
Table 19. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in lake-sediment samples collected in Rocky 

Mountain National Park and Glacier National Park in 2003.—Continued[<, less than; E, estimated concentration; %, percent; concentrations reported in micrograms per kilogram of sediment (dry weight); shaded cells denote detectable concentrations]

Compound

Rocky Mountain National Park Glacier National Park

Black 

Lake

07/31/2003

Lake 

Haiyaha

08/13/2003

Ypsilon 

Lake

07/24/2003

Atsina 

Lake

09/11/2003

Lake 

Janet

09/13/2003

Mokowanis 

Lake

09/10/2003

Slide 

Lake

09/9/2003

Stoney Indian 

Lake

09/12/2003

Acetochlor <1 <2.0 <1 <1 <1 <1 <1 <1Alachlor <1 <1 <1 <1 <1 <1 <1 <1Atrazine <1 <1 <1 <1 <1 <1 <1 <1Azinphos-methyl <5 <5 <5 <5 <5 <5 <5 <5Azinphos-methyl, oxygen analog <30 <30 <30 <30 <30 <30 <30 <30Benfluralin <1 <1 <1 <1 <1 <1 <1 <1Carbaryl <2 <2 <2 <2 <2 <2 <2 <22-Chloro-2,6-diethylacetanilide <1 <1 <1 <1 <1 <1 <1 <1

2-Chloro-4-isopropylamino-6-amino-s-triazine <2 <2 <2 <2 <2 <2 <2 <2

4-Chloro-2-methylphenol <10 <10 <10 <10 <10 <10 <10 <10

Chlorpyrifos <1 <1 <1 <1 <1 <1 <1 <1

Chlorpyrifos oxygen analog <30 <30 <30 <30 <30 <30 <30 <30

Cyfluthrin <20 <20 <20 <20 <20 <20 <20 <20

Cypermethrin <20 <20 <20 <20 <20 <20 <20 <20

Dacthal E0.25 <1 <1 E0.10 <1 <1 <1 E0.09

Diazinon <1 <1 <1 <1 <1 <1 <1 <1

Diazinon, oxygen analog <5 <5 <5 <5 <5 <5 <5 <5

3,4-Dichloroaniline <75 <75 <75 <75 <75 <75 <75 <75

Dichlorvos <30 <30 <30 <30 <30 <30 <30 <30

Dicrotophos <3 <3.6 <3 <3 <3 <3 <3 <3

Dieldrin <2 <2 <2 <2 <2 <2 <2 <2

2,6-Diethylaniline <30 <30 <30 <30 <30 <30 <30 <30

Dimethoate <2 <53 <2 <2 <8.0 <2 <2 <2

Ethion <2 <2 <2 <2 <2 <2 <2 <2

Ethion monoxon <2 <2 <2 <2 <2 <2 <2 <2

2-Ethyl-6-methylaniline <30 <30 <30 <30 <30 <30 <30 <30

Fenamiphos <30 <30 <30 <30 <30 <30 <30 <30

Fenamiphos sulfone <10 <10 <10 <10 <10 <10 <10 <10

Fenamiphos sulfoxide <10 <10 <10 <10 <10 <10 <10 <10

Fipronil <1 <1 <1 <1 <1 <1 <1 <1

Fipronil sulfide <1 <1 <1 <1 <1 <1 <1 <1

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment  47
Table 19. Concentrations of current-use pesticides analyzed by gas chromatography/electron-impact mass spectrometry in lake-sediment samples collected in Rocky 

Mountain National Park and Glacier National Park in 2003.—Continued[<, less than; E, estimated concentration; %, percent; concentrations reported in micrograms per kilogram of sediment (dry weight); shaded cells denote detectable concentrations]

Compound

Rocky Mountain National Park Glacier National Park

Black 

Lake

07/31/2003

Lake 

Haiyaha

08/13/2003

Ypsilon 

Lake

07/24/2003

Atsina 

Lake

09/11/2003

Lake 

Janet

09/13/2003

Mokowanis 

Lake

09/10/2003

Slide 

Lake

09/9/2003

Stoney Indian 

Lake

09/12/2003

Fipronil sulfone <1 <1 <1 <1 <1 <1 <1 <1Fipronil, desulfinyl <1 <1 <1 <1 <1 <1 <1 <1Fipronil amide, desulfinyl <1 <1 <1 <1 <1 <1 <1 <1Fonofos <1 <1 <1 <1 <1 <1 <1 <1Fonofos, oxygen analog <5 <5 <5 <5 <5 <5 <5 <5Hexazinone <44 <23 <45 <1 <1 <1 <1 <1Iprodione <10 <10 <10 <10 <10 <10 <10 <10Isofenphos <2 <2 <2 <2 <2 <2 <2 <2Malathion <2 <2 <2 <2 <2 <2 <2 <2Malathion, oxygen analog <5 <5 <5 <5 <5 <5 <5 <5Metalaxyl <1 <1 <1 <1 <1 <1 <1 <1Methidathion <2 <18.0 <2 <2 <2 <2 <2 <2Metolachlor <1 <1 <1 <1 <3.0 <1 <1 <1Metribuzin <4 <5.0 <4 <4 <4 <4 <4 <4Myclobutanil <10 <1 <1 <1 <1 <1 <1 <11-Naphthol <10 <10 <10 <10 <10 <10 <10 <10Parathion-methyl <2 <2 <2 <2 <2 <2 <2 <2Parathion-methyl, oxygen analog <5 <5 <5 <5 <5 <5 <5 <5Pendimethalin <1 <1 <1 <1 <1 <1 <1 <1Phorate <5 <5 <5 <5 <5 <5 <5 <5Phorate, oxygen analog <7 <7 <7 <7 <7 <7 <7 <7Prometon <2 <2 <2 <2 <2 <2 <2 <2Prometryn <2 <2 <2 <2 <2 <2 <2 <2cis-Permethrin <5 <5 <5 <5 <5 <5 <5 <5trans-Permethrin <5 <5 <5 <5 <5 <5 <5 <5Propyzamide <2 <2 <2 <2 <2 <2 <2 <2Simazine <2 <2 <2 <2 <2 <2 <2 <2Tebuthiuron <3 <3 <3 <3 <3 <3 <3 <3Terbufos <3 <3 <3 <3 <3 <3 <3 <3Terbufos-oxygen analog sulfone <5 <5 <5 <5 <5 <5 <5 <10Terbuthylazine <1 <1 <1 <1 <1 <1 <1 <1Trifluralin <1 <1 <1 <1 <1 <1 <1 <1α-HCH-d6 surrogate, % recovery 50 61 67 60 52 58 133 85Diazinon-d10 surrogate, % recovery 122 123 106 124 108 116 106 114

48  Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Table 20. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass 

spectrometry in lake-sediment samples collected in Rocky Mountain National Park and Glacier National Park in 2003.—Continued

[<, less than; E, estimated concentration; %, percent; concentrations reported in micrograms per kilogram of sediment (dry weight); shaded cells denote 

detectable concentrations; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound

Rocky Mountain National Park Glacier National Park

Black 

Lake

7/31/2003

Lake 

Haiyaha

8/13/2003

Ypsilon 

Lake

7/24/2003

Atsina 

Lake

9/11/2003

Lake 

Janet

9/13/2003

Mokowanis 

Lake

9/10/2003

Slide 

Lake

9/9/2003

Stoney Indian 

Lake

9/12/2003

Aldrin <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

Benfluralin <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Chlorpyrifos <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

cis-Chlordane <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

trans-Chlordane <0.1 <0.1 0.68 <0.1 <0.1 <0.1 <0.1 <0.1

Dacthal (DCPA) E0.26 <0.27 <0.80 E0.13 <0.12 E0.11 <0.1 E0.12

o,p’-DDD <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

o,p’-DDE <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

o,p’-DDT <6.4 <6.4 <6.4 <6.4 <6.4 <6.4 <6.4 <6.4

p,p’-DDD <15 <15 <15 <15 <15 <15 <15 <15

p,p’-DDE 3.5 <4.0 <4.0 <4.0 <4.0 <4.0 <4.0 <4.0

Dieldrin <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

Endosulfan I <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Endosulfan II <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Endosulfan sulfate 0.44 <0.2 E1.2 E0.15 E0.15 E0.12 <0.2 E0.12

Endrin <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

Endrin aldehyde <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

Endrin ketone <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

Fipronil <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4

Fiponil sulfide <6.4 <6.4 <6.4 <6.4 <6.4 <6.4 <6.4 <6.4

Fipronil amide, desulfinyl <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

α-HCH <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

β-HCH <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

δ-HCH <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

γ-HCH (Lindane) <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

Heptachlor epoxide <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

Hexachlorobenzene (HCB) <0.34 E2.3 <1.2 <0.13 <0.16 <0.11 <0.18 <0.14

Mirex <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

cis-Nonachlor 0.31 <0.2 1.0 0.13 <0.2 <0.2 <0.2 <0.2

trans-Nonachlor E0.29 <0.2 0.94 0.11 <0.2 <0.2 <0.2 0.10

Octachlorostyrene <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

Oxychlordane <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

Pentachloroanisole (PCA) <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Trifluralin <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB congeners

PCB 70 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6 <1.6

PCB 101 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

PCB 110 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8 <0.8

PCB 118 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 138 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 146 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 149 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4 <0.4

PCB 151 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 170 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment  49
was detected in only one snow sample (table 15) collected during the study, perhaps because the analytical detection limits 

were not low enough to detect these compounds.

To date, there have been few studies of pesticides and 

other organic compounds in lake or stream sediment in highelevation parks in the Western United States against which to 

compare the results of this study. The most comparable data 

are from the sediment core collected at Mills Lake by the 

USGS in 1999 (P.C. Van Metre, unpub. data, 2000). The surface sediments (0–3 cm) from Mills Lake, which is about 2 km 

downstream from Black Lake, had a DDD concentration of 3.2 

μg/kg and a DDE concentration of 2.7 μg/kg, which are very 

similar to the concentrations in Black Lake (2.2 μg/kg DDD 

and 4.7 μg/kg DDE; table 17) measured in this study. Stephens 

and Deacon (1997) analyzed streambed sediment and wholebody fish samples from the Colorado River near the western 

boundary of ROMO as part of the USGS National Water-Quality Assessment Program (NAWQA). None of the 33 organochlorine pesticides and PCBs analyzed for, which included 

DDT, DDE, and dacthal, were detected in the sediment; 

however, DDE was detected in a brown trout tissue sample 

collected at the same site. Sediment and fish tissue from North 

Saint Vrain Creek near the southeast boundary of ROMO were 

analyzed for organochlorine pesticides and PCBs as part of the 

South Platte NAWQA study (Tate and Heiny, 1996). Similar to 

the other NAWQA study, no organochlorine compounds were 

detected in sediment at this site and only DDE was detected 

in fish tissue. Heit and others (1984) determined levels of the 

PCB and PAHs in surface sediments (0–2 cm) from four lakes 

in ROMO including Lake Haiyaha, which was sampled as part 

of this study. Total PCB concentrations in the lakes ranged 

from 21 to 540 μg/kg (dry weight), and PAH concentrations 

(not measured in this study) ranged from 80 to 375 μg/kg. 

The total PCB concentration at Lake Haiyaha was 160 μg/kg 

compared to less than 15 μg/kg measured as part of this study. 

This may reflect differences in the age of the lake sediments, 

which were nearly 20 years older in the Heit and others (1984) 

study than sediments analyzed as part of this study.

Sediment cores from lakes in six National Parks in the 

Western United States (including ROMO and GLAC) are 

being collected and analyzed for semivolatile organic compounds as part of WACAP (National Park Service, 2004). 

Preliminary results from Pear Lake in Sequoia National 

Park in California showed detectable levels of endosulfans 

and dieldrin in lake sediments that were deposited after 

2000 (National Park Service, 2005). Rhea and others (2005) 

measured PAH concentrations in sediment from lakes in 

Grand Teton National Park in Wyoming. Sediment concentrations of total PAHs ranged from 5.7 to 471 μg/kg, which 

were largely attributed to terrestrial and biogenic sources 

rather than anthropogenic sources. Several organochlorine 

compounds were measured in a sediment core from Wonder 

Lake in Denali National Park in Alaska (Cubala and others, 

1995). Both DDE and DDT were detected only in surface 

sediments (less than 40 years old) at concentrations of 0.32 

and 0.15 μg/kg, respectively (Cubala and others, 1995). Other 

detected compounds in surface sediments from Wonder Lake 

included chlordane, γ-HCH (lindane), HCB, and several PCB 

congeners. In conclusion, this comparison indicates detections 

and concentrations of pesticides and other organic compounds 

observed in this study are similar to published results for 

similar studies.

Table 20. Concentrations of organohalogen compounds analyzed by gas chromatography/electron-capture negative ion mass 

spectrometry in lake-sediment samples collected in Rocky Mountain National Park and Glacier National Park in 2003.—Continued

[<, less than; E, estimated concentration; %, percent; concentrations reported in micrograms per kilogram of sediment (dry weight); shaded cells denote 

detectable concentrations; PCB, polychlorinated biphenyls; PBDE, polybrominated diphenyl ethers]

Compound

Rocky Mountain National Park Glacier National Park

Black 

Lake

7/31/2003

Lake 

Haiyaha

8/13/2003

Ypsilon 

Lake

7/24/2003

Atsina 

Lake

9/11/2003

Lake 

Janet

9/13/2003

Mokowanis 

Lake

9/10/2003

Slide 

Lake

9/9/2003

Stoney Indian 

Lake

9/12/2003

PCB congeners—Continued

PCB 174 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 177 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 180 0.37 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 183 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 187 0.29 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 194 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PCB 206 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

PBDE congeners

PBDE 47 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

PBDE 99 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

PBDE 100 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

PBDE 153 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

PBDE 154 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2 <3.2

α-HCH-d6 surrogate, 

% recovery

55 56 55 61 58 62 65 70

50 Organochlorine Compounds and Current-Use Pesticides in Snow and Lake Sediment, 2002–03
Summary

This report describes the occurrence and distribution of 

selected organochlorine compounds and current-use pesticides in snow and lake-sediment samples collected in Rocky 

Mountain National Park (ROMO) in Colorado and Glacier 

National Park (GLAC) in Montana during 2002–03. This 

study was conducted in cooperation with the National Park 

Service to provide baseline information on organic contaminants and to assess if current levels of these compounds pose 

a threat to aquatic organisms. This report includes data for 

snow samples that were collected at eight sites in ROMO 

and eight sites in GLAC during spring of 2002 and 2003 and 

data for surface sediments that were collected at 11 lakes 

in ROMO and 10 lakes in GLAC during summer months of 

2002 and 2003. Samples were analyzed for organochlorine 

compounds by gas chromatography with electron-capture 

detection and current-use pesticides by gas chromatography 

with electron-impact mass spectrometry. A subset of samples 

was reanalyzed using a third instrumental technique (gas chromatography with electron-capture negative ion mass spectrometry) to verify detected concentrations in the initial analysis 

and to investigate the presence of additional compounds.

Because atmospheric deposition is the primary pathway 

by which contaminants enter remote high-elevation areas, snow 

samples were collected to determine which pesticides are currently reaching these ecosystems and at what rates. Snow was 

selected as a sample medium because snowfall provides most of 

the annual precipitation in high-elevation areas. Snow sampling 

has an advantage in that a single full-depth snowpack sample 

collected at maximum accumulation represents wet and dry 

deposition for the entire winter period. The snow sampling sites 

for this study were selected along elevation gradients on each 

side (east-west) of the Continental Divide. In ROMO, snow was 

collected at eight sites that spanned an elevation range of about 

660 m, and in GLAC, snow was collected at eight sites that 

spanned an elevation range of about 700 m.

In snow samples, the pesticides most frequently detected 

were endosulfan, dacthal, and chlorothalonil, all of which are 

chlorinated pesticides that currently are registered for use in 

North America. The insecticide endosulfan (including the isomers endosulfan I, endosulfan II, and the degradate endosulfan 

sulfate) was detected in all of the snow samples analyzed by 

GC/ECNIMS in concentrations ranging from 0.07 to 1.18 ng/L. 

Dacthal, a herbicide, was detected in 50 percent of the samples 

analyzed by GC/EIMS in concentrations ranging from 0.33 to 

2.2 ng/L. Chlorothalonil, a fungicide, was detected in all but 

two of the samples analyzed by GC/ECNIMS in concentrations 

ranging from 0.51 to 2.36 ng/L. Of the historical-use pesticides, 

dieldrin, HBC, and trans-nonachlor were detected in snow but 

only in one sample each. The concentrations of the detected 

pesticides in snow were not related to site elevation or location 

relative to the Continental Divide and were not notably different between forest and meadow sites. Concentrations were 

similar between the two parks with the exception of dacthal, 

which was slightly higher in ROMO compared to GLAC, which 

may reflect closer proximity of ROMO to agricultural areas. 

Because the snow-sampling sites are remote, the most reasonable source of these pesticides is regional atmospheric transport 

from surrounding agricultural areas and subsequent wet and 

dry deposition to the snowpack. Estimated annual deposition 

rates of endosulfan, dacthal, and chlorothalonil were 0.7, 1.0, 

and 1.2 μg/m2 in ROMO and 3.0, 1.2, and 1.0 μg/m2 in GLAC, 

respectively. The larger deposition rates in GLAC primarily 

are a function of greater precipitation amounts in that park. 

Preliminary results indicate deposition during summer months 

was substantially greater than during winter, which emphasizes 

the importance of year-round monitoring to improve estimates 

of pesticide deposition to high-elevation ecosystems.

Surface sediments from lakes were collected to determine 

pesticide occurrence in sediments and if current levels of these 

compounds might pose a risk to aquatic organisms. Sediments 

were collected at 11 lakes in ROMO and 10 lakes in GLAC 

during summer months. Lakes selected for this study were 

high-elevation, oligotrophic lakes that supported trout populations. Lakes in ROMO ranged in elevation from 2,903 to 

3,371 m and lakes in GLAC ranged from 1,463 to 1,926 m.

DDE and DDD were the most frequently detected 

compounds in lake-sediment samples. DDE and DDD are 

degradation products of DDT, which is a well-documented, 

persistent organochlorine insecticide that has been banned 

from use in the United States since 1972. In ROMO, all 

surface-sediment samples had low but detectable concentrations of DDE and one lake had detectable DDT. In GLAC, 

9 of the 10 lakes had detectable concentrations of DDE in 

surface sediment. Although DDD and DDE were detected in 

most of the surface sediments, the concentrations were well 

below levels where harmful effects for benthic organisms are 

observed and probably pose little threat to aquatic organisms. 

Sediment concentrations of DDE and DDD were not related to 

lake elevation, surface area or depth, or lake location relative 

to the Continental Divide. The only notable spatial pattern was 

higher DDE and DDD concentrations in ROMO compared 

to GLAC, which may reflect closer proximity of ROMO to 

urban and agricultural areas. DDD and DDE concentrations in 

a sediment core from Mills Lake in ROMO showed increases 

with depth with the highest concentrations measured in sediments deposited during the 1970s, which correlates with its 

ban from usage in 1972. This result indicates that atmospheric 

deposition of DDT and possibly other banned organochlorine 

compounds to high-elevation parks has been in decline since 

their agricultural and industrial uses were discontinued.

Other commonly detected compounds in lake sediments included dacthal, endosulfan sulfate, and chlordane. 

Dacthal was detected in 50 percent of samples and endosulfan sulfate was detected in 75 percent of samples analyzed 

by GC/ECNIMS. Concentrations of both compounds were 

low, ranging from 0.11 to 0.26 μg/kg for dacthal and 0.12 to 

1.2 μg/kg for endosulfan sulfate. Both dacthal and endosulfan were detected in nearly all the snow samples, confirming 

that some current-use pesticides entering aquatic ecosystems 

through atmospheric deposition are persistent enough to be 

accumulating in sediments in high-elevation lakes and potentially in aquatic biota as well.

Summary  51
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