INTRODUCTION

Springs located in the Green

River Basin, Kentucky, are valuable

natural resources and important

sources of public and domestic water

supplies. Ground water and springs in

the Green River Basin potentially are

vulnerable to increased concentrations

of pesticides and nitrates associated

with agricultural activities, such as

pesticides and nitrates, because of the

presence of karst topography. The karst

topography can allow rapid recharge of

flow through fractures in rock and

solutional conduits, providing little

opportunity for natural filtering to

occur. Understanding the extent and

potential severity of ground-water

contamination in karst areas is

therefore crucial to protecting the

public and water resources in the

Green River Basin.

There is potential for groundwater contamination associated with

the use of pesticides and fertilizers in

the Green River Basin because of the

extensive agricultural development of

land. By sampling the water quality of

karst springs and examining the use

and detections of pesticides,

information can be provided to better

evaluate ground-water quality and

agricultural nonpoint-source pollution

in the Green River Basin, and assist

resource managers in the planning and

implementation of nonpoint-source

pollution-control programs.

In 2001, the U.S. Geological

Survey (USGS) began a 5-month study

in cooperation with the Kentucky

Department of Agriculture to evaluate

the occurrence and distribution of

pesticides and nutrients in springs in

the Green River Basin. This paper

summarizes data on the concentrations

and frequency of detection of

pesticides and nutrients in samples

from eight selected springs and

presents pesticide sales data (pounds of

active ingredient) from the year 2000

as a surrogate for application rates.

FIELD AND

LABORATORY METHODS

The USGS collected pesticide

and nutrient samples from eight

springs (fig.1 and table 1). Samples

were collected every 2 weeks during

May–September 2001. General

procedures for the collection of waterquality samples and equipment

cleaning are described in Shelton

(1994). Water samples were analyzed

by the USGS National Water-Quality

Laboratory in Denver, Colorado, for

50 pesticide compounds using methods

described by Zaugg and others (1995).

The laboratory reporting level (LRL)

for detected pesticides are listed in

table 2. A detailed discussion of LRL’s

can be found in Childress and others

(1999). Nutrient samples (ammonianitrogen (NH3-N), nitrite plus nitratenitrogen (NO2 + NO3-N), total

phosphorus (TP), and orthophosphate

(orthoP)) also were analyzed by the

USGS National Water-Quality

Laboratory using methods described in

Fishman and Friedman (1989).

PESTICIDES AND NUTRIENTS IN KARST SPRINGS IN THE

GREEN RIVER BASIN, KENTUCKY, MAY–SEPTEMBER 2001

MAJOR FINDINGS

• Nine different pesticides were detected in eight karst springs sampled in the Green River drainage basin.

• The five most frequently detected pesticides at all springs were atrazine (100 percent), simazine (93 percent),

metolachlor (80 percent), tebuthiuron (66 percent), and prometon (58 percent).

• The pesticides detected were not necessarily the pesticides most heavily applied in the Green River drainage

basin.

• Nitrite plus nitrate-nitrogen concentrations did not exceed the U.S. Environmental Protection Agency (USEPA)

drinking water standard (10 milligrams per liter) at any of the eight springs.

Lost River Blue Hole Spring near Bowling

Green, Kentucky.

In cooperation with the Kentucky Department of Agriculture

U.S. Department of the Interior USGS Fact Sheet 133-01

U.S. Geological Survey January 2002
Table 1. Selected spring sampling sites in the Green River Basin, Kentucky

[USGS, U.S. Geological Survey]

Map

reference

number

(see

fig. 1)

USGS

station

number USGS station name Latitude Longitude

Number

of

samples

1 373320086001601 Waddel Spring near Harcourt, Kentucky 37 ̊33’20”N 86 ̊00’16”W 8

2 373608085585101 Boiling Spring at Star Mills, Kentucky 37 ̊36’08”N 85 ̊58’51”W 8

3 371528085545301 Gorin Mill Spring near Munfordville, Kentucky 37 ̊15’28”N 85 ̊54’53”W 8

4 371044085542001 Hidden River Cave at Horse Cave, Kentucky 37 ̊10’44”N 85 ̊54’20”W 8

5 365713086282103 Lost River Blue Hole Spring near Bowling Green, Kentucky 36 ̊57’13”N 86 ̊28’21”W 8

6 365526086382801 Finney Spring near South Union, Kentucky 36 ̊55’26”N 86 ̊38’28”W 8

7 365415086435001 Crawford Blue Hole Spring near Auburn, Kentucky 36 ̊54’15”N 86 ̊43’50”W 7

8 364832086313701 Drakes Spring near Woodburn, Kentucky 36 ̊48’32”N 86 ̊31’37”W 8

Table 2. Summary of the concentrations, detection frequencies, and aquatic-life criteria of the detected

pesticides in samples collected from eight springs, Green River Basin, Kentucky, May–September 2001

[μg/L, micrograms per liter; --, not established]

Pesticide

name Trade name

Type of

pesticide

Laboratory

method

reporting

level

(μg/L)

Detection

frequency,

in percent

(number of

samples)

Median

concentration

of detections

(μg/L)

Maximum

concentration

of detections

(μg/L)

Waterquality

criteria for

aquatic life

(μg/L)

Acetochlord Harness Plus, Surpass Herbicide 0.004 14 (59) 0.004 0.099 --

Atrazined AAtrex, Atred Herbicide .007 100 (59) .159 7.40 a1.8

Chlorpyrifos Brodan, Dursban Insecticide .005 2 (59) .005 .011 b.041

Metolachlor Dual, Pennant Herbicide .013 80 (59) .035 .343 a7.8

Metribuzin Lexone, Sencor Herbicide .006 5 (59) .006 .011 a1

Napropamide Devrinol, Naproguard Herbicide .007 3 (59) .007 .011 --

Prometon Pramitol Herbicide .015 58 (59) c.014 .468 --

Simazine Aquazine, Princep Herbicide .011 93 (59) .019 .210 a10

Tebuthiuron Spike, Tebusan Herbicide .016 66 (59) c.014 .043 a1.6

a

Environment Canada, 1999

b

U.S. Environmental Protection Agency, 1999

c

Estimated value

d

Restricted-use pesticide

Figure 1. Location of spring-sampling sites in the Green River Basin, Kentucky.
Approximately 30 percent of the

samples analyzed were quality-control

samples, which included 12 field

blanks, 7 concurrent replicates, 4 field

spikes, and 1 laboratory blank. Field

blanks were collected to ensure that no

contamination occurred during

sampling and processing of the

samples. A blank is a type of water

solution that is intended to be free of

the analytes of interest. Concurrent

replicates were used to evaluate the

reproducibility of the laboratory

analytical techniques. A concurrent

replicate is a type of sample collected

simultaneously by use of two or more

samplers. Field-spike samples were

used to determine bias as a result of

matrix interference. A spike is a type

of sample in which known amounts of

pesticides are added to water. Qualitycontrol-sample results indicated good

laboratory performance and no

systematic contamination.

PESTICIDES

Pesticides have become an

integral part of controlling insects,

weeds, fungi, and bacteria in both

agricultural and urban settings. The use

of pesticides has increased over the last

40 to 50 years, which has resulted in

increased crop production and

controlled public health hazards

(Larson and others, 1997); however,

there are increased concerns about the

possible harmful effects of increased

pesticide concentrations on the

environment and human health.

Of the 50 pesticides analyzed,

8 herbicides and 1 insecticide were

detected at or above a common method

reporting level (CMRL) of 0.01

micrograms per liter (μg/L) at the 8

springs. A CMRL allows the detection

frequencies of pesticides to be

compared to each other. Adjusted data,

using a CMRL, were used to compare

detection frequencies, whereas

unadjusted data were used in statistical

analyses. The detected pesticides in the

springs were atrazine, simazine,

metolachlor, tebuthiuron, and

prometon (fig. 2). Based on estimated

pesticide sales data for agricultural

applications in 2000, a total of

1.5 million pounds of herbicides

(fig. 3) and 18,000 pounds of

insecticides (fig. 3) were applied in the

Green River Basin (Ernest Collins,

Kentucky Department of Agriculture,

written commun., 2001).

The pesticides detected were not

necessarily the pesticides most heavily

applied (in pounds of active ingredient)

in the Green River Basin. Acetochlor, a

restricted-use pesticide, was found in

only 14 percent of the samples, but was

one of the most heavily applied

pesticides (table 2 and fig. 3). It should

be noted that pesticide-sales data were

used as a surrogate for actual pesticideapplication rates. Whereas sales data

are a good indication of intended use,

they do not necessarily reflect actual

pesticide use (Barbash and Resek,

1996).

Figure 3. Estimated sales data for 2000 (in

pounds per active ingredient) of selected

herbicides and insecticide in the Green

River Basin, Kentucky.

Figure 2. Detection frequencies for

selected herbicides and insecticides at

eight spring-sampling sites in the Green

River Basin, Kentucky.

Only six of the listed pesticides

in table 2 have an aquatic-life criterion

assigned to them by the

USEPA (1999a) or the Canadian

Council of Resource and Environment

Ministers (Environment Canada,

1999). An aquatic-life criterion is a

numerical criterion designed to prevent

unacceptable long-term (years and

decades) and short-term (days and

weeks) effects on aquatic organisms.

Atrazine, a restricted-use pesticide,

was the only pesticide detected at

concentrations greater than its

established aquatic-life criterion of

1.8 μg/L (table 2).

The maximum concentrations of

four pesticides were detected in

samples collected at Finney Spring:

atrazine (7.40 μg/L); metolachlor

(0.343 μg/l); napropamide

(0.011 μg/L); and simazine

(0.210 μg/L) (table 2). Maximum

concentrations of acetochlor

(0.099 μg/L), chlorpyrifos

(0.011 μg/L), metribuzin

(0.011 μg/L), and tebuthiuron

(0.043 μg/L) were observed at Lost

River Blue Hole Spring. The

maximum concentration of prometon

was observed at Gorin Mill Spring

(0.468 μg/L). Median concentrations

of selected pesticides ranged from

0.004 to 0.159 μg/L (table 2).

NUTRIENTS

More than 60 water samples

were collected at the eight springs and

analyzed for nutrient species:

ammonia-nitrogen (NH3-N), nitrite

plus nitrate-nitrogen (NO2+NO3-N),

total phosphorus (TP), and

orthophosphate (orthoP).

Concentrations of NH3-N were at or

below the method reporting level of

0.04 milligrams per liter (mg/L) of N

(fig. 4a), except for Crawford Blue

Hole and Finney Spring.

Nitrite and nitrate are inorganic

ions produced during various stages of

the nitrogen cycle. Nitrate is the most

predominate ion in well-oxygenated

water because of the rapid oxidation of

nitrite. Concentrations of nitrate
Figure 4. Distributions of ammonia-nitrogen (A), nitrate plus nitrate-nitrogen (B), total phosphorus (C),

and orthophosphate (D) concentrations in eight springs in the Green River Basin, Kentucky.

greater than 10 mg/L in drinking water

can have adverse human-health effects,

especially to infants whose digestive

systems convert nitrate to nitrite

thereby reducing the oxygen-carrying

capacity of blood and resulting in

methemoglobinemia (blue-baby

syndrome) (U.S. Environmental

Protection Agency, 1999b). Nitrite plus

nitrate-nitrogen concentrations from

the eight springs ranged from 2.92 to

8.39 mg/L (fig. 4b). The highest

NO2+NO3-N concentration was

measured at Finney Spring (fig. 4b).

This high concentration could be a

localized effect possibly caused by

land use; further study is needed to

determine this effect.

Although there is no established

aquatic-life criterion for dissolved

phosphorus, the USEPA recommends a

maximum concentration of total

phosphorus of 0.1 mg/L to discourage

excessive growth of aquatic plants and

algae. Total phosphorus concentrations

in 13 percent of the samples were

greater than 0.1 mg/L. The highest TP

concentration among the springs

sampled was 0.28 mg/L in Finney

Spring (fig. 4c). The high TP

concentrations possibly were

associated with high values of turbidity

measured at this site because

phosphorus can adsorb to sediment

particles. The median concentration of

TP for all springs sampled was

0.06 mg/L. Orthophosphate

concentrations ranged from 0.02 to

0.18 mg/L (fig. 4d).

REFERENCES CITED

Barbash, J.E., and Resek, E.A., 1996,

Pesticides in ground water—

distribution, trends, and governing

factors: Chelsea, Mich., Ann Arbor

Press, Inc., 588 p.

Childress, C.J., Foreman, W.T., Connor, B.F.,

and Maloney, T.J., 1999, New reporting

procedures based on long-term method

detection levels and some

considerations for interpretation of

water-quality data provided by the

U.S. Geological Survey National WaterQuality Laboratory: U.S. Geological

Survey Open-File Report 99-193, 24 p.

Environment Canada, 1999, Canadian water

quality guidelines for the protection of

aquatic life, summary tables: accessed

October 26, 2001,

http://www.ec.gc.ca/ceqg-rcqe.

Fishman, M.J., and Friedman, L.C., eds.,

1989, Methods for determination of

inorganic substances in water and fluvial

sediments: U.S. Geological Survey

Techniques of Water-Resources

Investigations, book 5, chap. A1, 545 p.

Larson, S.J., Capel, P.D., and Majewski,

M.S., 1997, Pesticides in surface

waters—Distribution, trends, and

governing factors: Chelsea, Mich.,

Ann Arbor Press, Inc., 390 p.

Shelton, L.R., 1994, Field guide for collecting

and processing stream-water samples

for the National Water-Quality

Assessment Program: U.S. Geological

Survey Open-File Report 94-455, 42 p.

U.S. Environmental Protection Agency,

1999a, Compilation of national

recommended water quality criteria and

EPA’s process for deriving new and

revised criteria: Office of Water,

accessed October 26, 2001,

http://www.epa.gov/OST/standards/

wqcriteria.html.

_____1999b, Children and drinking water

standards: Washington, D.C., Office

of Water, EPA 815-K-99-001,

December 1999, 15 p.

Zaugg, S.D., Sandstrom, M.W., Smith, S.G.,

and Fehlberg, K.M., 1995, Methods of

analysis by the U.S. Geological Survey

National Water Quality Laboratory—

Determination of pesticides in water by

C-18 solid-phase extraction and

capillary-column gas chromatography/

mass spectrometry with selected-ion

monitoring: U.S Geological Survey

Open-File Report 95-181, 49 p.

For more information contact:

Angela S. Crain

U.S. Geological Survey

9818 Bluegrass Parkway

Louisville, KY 40299

(502) 493-1900 ext. 1943

e-mail: ascrain@usgs.gov

Internet: http://ky.water.usgs.gov

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