Figure 1. Extent of the Kirkwood-Cohansey aquifer system in New Jersey, areas of agricultural land use, and locations of wells

sampled for analysis of radium concentrations, 1988-96.

U.S. Department of the Interior

U.S. Geological Survey

Radium-226 and Radium-228 in Shallow Ground Water,

Southern New Jersey

Fact Sheet FS-062-98

June 1998

 Concentrations of total radium (the sum of radium-226 and radium-228) and gross alpha-particle activities in drinking water

that exceed the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Levels (MCLs) are known to cause

cancer. Results of investigations by the U.S. Geological Survey (USGS) in cooperation with the New Jersey Department of

Environmental Protection (NJDEP) indicate that concentrations of total radium in water samples from 33 percent of 170 wells

in the Kirkwood-Cohansey aquifer system in southern New Jersey exceeded the MCL of 5 pCi/L (picocuries per liter) (fig. 1).

Wells containing water in which concentrations of total radium were greater than the MCL typically are found where the

Bridgeton Formation crops out, in or near an agricultural area, where ground water is acidic (pH less than 5), and where

nitrate concentrations generally exceed 5 mg/L (milligrams per liter). Leaching of nitrogen, calcium, and magnesium from

agricultural chemicals (fertilizer, lime) applied to cropland may increase the mobility of radium in ground water. Gross alphaparticle activities exceeded the USEPA MCL of 15 pCi/L in water from 14 percent of 127 wells. A statistically significant 2:1

ratio between gross alpha-particle activity and concentration of total radium indicates that gross alpha-particle activity can

be used as a screening tool to predict the presence of water that may have a high total-radium concentration.

40°

75°

39°

30'

74°

30'

Extent of the KirkwoodCohansey aquifer system

Area of agricultural land on the

Bridgeton Formation outcrop

Pinelands

NEW

JERSEY

75° 74°

41°

40°

39°

Area of 

detail

0 20 40 MILES

0 20 40 KILOMETERS

EXPLANATION

Kirkwood Formation outcrop

Cohansey Sand outcrop

Bridgeton Formation outcrop

Agricultural land

Total radium concentration less than

5 picocuries per liter 

Total radium concentration greater than

5 picocuries per liter

PUBLIC-SUPPLY WELLS

EXPLANATION

ALL OTHER WELLS

Total radium concentration less than

5 picocuries per liter 

Total radium concentration greater than

5 picocuries per liter

0 5 10 MILES

0 5 10 KILOMETERS

ATLANTIC

OCEAN

DELAWARE BAY
concentration of total dissolved radium, which is defined as the

sum of radium-226 and radium-228 concentrations, is 5 pCi/L

(U.S. Environmental Protection Agency, 1976). For gross alphaparticle activity, the USEPA MCL is 15 pCi/L (U.S. Environmental Protection Agency, 1976). Activity is the number of radioactive disintegrations in a given quantity of material per unit time.

Gross alpha-particle activity is a measure of the total amount of

radioactivity in a water sample attributable to the radioactive

decay of alpha-emitting radioactive elements. Activity in water is

expressed in units of picocuries per liter, where 1 pCi/L is equal

to 2.2 radioactive disintegrations per minute per liter of water.

Because radium-226 emits an alpha particle, gross alpha-particle

activity can be used as a screening tool to predict the presence of

radium in a water sample, if large amounts of other alphaemitting radioactive elements are absent.

Radium in ground water in southern New Jersey

 During routine regulatory monitoring conducted by the

NJDEP, naturally occurring radium was detected at concentrations greater than the MCL in water from public supply wells

screened in the Kirkwood-Cohansey aquifer system. From 1988

to 1996, the USGS, in cooperation with the NJDEP, conducted

several sampling programs to determine the distribution of total

dissolved radium in the aquifer system and to identify factors that

contribute to the presence of high concentrations of total dissolved radium.

 The Kirkwood-Cohansey aquifer system is a regionally

extensive unconfined (water-table) aquifer that underlies about

two-thirds of the New Jersey Coastal Plain (fig. 1). It is a major

source of drinking water in much of southern New Jersey. In

most areas, the aquifer consists of two geologic formations, the

Cohansey Sand and the Kirkwood Formation. The Cohansey

Sand is mainly a light-colored, medium- to coarse-grained quartz

sand with some gravel and silt (Zapecza, 1989). The Kirkwood

Formation is a fine- to medium-grained quartz and silty sand in

inland areas and grades to clay in coastal areas. A surficial

deposit of feldspathic gravel known as the Bridgeton Formation

discontinuously overlies the Cohansey Sand and, in places, the

Kirkwood Formation on topographic highs, especially in southwestern New Jersey. These three hydraulically connected units

form the aquifer system, although the Bridgeton Formation is

present primarily in recharge areas. The Bridgeton Formation

contains a greater concentration of natural radioactive elements

than the other two formations because it was deposited by the

ancestral Hudson River (Martino, 1981), which drained rocks to

the north that were enriched in radioactive minerals relative to the

source material for the Kirkwood Formation and the Cohansey

Sand.

What is radium and why is it present in water?

 Unstable radioactive elements are found in a wide

range of concentrations in all rocks, soil, and water. The most

common radioactive elements, uranium and thorium, decay

slowly and produce other radioactive elements, such as radium,

which in turn undergo still further radioactive decay. These

radioactive product elements have different chemical properties,

decay at different rates, and emit different levels of radiation

energy than either uranium or thorium.

 The two most common isotopes of radium are radium226 and radium-228. Radium-226 has a long half-life (1,600

years) compared to that of radium-228 (5.75 years). A half-life is

the time required for half of the initial amount of the radionuclide

to decay. Radium-226 decays by emitting the nucleus of a helium

atom (alpha particle), whereas radium-228 emits an electron

(beta particle).

 Radium is only moderately soluble in water and only

under certain geochemical conditions (Zapecza and Szabo,

1988); radium-226 and radium-228 are equally soluble. Radium

can enter ground water by dissolution of aquifer materials, by

desorption from rock or sediment surfaces, and by ejection from

minerals during radioactive decay.

Why is radium in drinking water of concern?

 Radium in drinking water is known to increase cancer

risk, primarily for bone and sinus cancers (Mays and others,

1985). As radium decays, the radiation that is emitted can strip

electrons from the atoms with which it collides, causing the

atoms to become charged or “ionized.” The ionizing alpha and

beta radiation emitted by radium consists of particles that move

slowly and cannot penetrate skin. If radium is ingested, however,

especially dissolved in water, the emitted alpha- and beta-particle

radiation can ionize and damage cell tissue. Human bone tissue

accumulates radium rather than allowing it to be removed from

the body, thereby exposing the bones to tissue-damaging alpha or

beta radiation. Damage from continuous exposure can potentially

cause cancer. Because it accumulates in the body, radium is

considered to pose a greater cancer risk than most other radioactive elements.

What level of radium or gross alpha-particle activity in

drinking water is a significant health risk?

 The USEPA MCL for radioactivity in drinking water is

set at the level of a 1 in 10,000 risk of a fatal cancer if 2 liters of

water per day is consumed for 70 years. The MCL for the

Dissolved constituent

Concentration or activity

(picocuries per liter)

 Minimum Maximum Median

(radium-226 plus radium-228)

5 Bone cancer 170 <1 30.3 3.8 33

Gross alpha-particle activity 15 Cancer 127 <0.6 43.3 5.4 14

Table 1. Summary statistics for radium concentrations and gross alpha-particle activity in water from wells in the Kirkwood-Cohansey

aquifer system, southern New Jersey, 1988-96 [USEPA, U.S. Environmental Protection Agency; MCL, Maximum Contaminant Level]

Total radium

Percentage of samples

 with concentration or

activity above the 

MCL

Number

of wells

sampled

Potential health effects

from ingestion of water

(Mays and others, 1985)

USEPA

MCL

(picocuries 

per liter)
0

pH, IN pH UNITS

0

50

10

20

30

40

NUMBER OF SAMPLES

4.00 - 4.39

4.40 - 4.59

4.60 - 4.79

4.80 - 4.995.00 - 5.19

5.20 - 5.39

5.40 - 7.85

27%

54%

44%

30%

23%

6%

26%

54%

Number of samples in which the concentration of total radium

was greater than 5 picocuries per liter

Number of samples in which the concentration of total radium

was less than 5 picocuries per liter

Percentage of total number of samples in each range in which the

concentration of total radium was greater than 5 picocuries per liter

EXPLANATION

Figure 3. Number of water samples in which the concentration

of total radium exceeded 5 picocuries per liter as a function of

pH, Kirkwood-Cohansey aquifer system, southern New Jersey,

1988-96.

Figure 2. (a) Concentration of total radium as a function of gross alpha-particle activity; (b) concentration of radium-226 as a function

of concentration of radium-228; and (c) concentration of total radium as a function of nitrate plus nitrite concentration in water from wells

in the Kirkwood-Cohansey aquifer system, southern New Jersey, 1988-96.

Sampling Program

The USGS sampled a regional network of 170 wells,

including public-supply, domestic, and observation wells, to

characterize the distribution of total dissolved radium in the

Kirkwood-Cohansey aquifer system in southern New Jersey

(Kozinski and others, 1995; Szabo and others, 1997). Samples

were analyzed for radium concentration and for gross alphaparticle activity by using USEPA-approved techniques (Krieger

and Whitaker, 1980) about 1 month after collection. Sampling

density was greatest in the southwestern part of the study area

(fig. 1) because of the large rural and suburban population that

depends solely on water from the Kirkwood-Cohansey aquifer

system for water supply, and because concentrations of total

dissolved radium were highest in this area. Sampling density was

lowest in the central part of the study area (the Pinelands; fig. 1)

because of the absence of residences (and wells) in this area.

Because sampled wells were not distributed evenly throughout

the study area, the data set of measured total dissolved radium

concentrations may be biased.

Radium concentrations in ground water

 The concentration of total radium in water from 56 (33

percent) of the 170 wells sampled was greater than the 5-pCi/L

MCL (table 1). Concentrations of total dissolved radium ranged

from <1.1 to 30.3 pCi/L, with a median (midpoint value) of 3.8

pCi/L. Gross alpha-particle activities in 18 (14 percent) of the

127 samples for which data were available were greater than the

15-pCi/L MCL. Gross alpha-particle activities ranged from <0.6

to 43.3 pCi/L, with a median of 5.4 pCi/L. Gross alpha-particle

activity and total radium concentration were significantly (95-

percent or greater statistical confidence interval) correlated

(Spearman rank correlation coefficient, rs = +0.90); the ratio

typically was about 2:1 (fig. 2a). Concentrations of radium-226

and radium-228 also were significantly correlated (rs = +0.70).

The median ratio of the concentrations of radium-228 to radium226 was 1.06 (fig. 2b). This ratio indicates that radioactive

minerals in the sands that make up the aquifer system are the

likely source of the dissolved radium because they also contain

both radioisotopes in nearly equal proportions (Szabo and others,

1997), whereas likely anthropogenic sources of radium, such as

phosphate-bearing fertilizers, tend to contain much more radium226 than radium-228.

Relation of radium to other chemical constituents

 Results of a rank-order-regression statistical model

indicate that water from the Kirkwood-Cohansey aquifer system

in which the nitrate concentration was greater than 5 mg/L

typically contained total radium in concentrations greater than

5 pCi/L (fig. 2c). Of 63 samples with a nitrate concentration

greater than 5.0 mg/L, 41 (65 percent) had total radium concentrations greater than 5.0 pCi/L. In contrast, of 92 samples with a

nitrate concentration less than 5.0 mg/L, only 14 (15 percent) had

total radium concentrations greater than 5.0 pCi/L. Of 75 samples

with a dissolved-magnesium concentration greater than or equal

0 35 10 20 30

CONCENTRATION OF NITRATE PLUS NITRITE

(AS NITROGEN), IN MILLIGRAMS PER LITER

0

35

20

CONCENTRATION OF TOTAL RADIUM,

IN PICOCURIES PER LITER

Concentration of nitrate plus nitrite

0 14 5 10

CONCENTRATION OF RADIUM-228,

IN PICOCURIES PER LITER

0

14

5

10

CONCENTRATION OF RADIUM-226,

IN PICOCURIES PER LITER

Maximum Contaminant Level for

1:1

1:1

2:1

EXPLANATION

0 45 10 20 30 40

GROSS ALPHA-PARTICLE ACTIVITY,

IN PICOCURIES PER LITER

0

20

5

10

15

CONCENTRATION OF TOTAL RADIUM,

IN PICOCURIES PER LITER

2:1

total radium (5 picocuries per liter)

(a) (b) (c)

5 milligrams per liter
A B AB C

WELL-LOCATION CLASS

0

100

20

40

60

80

NUMBER OF SAMPLES

EXPLANATION

Total radium concentration

Total radium concentration

Samples from wells in

agricultural area

Samples from wells in Bridgeton

Formation outcrop area

A

3.9 (25)

2.2 (8)

5.1 (52)

3.3 (16) 5.1 Median total radium concentration

in picocuries per liter

B

AB

C

Samples from wells in agricultural and

in Bridgeton Formation outcrop area

Samples from wells in neither agricultural

nor Bridgeton Formation outcrop area

(52) Percentage of samples in which

total radium concentration

>5 picocuries per liter 0

100

20

40

60

80

PUBLIC

SUPPLY

DOMESTIC,

INSTITUTIONAL

OTHER

3.7 (21)

3.9 (43)

3.6 (32)

> 5 picocuries per liter

< 5 picocuries per liter

(a) (b)

4 7 5 6

pH, IN pH UNITS

DEPTH OF WELL, IN FEET

BELOW LAND SURFACE

0 35 10 20 30

CONSTITUENT CONCENTRATION

0

120

20

40

60

80

100

0 200 100

CONCENTRATION OF TRITIUM,

IN PICOCURIES PER LITER

EXPLANATION

Concentration of total radium, in picocuries per liter

Concentration of NO2+NO3 , in milligrams per liter as N

Approximate depth of ground

1963 Older Younger

water recharged in about 1963

(a) (b) (c)

Figure 5. (a) Concentration of total radium and nitrite plus nitrate (NO +NO ), (b) concentration of tritium, and (c) pH as a function

of depth in samples of water from nested observation wells in the Kirkwood-Cohansey aquifer system, southern New Jersey, 1991.

Figure 4. Percentage of water samples in which total radium concentration exceeded the Maximum Contaminant Level by (a) welllocation class and (b) well type, Kirkwood-Cohansey aquifer system, southern New Jersey, 1988-96.

2 3

to 3 mg/L, 47 (63 percent) had total radium concentrations

greater than 5 pCi/L. Of 95 samples with a dissolved-magnesium

concentration less than 3 mg/L, total radium concentrations in

only 9 (9 percent) exceeded the MCL of 5 pCi/L. Concentrations

of total radium greater than 5 pCi/L also were related to low pH

(acidic water). Of the 56 water samples in which the concentration of total radium exceeded 5 pCi/L, 34 (61 percent) had a pH

< 4.8 (fig. 3). Statistically significant Spearman rank correlation

coefficients for concentrations of total dissolved radium relative

to those of nitrate and magnesium were +0.65 and +0.64,

respectively. Although concentrations of total radium also were

correlated with those of other dissolved constituents, these

relations were less strong (Kozinski and others, 1995).

Relation of radium concentration to agricultural land

use and geology

Radium concentration and gross alpha-particle activity, as

well as concentrations of nitrate and magnesium, were highest in

water from wells in agricultural areas overlying the outcrop of

the Bridgeton Formation. Of the 56 water samples in which the

concentration of total radium exceeded 5 pCi/L, 40 (71 percent)

were from wells in areas of both agricultural land use and the

Bridgeton Formation outcrop. Of the 19 samples in which gross

alpha-particle activity was greater than 15 pCi/L, 15 (79 percent)

were collected from wells in agricultural areas overlying the

outcrop of the Bridgeton Formation.

More than half the samples from wells in agricultural areas

overlying the Bridgeton Formation outcrop contained total

radium in concentrations exceeding the MCL (fig. 4). The

median total dissolved radium concentration for these samples

was 5.1 pCi/L. The median concentration of total radium in water

from wells in all non-agricultural land-use categories combined

was less than 5 pCi/L, and concentrations in only a small

percentage of these samples exceeded the MCL.

Relation of radium concentration to well depth

To evaluate the distribution of total radium with depth and

its relation to the distribution of water chemistry and tritium with

depth in the aquifer system, water samples collected from 15

nested observation wells at five sites were analyzed for radium226, radium-228, gross alpha-particle activity, tritium, and major

ions. Because the Kirkwood-Cohansey aquifer system consists

mainly of quartz sand that, for the most part, does not react with

water, the quality of the ground water is controlled primarily by

the quality of the recharge water at the time it entered the aquifer.

Tritium concentrations can be used to estimate the date of

recharge of young ground water because tritium concentrations in

the atmosphere were highest in the early 1960’s as a result of

above-ground testing of nuclear devices.

Concentrations of radium and gross alpha-particle activities

were highly variable with depth but were consistently lowest in

the deepest wells. Concentrations of total radium in water from
Figure 6. Processes that result in elevated concentrations of

nitrate, magnesium, and radium in water in areas where agricultural land overlies the Kirkwood-Cohansey aquifer system,

southern New Jersey. (Modified from Szabo and others, 1997)

Some radium in ground water

and lime

Displacement of radium from

sorption/exchange sites

Increase of radium in ground

water

Typical Aquifer Conditions

Low-pH soils with low nutrient

 concentrations and low number 

of available sorption sites

Minimal weathering of

sediments--acidity of precipitation

is not neutralized

Low pH--number of sorption sites

in the aquifer is limited

Low pH--number of sorption sites

in the aquifer is limited

Nitrification of ammonia

fertilizer--pH is lowered

Addition of lime and nitrogen fertilizer to increase crop yields

High rate of leaching of nutrients

Increasing concentrations of

nitrate, magnesium, and calcium

in ground water

Increase in magnesium--increase

in competition for sorption/

exchange sites for radium

Aquifer Beneath

Agricultural Land

depths greater than about 80 feet below land surface were less

than 1.75 pCi/L (fig. 5a). Corresponding tritium values of less

than 10 pCi/L at depths greater than 80 feet indicate that the

water was recharged more than 35 years ago (fig. 5b), and

therefore, probably predates the intensive use of modern agricultural chemicals, such as nitrogen-bearing fertilizers. Consequently, nitrate concentrations at depths greater than 80 feet were

equal to or less than 5 mg/L (fig. 5a).

Water from shallow and medium depths (10-75 feet below

land surface) generally contained higher concentrations of total

radium (maximum, 30 pCi/L) than water from the deep wells

(maximum, < 1.75 pCi/L). Tritium concentrations greater than

100 pCi/L at depths of about 80 feet below land surface correspond to the depth of penetration into the aquifer system of water

recharged in the early 1960’s. Tritium concentrations to about 75

feet below land surface generally were about 50 pCi/L, indicating

that the water was recharged less than about 30 years ago, during

a period of intensive use of modern agricultural chemicals.

Consequently, most nitrate concentrations at shallow and medium

depths were greater than 5 mg/L (fig. 5a).

 The pH of water from the nested wells increased with

depth (fig. 5c). The pH of the shallow ground water is low as a

result of acidic precipitation and the biological transformation of

nitrogen-bearing fertilizers. As recharge penetrates the aquifer

system, the water is slowly neutralized by the chemical reactions

of natural weathering, such as the dissolution of feldspar from

sand grains, and the solubility of radium decreases. The increase

in pH with depth corresponds roughly with the decrease in the

concentrations of dissolved radium and nitrate; these chemical

relations are similar to those observed in water from wells in the

regional well network (fig. 3).

Although total radium concentrations were greatest in

water from medium depths, radium in the aquifer sediments is

not enriched at the depths at which these wells are screened

(Szabo and others, 1997). These results indicate that the chemistry of the water rather than the radium content of the sediment is

primarily responsible for the high concentrations of radium. The

flow diagram in figure 6 illustrates the effects of both natural

water quality and water quality altered by the addition of

agricultural chemicals on the mobility of radium in the

Kirkwood-Cohansey aquifer system, and identifies mechanisms

that may increase radium mobility in shallow ground water in

agricultural areas.

Relation of radium to well type

 The MCL for total radium was exceeded less frequently

in water from public-supply wells than in water from domestic or

other types of wells (fig. 4), possibly because public-supply wells

typically are distant from agricultural areas and generally are

associated with lower nitrate concentrations, greater pumping

rates, and substantially deeper intakes than other well types (table

2). Because public-supply wells discharge large volumes of

water, they typically withdraw and integrate water from different

land-use areas and depths, resulting in a measured total radium

concentration that is lower than the highest concentration within

a small depth interval in the aquifer near the well. The frequent

detection of high radium concentrations in domestic and institutional wells may be due to their location in agricultural areas,

their location where nitrate concentrations are high, and their

typically short, medium-depth screens, which intercept young,

radium-rich water without appreciable dilution.

Summary and Discussion

 Ground water containing total radium in concentrations

greater than the 5-pCi/L MCL is widespread (33 percent of 170

samples) in the Kirkwood-Cohansey aquifer system in southern

New Jersey. Gross alpha-particle activity exceeded the 15-pCi/L

MCL in a significant number of samples (14 percent of 127

samples). Concentrations of total radium greater than 5 pCi/L are

Well type

Public-supply 93 38 2.8

Domestic,

institutional 63 81 5.95

Other 50 67 3.8

Table 2. Well type and median depth to open interval, percentage

of wells located in agricultural areas, and median nitrate concentration in water from wells in the Kirkwood-Cohansey aquifer

system, southern New Jersey, 1988-96 [mg/L, milligrams per liter]

Median depth to

top of well screen

(feet below land

surface)

Percentage of

wells located in

agricultural

areas

Median concentration of nitrate plus nitrite

(mg/L)
most likely to be present in shallow to moderately deep (as much

as 80 feet below land surface) ground water that has been

recharged since the early 1960’s (the time of greatest fertilizer

application), is acidic (pH < 5), is located on the Bridgeton

Formation outcrop and in areas of current or historical agricultural land use, and has been contaminated with nitrate to concentrations of about 5 mg/L or more.

 Public-supply utilities and homeowners whose wells are

screened in the Kirkwood-Cohansey aquifer system and meet any

of the above criteria need to test their water for the presence of

radium and gross alpha-particle activity (New Jersey Department

of Environmental Protection, 1997). Because gross alpha-particle

activity is significantly correlated to total radium concentration, it

can be used as a cost-effective screening tool. Analysis of water

for gross alpha-particle activity is much less costly than analysis

for radium; therefore, a homeowner whose well produces water

containing gross alpha-particle activity greater than 5 pCi/L can

save the expense of additional analytical costs and simply treat

the water for radium (New Jersey Department of Environmental

Protection, 1997). Drinking water from public-supply systems

can be treated, or other options, such as blending, can be pursued,

to ensure limited exposure of consumers to radiation. Many

treatments that can effectively reduce the concentration of radium

and gross alpha-particle activity (New Jersey Department of

Environmental Protection, 1997) are available to homeowners.

Other options, such as drilling a deep well, using bottled water,

or connecting to a public-supply utility, also are available.

Information about all of these options can be obtained from the

local health department or the NJDEP Bureau of Safe Drinking

Water.

Investigations by the USGS are ongoing to evaluate the

distribution of other radium isotopes in the Kirkwood-Cohansey

aquifer system in New Jersey and their contribution to the gross

alpha-particle activity in the water supply. Results of these

studies will improve the understanding of the potential health

risks to water consumers from radioactivity.

—Zoltan Szabo and Vincent dePaul

References Cited

Kozinski, Jane, Szabo, Zoltan, Zapecza, O.S., and Barringer,

T.H., 1995, Natural radioactivity in, and inorganic chemistry

of, ground water in the Kirkwood-Cohansey aquifer system,

southern New Jersey, 1983-89: U.S. Geological Survey WaterResources Investigations Report 92-4144, 130 p.

Krieger, H. L., and Whitaker, E.L, 1980, Prescribed procedures

for measurement of radioactivity in drinking water: U.S.

Environmental Protection Agency Manual EPA-600/4-80-032,

111 p.

Martino, R.L., 1981, The sedimentology of the late Tertiary

Bridgeton and Pensauken Formations in southern New Jersey:

New Brunswick, N.J., Rutgers University, unpublished Ph.D.

dissertation, 299 p.

Mays, C.W., Rowland, R.E., and Stehney, A.F., 1985, Cancer risk

from the lifetime intake of Ra and U isotopes: Health Physics,

v. 48, p. 635-647.

New Jersey Department of Environmental Protection, 1997, A

homeowner’s guide to radioactivity in drinking water:

Trenton, N.J., New Jersey Department of Environmental

Protection, Bureau of Safe Drinking Water, June 1997, 4 p.

Szabo, Zoltan, Rice, D. E., McLeod, C.L., and Barringer, T.H.,

1997, Relation of distribution of radium, nitrate, and pesticides to agricultural land use and depth, Kirkwood-Cohansey

aquifer system, New Jersey Coastal Plain, 1990-91: U.S.

Geological Survey Water-Resources Investigations

Report 96-4165A, 107 p.

U.S. Environmental Protection Agency, 1976, National

primary drinking-water regulations: Washington, D.C.,

Office of Water Supply, U.S. Environmental Protection

Agency Report EPA-570/9-76-003.

Zapecza, O.S., 1989, Hydrogeologic framework of the New

Jersey Coastal Plain: U.S. Geological Survey Professional

Paper 1404-B, 49 p., 24 pl.

Zapecza, O.S., and Szabo, Zoltan, 1988, Natural radioactivity in

ground water—A review, in Moody, D.W., Chase, E.B., and

Paulson, R.W., comp., National Water Summary 1986—

Ground-water quality: Hydrologic conditions and events:

U.S. Geological Survey Water-Supply Paper 2325, p. 50-57.

For additional information contact:

District Chief

U.S. Geological Survey

810 Bear Tavern Road, Suite 206

West Trenton, New Jersey 08628

email: dc_nj@usgs.gov