Concentrations and environmental fate of Ra in cation-exchange regeneration brine waste disposed to...

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Concentrations and environmental fate of Ra in cation-exchange

erseyined.non-

eptic-ion incatings falls

ystem;

www.elsevier.com/locate/jenvradJournal of Environmental Radioactivity 99 (2008) 947e964

regeneration brine waste disposed to septic tanks andaccumulation in sludge, New Jersey Coastal Plain, USA

Zoltan Szabo a,*, Eric Jacobsen a, Thomas F. Kraemer b, Bahman Parsa c

a U.S. Geological Survey, 810 Bear Tavern Road, W. Trenton, NJ 08628, USAb U.S. Geological Survey, 12201 Sunrise Valley Road, Reston, VA 20192, USA

c N.J. Department of Health and Senior Services, CN-308, Trenton, NJ 08625, USA

Accepted 9 November 2007

Available online 21 February 2008

Abstract

Concentrations of Ra in liquid and solid wastes generated from 15 softeners treating domestic well waters from New JCoastal Plain aquifers (where combined Ra (226Ra plus 228Ra) concentrations commonly exceed 0.185 Bq L�1) were determSofteners, when maintained, reduced combined Ra about 10-fold (<0.024 Bq L�1). Combined Ra exceeded 0.185 Bq L�1 at 1maintained system. Combined Ra was enriched in regeneration brine waste (maximum, 81.2 Bq L�1), but concentrations in stank effluents receiving brine waste were less than in the untreated ground waters. The maximum combined Ra concentrataquifer sands (40.7 Bq kg�1 dry weight) was less than that in sludge from the septic tanks (range, 84e363 Bq kg�1), indiRa accumulation in sludge from effluent. The combined Ra concentration in sludge from the homeowners’ septic systemwithin the range reported for sludge samples from publicly owned treatment works within the region.Published by Elsevier Ltd.

Keywords: 226Ra; 228Ra; 40K; Alpha-particle radioactivity; Gamma-ray spectroscopy; Ground water; Cation exchange; Acidity; Septic s

Sludge

1. Introduction

L) ofm ofestedhave

actedels of

In 2000, the U.S. Environmental Protection Agency (USEPA) finalized a maximum contaminant level (MC0.555 Bq L�1 (15 pCi L�1) for gross alpha-particle activity and 0.185 Bq L�1 (5 pCi L�1) for combined Ra (su226Ra and 228Ra) (USEPA, 2000a). Radium is a known human carcinogen that poses health risk when ing(Mays et al., 1985; USEPA, 1999). Both 226Ra, an alpha-particle emitter, and 228Ra, a beta-particle emitter,sufficiently long half-lives (1602 and 5.75 years, respectively) to accumulate on a time scale of years when extrfrom water or brine, whereas 224Ra, with a half-life of 3.64 days, is less likely to accumulate (unsupported) to levconcern.

* Corresponding author. Tel.: þ1 609 771 3929; fax: þ1 609 771 3915.

E-mail address: [email protected] (Z. Szabo).

0265-931X/$ - see front matter Published by Elsevier Ltd.

doi:10.1016/j.jenvrad.2007.11.009

mailto:[email protected]

http://www.elsevier.com/locate/jenvrad

Concentrations of Ra isotopes in water samples from the aquifers of the New Jersey Coastal Plain have beengical1997Newothyzabo

unitss thatdingset al.,rs fore me-rinestheyCl in

et al.,aste

ludgeantial

into

waterthatthe

urcestions

Ra inse ofangetemssedi-mentight

948 Z. Szabo et al. / Journal of Environmental Radioactivity 99 (2008) 947e964

identified as frequently exceeding the combined Ra MCL. In a series of studies conducted by the U.S. GeoloSurvey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP) fromto 2002, concentrations of Ra isotopes in water samples from the 2 major unconfined aquifer systems in theJersey Coastal Plain, the KirkwoodeCohansey in southeastern New Jersey and the PotomaceRaritaneMagimmediately adjoining the Fall Line (see Fig. 1 for general location), were determined (Focazio et al., 2001; Set al., 2005). Combined Ra activities were greater than 0.185 Bq L�1 in 31% of samples.

Water softeners (cation-exchange units) are widely available and are convenient whole-house Ra treatmentfor domestic well water, because the units efficiently remove Ra (about 90% removal) along with constituentcause water hardness, such as Ca and Mg, as well as other cationic constituents such as Fe (Lucas, 1987). The finregarding widespread elevated Ra concentrations in ground water in New Jersey (Kozinski et al., 1995; Szabo2005), as well as elsewhere in the country (Focazio et al., 2001) have led to the increased use of water softenepurposes of Ra removal (NJDEP, 2004). Proper maintenance includes regular regeneration of the cation-exchangdia with sodium (Na) or potassium (K) chloride (Cl) brine solutions (Bowie, 1995). The waste (regeneration) b(presumably bearing large concentrations of Ra) commonly are flushed to septic systems. It is assumed that thereare diluted and dispersed to the environment. The regeneration brine wastes are suspected to be a major source ofwater in shallow aquifers where unsewered residential development has taken place (Thomas, 2000; Barringer2006). The concentrations of Ra within the various waste media and the environmental fate of the Ra-bearing whave been little studied, warranting this investigation. There is also a potential issue related to the hauling of sfrom private septic tanks to publicly owned treatment works (POTWs), whether Ra from this source is a substcontribution to the overall load at the southern New Jersey POTWs depending on whether or not Ra is sequesteredsludges within the septic tanks.

The disposal of waste residuals from treatment processes designed to remove radionuclides from drinkinghas long been of concern (Parrotta, 1991). The national assessment of radionuclide concentrations, includingof Ra, in waste sludge from POTWs found that the highest concentrations of Ra were present in sludge fromAtlantic Coastal Plain region (ISCORS, 2003). The contribution of Ra to the POTW sludge from private sowas addressed indirectly by considering them as a source, but independent measurements of Ra concentrawere not made.

This study characterizes Ra concentration in waste media associated with the cation-exchange treatment ofdrinking water in the (rarely studied) private-well setting in the Coastal Plain of New Jersey (Fig. 1). The phastudy detailed in this article examined the fate of Ra from entry into the home, sequestration onto the cation-exchresin, sequestration into cation-exchange regenerative brine waste, and disposal of the brine wastes into septic sys(Fig. 2). The Ra concentrations in sludge were compared to Ra concentrations in native soils and vadose-zonements that were sampled at locations near the homes from where the sludge was obtained to provide initial assessof the relative importance of Ra in the sludge relative to the soil in the local areas that are typical of those that mreceive sludge-bearing soil amendments.

2. Sampling and analytical methods

whereithoutrowlyivate-Jerseyta de-esternbeachns of, and

2.1. Sampling location

Residential sites were considered where cation-exchange treatment units were used to soften domestic well water andregeneration brine waste disposal was to septic tanks that had not been evacuated for at least a year. Control sites wcation-exchange treatment systems were not included as part of the sampling effort, because the objective of this narfocused study was to characterize the concentration and fate of Ra in water-treatment waste disposal media. The prwell sampling network consisted of 18 sites, 15 of which were in the Coastal Plain of southern and central New(Fig. 1). The wells were completed either in the unconsolidated iron-rich, occasionally feldspathic, Cretaceous-age delposits forming the PotomaceRaritaneMagothy aquifer system along the Fall Line (unconformity) that forms the northwboundary of the Coastal Plain (Fig. 1) or in the areally extensive quartzose Miocene and Tertiary age seaward dippingand river sand deposits forming the KirkwoodeCohansey aquifer system farther to the south and east. Detailed descriptiothe geology, hydrology, and chemistry of these aquifers were provided by Zapecza (1989), Kozinski et al. (1995)Kauffman et al. (2001).

2.2. Sampling procedures

994),acting

11407

11406

151520

151522330958330682

291448

51506

231406

230786 231363

231410

110916

231412

231407 MONMOUTH

Areal extent of the unconfined Kirkwood-Cohansey aquifer system

Site and number

EXPLANATION

110916

FALL LINE

75°

40°30’

40°

39°

74°

0

0

10

10

20 MILES

20 KILOMETERS

110694

330681151059151056

Soil core site and number330681

39°30’

74°30’75°30’

370498

41°

Potomac-Raritan-Magothy aquifer system adjoins the Fall Line

151053

Fig. 1. Sampling-site locations for Ra in ground water, in waste products, and in soils, New Jersey Coastal Plain, 2003e2004.

949Z. Szabo et al. / Journal of Environmental Radioactivity 99 (2008) 947e964

Most aspects of the ground-water low-level trace-element sampling techniques recommended by Horowitz et al. (1Ivahnenko et al. (1996), and Olson and DeWild (1999), including acid (5% HCl) purges and soaks of all equipment cont

the samples, to preserve sample integrity were incorporated into the sampling program, including that for the waste media.Table 1 summarizes the sampling equipment used, the equipment cleaning process, the type of samples collected, and sample

ed re-usingted asof theashed

staltic0-mmsitingnative

bailera stiff. The

Pumping fromwell

Septicsystem

NOT TO SCALE

EXPLANATION

Water table

Ground-water flow

1. Initial radium source from aquifer: well water for drinking, into the home --> 2. Human ingestion exposure endpoint: treated drinking water after flow through treatment unit--> 3. Radium-brine waste: regeneration brine waste discharge from treatment unit--> 4. Septic system: 4a. Septic system effluent (liquid), and/or 4b. Septic sludge (solid)--> 5. Environmental dispersion: Shallow ground water (at the water table) from shallow observation well downgradient of shallow soil in leachfield receiving briny effluent waste.

2

1

3

4ab

5

Treatmentsystem waste

Water tablesampling point

Media 1-4detailed this article

Fig. 2. Sampling scheme, including Ra in ground water and in components of treatment in the home including treated water, regeneration waste

brine, septic effluent after brine disposal to septic systems, and sludge. Dispersal of the septic waste effluents to the environment is described in

a companion study (Szabo et al., submitted for publication).


preservation.

2.2.1. Brine wastes from cation-exchange regenerationThe regeneration cycle for the cation-exchange treatment units was initiated manually as close as possible to the schedul

generation brine cycle set by the automatic timers included with the units. The volume of water treated was estimated eitherwater meters already existing in the systems or on the basis of household size, assuming average water use per resident (repor340 L/day (85 gallons/day) in New Jersey; Hutson et al., 2004), and the operating parameters of the system. About one-thirdregeneration brine waste flow was diverted and composited throughout the 20e30 min regeneration period into an acid w20-L polyethylene container.

2.2.2. Septic-tank liquidsSeptic-tank liquids were pumped directly from 4 to 5 points in the septic tank (Miller, 1996) using a high-volume peri

pump with pre-cleaned Teflon-lined polyethylene tubing. The septage effluent (liquids) then were filtered through a 10mesh polyethylene or nylon bag to remove solid particles, discharged directly into a pre-cleaned polyethylene bucket (compoand homogenization), and pumped through a 0.45-mm polysulfone filter into sample bottles in a manner similar to samplingground water as described by Ivahnenko et al. (1996).

2.2.3. Septic-tank solidsSamples of the moderately thick settled sludge were collected from the bottom of the septic tank by scooping with a

with a 1-way valve or by pumping with a vacuum. Sludge/sediment from the bottom of each tank was collected into2.5-cm PVC tube with a ball-type check valve (ColeeParmer F/07090-11 or equivalent) to prevent backflow (Table 1)

average thickness of the settled sludge/sediment layer within the septic tank was determined by measurement of the level ofsludge within the PVC bailer. The tube was drained into a 30-L polyethylene bucket lined with a 100-mm mesh nylon filter

996).sablechest

, andHach

o, butlong

ptions

licateckets,ment

tationod or

Table 1

Filtration and sampling equipment, sampling bottles, and generalized equipment cleaning scheme for sampling

Pore size

(micron)

Manufacturer,

product

Design Surface

area (m2)

Material Pre-cleaning

Filters

0.45 Gelman 12175 Tortuous-path capsule 0.071 Polysulfone 16-h 5% HCl soak and

DI rinse (Olson and DeWild, 1999)

100 ColeeParmer K-1523-70 2 L Bag filter 0.18 Nylon DI rinse

Type Sample type Preservation

Sampling bottles

High-density polyethylene, acid washed, 0.25 L Trace elements, major cations Nitric acid to pH 2

High-density polyethylene, acid washed, 1 L and 8 L Radionuclides Nitric acid to pH 2

High-density polyethylene, 0.5 L Chloride None

High-density polyethylene, opaque, 0.125 L Nutrients Stored at 4 �C

High-density polyethylene, acid washed, 20 L Sludge Dried at 104 �C for analysis

Polyethylene, wide-mouth, 0.25 L Sediment Air dried for analysis

Type Sample type Pre-cleaning

Tubing, pumping equipment

High-density Teflon-lined polyethylene tubing

(Jensen Inert TTL 0308-0102)

All pumped samples, including

septic-tank effluent

Sequential soapy water, 5% HCl,

and DIW rinse (Ivahnenko et al., 1996)

Mechanical bladder pump (Geoprobe MB470) Ground water 5% HCl and DIW rinse of Teflon bladder

Corrugated rubber tubing with 2-way steel flow splitting valve Septage (sludge, effluent) Rinse with native septage

Polyethylene bailer with 1-way valve Septage (sludge, effluent) DIW rinse

Hand pump, tubing, and check valve (ColeeParmer F/07090-11) Septage (sludge, effluent) DIW rinse

HCl, hydrochloric acid; DIW, de-ionized water. Any use of trade, product or firm names is for descriptive purposes only and does not imply

endorsement by the U.S. Government or the State of New Jersey.


bag. Multiple grab samples were collected from up to 5 locations from the bottom of the tank and composited (Miller, 1The nylon filter bags were allowed to drain liquid for 1e2 h. The composited sludge was oven dried at 104 �C. Dispomasks, gloves, and Tyvek suits were worn during sample collection with dosimeters (Global Dosimetry Solutions) wornheight.

2.2.4. Ground-water samplingThe private supply wells were purged for a period of 30e60 min until physical and chemical properties were stabilized

water turbidity was lowered to levels on the order of 0.5e2.0 NTU. Turbidity was monitored every 3e5 min by use of aRatio/2100P Portable Turbidimeter (Ivahnenko et al., 1996; Wilde and Radtke, 1999).

2.2.5. Soil coringSoil coring of the unsaturated zone overlying the KirkwoodeCohansey aquifer system was completed at 5 sites adjacent t

not exactly co-located with, the domestic well sites sampled from that aquifer (Fig. 1). Split-spoon samples of the soil, 0.61-mwere collected in butyl acetate liners. Samples (200 g) most representative of overall lithology on the basis of field descriwere selected for gamma-ray spectroscopy after extrusion and air drying in the laboratory.

2.2.6. Quality assuranceFor quality control and to determine variability that may have occurred in constituent concentrations during sampling, rep

samples were collected of one or more matrix at 12 sites. For composited wastes, the replicates were collected from the bufilling each sample bottle partway, and then alternating to the other bottle, back and forth, till both bottles were filled. Equipblanks were collected before fieldwork was initiated to insure adequacy of cleaning procedures.

2.3. Analytical methods

Concentrations of Ra radionuclides were determined after chemical separation from the water sample by co-precipiwith barium or lead sulfate (Table 2). Concentrations of 226Ra were determined either by the planchet counting meth

the 222Rn de-emanation method (Krieger and Whittaker, 1980); the latter is the more sensitive technique (USEPA, 1997). Con-centrations of 228Ra were determined by the beta counting of the ingrown 228Ac progeny (Parsa and Hoffman, 1992; USEPA,

n datatimes

ction,dmin-

withon ofafter

scopyn ap-

alysesndard

Table 2

Description of methods for analysis of ground water, cation-exchange regeneration brine waste, septic effluent, and soil and sludge samples col-

lected by the U.S Geological Survey at domestic well sites, New Jersey Coastal Plain, 2003e2004

Constituent Laboratory reporting level Method Citation

226Ra 0.0037 Bq L�1 222Rn de-emanation (EPA 903.1) USEPA (1997)226Ra Variable,

0.0111e0.0185 Bq L�1Planchet count after barium sulfate co-precipitation

(EPA 903.0)

Krieger and Whittaker (1980)

228Ra Variable,

0.0185e0.037 Bq L�1Beta counting of 228Ac ingrowth after barium or

lead co-precipitation (EPA 904.0)

USEPA (1997), Parsa and

Hoffman (1992)224Ra Variable,

0.0111e0.0185 Bq L�1Gamma spectroscopy after barium or

lead co-precipitation

Parsa (1998),

Focazio et al. (2001)

Gross alpha

(48e72 h and

30 day holding time)

Variable,

0.037e0.111 Bq L�1Low-background proportional count (EPA 900.0)

after evaporation for low dissolved solids ground

water or drinking water samples or after

co-precipitation for high dissolved solids brine

or septic effluent samples

Parsa (1998), USEPA (1997)

Gross beta

(48e72 h and

30 day holding time)

Variable,

0.037e0.148 Bq L�1Low-background proportional count after

evaporation (EPA 900.0)

Krieger and Whittaker (1980)

pH 0.1 standard units Field electrode Wilde and Radtke (1999)

Specific conductance 1 microsiemen per

centimeter (mS cm�1)

Field electrode Wilde and Radtke (1999)

Major cations and iron Variable by analyte;

0.001e0.02 mg L�1Inductively coupled plasma-optical spectroscopy

(ICP-OES)

Harris et al. (1997)

Uranium, select

trace elements

Variable by analyte;

typically 0.0002 mg L�1Inductively coupled plasma-Mass spectrometry

(ICP-MS)

Faires (1993)

Nitrate plus nitrite;

nitrite; ammonia;

chloride

0.1; 0.01; 0.02, all

as mg L�1 N; and

0.1 mg L�1, respectively

Ion chromatography Fishman and Friedman (1989)

Ra isotopes, equivalent,

in soil or sludge

Variable, about

1.7e3.5 Bq kg�1Gamma spectroscopy with density correction Nemeth and Parsa (1992)

1 Bq L�1¼ 27.027 pCi L�1.


1997). The relatively high laboratory reporting level (LRL) of 228Ra was a limitation in obtaining quantifiable concentratiofor media containing low Ra concentrations such as the treated drinking water, as the LRL for 228Ra typically was 3e5higher than that of 226Ra.

Gross alpha-particle and beta-particle activity was generally analyzed within 48 h (maximum, 72 h) after sample colleas recommended for monitoring programs by USEPA (USEPA, 2000b) and required by the State of New Jersey (NJ Aistrative Code, 2002) on the basis of the studies of Parsa (1998). Activities were determined using planchet counting230Th and 137Cs as the standards, respectively. A modification of the co-precipitation technique was used for preparatithose samples with specific conductance greater than about 1000 mS/cm. More than half the samples were re-counted30 days.

Background soil samples and dried sludge were analyzed for equivalent Ra by detecting progeny with gamma spectrousing a plate detector (about 10% efficiency) and polyethylene sample containers with fixed geometry with density correctioplied (Nemeth and Parsa, 1992). Analytical precision was poor for low-weight sludge samples (less than 100 g), and those anare not reported here. Concentrations of non-radioactive inorganic constituents in liquid phases were determined by stamethods (Table 2). Dilution was used for liquid samples with specific conductance greater than 2000 mS/cm.

2.4. Statistical and mass-balance methods

rationed onantialartile

To characterize the Ra in the sampled media, the quartiles (median, and the 25th and 75th percentile) of the Ra-concentdata are reported, as are the minima or maxima. Concentration ratios were computed and mass ratios were estimated (basthe estimated flows; see Supplementary information) as the Ra was transferred from media to media. Because of the substvariability (as with the concentration data), ratio and mass transfer results are presented in terms of the median and inner-qurange.

3. Results

atoryvari-catesgen-

dard-10%)ivity,et ofgrosserlap

fromn forticalples

s thesults

ered,ivelytions(the

L�1).wasents

istentand

ctionrticleL�1.

rticleearlyners

ped by


3.1. Quality assurance (equipment blanks and replicates)

Neither radionuclide of Ra was detected in the equipment-blank samples. Sequential replicate and laborduplicate samples reasonably reproduced results for the initial environmental samples, considering the highlyable nature of the media sampled. The median relative percent differences (RPDs) from the grouping of replifrom the more dilute media of ground water and treated water as well as the more concentrated media of reeration brine wastes and septic effluents were less than the median values of the relative analytical 2-standeviation precision estimate of the individual sample analyses for these media (Table 3). One set of 10 (replicate results for samples from the more dilute media for concentrations of 228Ra, gross alpha-particle actand gross beta-particle activity were outside the range of overlap of the respective precision estimates. One s7 (14%) replicate results for samples from the more concentrated media for concentrations of 228Ra andalpha-particle activity, and 3 sets of 6 (50%) for gross beta-particle activity were outside the range of ovof the respective precision estimates.

The maximum RPDs for gross alpha-particle and beta-particle activities, and for 226Ra and 228Ra werereplicate samples of regeneration brine waste and septic effluent, and the value of the median relative precisiogross alpha-particle and gross beta-particle activities with the high total dissolved solids (TDS) was greater (analyprecision was lower) in the waste media than in more dilute media; the analytical methods perform best in samwith TDS typical of drinking water (Krieger and Whittaker, 1980). The moderate analytical precision indicateneed for repeat testing to gain increased confidence in the individual results. Differences among replicate rewere generally on the order of the (modest) analytical precision.

3.2. Ra concentrations and radioactivity in untreated ground water

The maximum concentrations of 226Ra plus 228Ra were 1.54 and 0.333 Bq L�1 (41.5 and 9.0 pCi L�1) in filtuntreated water from the KirkwoodeCohansey and PotomaceRaritaneMagothy aquifer systems, respect(Fig. 3). (Analytical results for all the samples are presented by Deluca et al., 2006.) The combined Ra concentrain 10 of the 15 wells sampled were greater than 0.1 Bq L�1 and in 6 (40%) were greater than 0.185 Bq L�1

USEPA 5 pCi L�1 MCL). The median combined Ra concentration for all the sites was 0.152 Bq L�1 (4.1 pCiBoth the median value of the combined Ra concentrations and the frequency at which the 0.185 Bq L�1 MCLexceeded are about the same as for the data from the New Jersey Coastal Plain regional-scale aquifer assessm(Kozinski et al., 1995; Szabo et al., 2005). The median pH of the ground-water samples was 4.9, also conswith the previously determined median. The maximum concentrations of 226Ra and 228Ra were 0.8060.729 Bq L�1, respectively (Table 4), and the maximum gross alpha-particle activity 72 h after sample collewas 4.22 Bq L�1 in filtered untreated water from the KirkwoodeCohansey aquifer system. The gross alpha-paactivities in 6 of the 15 wells sampled were greater than 0.555 Bq L�1 (Fig. 4) and in 3 were greater than 1 BqThe median alpha-particle activity for all the sites was 0.41 Bq L�1 (11 pCi L�1). The highest gross alpha-paactivities correspond to the highest concentrations of 226Ra. In the aquifers of the New Jersey Coastal Plain, nall of the gross alpha-particle activity is derived from 226Ra and 224Ra (Szabo et al., 2005), and thus homeow

Table 3

Median relative analytical precision estimate and relative percent difference for replicates for analyses of radionuclides or radioactivity, grou

dilute (ground water and treated water) or more concentrated sample type (brine waste, septic-tank effluent), for homeowner study, New Jersey

Coastal Plain, 2003e2004

Quality-assurance measure 226Ra (%) 228Ra (%) Alpha activity (48e72 h) (%) Beta activity (48e72 h) (%)

Dilute samples

Median relative analytical precision estimate 37 38 46 20

Median relative percent difference, replicates 16 6 20 24

More concentrated samples

Median relative analytical precision estimate 8 21 52 30

Median relative percent difference, replicates 16 16 23 15

Relative precision was biased high by low results for treated water.

test their drinking water for gross alpha-particle activity (NJDEP, 2004) instead of individual Ra isotopes. The max-�1 the

water

temsntra-

ethodalue,oval,alue,tivity.le ra-mumt one

binede not

*

*

*

*

*

*

** *

0.1

1

10

100

SITES SAMPLED

1109

16

0114

06

0114

07

3306

82

3309

58

1515

22

1515

20

0515

06

2914

48

Ground water (well)TreatedRegeneration brine wasteSeptic effluent

0.01

0.001

2314

06

2314

12

2314

07

2314

10

2313

63

2307

860.0001

Not

mai

ntai

ned

Mai

ntai

ned

Kirkwood-Cohanseyaquifer system

Potomac-Raritan-Magothy aquifer system

5 pCi/L MCL

ND ND ND

ND No data

Not

mai

ntai

ned

ND

* Only 226Ra determined

226 R

AD

IU

M P

LU

S 228R

AD

IU

M, B

EC

QU

ER

EL

S P

ER

L

IT

ER

Fig. 3. Concentrations of 226Ra plus 228Ra, by media in the treatment process, for sites in the KirkwoodeCohansey and PotomaceRaritane

Magothy aquifer systems, New Jersey Coastal Plain, 2003e2004. The upper horizontal dashed line indicates 0.185 Bq L�1, the USEPA 5 pCi L�1

MCL.


imum gross beta-particle activity 72 h after sample collection was 1.76 Bq L in filtered untreated water fromKirkwoodeCohansey aquifer system. Both 228Ra and 40K contribute substantially to the beta-particle activity offrom the southern New Jersey aquifer systems (Welch et al., 1995).

3.3. Ra concentrations and radioactivity in cation-exchange treated water

The concentrations of combined Ra or of 226Ra in the water after passage through the cation-exchange systypically were below 0.1 Bq L�1 (only 2 samples had concentrations greater than this value, Fig. 3); and concetions were often at or below the LRL of 0.0037 Bq L�1 for 226Ra determined by the 222Rn de-emanation m(USEPA, 1997) (Table 2). Typical removal of 226Ra was on the order of 90% (median, 91%; 75th percentile v96%). The substantial removal of Ra also decreased the amount of alpha-particle radioactivity (median rem71%; 75th percentile value, 94%) and beta-particle radioactivity (median removal, 82%; 75th percentile v90%). At site 230786, where KCl was used as the salt for the regeneration brine, the gross beta-particle acincreased post treatment, but otherwise also was typically lowered (see Fig. SI-1, Supplementary information)

At 3 sites (of 15 or 20%) in the Coastal Plain, cation-exchange did not substantially reduce the alpha-particdioactivity (first quartile, 37% removal), and the Ra concentration was little reduced either (as indicated by maxivalues in Table 5). The details for these 3 sites (sites 110916, 330958, and 231363) are visible in Figs. 3 and 4. Asite, a non-maintained cation-exchange treatment unit provided cation-exchange ‘‘treated’’ water that had comRa concentration greater than 0.185 Bq L�1 (the USEPA MCL). In 2 of these 3 situations, homeowners wer

maintaining the treatment systems, either because the systems were incorrectly plumbed and the regeneration brineain-

angeo and

-fold.g. 3),

ateraste

Table 4

Summary of distributional statistics for selected radionuclide and water-quality constituents in filtered ground-water samples, New Jersey Coastal

Plain, 2003e2004

Constituent Units Number Minimum 1st Quartile Median 3rd Quartile Maximum

All samples

pH (standard units) Standard 15 4.2 4.6 4.9 5.1 5.8

Specific conductance mS cm�1 15 21 85 175 241 284

Chloride mg L�1 15 2.21 6.63 17.6 28.6 55.7

Sodium mg L�1 15 1.36 4.65 6.53 13.5 33.7

Calcium mg L�1 15 0.21 3.97 8.67 12.3 25.1

Potassium mg L�1 12 0.27 1.10 2.09 2.72 4.76226Ra Bq L�1 15 <0.0037 0.017 0.051 0.097 0.806228Ra Bq L�1 14 <0.015 0.063 0.091 0.128 0.729226Ra plus 228Ra Bq L�1 15 <0.019 0.068 0.152 0.269 1.536

Alpha activity (48e72 h) Bq L�1 15 <0.037 0.167 0.414 0.797 4.224

Beta activity (48e72 h) Bq L�1 15 0.070 0.223 0.370 0.498 1.765

KirkwoodeCohansey aquifer system



Chloride mg L�1 9 2.21 5.70 16.0 20.8 37.6

Sodium mg L�1 9 1.36 4.4 6.0 14.1 20.1

Calcium mg L�1 9 0.21 2.35 8.68 13.8 25.1

Potassium mg L�1 6 0.27 0.78 1.37 3.41 4.76226Ra Bq L�1 9 0.012 0.018 0.075 0.189 0.806228Ra Bq L�1 8 0.041 0.072 0.107 0.185 0.729226Ra plus 228Ra Bq L�1 9 0.012 0.077 0.188 0.318 1.536



PotomaceRaritaneMagothy aquifer system



Chloride mg L�1 6 5.54 15.0 23.4 29.1 55.7

Sodium mg L�1 6 2.95 5.6 7.8 11.9 33.7

Calcium mg L�1 6 0.92 5.83 7.89 10.7 13.5

Potassium mg L�1 6 0.84 2.06 2.28 2.60 2.88226Ra Bq L�1 6 <0.0037 0.015 0.041 0.051 0.061228Ra Bq L�1 6 <0.015 0.028 0.077 0.115 0.272226Ra plus 228Ra Bq L�1 6 <0.019 0.044 0.118 0.165 0.333

Alpha activity (48e72 h) Bq L�1 6 0.048 0.142 0.407 0.638 1.352


1 Bq L�1¼ 27.027 pCi L�1. Concentrations of combined Ra greater than 0.185 Bq L�1 (USEPA 5 pCi L�1 MCL) and gross alpha-particle activity

greater than 0.555 Bq L�1 (USEPA 15 pCi L�1 MCL) are shown in bold type. The concentration of 228Ra could not be determined in 1 sample;

combined Ra was set equal to the concentration of 226Ra.


bypassed the treatment media or the salt tank was not properly filled. At the 3rd site (231363), despite proper mtenance, the treatment unit was not functioning as expected and the Ra-removal performance of the cation-exchresin was among the lowest observed, though some Ra was removed. The resin was installed about 12 years agperhaps exchange capacity was exhausted.

3.4. Ra concentrations and radioactivity in regeneration brine waste from cation-exchange treatment units

Regeneration brine waste was enriched in Ra relative to filtered untreated ground water by as much as 195Maximum concentration of combined Ra in the regeneration brine waste was 81.2 Bq L�1 (2200 pCi L�1) (Fiwith a median value of 2.28 Bq L�1 (Table 6) representing more than 30-fold enrichment relative to the ground-wconcentration (median ratio, 35). The more than 30-fold enrichment typical of Ra in the regeneration brine w

relative to the ground water is consistent with the typical 90e95% Ra-removal rate from the incoming ground water.226 228 �1 spec-

stem,tivityKirk-ation

0.001

0.01

0.1

1

10

100

1,000G

RO

SS

A

LP

HA

-P

AR

TIC

LE

A

CT

IV

IY

TY

, B

EC

QU

ER

EL

S P

ER

L

IT

ER

15 pCi/L MCL

Ground water (well)TreatedRegeneration brine wasteSeptic effluent

Kirkwood-Cohanseyaquifer system Potomac-Raritan-

Magothy aquifer system

SITES SAMPLED

1109

16

0114

06

0114

07

3306

82

3309

58

1515

22

1515

20

2314

07

2314

10

2313

63

0515

06

2914

48

2314

06

2314

12

2307

86

Fig. 4. Gross alpha-particle activities, by media in the treatment process, for sites in the KirkwoodeCohansey and PotomaceRaritaneMagothy

aquifer systems, New Jersey Coastal Plain, 2003e2004. The horizontal dashed line indicates 0.555 Bq L�1, the USEPA 15 pCi L�1 MCL.


The maximum concentrations of Ra and Ra in regeneration brine wastes were 47.0 and 59.3 Bq L , retively, with the former from a treatment system that derived water from the KirkwoodeCohansey aquifer syand the latter, from the PotomaceRaritaneMagothy aquifer system (Table 6). Maximum gross alpha-particle acwas 118 Bq L�1 (3180 pCi L�1) in regeneration brine waste from a treatment system that derived water from thewoodeCohansey aquifer system (Fig. 4). The maximum gross beta-particle activity was 992 Bq L�1 in regener

Table 5

Summary of distributional statistics for selected radionuclide and water-quality constituents in treated (cation exchange) drinking water, New Jersey

Coastal Plain, 2003e2004


All samples


Specific conductance mS cm�1 14 95.8 200 245 285 521

Chloride mg L�1 8 5.58 35.2 41.5 55.7 75.4

Sodium mg L�1 15 2.5 13.4 28.2 47.3 88.2

Calcium mg L�1 14 0.01 0.09 0.69 11.4 184a

Potassium mg L�1 6 0.095 0.18 0.91 2.62 89.6226Ra Bq L�1 15 <0.0037 <0.0037 <0.0037 0.006 0.152a

228Ra Bq L�1 6 <0.015 <0.0015 0.011 0.078 0.276a

Alpha activity (48e72 h) Bq L�1 15 <0.019 0.0032 0.062 0.150 1.500a

Beta activity (48e72 h) Bq L�1 15 <0.037 0.042 0.078 0.231 2.664

1 Bq L�1¼ 27.027 pCi L�1. Concentrations of Ra greater than 0.185 Bq L�1 (USEPA 5 pCi L�1 MCL), gross alpha-particle activity greater than

0.555 Bq L�1 (USEPA 15 pCi L�1 MCL), and gross beta-particle activity greater than 1.85 Bq L�1 (USEPA 50 pCi L�1 MCL screen) are shown

in bold type. The concentration of 228Ra was generally too low to allow quantification and was not determined in every sample.a Cation-exchange treatment unit not maintained.

brine waste at site 230786, where KCl was used as the salt, and the K concentration of the brine waste was�1

ivelyange26Rasitesrtile;rticle

ain-ation

Table 6

Summary of distributional statistics for selected radionuclide and water-quality constituents in filtered samples of regeneration brine waste discharge

from cation-exchange units treating domestic well water, New Jersey Coastal Plain, 2003e2004


All samples


Specific conductance mS cm�1 15 207a 56 000 70 400 101 100 676 000

Chloride mg L�1 13 1120 15 600 21 300 29 300 60 800

Sodium mg L�1 13 747 8200 14 200 18 600 33 500

Calcium mg L�1 13 0.55 76.3 329 1300 4150

Potassium mg L�1 7 4.44 14.1 53.1 249 28 600226Ra Bq L�1 14 0.007 0.096 0.592 4.20 47.0228Ra Bq L�1 14 0.020 0.474 1.41 6.06 59.3226Ra plus 228Ra Bq L�1 14 <0.052 0.367 2.28 15.3 81.2

Alpha activity (48e72 h) Bq L�1 15 0.270a 4.47 9.25 16.6 118

Beta activity (48e72 h) Bq L�1 14 0.418 8.47a 12.1 25.1 992



Specific conductance mS cm�1 9 207a 49 200 52 000 70 400 92 000

Chloride mg L�1 8 1120 14 780 21 300 24 800 33 990

Sodium mg L�1 7 747 4470 11 380 16 385 22 660

Calcium mg L�1 7 0.55 103 613 1180 3240226Ra Bq L�1 8 0.022 0.910 2.17 13.1 47.0228Ra Bq L�1 8 0.050 1.54 2.40 7.76 34.2226Ra plus 228Ra Bq L�1 8 0.073 2.45 4.58 20.9 81.2

Alpha activity (48e72 h) Bq L�1 9 0.270a 1.29 10.33 26.3 118




Specific conductance mS cm�1 6 25 000 83 075 128 150 152 375 676 000

Chloride mg L�1 5 11 464 26 260 29 290 50 658 60 800

Sodium mg L�1 6 2810 11 410 17 300 27 225 33 500

Calcium mg L�1 6 10.6 110 270 1560 4150

Potassium mg L�1 5 4.44 15.2 53.1 352 28 600226Ra Bq L�1 6 0.007 0.063 0.289 0.536 5.73228Ra Bq L�1 6 0.020 0.284 0.791 0.899 59.3226Ra plus 228Ra Bq L�1 6 <0.052 0.348 1.09 1.43 65.0


Beta activity (48e72 h) Bq L�1 6 6.29 9.99 16.28 48.7 992

1 Bq L�1¼ 27.027 pCi L�1. Concentrations of Ra greater than the 0.185 Bq L�1 (USEPA 5 pCi L�1 MCL), gross alpha-particle activity greater

than the 0.555 Bq L�1 (USEPA 15 pCi L�1 MCL), and gross beta-particle activity greater than 1.85 Bq L�1 (USEPA 50 pCi L�1 MCL screen)

are shown in bold type. The concentration of either 226Ra or 228Ra could not be determined in 1 sample; combined Ra was set equal to the concen-

tration of the Ra isotope that was determined.a Cation-exchange treatment unit not maintained or not functioning effectively.


26 800 mg L .At 5 of the sites in the Coastal Plain, the concentrations of combined Ra in regeneration brine wastes were relat

low (less than or equal to 0.56 Bq L�1) (Fig. 3). Brine was not being properly used to regenerate the cation-exchresin at sites 110916 and 330958 and the waste liquids showed little or no Ra enrichment. The median ratio of 2

and combined Ra in the regeneration brine waste relative to the untreated ground water for all the Coastal Plainwas 29 and 35, respectively, but was less than 12 for the sites with the lowest Ra-removal efficiencies (bottom quadata not shown). The regeneration brine waste at site 231363 contained combined Ra concentration and alpha-paactivity of 1.27 and 8.51 Bq L�1, respectively, which were below the median values for the study, despite proper mtenance. At site 231410, cation-exchange was effective at removing Ra from the ground water, but the regenerbrine contained little Ra.

3.5. Ra concentrations and radioactivity in septic-tank liquids

weret the

nitial1 sitef then theange,ngedxceptquids


Concentrations of combined Ra in the septic-tank liquids ranged from 0.026 to 0.243 Bq L�1 (Fig. 3) andtypically about two-thirds (median, 65%; inner-quartile range, 40e104%) that of the untreated ground water aindividual sites. At 5 sites, the combined Ra concentration in the septic-tank liquid equaled or exceeded the iground-water concentration. The 226Ra was higher in the septic system liquid than the ground water at onlyand concentrations of 226Ra were typically about one-third (median, 32%, inner-quartile range, 16e64%) oground-water concentration. Gross alpha-particle radioactivity distribution pattern followed the same trend iseptic-tank liquids as the 226Ra; the median activity was also about one-third (median, 31%; inner-quartile r14e123%) of the ground-water activity (Fig. 4). The gross beta-particle activity in septic-tank liquids, which rafrom 0.108 to 2.775 Bq L�1 (median, 0.715 Bq L�1), was greater than that of the ground water (Tables 4 and 7), efor 2 sites. The concentrations of K ranged from 7.58 to 31.2 mg L�1 (median, 14.1 mg L�1) in the septic-tank liwhereas they ranged from 0.27 to 4.76 mg L�1 (median, 2.09 mg L�1) in the ground water.

Table 7

Summary of distributional statistics for selected radionuclide and water-quality constituents in septic system effluent (liquid component of septage)

receiving ion-exchange regeneration brine from water softening units used to treat domestic well water, New Jersey Coastal Plain, 2003e2004


All samples


Specific conductance mS cm�1 12 1000 1205 1630 2150 19 790

Chloride mg L�1 12 64.6 174 425 603 6330

Sodium mg L�1 12 37.4 141 280 402 3990

Calcium mg L�1 12 6.56 21.2 26.5 34.8 69.4

Potassium mg L�1 9 7.58 9.57 14.1 15.0 31.2226Ra Bq L�1 12 <0.0037 0.012 0.032 0.066 0.117228Ra Bq L�1 10 0.026 0.057 0.102 0.128 0.242226Ra plus 228Ra Bq L�1 12 0.026 0.036 0.158 0.191 0.243






Chloride mg L�1 8 64.6 318 458 603 736

Sodium mg L�1 8 37.4 224 289 402 612

Calcium mg L�1 8 6.56 22.2 30.5 43.5 69.4

Potassium mg L�1 5 7.58 9.57 10.3 17.5 31.2226Ra Bq L�1 7 0.015 0.0301 0.0478 0.0799 0.117228Ra Bq L�1 6 0.043 0.0977 0.102 0.110 0.174226Ra plus 228Ra Bq L�1 7 0.026 0.0523 0.158 0.191 0.237





Specific conductance mS cm�1 4 1150 1210 1290 5965 19 790

Chloride mg L�1 4 155 173 255 1830 6330

Sodium mg L�1 4 114 141 153 1120 3990

Calcium mg L�1 4 16.8 20.1 22.6 25.9 31.8

Potassium mg L�1 4 8.99 12.8 14.4 14.8 15.0226Ra Bq L�1 4 <0.0037 <0.0037 0.0037 0.0153 0.044228Ra Bq L�1 4 0.026 0.0326 0.0839 0.160 0.242226Ra plus 228Ra Bq L�1 4 0.0321 0.0357 0.107 0.194 0.243



1 Bq L�1¼ 27.027 pCi L�1. Concentrations of Ra greater than 0.185 Bq L�1 (USEPA 5 pCi L�1 MCL), gross alpha-particle activity greater than

0.555 Bq L�1 (USEPA 15 pCi L�1 MCL), and gross beta-particle activity greater than 1.85 Bq L�1 (USEPA 50 pCi L�1 MCL screen) are shown

in bold type. The concentration of 228Ra could not be determined in 2 samples; combined Ra was set equal to the concentration of 226Ra.

All liquid samples from the septic tanks were considerably different in chemical composition than the native�1 dian,

eater

at orudgeationzonesite

cen-bouteaterivity.d for

d theof Raf the


ground water. Especially notable were the high concentrations of Cl (maximum, 6330 mg L ; me425 mg L�1), Ca and Na (Table 7). The pH of the septic effluent was typically at least 1e2 full pH units grthan typical ground water in the sandy Coastal Plain aquifers, ranging from 6.2 to 7.4 (median, 6.8).

3.6. Ra concentration in sludge, soil, and sediment

The combined Ra concentration in soils and sandy sediments from the unsaturated zone and sediments frombelow the water table ranged from 10 to 40.7 Bq kg�1 dry weights (Table 8). The combined Ra concentration in slfrom the septic tanks ranged from 84 to 363 Bq kg�1 dry weights (Table 9). The maximum combined Ra concentrin the sludge is about 10-fold greater than the maximum combined Ra concentration in the sandy soil and vadose-sediments, but the sludge-to-soil combined Ra ratio was about 37 for well site 330682 and nearby soil coring330681 (Fig. 1). Even the minimum combined Ra concentration in the sludge is greater than the maximum contration in the soil or sediment. In contrast with the soil or sediment where the 226Ra to 228Ra ratio was typically a1.0, 226Ra was clearly the predominant source of radioactivity in 2 of the samples of sludge. Combined Ra was grthan 40K in all samples of sludge, whereas, in the soils and sediments, 40K was the predominant source of radioactThe combined Ra concentration in sludge from the homeowners’ septic systems falls within the range reportesludge samples from POTWs from the Atlantic Coastal Plain (ISCORS, 2003).

4. Discussion

4.1. Mass transfer of Ra from wastes to the environment

The mass of Ra being processed in the home ultimately depends upon the amount of water used in the home anconcentration of Ra in the ground water entering the home as potable water from the well. The concentrationsare substantially different in each of the media evaluated in the home treatment system environment. Because o

Table 8

Concentration of equivalent 228Ra and equivalent 226Ra at selected depths in sandy sediment from soil, from the unsaturated zone overlying the

water table or from the water table, in the KirkwoodeCohansey aquifer system at 5 sites in the southwestern part of the New Jersey Coastal Plain

Site

number

Sample depth

below land

surface (m)

Gross lithologic description Equivalent 228Raa

(as 228Ac) (Bq kg�1)

Equivalent 228Raa

(as 212Pb) (Bq kg�1)

Equivalent 226Raa


40K (Bq kg�1)

151056 4.6 Fine, medium, and

coarse sandb16.7� 4.8 18.5� 2.6 22.2� 2.9 137� 55

151056 7.6 Medium sand 20.4� 2.2 20.0� 1.8 18.9� 1.8 96.2� 25.9

151059 1.5 Coarse sand and gravel 13.0� 2.9 13.3� 1.5 9.2� 1.8 40.7� 29.6

151059 8.2c Coarse sandb 7.0� 1.8 4.1� 1.1 4.8� 1.1 <32

330681 5.8 Medium to coarse sand <9.9 4.8� 1.5 4.8� 1.5 170� 29

151053 6.7 Medium sand with gravel <7.4 2.3� 0.9 5.5� 1.1 <35.5

151053 9.8c Medium sandb <7.4 2.7� 0.9 4.1� 1.1 21.8� 18.9

110694 2.1 Medium sand with gravel 12.2� 2.9 9.6� 1.5 11.8� 1.8 85.1� 37.0

110694 3.7 Medium sand with gravel 13.3� 2.6 12.2� 1.8 1.1� 1.8 114� 37

110694 5.2 Medium and coarse sand

with gravel

8.1� 2.6 6.3� 1.5 8.5� 1.5 74.0� 25.9

110694 8.2c Medium and coarse sand

with gravel

<10.4 5.9� 1.5 9.6� 1.8 99.9� 37.0

110694 9.8c Medium and coarse sand

with gravel

6.3� 2.2 4.1� 1.1 4.1� 1.1 32.6� 21.8

1 Bq kg�1¼ 27.027 pCi kg�1. Concentrations of 40K greater than 111 Bq kg�1 (3000 pCi kg�1) are shown in bold type.a Equivalent radionuclide concentration is reported in terms of the radionuclide or radioactive progeny used to determine concentration by gamma

spectroscopy.b Samples split in laboratory for duplicate analyses; results matched within standard 2-sigma errors.c Samples at or just below the water table.

dynamic nature of the volume of waste at any time in the septic tank and the likely temporal variation in the Racult,rther

leastgs. 3teredlative% ofg thelargeabout

t 3 ofwnerd Rat unitater,

-tank

thana and226Raratio

y thatan is

n thefield,iquid

Table 9

Concentration of equivalent 228Ra and equivalent 226Ra in sludge collected from septic tanks in the New Jersey Coastal Plain, 2003e2004

Site number Sample weight

after drying a,b (g)

Sample description

after dryingaEquivalent 228Rac

(as 228Ac) (Bq kg�1)

Equivalent 228Rac


Equivalent 226Rac


40K (Bq kg�1)

110916d 339.5 Black fine powder 82.9� 2.5 118.0� 2.7 64.8� 1.8 112.5� 10.4

330682e 110.8 Thick black sand 91.8� 3.1 108.8� 2.6 255� 5.2 148.3� 17.8

151522 212.0 Black fine powder 62.9� 2.1 82.0� 2.9 54.6� 1.7 76.2� 11.8

231363 137.3 Black and tan fines 44.9� 2.26 51.4� 4.8 41.5� 2.6 <0.8

370498d,e,f 104.3 Coarse brown debris

and fibers

6.3� 1.2 <1.7 88.1� 1.6 84.7� 17.8

1 Bq kg�1¼ 27.027 pCi kg�1. Concentrations of Ra and K greater than 111 Bq kg�1 (3000 pCi kg�1) are shown in bold type.a Oven dried at 104 �C.b Samples less than 100 g had high relative errors and are not reported here.c Equivalent radionuclide concentration is reported in terms of the radionuclide or radioactive progeny used to determine concentration by gamma

spectroscopy.d Samples split in laboratory for duplicate analyses; results matched within standard 2-sigma errors.e Samples from septic tank not evacuated for about 10 years.f Samples from bedrock area in northwestern New Jersey; water-quality data are available from Deluca et al. (2006).


concentration in the septic-tank effluent, evaluating the environmental fate of the waste-borne radium is diffiespecially without high quality flow data, and the estimates presented here are considered a tool in guiding furesearch efforts.

4.1.1. Estimates of mass transfer of Ra from the treatment system to the septic tankThe cation-exchange treatment systems, when maintained, effectively removed Ra, typically resulting in at

a 10-fold reduction, and in some cases nearly a 100-fold reduction relative to the untreated ground water (Fiand 4). The Ra was re-concentrated into the brine during the resin regeneration process and did not remain sequeson the resin. The concentration of Ra in the brine typically was enriched about 30-fold (maximum, 195-fold) reto the concentration in untreated ground water. Even though the brine used in regeneration composed less than 5the total volume of liquids leaving the home and entering the septic tank, greater than 95% of the Ra departinhome to the septic tank was supplied by this small volume. The effluent in the septic tanks is a mixture ofvolumes of treated water containing hardly any Ra and a small volume of water (about 200 L) containing95% of the Ra passing through the home.

A somewhat unexpected issue of concern identified in this random survey of a small number of homes was tha15 (20%) cation-exchange treatment systems were not functioning effectively at Ra removal despite homeobelief to the contrary, and 1 of the non-functioning cation-exchange units was providing water with combineconcentration greater than 0.185 Bq L�1. At sites 110916 and 330958, because the cation-exchange treatmenwas not functioning, the ‘‘treated’’ water contained nearly all of the Ra initially entering the home from ground wand this discharged ‘‘treated’’ water, not regeneration waste brine, was the predominant source of Ra in the septiceffluent. At sites 231363 and 231410, the regeneration brines also contained less Ra than expected.

The combined Ra concentrations in the septic-tank liquids (range, 0.026e0.243 Bq L�1) were typically lowerthat found in the untreated ground water, the original source of the Ra. The median concentration ratios of 226R228Ra in regeneration brine wastes relative to the septic-tank effluents were 66 and 34, respectively. The medianand 228Ra mass ratios were 3.3 and 1.7, respectively (Table 10). The combined Ra mass concentration and massmedian values were about the same as the results for 228Ra (35 and 1.7, respectively). The mass ratio results implfor most of the sites, somewhat more Ra mass is discharged to the septic tank in regeneration waste brine threcovered from the septic-tank effluent (median recovery for combined Ra in effluent, 62%).

4.1.2. Estimates of Ra accumulation within the septic system sludgeOf the Ra discharged to the septic tank in regeneration brine, a large portion at the ‘‘typical’’ site resides i

effluent. Some of the Ra mass is discharged to the aquifer as liquid outflow of septic-tank effluent to the leachhowever, and some associates with reactive particles that settle and accumulate as sludge. (The fate of the l

effluent was investigated in a companion study, Szabo et al., submitted for publication). The combined Ra concentra-�1 um,

ima-cen-n thef thebeen

f par-accu-ationon ofminglatedis onrthe-half-n thenessrs of

e Racallys and

asteenior

Table 10

Concentration ratios and mass ratios for selected radionuclide and chloride in regeneration brine waste discharge from cation-exchange units treat-

ing domestic well water to septic system effluent (liquid component of septage) that received the brine waste, New Jersey Coastal Plain, 2003e2004

Site

number

Beta

radioactivity,

gross

Alpha

radioactivity,

gross

226Ra 228Ra Chloride Beta

radioactivity,

gross

Alpha

radioactivity,

gross

226Ra 228Ra Chloride

Concentration ratio, regeneration brine waste:septic effluent Mass ratio, regeneration brine waste:septic effluent

110916 0.61 3.4 2.72 2.3 0.25 0.03 0.17 0.14 0.12 0.01

011406 78.7 259 401 308 54.1 3.94 12.9 20.1 15.4 2.70

011407 20.9 139 53.1 19.8 45.9 1.04 6.97 2.67 0.99 2.29

330682 11.7 47.3 33.1 27.6 16.7 0.59 2.36 1.66 1.38 0.84

330958a e 1.39 e e 60.4 e 0.07 e e 3.02

151522 20.7 66.5 75.7 44.1 53.4 1.03 3.32 3.77 2.21 2.67

151520 20.1 7910 143 73.0 18.8 1.01 396 7.18 3.65 0.94

051506 36.8 1347 551 128 292 1.83 67.3 27.6 6.42 14.6

231412 111 34.1 2488 1715 392 5.53 1.71 124 85.7 19.6

231407 5.6 7.50 4.75 5.21 8.0 0.28 0.38 0.24 0.26 0.4

231410a 13.1 7.72 4.09 0.09 34.7 0.65 0.39 0.2 0.004 1.73

231363 11.0 47.9 66.2 33.9 146 0.55 2.4 3.31 1.70 7.31

Percentiles Summary of population distribution statisticsb

25th 11.56 8.97 5.27 5.57 17.7 0.58 0.46 0.26 0.28 0.89

50th 20.39 47.59 59.6 30.8 53.4 1.02 2.38 2.99 1.54 2.67

75th 38.97 121.1 337 114 122 1.94 6.06 16.8 5.72 6.12

a Concentrations of one or more radioactive constituent at or near reportable levels with proportionately large measurement errors.b Number of results are not equal for each constituent.


tions in sludge (maximum, 363 Bq kg dry weight) relative to the soil and vadose-zone sediments (maxim40.7 Bq kg�1) are elevated about 10-fold, indicating that the sludge has sequestered Ra. A volume-based approxtion using the thickness of the sludge (30 cm) for the site (330682) with the septic tank with the highest Ra contration in the sludge indicates that about 5500 Bq of Ra might be contained in the settled sludge. The mass of Ra isludge in the septic tank at this site is thus about 3.9 times the mass of Ra contained in the liquid filling the rest ovolume of the septic tank (about 8000 L times 0.177 Bq L�1 or about 1400 Bq). The sludge at the site had notevacuated for about 10 years, providing time for the solids to accumulate Ra from liquids in the septic tanks. Iticles have little Ra when introduced into the septic tank, then it can be approximated that about 5000 Bq hasmulated in the sludge in the 10 years from the liquids (brine wastes), which are the source of the Ra. The accumulrate is then 500 Bq per year or 1.37 Bq per day. If 2 individuals use 680 L per day with combined Ra concentrati0.150 Bq L�1, this amount alone results in 37 230 Bq of combined Ra discharged to the septic tank per year, assuno Ra mass loss. The calculation indicates only about 1.3% of the combined Ra entering the septic tank is accumuin the sludge. The Ra accumulation rate is not great because the residence time of the liquid effluent in the tankthe order of days or less. As accumulation time increases (years to tens of years), the ratio of 226Ra to 228Ra neveless increases in the sludge since the 226Ra half-life is so long that loss from decay is minimal, whereas the 228Ralife is 5.75 years. The 226Ra to 228Ra in the sludge at the site (330682) is about 2.3 whereas the 226Ra to 228Ra inearby soil (soil coring site 330681) is 1.0 and that of the ground water at site 330682 is also 1.0. The typical thickof settled sludge/sediment was about 15 cm (range, 2.5e45 cm) consistent with recollection of most site owneroutine maintenance thus avoiding substantial Ra accumulation.

4.2. Implications of study results

Sludge is hauled from private on-site waste disposal (septic) tanks to POTWs and thereby contributes to thcontent of the sludge there. Risk-based modeling assessments have concluded that sludge from septic tanks typido not contain Ra concentrations high enough to pose hazardous exposure levels to the sludge (waste) haulerhandlers (ISCORS, 2004a). A similar conclusion was reached using risk-based modeling regarding exposure to wdisposal workers at non-hazardous landfill operations (Smith et al., 2003). Radiation dose badges worn by the 2 s

authors during sampling activity did not indicate detectable dose, although the field-portable gamma scintilometerthan

thernf the

ncern988;

ORS,rthera re-plied

fromat as

eatedted’’

as re-fold)

binedncen-

thegion.ppear

erseyyticalQA)

ng ance ins wasuntysion.ry ofthodsaste-holasman-rsity)gues


registered a small increase in radiation (10e30% relative to background) in the immediate vicinity (less0.3 m) of containerized sludge. Radium enrichment in sludge derived from homeowner septic tanks in souNew Jersey, based on results of this study, do not appear to pose concern greater than or separate from, that oRa concentrated in the sludge at the POTWs in the region.

The disposal of sludge as amendments to soils raises multiple radiation exposure scenarios, with special cofor incorporation of Ra into plants and/or food crops growing in the soil (Tracy et al., 1983; Bettencourt et al., 1Linsalata et al., 1989; ISCORS, 2004a), leaching of the Ra (and metals) to ground water (Jacobsen, 2000; ISC2004a), and exposure to the gaseous 222Rn progeny (of 226Ra) emanating from the soil (ISCORS, 2004a,b). Fuground-water monitoring is proposed as a tool for understanding potential water-quality degradation, perhaps atsearch site, using a random nested design (Jacobsen, 2000), and mobilization of Ra from soils receiving land-apsludge in southern New Jersey is the focus of ongoing investigations (NJDEP, 2006a,b).

5. Conclusions

Cation-exchange treatment systems, when maintained, effectively removed combined Ra from ground watersthe Coastal Plain aquifers in New Jersey that contained combined Ra (226Ra plus 228Ra) at concentrations as gre1.54 Bq L�1 (42 pCi L�1). At least a 10-fold reduction relative to the presence of these constituents in untrfiltered ground water was observed. At one site, a non-maintained cation-exchange treatment unit provided ‘‘treawater that had combined Ra concentration greater than 0.185 Bq L�1 (the USEPA 5 pCi L�1 MCL). The Ra wconcentrated into the regeneration brine, which typically was enriched about 20- to 30-fold (maximum, 195-relative to the concentration in untreated ground water, and was discharged to on-site septic systems. ComRa concentrations in the effluent in the septic tanks ranged from 0.026 to 0.243 Bq L�1. The combined Ra cotration in sludge from the septic tanks ranged from about 0.084 to 0.363 Bq g�1, about a 10-fold increase fromconcentration in the sandy aquifer sediments, but within the range noted for sludge at POTWs within the reRadium enrichment in sludge derived from homeowner septic tanks, based on results of this study, does not ato pose concern greater than or separate from, that of the Ra in the sludge at the POTWs.

Acknowledgements

This project was completed cooperatively by the United States Geological Survey (USGS) and the New JDepartment Environmental Protection (NJDEP) Division of Science, Research and Technology. Additional analsupport was provided by the USGS Toxics Hydrology Program and the National Water Quality Assessment (NAWProgram. We thank NJDEP colleagues Dr. R. Lee Lippincott for administering the sampling program and for takiactive role in sampling-site selection, and Patricia Gardner, Eleanor Krukowski, and Jenny Goodman for assistandevising the initial plan for the multi-media sampling program. Additional assistance in finding sampling locationprovided by numerous local associations including Delaware Valley Regional Planning Commission, Salem CoWatershed Taskforce, Middlesex County Department of Health, and Stillwater Township Environmental CommisAssistance in developing sampling protocol for the regeneration brine waste was provided by Thomas BarKel-Tren Water Care. Assistance in testing the sampling of sludge using a variety of vacuum suction pumping mewas provided by Russell Reid Waste Hauling Services, Keansby, NJ. For drying sludge at the Morrisville, PA, Wwater Treatment Plant, we thank Dawn Rivera, and Rich Dulay, Superintendent. We thank USGS colleagues NicSmith and Eric Best for assistance with sample collection, Elizabeth Keller and Kristin Romanok for databaseagement, William Ellis for assistance with graphics, and Taryn Correll (student intern, Pennsylvania State Univefor equipment cleaning. We lastly acknowledge helpful suggestions to improve this manuscript by USGS colleaRalph Seiler, Brian Katz, and Edward Landa, and by Joseph Drago of Kennedy Jenks Associates.

Appendix A. Supplementary data

vpol.
Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.en2007.11.009.
http://dx.doi.org/doi:10.1016/j.envpol.2007.11.009

http://dx.doi.org/doi:10.1016/j.envpol.2007.11.009

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