Vol. 6 No. 4 CHIN. J. OCEANOL. LIMNOL. 19~8

PETROLEUM HYDROCARBON CONTAMINATION OF GROUND WATER IN TIVERTON, RHODE ISLAND, USA

Zheng Jinshu ( ~ ) (Third Institute of Oceanography, SOA)

James G. Quinn (Graduate School of Oceanography, University of Rhode Island, USA)

Received Nov. 23, 1907

Al~traet

Ground water samples from several private wells serving individual homes in Tiverton, Rhode Island

were analyzed for petroleum contamination over a 19-month period. The hydrocarbon concentrations initially

ranged from 68 to 2350 ppb and then gradually decreased to lower values, ranging from 6 to 1650 ppb, at the

end of the study.

Samples from the well with the highest hydrocarbon concentration (2350 to 1650 ppb) were investigated

in some detail because this was considered a possible source of the petroleum contamination in the area. These

studies indicated that most of the hydrocarbons were in the dissolved phase ( < 1.0gin} of the ground water

and that it contained large amounts of naphthalene, methyl and dimethyl naphthalenes, and ethyl

naphthalenes. In addition, the qualitative distribution of hydrocarbons changed as the concentration

decreased over the course of the investigation. There appeared to be preferential loss of the more volatile and

easily degraded components relative to the higher molecular weight and more refractory hydrocarbons.

Some of the wells at-this location are contaminated with at least two different petroleum products, i.e.

gasoline and fuel oil. The exact nature and source of the contaminant is not known; it may be spilled or leaking

petroleum products, or other materials containing petroleum hydrocarbons (e.g. commercial or industrial

cleaning solutions). Based on differences in the qualitative distribution of components, some of the wells

contain hydrocarbons that have been envlronmentally altered or that originate from a source other than the most contaminated well

INTRODUCTION

Several private wells in Tiverton, Rhode Island (Figure 1) were reported to be contaminated with petroleum products. The homeowners complained of a foul taste and strong fuel oil smell in their drinking water. In November 19B4, the U.S. Environmental Protection Agency laboratory in Lexington, Massachusetts conducted a site investigation using a field gas chromatograph. The results of this study indicated the presence of petroleum hydrocarbons in both water and soft samples, and subsequent laboratory analysis confirmed the contaminant to be #2 fuel oil OM. Mulhare, R.I. Department of Environmental Management, personal communication). Water samples were also analyzed by the R.I. Department of Health (RIDOH) in February and May 19B5 and found to be contaminated with fuel oil with concentrations as high as 1600 parts per billion (Table 1).

In order to provide more detailed information on the qualitative and quantitative distribution of the petroleum contaminants in the ground water from this coastal area, the organic geochemistry laboratory, oftheGraduate School of Oceanography ((;SO) at the University of Rhode Island (URI), continued the ir~esti~tion from October 1985 to May I9~ r. During this 19 month period, seven

368 C H I N E S E JOURNAL OF OCEANOLOGY AND LIMNOLOGY Vol. 6

a

Table 1 Coneentration (#g/I) of total hydrocarbons in Tiverton ground water umples from February 1985 to May 1987

R I D O H Laboratory

Home 2/26/85 5 2 2 _ ~ 3/7/86 6[19/86 5/7/87

28A 1000 1600 600 370 520

28B . . . . .

28C . . . . .

17 1000 400 200 100 110

18 100 100 200 150 - -

26 - - 400 - - 300 - -

29 100 100 < 2 5 < 2 5 - - b

27 100 ND - - 140 < 2 5

91 - - - - < 2 5 - - - -

7 100 ND - - < 2 5 - -

a #g/l=part per billion (ppb);

b ND =none detected.

J/ i lSl 28 29 l [

tq

Fig. 1 Location of the individual homes sampled for well water contamination

series of ground water samples were collected and analyzed. Most of these samples were analyzed for total hydrocarbons, but one sample was separated into dissolved and particulate components by filtration before analysis. All samples were analyzed by gas chromatography and several were further characterized by combined gas chromatography-mass spectrometry, The results of this investigation are described in this report.

METHODS

Four.liter brown bottles were used to collect water samples from outside faucets on individual homes in a residential section of Tiverton, RI (Figure 1). The homes obtained their water supply

N o . 4 P E T R O L E U M C O N T A M I N A T I O N O F G R O U N D W A T E R 3 6 9

from private wells. After the pumping system was started and water had been allowed to run for about five minutes, approximately 3.5 liters of water were collected in each bottle. The samples were delivered to the laboratory within two hours of collection and 5-10 ml of methylene chloride were added to each sample in order to retard microbial activity. The samples were stored in the dark at room temperature from a few hours to 48 hours before tbey were analyzed.

Analyses

When ready for analysis, internal standard hydrocarbon (n-C22 or a mixture of n-C22 and meta- terphenyl) in methanol was added to each sample and it was shaken for 30 s. Then, 300 ml of methylene chloride were added and it was again shaken for one minute to extract the total hydrocarbons from the water into the organic solvent. The layers were allowed to separate and the methylene chloride phase was isolated, solvent exchanged into hexane, and then reduced in volume to about 100/zl on a rotary evaporator at 20~ under vacuum. About 1 #1 of the concentrated extract was then analyzed by gas chromatography. The instrument used in these analyses was a Hewlett Packard model 5840A gas chromatograph (GC) with a flame ionization detector and equipped with a 15 meter DB-5 fused silica capillary column (0.25 mm i.d., 0.25/zm film thickness) from J & W Scientific, Inc. After injection, the column was held at 35~ for 5 minutes and then temperature programmed at 4~ to 290~ and held at that temperature for 10 minutes before recycling. The concentration of hydrocarbons in each sample was calculated based on the internal standards and the results have been corrected for small procedural blanks (Table 2).

a Table 2 Concentration (#g/I) of total hydrocarbons in Tiverton ground water samples

from October 1985 to May 1987

G S O / U R I Laboratory

Home 1 0 / 1 7 / 8 5 1 2 / 1 0 / 8 5 3171~_ 6 / 1 9 / 8 6 1 1 / 1 3 / 8 6 5 / 5 / 8 7 5 / 7 / 8 7

b 2 8 A 2 3 5 0 4 6 5 0 ~ 2 5 8 0 1 5 8 0 1 5 9 0 1 5 6 0 1 5 8 0

2 8 B - - 2 5 1 0 - - 2 2 4 0 1 8 8 0 1 6 5 0 - -

2 8 C - - 2 6 8 O . . . . .

17 7 0 8 1 3 2 0 1 0 4 0 1 0 1 0 1 5 0 0 0 5 1 3 5 9 9

18 2 9 0 1 1 5 0 5 5 3 5 0 3 2 5 5 - - - -

2 6 - - 9 3 8 - - - - 7 4 2 7 0 2 - -

2 9 - - 3 5 2 1 14 - - - - - -

2 7 6 8 6 - - 3 8 1 9 3 1 6 - -

9 1 - - - - 4 . . . .

7 - - - - - - 15 - - - - - -

d 7 e d d d 5 e, Blank 2 5 4 2 - -

a g ~ l = p a r t per billion ( p p b ) ;

b replicate samples - - taken one after the other from A to C after first flushing the system;

c sample collected without any flushing of the system;

d = distilled wta, r;

e ~ tap water.

370 C H I N E S E J O U R N A L OF O C E A N O L O G Y AND LIMNOLOGY Vol. 6

One sample from home 28 (December 19[k%28A) w a s analyzed for both saturated and unsaturated hydrocarbons by separation of the total hydrocarbon extract into two fractions using silica gel column chromatography. Sample 28B was analyzed for total hydrocarbons only, and sample 28C was filtered through a Whatman GF/C glass fiber filter (particle size retention about 1.0 #m) and the filtrate (dissolved or soluble portion) was extracted with methylene chloride and analyzed for hydrocarbons. (Both of these samples were also collected in December 1985). Several sample extracts were analyzed by combined gas chromatography-mass spectrometry (GC-MS) to confirm the identification of selected hydrocarbon components. The GC-MS used was a Finnigan MAT 4500 Series System containing a 15 meter DB-5 fused silica capillary column.

A complete description of the analytical methods used in this study can be found in Pruetl and Quinn (1985) and Zheng and Quinn (1987).

RKSULTS AND DISCUSSION

The results of the total hydrocarbon analyses of samples collected on seven dates over the 19 months study period are shown in Table 2. In general, a comparison of the data reported by the RIDOH laboratory (Table 1 ) and the GSO/URI laboratory (Table 2) shows that the latter values are ns~mlly 3 to 5 times higher than the former values when samples were collected on the same dates. An interlaboratory comparison of analyses of aqueous solutions containing various petroleum products, prepared by the RIDOH laboratory, indicates that the GSO/URI laboratory values were in very good agreement with the actual qualitative and quantitative values for these solutions (Table 3). The reasons for the poor agreement in analysis of ground water samples between the two laboratories are probably due to the different procedures used: RIDOH--rapid screening method using headspace analyses of volatile components employing a GC photoionization detector and external standards; GSO/URI - - relatively slow, detailed method using analyses of methylene chloride extracts of lipophihc components employing a GC flame ionization detector and internal standards.

Table 3 Results of 1986-1987 analyses of Rhode Island Delmrtmeut of Health ln~rcalibration samples

of petroleum products in aqueous solution

K n o w n Known GSO/UR1 GSO/UR1

Intercal ibra t ion concent ra t ion gas/oil concen t ra t ion gas/oil a

sample (#g]l)_ ~ - (#~/1)

Gasoline - h igh 960 - - 940 - -

Gasoline - low 124 - - 118 - -

# 2 fuel oil - h igh 850 - - 632 - -

#2 fuel oil - low 142 - - 92 - -

Gas/oil - h igh 1290 31/69 1270 42/58

Gas/oil - low 170 44/56 138 48/52

a percent by weight.

Based on the values presented in Table 2, the concentrations of total hydrocarbons at home 28 were fairly uniform from October 1985 to March 1986 (2350 to 2680 #g/l) and then decreased to

No. 4 PETROLEUM CONTAMINATION OF GROUND WATER 371

rather constant values from June 1986 to May 1987 (1560 to 1580 #g/l). The high value (4650 ttg/1) observed for sample 28A in December 1985 is probably because the sample was collected without any flushing of the water lines. (All other samples were collected after a 5 min flushng time.) In general, the agreement between duplicate samples on the same day or within two days, is quite good. One possible exception is the June 1905 date where the in'st sample is in very good agreement with those taken in November 1986 to May 1987, but the second sample is somewhat higher in concentration.

The levels at home 17 also changed over time with the highest concentration of hydrocarbons observed in December 1985 (1320/~g/1), then decreasing to 5004i00 gg/l in May 1987 (Table 2). However, a concentration of 15,000/~g/1 was observed in November 1906 and a reasonable explanation for this anomalous value has not been found. Home 18 showed a large increase in concentration from October to December 1905 and thereafter decreased to about the original level. Home 27 was higldy variable and increased in June and November 1906 and then decreased to a very low value in May 1987. Homes 26 and 29 decreased in concentration over the course of the study, and homes 91 and 7 had low values and were only sampled once.

Sample 28B (December 1985) was not fdtered so that it could be analyzed for total hydrocarbons. Sample 28C was fdtered and the fdtrate was analyzed for hydrocarbons. Those two

�9 . ~ . . �9

n l t , . .

I II1~

-~=.

)

i t I e ~IS>

a Increasing time and temperature

Fig. 2 Chromatograms of hydrocarbons in samples from home 28 in Oct. 1965 (a), Dec. 1985 (b) and May 1967 (c). The internal standard (IS) was nC22

372 CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY VoL 6

samples had essentially the same concentration (2510 vs 2680 #g/l; Table 2) and on this operational basis, the hydrocarbons in these samples, and presumably most of the other samples, are mostly in the dissolved or soluble phase ( < 1.0/am) and are not associated with particulate material in the ground water.

From the chrormtograms of samples from home 28 collected from October 1985 to May, 1~7, the series of hydrocarbons ranged in boiling point from xylene (Retention Time (RT) = 3.5 min) to n-Cz4 (RT =49.0 rain) as shown in Figure 2. In comparing the sample chromatograms with water soluble portions of various petroleum products, the range for gasoline was RT = 3.5 to 25.0 min, the RT for kerosene was 3.5 to 40.0 min, and the #2 fuel oil RT was 3.5 to 49.0 min (Figure 3). Thus, sample 28 has a boiling point distribution ranging from gasoline to fuel oil, and at least two different petroleum products could be present in this sample.

The separation of sample 28A (December 1985) into saturated and unsaturated hydrocarbon fractions (Figure 4) also provided additional information about the types of petroleum products present in this sample. Based on a comparison of unsaturated hydrocarbons from the water soluble portions of gasoline and #2 fuel oil (Figure 5), it is dear that aromatic hydrocarbons from these and other petroleum products could be contributing to the unsaturated fraction of sample 28.

!

i t~

t

ii b

l n e r e ~ i n g time and

t I ~ {IS)

temperature

Fig. 3Chromatograms of hydrocarbons in the water soluble portion of unleaded gasoline

(a), kerosene {b) and #2 fuel oil (c). The internal standard (IS) was nCz2

Several samples were analyzed by combined gas chromatography-mass spectrometry. Sample 28 (December 1985 and May 1987) and sample 26 (May 1987) showed several major aromatic

i tm O

Fig. 4

( IS

23

t-,2 t ~ r--

o~

Increas ing t ime and t e m p e r a t u r e - -

Chromatograms of hydrocarbons in the saturated (a) and unsaturated (b) fractions from home 28 in Dec. 1905. The

internal standard (IS) was nC22. Labelled peaks correspond to naphthalene (peak 1), 2-CH 3 naphthalene (peak 2), I-

CH 3 naphthalene (peak 3), and a series of dimethyl and ethyl naphthahnes (4)

O

~o

~

_ b IS)

Increasing time and t e m p e r a t u r e

Fig. 5 Chromatograms of unsaturated hydrocarbons in the water soluble portion of unleaded gasoline

(a) and #2 fuel oil (h). The internal standard (IS) was meta-terphenyl

374 CHINESE JOURNAL OF OCEANOLOGY AND LIMNOLOGY Vol. 6

components corresponding to naphthalene, methyl and dimethyl naphthalenes, and ethyl naphthalenes (see Figure 4). Sample 17 (May 5, 1987) shows no naphthalene and very few methyl naphthalenes (see Figure 6). Therefore, home 17 may have a different source of contamination than homes 26 and 28 or it may be more environmentally altered, possibly because of the length of time the contaminant has been underground. Thus, if the same source of contamination is responsible for all of the hydrocarbons at this location in Tiverton, the diffusion of components along the east-west direction (.samples 28, 27, 26; see Figure 1) may be faster than along the north-south gradient (sample 17 vs sample 28). The suspected location of the contamination is home 28 because of its uniformly high concentration of hydrocarbons over the 19 month study period.

IS)

o~

Increasing time and temperature

Fig. 6 Chromatogram of hydrocarbons in sample from home 17 in May 1987.

The internal standard (IS) was nC22

Based on the amount of total hydrocarbons with a RT = 3.5 to 16 min (nCt 2)' vs 16 min to 49 min (nCz4), the relative percentage of gasoline and fuel oil was estimated in samples from home 28. (See Table 3 for results of analyses on intercalibration samples.) The data in Table 4 shows that as sample 28 decreased in concentration from October 1985 to May 1987, the percentage of gasoline decreased from 58% to 22% with the last four samples giving a relatively narrow range of 1560-- 1590 #g/1 of total hydrocarbons, and 18 to 22% gasoline (see Figure 2 for changes in the

Table 4 Pereentage of gasoline and fuel oil hydroearbons in ground water samples

from home 28 during the period October 1985 to May 1987

Total

Sampling hydrocarbons Gasoline Fuel oil

date (#g/l)_ o / ~ o / ~

10117185 2350 58 42

12/10/85 2510 29 71

3/07/86 2580 16 84

6/19/86 1580 18 82

11/13/'86 1590 19 81

5/05/87 1560 19 81

5/07/87 1580 2 2 78

No. 4 PETROLEUM CONTAMINATION OF GROUND WATER

chromatograms of sample 28). Thus, these samples appear to be preferentially losing the more volatile and easily degraded gasoline components relative to the higher molecular weight and more refractory fuel oil hydrocarbons.

The exact type of material involved in the contamination of wells at this location is still unknown. However, the qualitative distribution of hydrocarbons suggests a mixture of at least two different petroleum products, i.e. gasoline and fuel oil, at some of the wells. The source of the contaminan~t may be spilled or leaking petroleum products, or other materials containing petroleum hydrocarbons (e.g. commercial or industrial cleaning solutions).

ACKNOWLEDGMENTS

We thank Mr Michael Annarummo of the R.I. Department of Environmental Management for his help in the initiation of this project, Mr. Michael Mulhare and Mr. David Sheldon ofR.I. DEM for collection of the samples, Dr. Walter Combs, Jr. and Ms. Paula.Jean Therrien of R.I. DOH for the preparation of the intercalibration samples, and Dr. Richard Pruell and Mr. Curt Norwood of the EPA Environmental Research Laboratory/Narragamett for their help with the GC-MS analyses.

Reference8

[1] Hoffman, E.J., G.L. Mills, J.S. Latimer and J. G. Quinn, 1984. Urban runoff as a source of PAH to coastal waters.

Environmental Science and Technology 18: 581)-587.

[21 Hoffman, E.J., J.S. Latimer, G.L. Mills, and J.G. Quinn, 1982. Petroleum hydrocarbons in urban runoff from a

commercial land use area. Journal of Water Pollutant Contribution 54: 1517-1525.

[3] Hurtt, A.C. and J.G. Quinn, 1979. Distribution of hydrocarbons in Narragansett Bay sediment cores. Environmental

Science and Technology 13: 829--8,36.

[4] Wade T.L. and J.G. Quinn, 1979. Geochemical distribution of hydrocarbons in sodiments from mid-Narraganseu Bay,

Rhode Island. Organic Geochemstry 1: 157-167.

[5] Pruell, R.J., and J.G. Quinn, 1985. Geochemistry of Organic Contaminants in Narragansett Bay Sediments. Estuarine

Coastal and Shelf Science 21: 295-312.