Assessment of groundwater contamination subsequent to an environmental release

WASTE MANAGEMENT, Vol. 10, pp. 261-268, 1990 Printed in the USA. All rights reserved.

0956-053X/90 $3.00 + .00 Copyright © 1990 Pcrgamon Prcss plc

ASSESSMENT OF G R O U N D W A T E R CONTAMINATION SUBSEQUENT TO AN ENVIRONMENTAL RELEASE M. T. Galceran, R. Rubio, and G. Rauret* Department of Analytical Chemistry, University of Barcelona, Diagonal 647, 08028 Barcelona, Spain

L. Alonso Servei de Medi Ambient, Diputaci6 de Barcelona, Spain

ABSTRACT. An episode of groundwater pollution occurred at the beginning of 1987 in the municipality of Les Franqueses del Vall6s (Catalonia, Spain) is studied. Conductivity, pH, chloride, ammonia nitrogen, cyanide, chemical oxygen demand, mercury, and the neutral plus basic fraction and acidic fraction from organic matter, as well as the total organic compounds, were chosen as significant pollutants. From the organic compounds detected, thirty of them were considered important because they occur with considerable frequency or they are present in high concentration. From the results obtained, the main pollution source, chemicals stored in damaged tanks buried in the soil, was established. A quick intervention of local authorities allowed a rapid decrease of environmental releases.

samples from some wells in the zone and from solvent distillation residues stored in damaged tanks located on the ground of the courtyard of a factory, allowed us to establish that the main pollution source was due to the products contained in these tanks. The local authorities closed the factory and when the main source was eliminated, a study ordered by the Diputaci6 de Barcelona about the main pollutants evolution with time was carried out. In the first step of the study, pH, conductivity, temperature, hardness, calcium, magnesium, sodium, potassium, chloride, alkalinity, sulphate, dry residue, nitrate, nitrite, chemical oxygen demand (permanganate), aluminium, iron, manganese, copper, cadmium, zinc, lead, arsenic, selenium, mercury, nickel, chromium (III) and (VI), cyanides, surfactants, and ammonia nitrogen, as well as organic matter extractable with methylene chloride at pH 8 were determined. From the information obtained in this first step, it was concluded that only some inorganic compounds showed levels of concentration high enough to be considered significant and attributable to any important pollution source. In contrast organic compounds seemed to play an important role in the episodic situation. For this reason only, pH, conductivity, chloride, ammonia nitrogen, cyanide, chemical oxygen demand, mercury, and the neutral plus basic fraction and acidic fraction from organic

INTRODUCTION

The most serious aquatic pollution incidents are those that damage groundwater because of the difficulty in elimination of pollutants from this compartment. This is the reason why groundwater pollution should be ascertained and studied as soon as an incident occurs (1). The risk of groundwater pollution is increased when the freatic layer is near the surface, as it happens to be in some zones of Valles Oriental, Catalonia (Spain) because the degradation process in the soil takes place to a lesser extent. In this case, any pollutant disposed or buried without enough protection in the soil can easily reach groundwater. It is necessary then to find the pollutant source to eliminate it before the damage becomes too serious. It is also important to carry out a continous assessment through a monitoring program (2), so that adequate decisions can be made about groundwater supply and irrigation uses. At the beginning of 1987 an episode of groundwater pollution was observed in the municipality of Les Franqueses del Valles in Catalonia (Spain). This zone is an agricultural and industrial area and it happens that the wells used for irrigation were seriously damaged accidentally. First, a complete analysis of

RECEIVED 12 OCTOBER 1989; ACCEPTED 11 MAY 1990. *To w h o m correspondence m a y be addressed.

261

262

matter, in addition to the total organic compounds concentration were chosen to carry out the study of the groundwater pollution evolution. This paper presents the results obtained in the study carried out in 1987, as well as the methodology employed in the determination of organic compounds.

EXPERIMENTAL

Aquifer Characteristics The polluted zone was in the alluvial aquifer of the Congost River, which is basically made of sand and gravel. This aquifer is of a free type, with a maximum thickness of 3 m. when it is water saturated. The freatic level is located at a depth of 3 - 4 m and its impermeable bed is of myocene clay.

Hydraulic Behaviour The aquifer is overloaded by infiltration from the surface water of the Congost River, from springs, and also from rain water. Generally groundwater flows down, following the flowline of the aquifer but when the aquifer water level is higher than the river it flows from the subsurface to the Congost River. Generally the river water and the groundwater are hydraulically disconnected due to the high contamination level of the river water which tends to make the riverbed waterproof.

Aquifer Exploitation The groundwater is used extensively for area village water supplies (Granollers, Les Franqueses, etc.) and for irrigation and industrial purposes. This aquifier is the more important source of supplying water to the zone because water of the Congost River is so polluted that it is impossible to be used, and the small underlying myocene aquifiers give small flows, only 1-2 m3/h in each well.

Sampling The sampling site is located in Les Franqueses del Vall6s in Catalonia, Spain. Nineteen wells located near the Congost River and extended over a small area as shown in Fig. 1 were sampled. The location of the studied wells, industrial and rural wells, were selected according to the relative position of the suspicious pollution source and the estimated flow line of the groundwater along the river. Sampling was performed by using either manual or pumping techniques, according to the well characteristics; when sampling was carried out manually, Niskin bottle model 101005, 51, (General Oceanics Inst. Inc. Miami, Florida U.S.A.) was used. Water samples for both general physico-chemical and inorganic parameters determination were sampled in polyethylene bottles, whereas for organic parame-

M . T . GALCERAN ET AL.

ters, determination glass bottles were used. The sampiing bottles were cleaned by the usual method (3). Sampling was carried out in March, July, and November of 1987. In Table 1 characteristics, the type of sampling and sampling dates are shown for the studied wells. Samples were stored at 4°C until they were analyzed. Aliquots used to determine trace metals were acidified to pH 2, and filtered through 0.45/lm membrane filters, and those used to determine cyanide and ammonia nitrogen were stored in alkaline and acidic medium, respectively.

Materials All chemicals were Merck-analytical grade or "suprapur" quality. Double-deionized water (Culligan Ultrapure GS 18.3 Mfl cm-1 resistivity) was used. All solvents, Carlo Erba analytical grade, were glass distilled. Glass microfiber filters (GF-C) Whatman 0.45/~m and cellulose ester membrane filters Gelman 0.45/~m, were used. The materials used for organic analysis were cleaned as follows: glassware was washed by sonication in a detergent solution and rinsed with doubledeionized water and acetone. Sodium sulfate, silica gel, and alumina were extracted with methylene chloride-methanol (2: 1) in a Soxhlet apparatus for 24 h. All distilled solvents were analyzed for residues by gaschromatography (GC) after concentrating from 100 mL to 10/zL. All glassware and plasticware used for trace-metal analysis were previously soaked in 100 mL/L nitric acid for at least 24 h and rinsed with double-deionized water.

Analytical Methods The general physico-chemical and the inorganic parameters were determined according to the Standard Methods, American Public Health Association (4). Cyanide was determined spectrophotometrically with a previous distillation step with UV-VIS Beckman model DU-7 (Irvine, California U.S.A.). Mercury was determined by atomic absorption spectrometry using the cold vapor technique with a Perkin-Elmer atomic absorption spectrophotometer model 4,000 with a double beam, deuterium lamp as background corrector and hollow catode lamp. Sodium borohydride was used as the reductant solution. The organic compounds were determined as follows: the sample (1,500 mL) was adjusted to pH 8 with sodium hydroxide and extracted with methylene chloride (three times with 50 mL each) to obtain the basic plus neutral fraction (B + N). The sample was then adjusted to pH 2 with hydrochloric acid and extracted with the same solvent also for three times to obtain the acid fraction (A). This fraction previously reduced to 2 mL, was esterified overnight with 10 mL of 20% borontrifluoride/methanol. Then the

GROUNDWATER CONTAMINATION

263

IAIII~.INO r-l..,.

Pll de Llerona

Pq)

T

M

=IN

,

rp,l ¢,gLL erona

.in •

/

N

~-"

qb

N It •

,

~

^N

i/

N

pl~ d'en Girbau

~,"-'. . N

A

"ll

:

1

qF'

,_

Nee. !

F

~ lJ

,¢ I re, Fr.nnueses~ B.Sanahuja

II

,,

- q,'--")~-jt

a,p

•

p

1

FIGURE 1. Location of the sampling points.

+

j

264

M . T . GALCERAN ET AL. TABLE 1 Studied Wells and Sampling Dates Date, 1987

Sample

Characteristics

Sampling

March

28 34 55 57 63 66 71 72 77 80 81 82 89 91 97 99 103 108 C.S.

R R R I

P P M M

X X X X

R I R I

M M P P

X X X X

R

P

X

R I I R

P P M P

X X X X

R

P

X

R

P

X

July

November

X X X X X X X X X

X X X X X X X X

X

X

X X X X

X X X X X X

X

R = rural, I = industrial, P = by pumping, M = manually.

boron-methanol complex was destroyed with 20 mL of water, and the fatty acids methylesters were extracted with 5 mL of n-hexane. All the individual fractions were concentrated to an appropriate volume (50-100/lL) by rotary evaporation, followed by evaporation under stream of cold and pure nitrogen. Extracted samples were analyzed by gas chromatography with a DANI (Monza, Italy) model 3,800 GC equipped with a flame ionization detector (FID) and splitless injector. The column was a RSL200 polydiphenylenylmethylsiloxane, fused silica, wall-coated open tubular column 0.2 mm diameter, 30 m long, film thickness 0.20 llm, and Helium was the carrier gas (26 cm/s). The temperature was programmed from 40°C to 260°C at 8°C/min. The injector and detector temperature were respectively 250°C and 260°C. The injection was in the splitless mode (hot needle technique) keeping the speed valve closed for 45 s. Compounds were identified by combined gaschromatography and mass-spectrometry (GC-MS) on a Hewlett Packard (Palo Alto, California U.S.A.) model 5985 GC-MS system. The gas chromatography column was 5% phenylmethylsilicone (0.52/~m film thickness) 0.2 mm diameter and 25 m long. Conditions were identical to those described above. Mass spectra were obtained by 70 eV electron impact. Tentative identification was accomplished by comparison of retention times and mass spectrometric data from the sample and standard compounds or data stored in the spectral libraries. The gas-chromatography analysis provided an estimation of the

total extractable organic compounds present, and also an estimation of specific organic compounds by using a FID-response factor obtained from the external standard methyl stearate. The GC-MS analysis allows an estimation of specific compounds, even in poorly resolved mixtures by integration of specific fragment ions; but in this work we used this technique only as a qualitative tool.

RESULTS A N D DISCUSSION

Results of the parameters chosen as significant pollutants are given in tables 2 to 4. They show generally high values of electrical conductivity in all the groundwater samples analyzed during the three sampling periods. The highest values were found in wells number 72 and 77 with a maximum in the samples collected in July showing that this saline pollution came from another source than the one which originates organic pollution. The chloride content, parameter strongly related to conductivity, shows the highest mean value in the same sampling period. Ammonia shows values higher than those in unpolluted waters in a great number of samples. In the third sampling period, the values show a remarkable decrease in all the wells, but in wells 71, 72, and 77 high concentration values still remained whereas basic plus neutral compounds show an important decrease. Special attention must be paid to the evolution of cyanide content in the wells studied. In March, cyanide was detected in six wells but only in samples 72 and 81 was the concentration markedly higher than the standard for potable waters CEE (5). These wells showed also the highest values of basic and neutral fraction. In the second and the third sampling a considerable decrease, not only in cyanides but also in the basic and neutral fraction and in the specific compound isocyanomethylbenzene, makes one wonder about a common origin of cyanides and some specific organic compounds. A further study about the behaviour of organic compounds containing cyano groups in cyanide determination in polluted waters showed that these kind of compounds give generally positive interference when three different analytical methods for cyanide determination, including the one used in the present study, are applied (6). A different behaviour was observed with chemical oxygen demand (COD), which showed the highest values in the third sampling period. The COD values measured were, in general, higher than those allowed for public water supplies. Mercury was detected only in two samples, 66 and 71, in the first sampling. The concentration values measured were lower than those tolerated for public water supplies.

265

G R O U N D W A T E R CONTAMINATION TABLE 2 Results of the Parameters Chosen as Significant Pollutants (March 1987) Sample

Parameter

(pS cm ')

(NH;) (mg L-')

CN- (total) (pg L -~)

Hg

pn

CI(mg L-')

Organic Basic + neutral Compounds

(mg L '0.,)

(pg L t)

(pg L ')

(pg L ' )

6.9 7.5 6.9 6.9 6.7 7.5 7.1 7.0 6.6 6.2 7.5 7.3 7.2 6.8 6.7

2,617 2,197 2,187 2,292 1,900 1,108 4,250 5,348 2,139 1,337 778 2,841 2,006 1,261 2,282

575 517 529 536 362 189 1,326 1,761 517 214 89 840 486 147 570

<0.03 <0.03 3.5 <0.03 <0.03 7.0 43 4.5 26 <0.03 <0.03 3.4 <0.03 <0.03 25

ND ND 3.1 0.6 ND ND 147 ND 148 ND ND 19.2 ND ND 14.0

7.07 3.40 8.48 3.52 2.44 16.4 62.3 16.0 51.9 1.88 0.28 11.9 2.68 0.72 28.0

<1.0 <1.0 <1.0 <1.0 9.9 <1.0 3.1 < 1.0 <1.0 < 1.0 < 1.0 <1.0 < 1.0 < 1.0 <1.0

26 711 18 17 23 154 225 14 287 8 9 58 38 19 51

46 30 80 61 120 201 175 95 86 87 44 330 42 53 145

Electrical Conductivity 28 34 55 57 66 71 72 77 81 82 89 91 97 103 C.S.

Nitrogen

Oxygen Demand

Organic Acid Compounds

ND = not detected.

The total amount of organic pollutants extracted from the basic and neutral and acidic compounds are indicated in Tables 2 through 4. From the total compounds detected, 30 of them were important because they occurred with considerable frequency in the analyzed samples or because they were present in high concentation in some of the wells studied. The tentatively identified compounds are indicated in Tables 5 to 7. The acidic compounds observed in all the wells were a mixture of fatty acids with minor amounts of

other compounds, such as aromatic carboxylic acids, phenols, and phtalic acid, the latter presentin a considerable amount in some of the wells, mostly in the third-sampling period (November 1987). Both the total concentration of acidic fraction (Tables 2 to 4), and the concentration of individual compounds were extremely variable but the fatty acids were present in all the wells, whereas compounds such as benzenecarbodithioic acid or 2,6,bis(1,1-dimethylethyl)phenol were detected only in some wells; probably due to specific contamination.

TABLE 3 Results of the Parameters Chosen as Significant Pollutants (July 1987) Sample

Parameter

(ItS cm -t)

(NH4+) (mg L ~)

CN- (total) (pg L-')

Hg

pn

CI(mg L -~)

Organic Basic + neutral Compounds

(mg L-'O2)

(pg L -~)

(pg L -L)

(pg L-')

6.9 6.9 7.2 6.9 7.2 7.3 7.0 7.0 7.2 6.9 7.8 6.9 7.0 6.9 7.0

3,060 3,110 4,030 3,240 1,650 1,016 7,000 5,580 1,780 2,930 1,017 3,000 2,820 4,210 3,200

704 754 972 716 278 194 1,077 1,512 387 632 103 790 794 972 692

0.26 0.07 0.26 10.75 0.67 6.64 9.67 7.10 <0.03 1.03 0.03 5.19 <0.03 0.32 14.78

ND ND ND 49 ND ND 10 ND ND 30 ND ND ND ND ND

6.52 7.36 8.83 18.95 2.91 14.34 14.81 18.07 3.41 8.50 2.53 9.00 7.15 12.23 13.68

< 1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 < 1.0 <1.0 <1.0

8 12 14 461 13 15 24 9 16 126 9 26 11 9 80

44 128 40 51 93 139 19 26 47 50 30 50 33 40 90

Electrical Conductivity 34 55 57 63 66 71 72 77 80 81 89 91 97 99 108

ND = not detected.

Nitrogen

Oxygen Demand

Organic Acid Compounds

266

M. T. G A L C E R A N ET AL. TABLE 4 Results of the Parameters Chosen as Significant Pollutants (November 1987)

Sample

34 55 57 63 66 71 72 77 81 89 91 97 99 103 108

Parameter

pH

Electrical Conductivity (/tS c m -~)

C1( m g L ~)

6.7 6.6 6.7 6.7 6.7 6.7 6.5 6.6 6.6 6.9 6.6 6.6 6.8 6.8 6.5

2,440 2,370 2,290 2,710 2,010 685 3,380 5,810 2,570 1,620 2,800 2,400 3,555 1,360 2,590

525 591 942 624 378 61 810 1,724 469 279 506 510 867 137 469

Nitrogen (NH;) (mg L-')

CN- (total) ( p g L -l)

Oxygen Demand (mg L-~02)

ND 4.0 ND ND ND ND ND ND ND 1.0 ND 8.0 4.0 ND ND

25.22 9.18 15.61 18.95 20.39 28.83 43.98 24.19 23.85 23.78 25.83 28.37 27.69 26.47 28.18

<0.03 0.37 <0.03 <0.03 <0.03 2.74 10.18 10.05 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <0.03

Hg ( p g L -~)

Organic Basic + neutral Compounds ( p g L ')

Organic Acid Compounds (~tg L - ' )

<1.0 <1.0 <1.0 <1.0 <1.0 < 1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

3 7 7 73 7 24 21 4 30 19 64 11 18 13 24

50 87 106 50 85 111 123 156 110 144 91 101 98 96 50

ND = not detected.

The base plus neutral compounds are of variable nature: phtalates used as plastifiers, 4-([4-methylphenyl] sulphonyl) morpholine used as antioxidant, octadecanol used in pharmaceutical and cosmetic industries, quinazolines, sulfur compounds (dimethyltrisulfide, carbonodithioic dimethyl ester) and other compounds some of them described as pollutants in groundwaters (7-11). The concentration of this frac-

tion was generally lower than the acidic one and high concentration of some specific compounds, such as isocyanomethylbenzene in wells 72 and 81 in the first sampling period and 4-([4-methyl-phenyl] sulphonyl)morpholine in well 63 in the second sampling period are probably indicative of specific contamination. The fact that some of the compounds, such as fatty

TABLE 5 Compounds Determined in the Analyzed Samples (March 1987) Well ( p g / L ) Compound

28

Dimethyltrisulfide Isocyanomethylbenzene/benzeneacetonitrile Carbonotrithioic dimethyl ester 2 Methylquinazoline Family acetamides Pentadecyl-dimethyl-dioxane isomer 4-((4-Methyl-phenyl)sulphonyl)morpholine 4 , 8 , 1 2 T r i m e t h y l 3 , 7 , 1 1 - t r i d e c a t r i e n e nitrile Diethylphtalate Bis(2-ethylhexyl)phtalate Diisooctyl phtalate 2,6 B i s ( 1 , l - d i m e t h y l - e t h y l ) p h e n o l Benzene carbothioic acid Benzene a-hydroxy acetic acid 2-(4-Chlorophenoxy)2-methylpropanoicacid n-nonenoic acid n-nonanoic acid n-tetradecanoic acid n-pentadecanoic acid n-hexadecenoic acid n-hexadecanoic acid n-octadecenoic acid n-octadecanoic acid

. .

34 . .

55 . .

1.9 13.5 2.3 0.9 0.6 1.2 3.4 1.1 . . . 0.1 0.2 . . . 0.7 0.4 2.2 1.5 2.5 1.7 0.7 3.5 4.3 3.1 9.2 5.9 2.3 2.5 2.9 1.4

. . . . 1.2 1.4 0.6 0.5 . . . 1.8 6.8 6.2 0.4 12.6 22.8 8.2 5.6

57 .

66

71

.

.

6.5

.

. -

.

76.8 . . 1.3 0.6 . . . 2.5 14.3 . . . . 0.7 0.9 . . . . 3.2 . . . . . 50.4 1.1 3.0 2.2 4.6 8.6 6.6 3.5 7.6 6.4 0.6 8.9 14.4 12.8 15.6 2 5 . 7 17.5 7.7 13.5 8.8 5.2 7.5 6.6

.

72

77

81

4.9 11.5 37.1 35.3 16.0 19.5 8.5 13.8 0.2 3.1 . . 13.0 0 . 3 12.1 0.4 0.4 . 5.7 4.8 0.5 1.5 3.7 2.1 1.5 5.2 7.2 6.1 13.6 5 . 6 10.3 0.4 11.2 12.6 8.9 2 2 . 4 20.3 2 0 , 4 8.4 8.4 8.4 7.0 5.7 6.9

82

CS

89

1.3 0.3 0.5 0.5 0.4 2.2 1.2 1.9 6.6 4.5 0.5 9.4 16.4 9.3 6.1

1.0 1.8 3.2 1.2 0.9 4.4 0.7 1.4 2.3 4.4 11.4 9.9 17.3 27.2 13.9 9.9

. . . 0.3 0.8 0.4 0.4 7.9 3.2 2.2 0.4 4.6 10.0 5.2 3.5

91

97

103

1.9 2.26 4.9 . . . . . . . . . 1.3 0.9 1.9 0 . 0 8 2.5 1.0 0 . 4 0.7 0.6 2.0 2.7 7.1 5.8 0.5 136.9 0.3 0.9 1.1 2.3 2.6 3.9 18.8 2.8 3.3 0.8 0.6 10.2 4.8 6.4 22.7 10.8 14.9 13.5 4.7 4.9 0.8 3.1 12.3

G R O U N D W A T E R

267

C O N T A M I N A T I O N

TABLE Compounds

Determined

in

the

6 Analyzed

Samples

(July

1987)

Well (ug/ L) 34

Compound

55

57

63

71

Dimethyltrisulfide . . Isocyanomethylbenzene/benzeneacetonitrile . . Carbonotrithioic d i m e t h y l e s t e r 2 Methyl quinazoline . . . 4((4-Methylphenyl)sulphonyl)morpholine B e n z o t h i o p h e n e , 3-phenyl . . 4,8,12-Trimethyl 3,7,1 l-tridecatienenitrile . . Dieth ylphtalate Di-n-butyl phtalate 0.5 0.8 Diisooctylphtalate 0.9 0.8 2,6-Bis(1,9-dimethyl ethyl)phenol Benzeneacetic acid . . . 2(4-Chlorophenoxy)2-methyl propanoic acid 17.1 55.2 Phtalic acid n-nonenoic acid 7.6 n-nonanoic acid n-dodecanoic acid 0.7 1.1 n-tetradecanoic acid 5.1 11.2 n-hexadecenoic acid 10.3 24.0 n-hexadecanoic acid 7.6 n-octadecenoic acid 0.9 8.3 n-octadecanoic acid

. . . . 16.6 . . . 36.4 . . . . . . . . 20.2 1.3 1.3 0.7 27.6 . . . . . . . 45.7 0.4 0.6 -

acids

wells

and

studied

phtalates

were

observed

and in all the three sampling

able amounts

ranging

from

the some

related

zone. wells

Other and

present

with the intensive compounds their

periods

0.5 to 110/tg/L,

that there could be compounds probably

in all the

were

concentration

.

66

.

-

-

2.6 19.8 11.1 3.5

-

3.2 3.3 14.5 2.9 6.2

. 1.6 1.8 12.9 1.1 1.0

.

-

-

2.1

-

1.8

2.1

-

0.6 0.8 9.6

1.0 9.4

.

-

-

-

4.6

These

use of

lowered

odithioic

in

the

3.4

.

. 0.8 0.2 1.6 .

.

.

.

. 18.0

. -

.

. .

. .

97

. . 2.5 . . . . . 2.8 1.8 -

. . .

. .

. .

99

108

-

1.7 6.1

0.7

10.1 -

. . 0.9 0.5 -

2.9 12.3 2.3 . . . . . . . . . . . 24.8 . . . . . . 0.8 0.1 0.6 0.6 0.6 3.6

-

-

3.4 12.8 5.2 10.7 5.1 13.8

compounds

could

was

1.5

2.7

6.6

. 2.7 10.5 4.7 0.9

. 2.7 3.4 8.5 2.4 2.8

4.9 12.9 16.6 4.5 12.8

be the result

of the 2-meth-

i n w e l l 71 in

in J u l y a n d it w a s n o t

Other

compounds

isocyanomethylbenzene, ester,

10.9

2.1

for instance,

76.8 /tg/L

to 9.9/~g/L

in November.

2.8

. . . 2.3 1.4 3.1 6.0 10.8 13.8 2.7 4.5 3.4 5.1

episode,

which

dimethyl

91

.

4.9

dimethyltrisulfide,

with

.

1.3

went down

observed

in

89

. .

3.6

ylquinazoline,

only

. .

. 1.7 4.0 8.1

81

.

. . . . 0.6 . . -

suggest

industrial

Determined

.

single-contamination

such

as

carbon-

2-(4-chlorophenoxy)-2-

7

TABLE Compounds

. .

9.5 18.2

March

80

. 3.4 . . 1.4 . . -

.

time.

77

in vari-

in the aquifer

present

. . . 9.9 . . 2.1 . 33.4 27.2

.

3.2

72

Analyzed

Samples

(November

1987)

Well (/tg/L) Compound

34

55

57

63

66

71

72

77

81

89

91

97

99

103

108

2.5 0.3 0.8 . . . . . . Bis dimethyl ethyl phenol . . . . . 1.6 . . . . 0.7 0.4 Imidazol dienones isomers 0.4 0.8 2.1 5.2 . . . . . Methyl pentadecyl 1,3 dioxane isomers 1-Isocyanate h a p h t h a l e n e 4.2 1.4 1.1 0.2 1.3 1.9 0.8 0.3 3.6 . . . . 0.6 . . . . . 1.9 Benzenesu lphocyanide 6.2 0.2 2.5 6.0 5.1 1.1 (1.6 0.4 3.7 4-((4-Methylphenyl)sulphonyl)morpholine 1.8 . . . . 0.4 1.6 . . . . . Octadecanol 0.1 0.5 0.4 2.2 1.3 0.5 0.8 0.6 4,8,12-Trimethyl-3,7,11-tridecatriene nitrile 0.4 0.2 0.2 0.3 0.9 Diethyl phtalate 1.5 0.6 0.2 2.3 0.6 0.6 0.9 0.9 Butyl 2-methylpropyl phtalate 0.2 0.6 2.7 1.7 1.0 0.5 3.6 0.7 2.8 Di-n-butyl phtalate 0.3 0.9 4.7 0.7 Diisooctyl phtalate 3.8 4.8 4.1 3.0 5.4 8.1 25.0 3.3 6.4 23.5 4.9 3.1 3.4 7.6 2.4 2-(4-Chlorophenoxy)2-methylpropanoic acid . . . . . 21.3 2.3 67.8 87.2 27.2 48.9 19.2 56.9 109.6 84.0 68.8 25.6 51.7 88.5 68.2 38.(/ Phtalic acid 1.6 1.5 1.6 3.7 3.2 3.9 4.1 1.8 3.6 2.6 3.4 1.7 1.1 Decanoic acid (isomer) 1.5 1.0 7.4 2.8 2.8 2.8 2.4 1.9 3.1 5.3 4.7 1.3 4.2 n-tetradecanoic acid n-pentadecanoic acid 1.1 1.7 . . . . . 0.3 n-hexadecenoic acid 5.5 5.7 2.6 2.6 5.5 9.0 7.1 5.5 3.4 9.1 7.4 3.5 0.6 2.1 0.7 1.3 6.0 8.5 6.2 9.2 13.4 15.5 13.9 11.1 17.9 12.9 12.3 4.4 6.9 6.0 n-hexadecanoic acid n-octadecenoic acid 3.8 2.4 2.6 1.6 4.5 11.7 5.8 5.3 3.4 8.2 3.3 3.5 2.2 2./) n-octadecanoic acid 2.1 2.2 2.2 8.3 3.4 4.9 5.7 5.0 6.5 7.9 3.9 3.4 2.0 1.5 2.5

268

methyl propanoic acid showed the same evolution. The lowering of these values could be related to the fact that the factory that stored the chemicals in damaged tanks placed on the soil, was temporary closed by the local authorities. Besides shutting down the factory the local authorities took steps to ensure that the pollutants remaining in the soil did not pass to the groundwater. So excavation of the affected soils in an area of 30 × 10 m and 5 m depth where the tanks were buried was performed. Also, a continuous pumping from a well, which has some transversal galleries across the aquifer, located 1.3 Km downstream, was also carried out. These actions allowed them to keep to some extent the pollution in a relatively small area preventing the enlargement of the problem to the other wells of the zone that are used for water supply, industry and irrigation purposes. This increase would have resulted in a significant contamination of the groundwater in a zone of high-industrial activity that would have been very difficult and expensive to solve. As a conclusion of this groundwater survey, it can be established that a quick intervention of the authorities allowed a rapid decrease in the extraneous pollution observed. Nevertheless, this zone shows a relatively high level of groundwater pollution probably due to the high industrial use of the zone near the Congost River, which receives several uncontrolled nontreated effluents. Moreover, the eventual detection of specific pollutants, for instance, chloride detected in July or phtalic acid in November should compel the establishment of a continuous assessment through a monitoring program. CAS REGISTRY NUMBERS

Dimethyltrisulfide, 3658-80-8; Benzeneacetonitrile, 140-29-4; Isocyanomethylbenzene, 10340-91-7; Carbonotrithioic dimethylester, 2314-48-9; 2-Methylquinazoline, 700-79-8; 2-Pentadecyl, 4-6-dimethyl 1-3 dioxane, 56599-77-0; 4((4Methyl-phenyl)sulfonyl) morpholine, 6339-26-0; Benzothiophene, 3-phenyl, 14315-12-9; 4,8,12 Trimethyl,3-7-11 tridecatriene nitrile, 6006-01-5; Octadecanol, 112-92-5; Diethylphtalate, 84-66-2; Buthyl 2-methylpropyl-

M . T . GALCERAN E T A L .

phtalate, 17851-53-5; Di-n-buthylphtalate, 84-742; Bis(2-ethylhexyl)phtalate, 117-81-7; Di-isooctylp h t a l a t e , 27554-26-3; 2,6 Bis(-1,1-dimethylethyl)phenol, 128-39-2; Benzene acetic acid, 103-822; Benzene carbothioic acid, 98-91-9; Benzene ahydroxyacetic acid, 515-30-0; 2(4-Chlorophenoxi) 2methyl propanoic acid, 55162-41-9; Phtalic acid, 8899-3; n-Nonenoic acid, 3760-11-0, n-Nonanoic acid, 112-05-0; n-Dodecanoic acid, 143-07-7; n-Tetradecanoic acid, 544-63-8; n-Pentadecanoic acid, 1002-84-2; n-Hexadecenoic acid, 2091-29-4; n-Hexadecanoic acid, 57-10-3; n-Octadecenoic acid, 50617-2; n-Octadecanoic acid, 57-11-4.

REFERENCES 1. Mackay, D. M., Roberts, P. V., and Cherry, J. A. Transport of organic contaminants in groundwater. Environ. Sci. Technol. 19:384-392 (1985). 2. Josephson, J. Groundwater monitoring. Environ. Sci. Technol 15:993-996 (1981). 3. Hunt, D. T. E. and Wilson, A. L. The chemical analysis of water, pp. 78-99. The Royal Society of chemistry, 2nd ed. Oxford (1986). 4. American Public Health Association. Standard Methods for the Examination of Water and Wastewater, 16th ed. APHA, Washington, DC. (1985). 5. European Community Council. Directive concerning the quality of drinking water. Brussels, Belgium (July 15, 1980). 6. Rubio, R., Galceran, Ma. T., and Rauret, G. Nitriles and isonitriles as interferences in cyanides determination in polluted waters. The Analyst 115:959-963 (1990). 7. De Smedt, E Modelling of groundwater transport of microorganic pollutants: State-of-the-art. In: Organic Micropollutants in the Aquatic Environment, pp. 387-400. G. Angeletti and A. Bj6rseth, eds. Kluwer Academic Publishers, Dordrecht, The Netherlands (1988). 8. Garman, J. R., Freund, T., and Lawles, E. W. Testing for groundwater contamination at hazardous waste sites. J. Chromatog. Sci. 25:328-337 (1987). 9. Stuermer, D. H., Ng, D. J., and Morris, C. J. Organic contaminants in groundwater near an underground coal gasification site in Northeastern Wyoming. Environ. Sci. Technol. 16:582-587 (1982). 10. Albaig6s, J., Casado, E, and Ventura, E Organic indicators of groundwater pollution by a sanitary landfill. Water Res. 20: 1153-1159 (1986). 11. Barber, L. B., Thurman, E. M., Schroeder, H. P., and Le Blanc, D. R. Long-term fate of organic micropollutants in sewage-contaminated groundwater. Environ. Sci. Technol. 22:205-211 (1988).