Cl-SO 4 Mass Ratio as an Indicator of Contamination of Freshwater Resources in Kuwait by Seawater and Oilfield Brine

Transcription

1 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Cl-SO Mass Ratio as an Indicator of Contamination of Freshwater Resources in Kuwait by Seawater and Oilfield Brine Amitabha Mukhopadhyay Water Research Center, Kuwait Institute for Scientific Research, P.O. Box, Safat, Kuwait amukhop@kisr.edu.kw Abstract-The mass ratio of chloride to sulfate in different samples of groundwater from the Raudhatain - Umm AL-Aish area of Kuwait was investigated to assess the extent of contamination of the groundwater by the seawater used for extinguishing the oil fire ignited by the Iraqi Army during the Gulf War and by the brine that gushed out with oil from the damaged wells. Previous investigations indicated that the seawater from the Arabian Gulf, which was used for fire fighting, had the total dissolved solids (TDS contents of, mg/l and a Cl/SO mass ratio of.. The brines produced with oil from the Sabriya and the Raudhatain oil fields adjacent to the freshwater fields of Umm Al-Aish and Raudhatan were characterized by TDS in the range of, to 6, mg/l and Cl/SO mass ratio in the range of to 6. In contrast, unpolluted (with no petroleum hydrocarbon groundwater in the water fields had TDS in the range of to, mg/l and Cl/SO mass ratio below.. It was, therefore, surmised that wherever groundwater in the study area had Cl/SO mass ratio values higher than about., contamination by seawater and/or oilfield brine could be suspected; and when this value exceeded., contamination by oilfield brine could be inferred. The current investigation observed Cl/SO mass ratio as high as. in areas where groundwater had high (>. soil oil equivalent [SOE] units hydrocarbon content. Positive correlations between TDS, hydrocarbon content and Cl/SO mass ratio in such areas suggested that hydrocarbons and salts from seawater and oilfield brine moved together and did contaminate the groundwater in some parts of the study area. Key Words-Groundwater; Pollution; Raudhatain; Umm Al-Aish; Petroleum Hydrocarbon I. INTRODUCTION Monitoring of the water quality in the freshwater fields of Raudhatain and Umm Al-Aish in Kuwait (Fig. since had established that the contamination of the freshwater resources in these areas was a result of hydrocarbon spilled over the surface from the oil wells damaged by the Iraqi Army in [][]. It had also been surmised that the seawater used subsequently for extinguishing the oil-well fires was another source of contamination, leading to the increase in the salinity of groundwater in the area. Brine, which was often produced with oil and had possibly flowed from at least some of the damaged wells, was an additional source of salt pollution. The freshwater in the areas under reference, however, occurred as lenses floating on the brackish to saline water. The encroachment of brackish to saline water from the surrounding areas and from below due to the production from these fields was, therefore, also a possibility. To prove conclusively the contamination by seawater and oilfield brine from surface, it was postulated that the higher values of the mass ratio of chloride to sulfate for seawater and brine might act as an indicator of the contamination of freshwater from these sources. The investigation reported here explored this possibility. Fig. Location map of water and oil fields of Kuwait DOI:.6/JWRHE - -

2 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Polluted southeastern part of the Raudhatain Water Field showing oil lakes, oil pits and courses of oil flows DOI:.6/JWRHE - -

3 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - II. METHODOLOGY Main methodology used in the study was the comparison of the Cl/SO mass ratio in seawater, oilfield brine and uncontaminated groundwater with that of groundwater suspected to be contaminated by one or both of the first two groups. The association of increasing hydrocarbon contamination with higher total dissolved solids content had been considered to be an indication of the pollution by dissolved solids sourcing from the ground surface where seawater and/or oilfield brine remained intermingled with oil accumulated in surface depressions (oil lakes or oil collection pits; Figs. and. Additionally, the salts left in the soil after the evaporation of these waters could also be the sources of pollution. It was hypnotized that the infiltrating rainwater has carried these salts, along with the dissolved hydrocarbons, to the groundwater during the winter rainy season. Cross-plots and linear regression, generated using GRAPHER software (ersion [], andcluster and discriminant analysis, carried out with SYSAT software system (ersion.. [6], were the main tools for exploring the association of polluted groundwater withsources of salts and hydrocarbons. It may be noted here that the presence of hydrocarbon has been taken as an indicator of pollution of groundwater, though it is theoretically possible that, at least in a few cases, groundwater may be contaminated by salts derived from seawater or oilfield brine or both without affected by hydrocarbon. Cl/SO Ratio in Seawater, Oilfield Brine and Uncontaminated Groundwater of Kuwait A. Seawater Dr. J. Floor Anthoni (6 has presented the average seawater composition as shown in Table (available at accessed on th April,. As per these data, the Cl/SO mass ratio for average seawater is: / =.6. The composition of seawater of the Arabian Gulf in Kuwait, as presented at and accessed on th April,, is shown in Table. The Cl/SO mass ratio for Arabian Gulf derived from these data is: / =.. B. Oilfield Brine in Kuwait The composition of brine produced with oil in North Kuwait is presented in Table (personal communication from Dr. EssamSayed, Senior Research Scientist at the Water Research Center of Kuwait Institute for Scientific Research. The total dissolved solids content of the brine samples ( in number ranges between, mg/l and, mg/l with an average value of,6 mg/l.the Cl/SO mass ratio for the same samples ranges in value from to 6 over a period of months with average at. TABLE MAJOR ION COMPOSITION OF AERAGE SEAWATER Chemical Ion alence Concentration ppm, mg/kg Part of Salinity % Molecular Weight mmol/ kg Chloride (Cl Sodium (Na Sulfate (SO Magnesium (Mg Calcium (Ca Potassium (K +... Bicarbonate (HCO Bromide (Br Borate (BO Strontium (Sr Fluoride (F TABLE MAJOR ION COMPOSITION OF SEAWATER IN THE MIDDLE EAST REGION (MG/L Chemical Ion Typical Seawater Eastern Mediterranean Arabian Gulf at Kuwait Red Sea at Jeddah Chloride (Cl - Sodium (Na + 6 Sulfate (SO - 6 Magnesium (Mg Calcium (Ca + Potassium (K Bicarbonate(HCO - 6 Strontium (Sr Bromide (Br - 6 Borate (BO Fluoride (F Silicate (SiO Iodide (I- < - - Others Total dissolved solids 6 DOI:.6/JWRHE - -

4 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Oil lake at the center of the Umm Al-Aish Water Field with courses of oil flows and near-by oil pits DOI:.6/JWRHE - 6 -

5 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Parameter TABLE RESULTS OF CHEMICAL ANALYSIS OF SALINE WATER SAMPLES COLLECTED FROM GC Date and Sample Reference KISR KISR KISR KISR KISR KISR KISR ph EC (ms 6 Ca Mg TSS 6 NH DO NO SO HCO -* 6 6 Cl Na + Ba. 6. Sr+ 6 K 6 6 SiO Al <. <.. <. <. <. Oil content..... TDS 6 Cl/SO * mg/l as CaCO Parameter TABLE (CONT'D. Date and Sample Reference KISR KISR KISR KISR KISR KISR KISR ph EC (ms Ca + Mg + 6 TSS 6 6 NH 6 DO <..6. NO SO HCO -* 6 Cl Na Ba Sr+ K 6 SiO Al <. <. <. <. <. Oil content....6 TDS 66 6 Cl/SO * mg/l as CaCO Statistics of the Main Parameters of Interest: DOI:.6/JWRHE - -

6 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Parameter Maximum Minimum Average Standard Deviation Coefficient of ariation Sulfate mg/l mg/l 66 mg/l mg/l.6 Chloride, mg/l 6, mg/l 6, mg/l,. mg/l. TDS, mg/l, mg/l,6 mg/l, mg/l. Cl/SO A. Graphical Analysis of Data III. RESULTS AND DISCUSSIONS Tables and indicate that uncontaminated groundwater (samples with non-detectable hydrocarbon in that area is characterized by TDS varying between, mg/l and Cl/SO between. and.. Though a general trend of the rise in Cl/SO mass ratio with the total dissolved solids content can be seen, the correlation between the two is not that significant (Fig.. The correlation is, however, strong (coefficient of determination, R,. where the groundwater contamination is confirmed by the high concentration of hydrocarbon derived pollutants (Fig., as in the Umm Al-Aish field. The distinctive chemical characteristics of seawater, oilfield brine, unpolluted and polluted groundwater with respect to the Cl/SO mass ratio and TDS contents can be visualized in Figs. 6a & 6b. As the spectrometric measurement data for hydrocarbon contents are not available for seawater and oilfield brine, hydrocarbon contents have not been used as a distinguishing parameter for these four water types. As shown in Figs. 6a and 6b, it is apparent that seawater and oilfield brine can be easily distinguished from groundwater with the help of Cl/SO mass ratio and TDS contents. Some overlap of the polluted and unpolluted groundwater can, however, be observed in these plots. It is discerned from Fig. that the overlap occurs when the degree of contamination is low (Cl/SO ratio less than and hydrocarbon content is below. SOE units.it may further be noted from these figures that while some of the samples have been polluted by both hydrocarbon and sea or brine water, others have mainly been affected by sea or brine water (high Cl/SO ratio and/or higher than mg/l TDS, but low hydrocarbon contents. This is more apparent in Fig. where variation of all three parameters has been taken in to account. This suggests contamination by seawater and/or oilfield brine independent of hydrocarbon contamination. We ll ID No. of Me a. TABLE CHLORIDE, SULFATE, CL/SO MASS RATIO AND TOTAL DISSOLED SOLIDS CONTENTS OF GROUNDWATER FROM NORTH KUWAIT Avg. l Max. l Sulfate Chloride Cl/S O Min. l STD l C No. of Me a. Avg. Max. l Min. l STD l C No. of Me a. Avg. l Total Dissolved Solids Max. l Min. l STD C DOI:.6/JWRHE - -

7 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - B U Well ID No. of Me a. Av g. (mg /l Ma x. (mg /l TABLE (CONTD. Sulfate Chloride Cl/S O Mi n. (mg /l STD C No. of Me a. Avg. Max. Min. l STD C No. of M ea. Av g. (m g/l Total Dissolved Solids UA UB 6U U UA UB UC U U UB U UB U UB U UA UB R RB 6 6 R Ma x. (m g/l Mi n. (m g/l STD C DOI:.6/JWRHE - -

8 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - RB 6R 6 6. R RA 6 6. RB R Well ID No. of M ea. Av g. (m g/l Ma x. (m g/l TABLE (CONTD. Sulfate Chloride Cl/ SO Mi n. (m g/l STD C R.... RB 66.. RA RB.. RC R.6. R RB.. RA.. RB.. RA RB RA- 6.. RB 6.. RC.. RA RB.. RA.. RB UA- UB.. No. of M ea. Avg. Max. l Min. l STD C No. of M ea. Avg Total Dissolved Solids Ma x. (m g/l Mi n. (m g/l STD C..... DOI:.6/JWRHE - -

9 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - UA- UB - UA UB TABLE (CONTD. Well ID No. of Me a. Av g. (mg /l Ma x. (mg /l Sulfate Chloride Cl/S O Mi n. (mg /l STD C UA UB.. UA UB RA RB 6.. RC 6.. RA 6.. RB 6R R UA.. UB 6.. UA 6.. UB 6.. 6UA UB UA.. 6UB 6U 6.. 6U RA 6.. 6RB.6. 6RA 6 No. of Me a. Avg. Max. Min. l STD C No. of M ea. Av g. (m g/l Total Dissolved Solids Ma x. (m g/l Mi n. (m g/l STD C.... DOI:.6/JWRHE - -

10 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - 6RB TABLE (CONTD. Well ID No. of Me a. Av g. (mg /l Ma x. (mg /l Sulfate Chloride Cl/S Mi n. (mg /l STD C 66RA RB.. 6RA.. 6RB RA 6.. 6RC U-.. U U- 6.. U R-.. R-.. 6A- PW R-6.. Notes: STD: Standard Deviation; No. of Me a. Avg. Max. Min. l STD C O No. of M ea. Av g. (m g/l Total Dissolved Solids Ma x. (m g/l Mi n. (m g/l STD C: Coefficient of ariation (Standard Deviation/Average TABLE HYDROCARBON CONTENTS OF GROUNDWATER SAMPLES FROM NORTH KUWAIT Well ID Field Hydrocarbon Hydrocarbon Pollution Status No. of Mea. Avg. (SOE Max. (SOE Min. (SOE STD (SOE Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted 6 Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain Not Detected Unpolluted Raudhatain... Not Determined Not Determined Polluted Raudhatain Polluted Raudhatain..... Polluted Raudhatain Polluted Raudhatain Not Detected Unpolluted Raudhatain..... Polluted 6 Raudhatain..... Polluted Umm Al-Aish Polluted C C. DOI:.6/JWRHE - -

11 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - B Umm Al-Aish Polluted Umm Al-Aish Polluted Umm Al-Aish..... Polluted Umm Al-Aish Polluted Umm Al-Aish Not Detected Unpolluted Umm Al-Aish Not Detected Unpolluted Umm Al-Aish..... Polluted TABLE (CONTD. Well ID Field Hydrocarbon Hydrocarbon Pollution Status No. of Avg. Max. Min. STD C Mea. (SOE (SOE (SOE (SOE U Umm Al-Aish..... Polluted UA Umm Al-Aish Polluted UB Umm Al-Aish... Polluted 6U Umm Al-Aish Polluted U- Umm Al-Aish..... Polluted UA Umm Al-Aish Polluted UB Umm Al-Aish..... Polluted UC Umm Al-Aish Not Detected Unpolluted U Umm Al-Aish Polluted U Umm Al-Aish Not Detected Unpolluted UB Umm Al-Aish Not Detected Unpolluted U Umm Al-Aish. Polluted UB Umm Al-Aish Not Detected Unpolluted U Umm Al-Aish..... Polluted UB Umm Al-Aish..... Polluted U Umm Al-Aish Polluted UA Umm Al-Aish Polluted UB Umm Al-Aish Polluted R Raudhatain Polluted RB Raudhatain Polluted R Raudhatain Polluted RB Raudhatain..... Polluted 6R Raudhatain Polluted R Raudhatain Polluted TABLE (CONTD. Well ID Field Hydrocarbon Hydrocarbon Pollution Status No. of Avg. Max. Min. STD C Mea. (SOE (SOE (SOE (SOE RA Raudhatain..... Polluted RB Raudhatain Not Detected Unpolluted R Raudhatain Polluted R Raudhatain..... Polluted RB Raudhatain... Polluted RA Raudhatain..... Polluted RB Raudhatain... Not Determined Not Determined Polluted RC Raudhatain Unpolluted R Raudhatain Polluted DOI:.6/JWRHE - -

12 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - R Raudhatain..... Polluted RB Raudhatain... Polluted RA Raudhatain Not Detected Unpolluted RB Raudhatain Not Detected Unpolluted RA Raudhatain Not Detected Unpolluted RB Raudhatain Not Detected Unpolluted 6 RA- Raudhatain Polluted 6 RB Raudhatain... Polluted 6 RC Raudhatain Not Detected Unpolluted RA- Raudhatain... Polluted -RB Raudhatain Not Detected Polluted RA Raudhatain..... Polluted RB Raudhatain Not Detected Unpolluted UA- UB Umm Al- Aish Umm Al- Aish Polluted..... Polluted TABLE (CONTD. Well ID Field Hydrocarbon Hydrocarbon Pollution Status No. of Mea. Avg. (SOE Max. (SOE Min. (SOE STD (SOE UA- Umm Al-Aish..... Polluted UB Umm Al-Aish Polluted -UA Umm Al-Aish..... Polluted UB Umm Al-Aish... Not Determined Not Determined Polluted UA Umm Al-Aish... Polluted UB Umm Al-Aish Polluted UA Umm Al-Aish Not Detected Unpolluted UB Umm Al-Aish Polluted RA Raudhatain..... Polluted RB Raudhatain Not Detected Unpolluted RC Raudhatain... Polluted RA Raudhatain Not Detected Unpolluted RB Raudhatain... Polluted 6R Raudhatain Polluted R Raudhatain..... Polluted UA Umm Al-Aish Polluted UB Umm Al-Aish..... Polluted UA Umm Al-Aish..... Polluted UB Umm Al-Aish Polluted 6UA Umm Al-Aish Polluted 6UB Umm Al-Aish..... Polluted 6UA Umm Al-Aish Polluted 6UB Umm Al-Aish..... Polluted 6U Umm Al-Aish Not Detected Unpolluted TABLE (CONTD. Well ID Field Hydrocarbon Hydrocarbon Pollution Status No. of Mea. Avg. Max. Min. STD C (SOE (SOE (SOE (SOE 6U Umm Al-Aish..... Polluted C DOI:.6/JWRHE - -

13 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - 6RA Raudhatain Not Detected Unpolluted 6RB Raudhatain Not Detected Unpolluted 6RA Raudhatain..... Polluted 6RB Raudhatain... Polluted 66RA Raudhatain Polluted 66RB Raudhatain Polluted 6RA Raudhatain Polluted 6RB Raudhatain Polluted 6RA Raudhatain Not Detected Unpolluted 6RC Raudhatain Not Detected Unpolluted U- Umm Al-Aish Not Detected Unpolluted U- Umm Al-Aish Not Detected Unpolluted U- Umm Al-Aish Polluted U- Umm Al-Aish Polluted R- Raudhatain Not Detected Unpolluted R-6A-PW Raudhatain Not Detected Unpolluted R-6 Raudhatain Not Detected Unpolluted Notes: STD: Standard Deviation; C: Coefficient of ariation (Standard Deviation/Average SOE: Standard Oil-Contaminated Soil Equivalents. In this study, the water extract of the polluted soil from the Well site in the Umm Al-Aish water field has been taken as the standard for the measurement of hydrocarbon content. The groundwater sample to be analyzed has been excited by ultraviolet (U radiation with a wavelength of nm. The hydrocarbon content has been expressed as the ratio of the area under the emitted fluorescence band (6 to nm for the analyzed groundwater sample, to that of the standard. Fig. Cross-plot of CL/SO mass ratio against total dissolved solids (TDS in unpolluted groundwater DOI:.6/JWRHE - -

14 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Cl/SO versus total dissolved solids (TDS plot in contaminated aquifer (a DOI:.6/JWRHE - 6 -

15 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - (b Fig. 6 Cross-plot of total dissolved solids (TDS versus CL/SO mass ratio for (a seawater, oilfield brine and groundwater; and (b seawater and groundwater from North Kuwait Fig. Cross-plot of hydrocarbon versuscl/so mass ratio for polluted and unpolluted groundwater from North Kuwait DOI:.6/JWRHE - -

16 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. -D plot of total dissolved solids (TDS, Cl/SO and hydrocarbon contents for groundwater samples from North Kuwait B. Statistical Analysis of Data r analysis of different combinations of Cl/SO mass ratio, hydrocarbon content and TDS values for groundwater (both polluted and unpolluted, seawater and oil field brine samples has been carried out to find out whether these parameters can group the water samples according to their source. In the first attempt, the available data were attempted to be classified into four clusters using TDS and CL/SO mass ratio. In the absence of compatible measurement of hydrocarbon across the groups, this parameter was not used for clustering. The results indicate that though oilfield brine and seawater can be easily grouped into separate clusters with the help of these two parameters (Fig. and Table 6, it is not possible to separate the polluted and unpolluted groundwater samples on the basis of these two parameters. ery low values of both the parameters for groundwater samples (both polluted and unpolluted with respect to those of seawater and brine are probably the cause of this failure. It may be noted here that the groundwater samples from wells -UA- and -UB are grouped in the 'seawater' cluster (Table 6 because of high TDS contents (>, mg/l and Cl/SO ratios (> and suggest very high level of contamination of groundwater by seawater in the vicinity of these two wells which are in close proximity of each other. Another point of interest is that the two brine samples with the lowest ( and the highest (6 Cl/SO ratio has been included inthe fourth cluster (Table 6. Results of the hierarchial cluster analysis of the data confirm the same result and are presented in Fig.. Fig. r analysis results of groundwater, seawater and oilfield brine samples based on Cl/SO mass ratio and total dissolved solids contents DOI:.6/JWRHE - -

17 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig..Hierarchial analysis results of groundwater, seawater and oilfield brine samples based on Cl/SO mass ratio and total dissolved solids contents The results of the linear discriminant analysis of the same data based on the same two parameters are also presented in Table 6. Table presents the classification matrix derived from the analysis. The results again point out the inability of Cl/SO and TDS values to correctly identify the groundwater samples that have been polluted by hydrocarbon when these values are low. The overlap of the polluted and unpolluted groundwater samples in such cases are indicated in the score plot presented in Fig.. The categorization of samples -UA- and -UB as seawater and the location of the two brine samples with the minimum and maximum Cl/SO ratio (samples Brine6 and Brine, respectively outside the general envelop of brine data are also illustrated in this figure. As can be seen from Table 6, the discriminant analysis using quadratic relation did not improve the situation in any substantive way. Fig. Canonical score of discriminant analysis of full data using total dissolved solids (TDS and Cl/SO mass ratio as predictors DOI:.6/JWRHE - -

18 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - TABLE 6 RESULTS OF CLUSTER AND DISCRIMINANT ANALYSES FOR GROUNDWATER AND OIL FIELD BRINE SAMPLES FROM NORTH KUWAIT AND TYPICAL SEAWATER FROM MIDDLE EAST Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A chb Ratio (SOE Group. Not Detected Unpolluted. Not Detected Unpolluted 6. 6 Not Detected Unpolluted 6. Not Detected Unpolluted. 6 Not Detected Unpolluted 6. Not Detected Unpolluted. Not Detected Unpolluted 6. 6 Not Detected Unpolluted 6. Not Detected Unpolluted. 6. Polluted.. Polluted 66.. Polluted.. Polluted 6. Not Detected Unpolluted.. Polluted 6.6. Polluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group Polluted B.. Polluted 6.. Polluted. 6. Polluted 6.. Polluted 6 6. Not Detected Unpolluted. 6 Not Detected Unpolluted.. Polluted U 6.. Polluted UA 6.. Polluted UB Polluted 6U 6.. Polluted U-.. Polluted UA.. Polluted UB.. Polluted UC.6 Not Detected Unpolluted U 6.. Polluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group U. 6 Not Detected Unpolluted UB. 6 Not Detected Unpolluted U.. Polluted UB 6. Not Detected Unpolluted U.. Polluted UB 6.. Polluted DOI:.6/JWRHE

19 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - U 6.. Polluted UA 6..6 Polluted UB Polluted R.. Polluted RB Polluted R. 6. Polluted RB 6.. Polluted 6R Polluted R..6 Polluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group RA Polluted RB.6 Not Detected Unpolluted R 6.. Polluted R.. Polluted RB.. Polluted RA. 6. Polluted RB 6.. Polluted RC. Not Detected Unpolluted R.6 6. Polluted R 6.. Polluted RB.. Polluted RA. 6 Not Detected Unpolluted RB 66.6 Not Detected Unpolluted RA. Not Detected Unpolluted RB. 6 Not Detected Unpolluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group 6 RA-. 6. Polluted 6 RB 6.. Polluted 6 RC Not Detected Unpolluted RA-.. Polluted -RB 6. 6 Not Detected Polluted RA.. Polluted RB. Not Detected Unpolluted UA-.. Polluted UB 6.. Polluted UA-.6. Polluted UB. 6.6 Polluted -UA Polluted UB. 6. Polluted UA. 6. Polluted UB 6..6 Polluted UA.6 6 Not Detected Unpolluted UB 6.. Polluted DOI:.6/JWRHE

20 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group RA.. Polluted RB.66 Not Detected Unpolluted RC.. Polluted RA. 6 Not Detected Unpolluted RB 6.6. Polluted 6R.. Polluted R.. Polluted UA Polluted UB Polluted UA.. Polluted UB..6 Polluted 6UA.. Polluted 6UB.6. Polluted 6UA. 6. Polluted 6UB Polluted 6U. Not Detected Unpolluted 6U 6.. Polluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group 6RA 6 6. Not Detected Unpolluted 6RB 6. 6 Not Detected Unpolluted 6RA.. Polluted 6RB Polluted 66RA 6.. Polluted 66RB Polluted 6RA.6. Polluted 6RB.. Polluted 6RA 66. Not Detected Unpolluted 6RC. 6 Not Detected Unpolluted U- 6. Not Detected Unpolluted U-. Not Detected Unpolluted U-..6 Polluted U-.. Polluted R-. Not Detected Unpolluted R-6A-PW.6 Not Detected Unpolluted R-6. Not Detected Unpolluted TABLE 6 (CONTD. Sample ID Sulfate Chloride Cl/SO TDS Hydr.Carb. WATERTYPE r ch A ch B Ratio (SOE Group Mediterranean. 6 NA Seawater Arabian Gulf. NA Seawater Red Sea. NA Seawater Typ.Seawater 6.6 NA Seawater Brine NA Brine Brine-6. 6 NA Brine DOI:.6/JWRHE

21 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Brine66 6. NA Brine Brine6 6. NA Brine Brine66 6. NA Brine Brine6.6 NA Brine Brine NA Brine Brine6 6. NA Brine Brine NA Brine Brine NA Brine Brine NA Brine Brine 6. NA Brine Brine 6. NA Brine Brine 6. NA Brine Notes for Table 6: SOE: Standard Oil-Contaminated Soil Equivalents; NA: Not available r Group: rs are based on Cl/SO and TDS; ch A: Discriminant analysis categorization success ( or failure (> based on Cl/SO and TDS; ch B: Discriminant analysis categorization success ( or failure (> based on Cl/SO and TDS (Quadratic relation. TABLE CLASSIFICATION MATRIX (CASES IN ROW CATEGORIES CLASSIFIED INTO COLUMNS Oilfield Brine Polluted Groundwater Seawater Unpolluted Groundwater % Correct Oilfield Brine Polluted Groundwater Seawater Unpolluted Groundwater Total r and discriminant analysis of only the groundwater samples have also been carried out where apart from TDS and Cl/SO mass ratio, hydrocarbon content has been used as a discriminating parameter. The summary results have been presented in Table. The overall efficiency of discrimination varied within the range of 6 % (Table with polluted water samples with low hydrocarbon and Cl/SO ratio often classified as unpolluted (Fig.. The cluster analysis results again grouped the polluted water samples with low Cl/SO ratio and low hydrocarbon contents with the unpolluted samples (Table and Figs. and. Invasion by seawater or brine was not significant in these cases. Fig. Classification of groundwater samples using discriminant analysis DOI:.6/JWRHE

22 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. r analysis results of groundwater samples based on Cl/SO mass ratio, total dissolved solids and hydrocarbon contents Fig. Hierarchial cluster analysis results of groundwater samples based on Cl/SO mass ratio, total dissolved solids and hydrocarbon contents DOI:.6/JWRHE

23 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Sampl e ID Sulfat e TABLE RESULTS OF CLUSTER AND DISCRIMINANT ANALYSES FOR GROUNDWATER SAMPLES FROM NORTH KUWAIT Chlori de Cl/S O Ratio TDS l Hydr.Ca rb. (SOE WATERTY PE r-a r-b r-c ch A ch B ch C. Not Unpolluted. Not Unpolluted 6. 6 Detected Not Unpolluted 6. Detected Not Unpolluted. 6 Detected Not Unpolluted 6. Detected Not Unpolluted. Detected Not Unpolluted 6. 6 Detected Not Unpolluted 6. Detected Not Unpolluted. 6 Detected. Polluted.. Polluted 66.. Polluted.. Polluted 6. Not Unpolluted. Detected. Polluted 6.6. Polluted Sample ID Sulfa te Chlori de Cl/S O Ratio TDS l Hydr.Ca rb. (SOE WATERTY PE TABLE (CONTD. r-a r-b r-c ch A ch B ch C Polluted B.. Polluted 6.. Polluted. 6. Polluted 6.. Polluted 6 6. Not Unpolluted. 6 Detected Not Unpolluted. Detected. Polluted U 6.. Polluted 6.. Polluted UA Polluted 6U UB 6.. Polluted U-.. Polluted.. Polluted UA.. Polluted UB.6 Not Unpolluted U UC 6. Detected. Polluted Sampl e ID Sulfa te Chlori de Cl/SO Ratio TDS l Hydr.Car b. (SOE WATERTY PE TABLE (CONTD. r-a r-b r-c ch A ch B ch C U. 6 Not Unpolluted Detected. 6 Not Unpolluted UB Detected U.. Polluted 6. Not Unpolluted UB Detected U.. Polluted 6.. Polluted UB U 6.. Polluted UA 6..6 Polluted ch D ch D ch D DOI:.6/JWRHE - -

24 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP Polluted UB R.. Polluted Polluted RB R. 6. Polluted 6.. Polluted RB 6R Polluted R..6 Polluted Sample ID Sulfa te Chlori de Cl/S O Ratio TDS l Hydr.Ca rb. (SOE TABLE (CONTD. WATERT YPE r-a r-b r-c ch A ch B ch C RA Polluted RB.6 Not Unpolluted R 6. Detected. Polluted R.. Polluted RB.. Polluted RA. 6. Polluted RB 6.. Polluted RC. Not Unpolluted R.6 6 Detected. Polluted R 6.. Polluted RB.. Polluted RA. 6 Not Unpolluted RB 66.6 Detected Not Unpolluted RA. Detected Not Unpolluted RB. 6 Detected Not Detected Unpolluted TABLE (CONTD. Sample ID Sulfate Chlorid e Cl/SO Ratio TDS Hydr.Carb. (SOE WATERT YPE r -A Clus ter-b Clus ter-c Disc.M atch A Disc.M atch B Disc. Matc h C ch D 6 RA-. 6. Polluted 6 RB 6.. Polluted 6 RC Not Detected Unpolluted RA-.. Polluted -RB 6. 6 Not Detected Unpolluted RA.. Polluted RB. Not Detected Unpolluted UA-.. Polluted UB 6.. Polluted UA-.6. Polluted UB. 6.6 Polluted -UA Polluted UB. 6. Polluted UA. 6. Polluted UB 6..6 Polluted UA.6 6 Not Detected Unpolluted UB 6.. Polluted Sample ID Sulfa te Chlori de Cl/SO Ratio TDS Hydr.Ca rb. (SOE TABLE (CONTD. WATERT YPE r-a r-b r-c ch A ch B ch C RA.. Polluted Disc.Mat ch D ch D DOI:.6/JWRHE - 6 -

25 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - RB.66 Not Unpolluted Detected RC.. Polluted RA. 6 Not Unpolluted Detected RB 6.6. Polluted 6R.. Polluted R.. Polluted UA Polluted UB Polluted UA.. Polluted UB..6 Polluted 6UA.. Polluted 6UB.6. Polluted 6UA. 6. Polluted 6UB Polluted 6U. Not Unpolluted Detected 6U 6.. Polluted Sample ID Sulfa te Chlori de Cl/SO Ratio TDS Hydr.Ca rb. (SOE TABLE (CONTD. WATERT YPE r-a r-b r-c ch A ch B ch C 6RA 6 6. Not Unpolluted Detected 6RB 6. 6 Not Unpolluted Detected 6RA.. Polluted 6RB Polluted 66RA 6.. Polluted 66RB Polluted 6RA.6. Polluted 6RB.. Polluted 6RA 66. Not Unpolluted Detected 6RC. 6 Not Unpolluted Detected U- 6. Not Unpolluted Detected U-. Not Unpolluted Detected U-..6 Polluted U-.. Polluted ch D R-. Not Unpolluted Detected R-6A-.6 Not Unpolluted PW Detected R-6. Not Detected Unpolluted Notes for Table : SOE: Soil oil equivalent; r-a: rs based on Cl/SO and TDS; r-b: rs based on Cl/SO and Hydrocarbon; r-c: rs based on Cl/SO, Hydrocarbon and TDS; ch A: Discriminant analysis categorization success ( or failure (> based on Cl/SO and TDS; ch B: Discriminant analysis categorization success ( or failure (> based on Cl/SO and Hydrocarbon; ch C: Discriminant analysis categorization success ( or failure (> based on Cl/SO and TDS (Quadratic relation; ch D: Discriminant analysis categorization success ( or failure (> based on Cl/SO, hydrocarbon and TDS TABLE CLASSIFICATION MATRIX FOR GROUNDWATER ONLY (CASES IN ROW CATEGORIES CLASSIFIED INTO COLUMNS Polluted Groundwater Unpolluted Groundwater % Correct Classification Parameters: TDS and Cl/SO Mass Ratio DOI:.6/JWRHE - -

26 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Polluted Groundwater Unpolluted Groundwater Total 6 Classification Parameters: Hydrocarbon and Cl/SO Mass Ratio Polluted Groundwater Unpolluted Groundwater Total Classification Parameters: TDS, Hydrocarbon and Cl/SO Mass Ratio Polluted Groundwater Unpolluted Groundwater Total C. Cl/SO Ratio in the Contaminated Groundwater of North Kuwait It may be concluded from the above that in the study area, a Cl/SO mass ratio greater than about. should indicate contamination of shallow groundwater either by seawater or by brine produced with oil from deeper levels. When this mass ratio is higher than., significant contamination by brine coproduced with oil should be indicated. Where the infiltrating water has carried the salts from seawater and brine along with the hydrocarbon contaminants, the correlation between the concentrations of total dissolved solids and Cl/SO mass ratio is strong, as seen in the Umm Al-Aish Field (Fig.. The relations between organic concentration and parameters like TDS and Cl/SO mass ratio are also relatively strong under these circumstances (Figs. and 6. The Cl/SO mass ratio can thus be used to map the extent and degree of intensity of contamination by seawater or brine where the groundwater is fresh to brackish. Fig. Cross-plot of organic concentration against Cl/SO mass ratio in polluted groundwater DOI:.6/JWRHE - -

27 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. 6Cross-plot of organic concentration against TDS in polluted groundwater In general, the intensity of pollution by both hydrocarbon and seawater/brine, is lower in the Raudhatain Field than that in the Umm Al-Aish Field. This is clearly shown in the separate cross-plots for the two fields (Figs. -. As can be seen from these plots, the maximum value of Cl/SO mass ratio in Raudhatain Field is. (Fig. whereas that for Umm Al-Aish Field reaches. (Fig.. Similarly, the maximum level of organic contents measured in the Raudhatain Field is. SOE (soil oil equivalent units (Fig.. Actually, except for the two wells (R and 6RB, organic contents in Raudhatain monitoring wells does not exceed. SOE. In contrast, that for the Umm Al-Aish Field is. SOE units (Fig.. It can be further observed that in unpolluted and slightly polluted groundwater, the correlations amongcl/so mass ratio, hydrocarbon content and TDS are not very strong,in general (Figs.,,, and.the exception to this observation is the relation between hydrocarbon content and TDS in the Raudhatain Field for hydrocarbon content in the range of.6 and. SOE (R =.; Fig.. The correlations are much better above a hydrocarbon concentration value of. SOE (Figs.,, 6 and. This suggests that the lower values of hydrocarbon content (estimated through fluoroscopic measurements is indicating the presence of other types of organics (possibly humic acids that is not associated with the recent contamination.in both the fields, there are wells that display high (>.Cl/SO ratios without significant (>. SOE units hydrocarbon contents (Figs. and that may suggest contamination by seawater or oil co-produced brine only without accompanying hydrocarbon pollution. Fig. Cross-plot of CL/SO mass ratio against total dissolved solids (TDS in Raudhatain Field DOI:.6/JWRHE - -

28 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Cross-plot of CL/SO mass ratio against total dissolved solids (TDS in Umm Al-Aish Field Fig. Cross-plot of hydrocarbon content against total dissolved solids (TDS in Raudhatain Field Fig. Cross-plot of hydrocarbon content against total dissolved solids (TDS in Umm Al-Aish Field DOI:.6/JWRHE - -

29 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Cross-plot of hydrocarbon content against Cl-SO mass ratio in Raudhatain Field Fig. Cross-plot of hydrocarbon content against Cl-SO mass ratio in Umm Al-Aish Field Fig. Relation between Cl/SO mass ratio and total dissolved solids (TDS in polluted groundwater of Raudhatain Field DOI:.6/JWRHE - -

30 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Relation between Cl/SO mass ratio and total dissolved solids (TDS in polluted groundwater of Umm Al-Aish Field Fig. Relation between hydrocarbon content and total dissolved solids (TDS in slightly polluted groundwater of Raudhatain Field DOI:.6/JWRHE - -

31 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. 6 Relation between hydrocarbon content and total dissolved solids (TDS in polluted groundwater of Umm Al-Aish Field Fig. Relation between hydrocarbon content and Cl/SO mass ratio in slightly polluted groundwater of Raudhatain Field. (No apparent relation between hydrocarbon and seawater pollution DOI:.6/JWRHE - -

32 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. - Fig. Relation between hydrocarbon content and Cl/SO mass ratio in polluted groundwater of Umm Al-Aish Field I. SUMMARY AND CONCLUSIONS In the unpolluted (not contaminated by petroleum hydrocarbon fresh to brackish groundwater of Raudhatain Umm Al- Aish area with TDS values in the range of to, mg/l, the Cl/SO mass ratio does not exceed a value of.. The same parameter has a value of. for the water of the Arabian Gulf (TDS, mg/l used for extinguishing the oil well fires of Gulf War. The brines produced with oil in the Sabriya and Raudhatain oil fields adjacent to these water fields are characterized by the Cl/SO mass ratio in the range of to 6. Thus a Cl/SO mass ratio higher than. in the groundwater of this area should indicate contamination either by seawater or the brine produced with oil. If this value exceeds., contamination by oilfield brine should be inferred. In fact, high values of Cl/SO mass ratio that reached., have been observed in the hydrocarbon contaminated (petroleum hydrocarbon contents higher than. SOE units groundwater in these fields. It has been concluded from this observation that the salts from seawater used for fire fighting and those from brine that flowed along with oil from the damaged oil wells have been left in the soil along with the petroleum hydrocarbons. Subsequently, rainwater infiltrating through the soil has picked up these salts along with the petroleum hydrocarbons and/or their degradation products and carried these contaminants to the groundwater. There are some instances of groundwater having high (>. Cl/SO ratio without significant (>. SOE units hydrocarbon content. This suggests contamination by seawater and/or oilfield brine only that has flowed independently of oil flows from the damaged wells. There are also instances of hydrocarbon contamination without significant salt pollution (Cl/SO ratio. ACKNOWLEDGEMENT The work has been partially funded by Kuwait Foundation for Advancement of Sciences (KFAS after a thorough evaluation of the study proposal that outlines the objectives of the study, expected outputs and methodology to be used. KFAS has provided blanket permission for the publication of the results of all scientific projects financed by it in international refereed journals. The comments from three reviewers have been very helpful in enhancing the quality of the manuscript. The permission for the publication of the paper from the management of Kuwait Institute for Scientific Research (KISR (Report No.: KISRXXXXX is gratefully acknowledged. REFERENCES [] Al-Sulaimi, J.; M.N. iswanathan; and F. Székely, Effects of oil pollution on fresh groundwater in Kuwait. Environmental Geology :6-6,. [] Anthoni, J. F. 6. The chemical composition of seawater. Available at and accessed on th April,. [] APHA, Standard method for the examination of water and wastewater. American Public Health Association, Washington, D.C., USA, DOI:.6/JWRHE - -

33 Journal of Water Resource and Hydraulic Engineering Jan., ol. Iss., PP. -. [] Golden Software Inc., GrapherTM Quick Start Guide. Golden Software,Inc., Golden, Colorado, USA,. [] Mukhopadhyay, A.; E. Al-Awadi; M. Quinn; A. Akber, M. Alsenafy; and T. Rashid, Ground Water Contamination in Kuwait Resulting from Gulf War: A Preliminary Assessment. Groundwater Monitoring & Remediation, (:-,. [6] SYSAT, SYSAT : Getting Started. Sysat Software Inc., Chicago, IL 666, USA,. DOI:.6/JWRHE - -