Research Journal of Environmental and Earth Sciences 4(7): 756-768, 2012 ISSN: 2041-0492 © Maxwell Scientific Organization, 2012 Submitted: June 07, 2012 Accepted: July 04, 2012 Published: July 25, 2012 Multivariate Statistical Approach to Geochemical Methods in Water Quality Factor Identification; Application to the Shallow Aquifer System of the Yarmouk Basin of North Jordan Awni Batayneh and Taisser Zumlot Department of Geology and Geophysics, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia Abstract: The study of groundwater hydrogeochemistry of the sedimentary rock shallow aquifer system in the Yarmouk Basin of north Jordan produced a large geochemical dataset. Groundwater samples were collected at 36 sites in October 2009 (dry season) and in May 2010 (wet season) over a 1426 km2 study area and analyzed for major and minor ions. The large number of data can lead to difficulties in the integration, interpretation and representation of the results. Two multivariate statistical methods, Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA), were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples and to identify geochemical processes controlling groundwater geochemistry. This subgroup consisted of 36 samples and 28 parameters (Ca2+, Na+, Mg2+, K+, Cl-, HCO3-, NO3-, SO42-, Al, B, Ba2+, Be, Bi, Cd, Co, Cr, Cu, Fe2+, Li, Mn2+, Ni, Pb, Sb, Se, Zn, P, Sr, V). Seven geochemically distinct clusters, C1-C7, resulted from the HCA. Calcium and magnesium are the dominant ions in the groundwater of the basin (clusters C1, C5 and C7), while bicarbonate is the most abundant of the anions (clusters C2 and C3). A total of five PCA components were extracted for dry and wet seasons, where it accounts 68.6 and 72.6% of the total variance in the dataset, respectively. For dry and wet season water samples characteristic loadings, two components were defined as the salinity and hardness components, while the other components were related to more local and geologic effects. Keywords: Hierarchical cluster analysis, hydrochemistry, multivariate techniques, north Jordan, principal component analysis, Yarmouk Basin quantitative approach for interpreting and representing data concerning groundwater pollutants and geochemistry. Steinhorst and Williams (1985), Olmez et al. (1994), Farnham et al. (2003), Chen-Wuing et al. (2003), Love et al. (2004), Cloutier et al. (2008) and Farooq et al. (2010) adopted factor analysis technique for groundwater contamination and geochemical evolution and to identify rock water interaction processes. Cluster analysis was used to interpret the hydrochemical data based on factor scores (Suk and Lee, 1999; Reghunath et al., 2002; Ji-Hoon et al., 2005; Belkhiri et al., 2011). In addition, multivariate analysis was used to interpret relationship among the chemical variables and the processes involved and to show the regional impact of human activities on groundwater composition (Lawrence and Upchurch, 1982; Usunoff and Guzma´n-Guzma, 1989; Razack and Dazy, 1990; Briz-kishore and Murali, 1992; Melloul and Collin, 1992; Schot and Van der Wal, 1992; Subyani and Al Ahmadi, 2010). Moreover, multivariate statistical methods can also help understand groundwater flow in complex aquifer systems (Farnham et al., 2000; Stetzenbach et al., 2001). INTRODUCTION The composition of groundwater in arid and semi arid regions is controlled by many processes, including evapotranspiration, depositional environment and type of interaction between water and aquifer and human activities. Increase knowledge of geochemical process could lead to better understanding that can contribute to effective groundwater management and utilization. Because of the complexities of the regional conditions and hydrochemical processes and because of large amounts of basic information regarding the groundwater chemistry evaluation, advance techniques are required to interpret observed relationship among variables. The early study of groundwater hydrochemistry is the use of different maps and graphical representations to interpret the geochemical data, such as: Piper diagram (Piper, 1944), Stiff pattern diagram and scatter plots of chemical parameters. Recently and with increasing number of chemical and physical variables of groundwater, a wide range of multivariate statistical techniques are now used. Cluster analysis and factor analysis are frequently applied as a Corresponding Author: Awni Batayneh, Department of Geology and Geophysics, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia, Tel.: +966-56-8086395 756 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Fig. 1: Context of the study area: (a) Location map of north Jordan showing principal physiographic features (Batayneh, 2010), (b) geology (Batayneh, 2012) and (c) drainage systems of the Yarmouk Basin (Ta’any et al., 2007) The main objectives of this scientific paper was to better identify the processes controlling the geochemical evolution of groundwater in the study area by using two well-proven multivariate methods to analyze the geochemical data, Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA). Given the geological setting of the study area, HCA and PCA may be able to help distinguish the role of geological and hydrogeological contexts. A methodological study was also applied in order to assess the relative applicability and complementarity of HCA and PCA in achieving the scientific objective, compared to conventional geochemical grouping. Context of the study area: Geology and hydrogeology: Yarmouk Basin is a transboundary basin shared between Jordan and Syria with a total area of about 7240 km2. The basin is located in north Jordan area between coordinates 32°20′ to 32°45′ N and longitudes 35°42′ to 36°23′ E, covering an area of about 1,426 km2 (Fig. 1a). North Jordan area is part of the Mediterranean semi-arid climate which is characterized by limited precipitation occurring in the winter and hot dry summer. The average annual rainfall is 475 mm, mostly occurring between November and April,peakinginJanuary(http://met.jometeo.gov.jo/acc_r ain). From a geological point of view, the outcroppings rocks in the study area are of Upper Cretaceous to Tertiary age formations (Makhlouf et al., 1996; Moh’d, 2000). The oldest is the Wadi Es-Sir Limestone (WSL) formation of Turonian age. It is essentially composed of limestone and mainly exposed on the southwest part of the Yarmouk Basin (Fig. 1b). The overlying sedimentary sequences are of Santonian to Eocene age and includes in ascending order: Wadi Umm Ghudran (WG), Amman Silicified Limestone (ASL), Muwaqqar Chalk-Marl (MCM), Umm Rijam Chert-Limestone (URC) and Wadi Shallala (WS) formations. These comprise limestone, marl limestone, marl, chalk, chert and phosphorite sedimentary rocks. Basaltic flows (BS formation) of Oligocene age cover the eastern part of 757 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 the basin. Basalts are also found as small outcrops scattered on the north and northwest of the Yarmouk Basin (Fig. 1b). According to the study of Hawi (1990), Abderahman and Awad (2002), Abu-Jaber and Ismail (2003), Ta’any et al. (2007) and Batayneh et al. (2008) two systems of aquifer are present in north Jordan: • • The shallow aquifer (namely B4/5 aquifer) presents in the north and northwest of the Yarmouk Basin. It is recharged either along the elevated areas of Golan Heights and Ajlun Highlands, or due to local surface water infiltration through the URC and WS formations outcrops in the northern and northwestern parts of the basin. The second aquifer system (namely B2/A7 aquifer) is the most regionally extensive aquifer and the most important for water resources in north Jordan, because of the extended outcrop catchment areas located in the Ajlun Highlands and on the uplands of the Hermon Mountains. The drainage systems in the Yarmouk Basin are shown in Fig. 1c. The map shows three distinctive drainage patterns: • • • Areas in the north, northwest and eastern parts of the basin are dominated by a NW drainage trend A NE trend dominates areas in the southwest The central part of the basin dominated by N-S drainage trend The water table contours (Fig. 1c) indicate that the direction of groundwater flow is from south and east to the north and northwest and strongly coincides with topography and drainage patterns. Depth to water table with reference to sea level varies from artesian flow in the northwest area, to about 250 m below land surface near the central part. Cross section A-A’ illustrates the groundwater flow conceptual model and presents the main hydrostratigraphic units (Fig. 1d). Hydrochemistry: Ta’ any et al. (2007) and Batayneh et al. (2008) identified groundwater types according to majors cations (Ca2+, Na+, Mg2+, K+) and anions (Cl-, HCO3-, NO3-, SO42-) and showed that the shallow aquifer system of the Yarmouk Basin of north Jordan has a highly variable groundwater geochemistry. The concentration of the cations is of order (Ca2+ > Na+ > Mg2+ > K+) while that for anions is (Cl- > HCO3- > NO3> SO42-). Statistical analyses on groundwater (Batayneh et al., 2008) indicate positive correlation between the following pairs of parameters: Cl- and Mg2+ (r = 0.49), Cl- and K+ (r = 0.46), Cl- and Na+ (r = 0.74), SO42and Mg2+ (r = 0.23) and SO42- and K+ (r = 0.20). Water shows varying chemical facies (Ca2+-SO42-, Mg2+- SO42-, Na+-SO42-), which relates to the interaction with the geological formations of the basin (carbonates, dolomite, marl, basalt and various silicates) and evaporation. The dissolution of halite, calcite, dolomite and gypsum explains part of the observed Ca2+, Na+, Mg2+, Cl-, HCO3- and SO42-, but other processes, such as cation exchange and weathering of aluminosilicates also contribute to the water composition. METHODOLOGY Hydrochemical dataset: The regional hydrogeochemical characterization of the north Jordan shallow aquifer system was carried out in the 2004 and 2005 with the groundwater sampling of private, municipal and observation wells and springs. Water samples were collected twice in October 2006 (dry season) and May 2007 (wet season). A total of 36 water samples were collected from major springs of the Yarmouk Basin in northern Jordan. The sample sites, distributed over the northwest parts, cover the permeable URC and BS hydrostratigraphic units. A rigorous, but conventional and recognized, protocol was used for samples collection and preservation and the chemical analyses were performed in certified laboratories using standard methods. In situ field measurements were made on water samples for hydrogen ion concentration (pH), Electrical Conductivity (EC) and temperature. Groundwater samples were analyzed for major, minor and trace constituents for a total of 28 parameters, plus Total Dissolved Solids (TDS). These water samples were analyzed by using VISTA-MPX instrument with Charge-Coupled Device (CCD) Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) in the laboratories of the Department of Chemistry, Yarmouk University, Irbid, Jordan. The details of analytical data of major and minor ions are given in Table 1. In addition, some descriptive statistics such as mean, median, standard deviation, coefficient of variation and coefficient of skewness are also given. Data preparation for the multivariate statistical analysis: As mentioned, each sampling site is characterized by a large number of chemical and physical variables, making the regional hydrogeochemical study a multivariate problem. The multivariate statistical analysis is a quantitative and 758 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Table 1: Descriptive statistics for the 36 groundwater samples (concentration in mg/L). Min: Minimum; Max: Maximum; STD: Standard Deviation; CV: Coefficient of Variation Range ------------------------------------Parameters Min Max Mean Median STD CV Skewness Dry season Ca 26.8900 44.190 38.430 38.760 3.490 0.091 -1.094 Mg 4.4700 23.120 9.280 7.430 4.590 0.495 1.532 Na 11.8300 39.050 20.920 17.100 8.320 0.397 1.044 K 0.1300 63.540 6.910 2.020 13.880 2.010 3.049 Cl 5.2900 161.20 67.450 56.200 31.100 0.451 1.120 39.7500 90.140 68.100 69.780 12.700 0.187 -0.221 HCO3 8.1600 123.680 55.010 47.200 28.390 0.521 1.013 NO3 0.9400 55.980 24.100 21.470 15.580 0.676 0.375 SO4 Al 0.0070 0.365 0.057 0.025 0.077 1.352 2.699 B 0.0820 0.201 0.116 0.104 0.033 0.283 1.249 BA 0.0520 0.696 0.377 0.393 0.131 0.348 -0.256 Be 0.0010 0.001 0.001 0.001 0.001 0.252 1.781 Bi 0.0030 1.626 0.057 0.009 0.269 4.750 5.986 CD 0.0010 0.001 0.001 0.001 0.001 0.431 0.721 Co 0.0010 0.198 0.007 0.002 0.033 4.702 5.998 Cr 0.0010 0.006 0.003 0.003 0.001 0.468 0.528 Cu 0.0020 0.009 0.005 0.005 0.001 0.279 0.896 Fe 0.0010 0.292 0.041 0.006 0.075 1.826 2.431 Li 0.0020 0.012 0.004 0.003 0.002 0.581 1.938 Mn 0.0001 0.020 0.003 0.001 0.005 1.969 2.650 Ni 0.0030 0.062 0.010 0.007 0.010 1.007 4.476 Pb 0.0001 0.014 0.004 0.003 0.003 0.851 1.750 Sb 0.1410 1.153 0.576 0.530 0.262 0.455 0.492 Se 0.1100 0.054 0.022 0.021 0.008 0.370 1.827 Zn 0.002 1.354 0.049 0.007 0.224 4.547 5.960 P 0.004 0.170 0.033 0.019 0.040 1.218 2.709 Sr 0.200 1.110 0.415 0.31 0.220 0.531 1.758 V 10.84 81.88 27.59 21.12 16.39 0.594 1.818 Wet season Ca 32.860 46.990 40.980 41.200 2.940 0.070 -0.320 Mg 4.670 23.210 9.480 7.890 4.620 0.490 1.500 Na 12.500 40.500 21.250 17.880 8.680 0.410 0.990 K 0.190 63.930 6.590 1.6600 13.880 2.110 3.110 Cl 5.320 165.570 68.740 56.720 31.130 0.453 1.165 40.260 90.280 67.300 70.150 12.710 0.189 -0.228 HCO3 8.680 125.860 54.340 47.120 28.470 0.524 1.016 NO3 0.960 56.640 23.060 21.600 15.560 0.674 0.378 SO4 Al 0.009 0.120 0.027 0.022 0.020 0.730 3.500 B 0.072 0.176 0.104 0.093 0.028 0.270 1.070 BA 0.055 0.709 0.376 0.379 0.156 0.361 -0.049 Be 0.001 0.005 0.001 0.001 0.001 1.052 4.567 Bi 0.001 0.062 0.009 0.004 0.012 1.256 3.157 CD 0.001 0.004 0.001 0.001 0.001 1.726 4.406 Co 0.001 0.005 0.001 0.001 0.001 0.595 3.795 Cr 0.001 0.007 0.003 0.002 0.002 0.571 1.014 Cu 0.003 0.010 0.005 0.004 0.001 0.273 2.448 Fe 0.001 0.092 0.016 0.006 0.025 1.547 1.971 Li 0.002 0.011 0.004 0.003 0.002 0.609 1.589 Mn 0.001 0.020 0.002 0.001 0.005 1.934 3.116 Ni 0.031 0.064 0.047 0.045 0.008 0.178 0.251 Pb 0.001 0.008 0.003 0.003 0.002 0.454 0.480 Sb 0.042 0.574 0.243 0.215 0.132 0.541 0.866 Se 0.007 0.047 0.019 0.017 0.008 0.404 1.748 Zn 0.002 0.454 0.030 0.006 0.086 2.915 4.298 P 0.006 0.092 0.028 0.022 0.019 0.681 1.812 Sr 0.223 1.231 0.455 0.332 0.259 0.570 1.859 V 10.74 72.26 25.00 19.19 13.87 0.555 1.888 independent approach allowing grouping of groundwater samples and making correlation between chemical parameters. In this study, two multivariate methods were applied using SPSS 20 software package: 759 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Fig. 2: Dendrogram for 36 groundwater samples (dry season samples), showing the division into seven clusters analysis in Qmode the Hierarchical Cluster Analysis (HCA) and the Principal Components Analysis (PCA). Description of HCA and PCA techniques and the methodology used for their application can be found in Meng and Maynard (2001), Subba Rao et al. (2001), Cloutier et al. (2008) and Kanade and Gaikwad (2011). The multivariate statistical methods were applied to a subgroup of the whole hydrogeochemical dataset that consists of 36 groundwater samples and 28 parameters. These parameters include major constituents Ca2+, Na+, Mg2+, K+, Cl-, HCO3-, NO3- and SO42-, as well as minor and trace constituents Al, B, Ba2+, Be, Bi, Cd, Co, Cr, Cu, Fe2+, Li, Mn2+, Ni, Pb, Sb, Se, Zn, P, Sr and V. A certain number of parameters were excluded from the multivariate statistical analysis for the following reasons: parameters with additive characteristics such as EC and TDS and parameters that show small regional variation such as pH. The frequency diagrams of most chemical parameters do not follow a normal distribution; therefore HCA and PCA are carried out for the logarithmic transformation of data set because it is closer to the normality condition which is required for these analyses. Standardization was applied to the log normal distribution to ensure that each variable is weighted equally. RESULTS OF MULTIVARIATE STATISTICAL ANALYSIS Hierarchical Cluster Analysis (HCA) for water samples: The HCA is a data classification technique that widely applied in Earth sciences (Davis, 1986) and often used in the classification of hydrogeochemical data (Steinhorst and Williams, 1985; Schot and Van der Wal, 1992; Guler et al., 2002). The main result of the HCA performed on the 36 groundwater samples is the dendrogram (Fig. 2 and 3). In this study, the Euclidean distance is selected as the distance measure. The sampling sites with the larger 760 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Fig. 3: Dendrogram for 36 groundwater samples (wet season samples), showing the division into seven clusters analysis in Qmode similarity are first grouped. Next, groups of samples are joined with a linkage rule and the steps are repeated until all observations have been classified. With this geochemical dataset, Ward’s method was more successful to form clusters that are more or less homogenous and geochemically distinct from other clusters, compared to other methods such as the weighted pair-group average. Ward’s method is distinct from other linkage rules because it uses an analysis of variance approach to evaluate the distances between clusters. Other studies used Ward’s method as linkage rule in their cluster analysis (Adar et al., 1992; Schot and Van der Wal, 1992). Guler et al. (2002) also found that using the Euclidean distance as a distance measure and Ward’s method as a linkage rule produced the most distinctive groups. Figure 2 shows the dendrogram of water samples for dry season where it can be classified into seven groups based on a visual observation of the dendrogram, namely C1-C7. Observation of dendrogram shows some indications of the level of similarity between the seven clusters (Fig. 2). C1 and C2 have the lower linkage distance between the defined clusters, therefore, has the greater similarity between all clusters. It can be expected that the geochemistry of C1samples would have similarities with the ones of C2. Clusters C3 and C5 have an elevated linkage distance between the defined cluster. To describe the characteristics of each cluster of sample, Table 2 shows the median values of geochemistry data, including the 28 chemical elements. Samples from C1 cluster are characterized by high concentrations of Cu and by low concentrations of Na, SO4 and Cl in all clusters. Samples from C2 are characterized by lowest concentrations in HCO3, Ni and Zn of all clusters. Samples from C3 are characterized by high 761 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Table 2: Geochemical characteristics of each cluster for dry season (median concentration in mg/L, bold values: highest values; underlined values: lowest values) Parameters C1 C2 C3 C4 C5 C6 C7 Ca 36.44000 38.04500 36.04500 41.59500 38.78000 41.96500 34.27500 K 0.62000 4.02500 1.05500 0.56000 2.60000 42.45500 3.08000 Mg 5.90000 7.14000 6.57500 8.96000 6.37000 13.32500 19.47500 Na 14.66000 18.59000 18.81000 16.47000 16.80000 34.82000 35.45500 70.15000 59.76000 80.21500 75.03000 59.78000 59.78000 79.91000 HCO3 4.80000 26.88000 30.24000 24.48000 7.68000 44.64000 36.00000 SO4 Cl 47.20000 55.45000 62.39500 53.00000 56.80000 117.35000 115.150000 54.56000 61.69000 40.30000 33.48000 44.64000 55.49000 77.81000 NO3 Al 0.02408 0.01741 0.02718 0.04045 0.25320 0.02359 0.01635 B 0.09768 0.11241 0.14347 0.08719 0.09168 0.16712 0.13070 Ba 0.43654 0.36859 0.35440 0.47488 0.41657 0.25000 0.15842 Be 0.00048 0.00051 0.00080 0.00058 0.00061 0.00039 0.00065 Bi 0.00962 0.01386 0.03332 0.00642 0.00866 0.01005 0.00484 Cd 0.00052 0.00067 0.00095 0.00042 0.00025 0.00053 0.00055 Co 0.00142 0.00144 0.00144 0.00153 0.00177 0.00143 0.00234 Cr 0.00262 0.00301 0.00319 0.00172 0.00386 0.00382 0.00140 Cu 0.00541 0.00453 0.00524 0.00435 0.00391 0.00515 0.00514 Fe 0.00433 0.00552 0.00705 0.02577 0.27668 0.00901 0.00514 Li 0.00254 0.00261 0.00295 0.00287 0.00311 0.00459 0.00897 Mn 0.00030 0.00039 0.00081 0.00076 0.01717 0.00047 0.00037 Ni 0.00641 0.00520 0.00704 0.00979 0.00758 0.01125 0.01510 Pb 0.00163 0.00292 0.01049 0.00251 0.00678 0.00335 0.00169 Sb 0.57412 0.41512 0.76269 0.71135 0.53434 0.77219 0.34885 Se 0.01559 0.02127 0.01848 0.02284 0.01854 0.02607 0.02171 Zn 0.00674 0.00548 0.70629 0.00883 0.01499 0.01225 0.00683 P 0.01704 0.01858 0.01438 0.01769 0.16655 0.02807 0.01901 Sr 0.26000 0.30500 0.25500 0.42000 0.31000 0.43500 0.86500 V 17.11000 19.94000 18.06500 25.19500 17.07000 39.44500 64.75000 Table 3: Geochemical characteristics of each cluster for wet season (median concentration in mg/L, bold values: highest values; underlined values: lowest values) Parameters C1 C2 C3 C4 C5 C6 C7 Ca 39.09320 41.27470 39.04180 36.69810 44.84550 41.12420 42.41680 K 0.90066 1.97648 3.94878 1.63209 0.62200 1.38548 12.38270 Mg 5.71827 6.40644 8.26673 6.110490 9.63134 7.39187 13.15320 Na 13.5402 16.89610 25.80370 13.79060 17.70460 18.86610 35.04730 59.78000 79.91000 50.02000 70.15000 70.15000 79.91000 64.96500 HCO3 7.41000 39.36000 26.88000 21.12000 22.08000 6.58000 36.96000 SO4 Cl 47.50700 50.34330 76.93300 53.17950 53.88860 56.72480 114.86800 54.56000 43.40000 73.78000 42.78000 21.7000 47.74000 83.70000 NO3 Al 0.02369 0.02379 0.02721 0.01200 0.022190 0.06394 0.020950 B 0.07332 0.08958 0.11107 0.10286 0.08180 0.09360 0.13464 Ba 0.44112 0.41970 0.35889 0.33396 0.49329 0.37719 0.25876 Be 0.00052 0.00056 0.00056 0.00059 0.00039 0.00045 0.00076 Bi 0.00407 0.00691 0.00551 0.01629 0.00383 0.00189 0.01025 Cd 0.00016 0.00028 0.00017 0.00029 0.00013 0.00013 0.00053 Co 0.00113 0.00106 0.00066 0.00125 0.00115 0.00128 0.00162 Cr 0.00191 0.00286 0.00370 0.00268 0.00109 0.00166 0.00395 Cu 0.00395 0.00434 0.00421 0.00767 0.00410 0.00421 0.00480 Fe 0.00322 0.00303 0.00164 0.00834 0.00531 0.07740 0.00580 Li 0.00197 0.00239 0.00270 0.00315 0.00313 0.00245 0.00547 Mn 0.0004 0.00062 0.00020 0.00147 0.00055 0.01815 0.00101 Ni 0.04102 0.04034 0.04039 0.04881 0.05920 0.05190 0.04897 Pb 0.00249 0.00291 0.00113 0.00455 0.00345 0.00465 0.00296 Sb 0.19701 0.27525 0.17378 0.21379 0.39504 0.18597 0.15842 Se 0.01715 0.01283 0.01719 0.01518 0.01784 0.01875 0.02624 Zn 0.00472 0.00669 0.00573 0.27547 0.00863 0.00707 0.00587 P 0.01918 0.02378 0.01588 0.01608 0.02667 0.06478 0.02878 0.29511 0.33045 0.29093 0.30515 0.50260 0.42851 0.46360 Sr V 15.5822 17.81290 19.63150 14.97330 23.78260 18.16750 34.9646 concentrations in HCO3, Be, Bi, Cd, Pb and Zn and by the lowest concentrations for P and Sr of all clusters. Samples from C4 are characterized by high concentrations in Ba and by the lowest concentrations for K, NO3 and B of all clusters. Samples from C5 are characterized by high concentrations in Al, Cr, Fe, Mn 762 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Fig. 4: Dendrogram for 28 variables from cluster analysis in R-mode for dry season groundwater samples and P of all clusters. Samples from C6 are characterized by high concentrations in Ca, K, SO4, Cl, B and Sb and by the lowest concentrations for Be of all clusters. Samples from C7 are characterized by high concentrations in Mg, Na, NO3, Co, Li, Ni, Sr and V of all clusters. Figure 3 shows the dendrogram of water samples for wet season where it can be classified into seven groups, named C1-C7. Observation of dendrogram shows some indications of the level of similarity between the seven clusters (Fig. 3). Samples from C1 and C3 have the lower linkage distance between the defined clusters, therefore, has the greater similarity between all clusters. C2 and C4 are linked at a low distance. Also C5 and C6 are linked at a low distance. To describe the characteristics of each cluster of sample, Table 3 shows the median values of geochemistry data, including the 28 chemical elements for wet season. Samples from C1 are characterized by lowest concentrations for Mg, Na, Cl, B, Cu, Li and Zn of all clusters. Samples from C2 are characterized by high concentrations in HCO3 and SO4 and by the lowest concentrations for Ni and Se of all clusters. Samples from C3 are characterized by lowest concentrations for HCO3, Fe, Mn, Ni, Pb, P and Sr of all clusters. Samples from C4 are characterized by high concentrations in Bi, Cu and Zn and by the lowest concentrations for Ca, Al and V of all clusters. Samples from C5 are characterized by high concentrations in Ca, Ba, Ni, Sb and Sr and by the lowest concentrations for K, NO3, Be, Co and Cr of all clusters. Samples from C6 are characterized by high concentrations in Al, Fe, Mn, Pb and P and by the lowest concentrations for SO4, Bi and Cd of all clusters. Samples from C7 are characterized by high concentrations in K, Mg, Na, Cl, NO3, B, Be, Cd, Co, Cr, Li, Se and V and by the lowest concentration for Ba and Sb of all clusters. Hierarchical Cluster Analysis (HCA) for elements: The dendrogram (cluster tree) for the elements for dry season is shown in Fig. 4. The 28 elements for the dry season can be classified into two major groups: from Bi to P and from Mg to Se (Fig. 4). These elements can be further classified into five groups: (i) Bi, Co and Ni; (ii) Ca, Sb, Ba, HCO3, Cu, Be, Pb, Zn, Cd, Cr and NO3; (iii) Fe, Mn, Al and P; (iv) Mg, V, Li and Sr; and (v) 763 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Fig. 5: Dendrogram for 28 variables from cluster analysis in R-mode for wet season groundwater samples Table 4: Principal component loadings from PCA after rotation for the maximum variance for dry season Parameters PC1 PC2 PC3 Ca 0.066 0.049 -0.500 K 0.780 -0.015 -0.230 Mg 0.783 0.065 0.097 Na 0.924 -0.045 0.232 HCO3 0.002 -0.054 -0.026 SO4 0.589 -0.135 -0.258 Cl 0.733 0.072 0.116 NO3 0.162 -0.305 -0.077 Al -0.132 0.966 -0.023 B 0.803 -0.095 -0.022 Ba -0.774 0.158 -0.174 Be 0.060 0.168 0.465 Bi 0.044 -0.091 0.933 Cd 0.178 -0.269 0.132 Co 0.039 -0.089 0.973 Cr 0.329 0.193 0.012 Cu 0.120 0.042 -0.108 Fe -0.064 0.975 0.044 Li 0.665 0.070 0.161 Mn 0.013 0.905 0.084 Ni 0.205 0.057 0.906 Pb -0.107 0.232 0.160 Sb 0.024 -0.042 -0.267 Se 0.545 -0.163 -0.193 Zn -0.206 -0.096 0.021 P -0.043 0.915 -0.056 Sr 0.566 0.117 0.044 V 0.763 0.035 0.068 % of Variance 21.987 14.191 12.423 Cumulative % 21.987 36.178 48.601 Bold values: loadings > 0.5 764 PC4 -0.142 -0.387 0.522 0.077 0.654 0.165 0.026 -0.579 -0.040 -0.249 0.061 0.262 -0.240 -0.108 -0.224 -0.722 0.197 0.134 0.621 0.265 0.030 -0.087 -0.035 -0.058 0.157 -0.148 0.710 0.552 12.131 60.732 PC5 -0.180 -0.010 -0.223 -0.030 0.239 0.209 -0.073 -0.030 -0.022 0.323 -0.010 0.276 0.089 0.684 0.055 0.341 0.068 -0.053 -0.204 -0.022 -0.033 0.737 0.021 -0.157 0.681 -0.011 -0.308 -0.221 7.834 68.566 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Table 5: Groups of elements based on the principal components loading for dry season, 5 factors incorporate of the 68.566 variance Eigen value Major constituents Trace constituents Negative 6.156 K, Mg, Na, SO4, Cl B, Li, Se, Sr, V Ba 3.973 Al, Fe, Mn, P 3.478 Bi, Co, Ni Li, Sr, V Cr, NO3 3.397 Mg, HCO3 2.193 Cd, Pb, Zn Table 6: Principal component loadings from PCA after rotation for the maximum variance for wet season Parameters PC1 PC2 PC3 Ca 0.211 -0.249 0.215 K 0.594 0.03 -0.665 Mg 0.918 -0.039 0.312 Na 0.918 -0.045 -0.213 0.118 -0.144 0.404 HCO3 0.481 0.177 -0.066 SO4 Cl 0.726 -0.052 -0.161 0.047 0.169 -0.588 NO3 Al -0.153 -0.133 0.092 B 0.752 0.242 -0.464 Ba -0.788 -0.088 0.237 Be 0.030 0.970 -0.095 Bi 0.088 0.739 -0.286 Cd 0.062 0.977 -0.061 Co 0.079 0.944 0.010 Cr 0.121 0.559 -0.673 Cu -0.056 0.557 -0.068 Fe -0.05 -0.052 0.177 Li 0.849 0.202 0.389 Mn 0.164 0.034 0.211 Ni 0.279 0.101 0.720 Pb -0.025 0.536 0.261 Sb -0.209 -0.019 0.392 Se 0.839 0.043 0.118 Zn -0.02 0.052 -0.016 P 0.056 0.215 -0.121 Sr 0.774 -0.205 0.544 V 0.905 -0.048 0.313 % of Variance 25.364 16.526 12.116 Cumulative % 25.364 41.889 54.006 Bold values: loadings > 0.5. Na, B, K, Cl, SO4 and Se. The lowest linkage distances in the dendrogram of the 28 chemical parameters are Bi, Co and Ni. Other chemical elements linked at low distance include Fe, Mn, Al and P and Mg, V, Li and Sr. The dendrogram for the elements for wet season is shown in (Fig. 5). The 28 elements can be classified into two major groups: from Be to Ba and from Mg to SO4 (Fig. 5). These elements can be further classified into five groups: (i) Be, Cd, Co, Bi, Cr, NO3, Cu, Pb and Zn; (ii) Al, Fe, Mn and P; (iii) Ca, Ni, HCO3, Sb and Ba; (iv) Mg, V, Sr, Li, Se; and (v) Na, B, K, Cl and SO4. The lowest linkage distances in the dendrogram of the 28 chemical parameters are Be, Cd and Co. Other chemical elements linked at low distance include Al, Fe, Mn and P and Mg, V, Sr and Li. Principle Component Analysis (PCA): Principal component analysis is performed to reduce a large number of variables into a smaller number and for PC4 0.200 0.022 0.021 -0.010 0.111 -0.117 0.094 -0.269 0.769 -0.010 0.132 -0.020 -0.100 -0.035 0.088 -0.074 0.039 0.886 -0.044 0.860 0.017 0.327 0.003 0.067 -0.049 0.828 0.069 0.018 11.121 65.127 PC5 0.748 0.241 0.143 -0.01 0.191 0.243 -0.058 -0.052 0.223 -0.070 0.270 -0.058 0.115 -0.028 -0.073 -0.066 -0.222 -0.004 -0.015 -0.154 0.142 -0.456 0.543 -0.046 -0.729 0.123 0.143 0.166 7.451 72.578 further investigation of the relationships between the elements. The Principal Component (PCs) with Eigen values larger than 1 are extracted with the PC loadings rotated for the maximum variance. A total of five PCs are extracted for dry season, which account for 68.6 % of the total variance. Table 4 shows the PC loadings for dry season as well as their respective explained variance. Loading, that represent the importance of the variable for components, are bold for values greater than 0.5. Based on the PC loadings, the 28 elements can be grouped into five PCs groups (Table 5): (i) (K, Mg, Na, SO4, Cl, B, Li, Se, Sr and V) and (Ba); (ii) (Al, Fe Mn and P); (iii) (Bi, Co and Ni); (iv) (Mg, HCO3) and (Cr, NO3); and (v) (Cd, Pb and Zn). Factor (1) accounts for 21.98 % of the total variance and contains a high positive loading of K, Mg, Na, SO4, Cl, B, Li, Se, Sr and V and Ba with a negative loading. Factor (2) accounts for 14.19 % of the total variance and contains a high positive loading of Al, Fe Mn and P. Factor (3) accounts for 12.42% of the total variance and contains a 765 Res. J. Environ. Earth Sci., 4(7): 756-768, 2012 Table 7: Groups of elements based on the principal components loading for wet season, 5 factors incorporate of the72.578 variance Eigen value Major constituents Trace constituents Negative 7.102 K, Mg, Na, Cl B, Li, Se, Sr, V Ba 4.627 Bi, Cd, Co, Cr, Cu, Pb 3.393 Sr K, NO3, Cr 3.114 Al, Fe, P 2.086 Ca Sb Zn high positive loading of Bi, Co and Ni. Factor (4) accounts for 12.13% of the total variance and contains a high positive loading of Mg and HCO3 and NO3 and Cr with a negative loading. Factor (5) accounts for 7.83% of the total variance and contains a high positive loading of Cd, Pb and Zn. Also a total of five PCs are extracted for wet season, which account for 72.6 % of the total variance. Table 6 shows the PC loadings for wet season as well as their respective explained variance. Loading, that represent the importance of the variable for components, are bold for values greater than 0.5. Based on the PC loadings, the 28 elements can be grouped into five PCs (Table 7): (i) (K, Mg, Na, Cl, Li, Se, Sr and V) and (Ba); (ii) (Bi, Cd, Co, Cr, Cu and Pb); (iii) (Sr) and (K, NO3 and Cr); (iv) (Al, Fe and P); and (v) (Ca and Sb) and (Zn). Factor (1) accounts for 25.364 % of the total variance and contains a high positive loading of K, Mg, Na, Cl, Li, Se, Sr and V and Ba with a negative loading. Factor (2) accounts for 16.526 % of the total variance and contains a high positive loading of Bi, Cd, Co, Cr, Cu and Pb. Factor (3) accounts for 12.116% of the total variance and contains a high positive loading of Sr and a negative loading of K, NO3 and Cr. Factor (4) accounts for 11.121% of the total variance and contains a high positive loading of Al, Fe and P. Factor (5) accounts for 7.451% of the total variance and contains a high positive loading of Ca and Sb and with a negative loading of Zn. CONCLUSION The interpretation of the geochemical evolution of groundwater in the study area takes into account previous work that identified the origin of groundwater (Ta’any et al., 2007; Batayneh et al., 2008) and recognized the on-going geochemical processes that influenced groundwater geochemistry in this aquifer system. To further refine our geochemical interpretation, we applied well-proven multivariate statistical methods (HCA and PCA), which are wellsuited here because of highly variable groundwater geochemistry influenced by a variety of geological and hydrogeological factors. The HCA classified the 36 groundwater samples into seven geochemically distinct clusters (C1–C7). Calcium and magnesium are the dominant ions in the groundwater of this basin (clusters C1, C5 and C7), while bicarbonate is the most abundant of the anions (clusters C2 and C3). A total of five PCA components are extracted for dry and wet seasons, which account for 68.6 % and 72.6 % of the total variance of the dataset, respectively. Component 1 is characterized by highly positive loadings in K+, Mg2+, Na+, SO42-, Cl-, B, Li, Se, Sr and V for both seasons and is related to groundwater solute diffusion from the clay members and is defined as the salinity component. Enrichment of Na+ and Cl- is also possible, related to urban wastewaters and high rate of evapotranspiration. High loadings for K+, represents the contribution of agricultural activities and weathering of K-feldspar from surrounding geology. Mg2+ with SO42- highly positive loading suggest the importance of dissolution of carbonate rocks in this aquifer system and is defined as the hardness component. Also high SO42- is related to the long-history of evaporation process and also the effect of industrial pollution. Component 2 show high loading of Al, Fe2+, Mn2+ and P for dry season and show high loading of Bi, Cd, Co, Cr, Cu and Pb for wet season. Highly positive loadings for both Fe2+ and Mn2+ indicate a similar geochemical behavior for these parameters. The sources for these elements could be the dissolution of Fe-oxides and Mn-oxides and the oxidation of sulfide minerals. Phosphates primary come from shale and limestone and also from animal remains. The source for Al could be the dissolution of organic matter of black shale. Highly positive loadings of Bi, Cd, Co, Cr, Cu and Pb elements in the wet season may be related to anthropogenic activities such as agriculture, industry and urban life in the study area. Component 3 show high negative loading of K+, NO3 and Cr and high positive loading of Sr for wet season. 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