**3. Statistical analysis**

The descriptive statistics of heavy metals in the wells of the study area are demonstrated in **Table 1**. Minimum and maximum values of electrical conductivity are 830 and 2730 μS/cm with a mean value of 1451 μS/cm. The measured water temperatures varied from 14 to 18°C with a mean of 16°C. The pH values of the groundwater samples vary from 6.9 to 7.9 with a mean of 7.4 indicating that the waters were generally neutral to slightly alkaline. pH does not show significant positive correlation with any heavy metals, while it shows negative correlation with Fe, Zn and Cd (**Table 2**). This indicates that influence of pH on heavy metals was different in groundwater of the studied area. The mean concentration of Al, Cd, Cu, F, Fe, Pb, Si and Zn was 0.05, 0.066, 0.241, 0.129, 0.255, 0.087, 21.6 and 0.148 mg/l, respectively. Moreover, the mean values of the heavy metal contents in the groundwater follow the decreasing order: Si > Fe > Cu > Zn > F > Pb > Cd > Al.

Assessment of Heavy Metals Contamination in Groundwater: A Case Study of the South of Setif… http://dx.doi.org/10.5772/intechopen.75734 19

**Figure 1.** Location of the study area and the samples.

In the present study, factor analysis (FA) and cluster analysis (CA) were used to evaluate the concentrations of heavy elements in groundwater samples.

### **3.1. Factor analysis**

Groundwater is the principal natural water resources for both drinking and agricultural purposes. Nowadays one of the most important environmental issues is groundwater contamination [2, 3]. In areas where population density is high and human use of the land is intensive, groundwater is especially vulnerable. Virtually any activity whereby chemicals or wastes may be released to the environment, either intentionally or accidentally, has the potential to pollute groundwater. When

Heavy metals are among the major contaminants of groundwater sources [4]. Some of these heavy metals are essential for the growth, development and health of living organisms, whereas others are non-essential as they are indestructible and most of them are categorized as toxic species on organisms [5]. Nonetheless, the toxicity of heavy metals depends on their concentration levels in the environment. With increasing concentrations in environment and decreasing the capacity of soils toward retaining heavy metals, they leach into groundwater and soil solution. Thus, these toxic heavy metals can be accumulated in living tissues and concentrate through the food chain. The main objectives of this study are: (1) to determine the spatial variation of heavy metals using multivariate statistical techniques, (2) to assess the potential health risk assessment of

The study area is located in the east of Algeria and the south of Setif (**Figure 1**). It is characterized by intensive agricultural and human activities. The climate of this area is semi-arid, with a mean annual temperature and precipitation of 15.2°C and 296 mm/year, respectively [6].

In the current study, 18 wells were collected (**Figure 1**) and 11 parameters (T, pH, EC, Al, Cd, Cu, F, Fe, Pb, Si and Zn) were analyzed using standard procedures [7]. The electrical conductivity (EC), pH and the temperature (T) were measured by multi-parameter WTW (P3 MultiLine pH/LF-SET). The concentrations of heavy metals were determined by Graphite

The descriptive statistics of heavy metals in the wells of the study area are demonstrated in **Table 1**. Minimum and maximum values of electrical conductivity are 830 and 2730 μS/cm with a mean value of 1451 μS/cm. The measured water temperatures varied from 14 to 18°C with a mean of 16°C. The pH values of the groundwater samples vary from 6.9 to 7.9 with a mean of 7.4 indicating that the waters were generally neutral to slightly alkaline. pH does not show significant positive correlation with any heavy metals, while it shows negative correlation with Fe, Zn and Cd (**Table 2**). This indicates that influence of pH on heavy metals was different in groundwater of the studied area. The mean concentration of Al, Cd, Cu, F, Fe, Pb, Si and Zn was 0.05, 0.066, 0.241, 0.129, 0.255, 0.087, 21.6 and 0.148 mg/l, respectively. Moreover, the mean values of the heavy metal contents in the groundwater follow the decreasing order:

Furnace Atomic Absorption Spectrophotometer (Perkin-Elmer AAnalyst 700).

ground water becomes contaminated, it is difficult and expensive to clean up.

18 Achievements and Challenges of Integrated River Basin Management

heavy metals and (3) take preventive and protective measures.

**2. Study area and data analysis**

**3. Statistical analysis**

Si > Fe > Cu > Zn > F > Pb > Cd > Al.

Factor analysis was employed to find and interpret the structure of the underlying data set through a reduced new set of orthogonal (non-correlated) variables (principal components, PCs), arranged in decreasing order of importance. Besides considerable data reduction, PCs can explain the entire multidimensional data set variability without losing much original information. FA with Varimax rotation of standardized component loadings was conducted for extracting and deriving factors, respectively, and those PCs with eigenvalue >1 were retained [8–10]. The distribution manner of individual association of element in groundwater was determined by principal component method (results are shown in **Table 3**). Statistical treatment of these data indicates their association and grouping with three factors explained most of the variability (total variance explained was about 75.69% variance for the groundwater data). The relations among the heavy metals based on the first three factors are illustrated in **Figure 2** in three-dimensional space.


Remarks: All values are in mg/l except pH, T (°C) and EC (μSiemens/cm). "Min": minimum; "Max": maximum; "SD": standard deviation; "CV" (in %): coefficient of variation.

**Table 1.** Statistical summary of physicochemical parameters in groundwater samples.

The first factor shows 39.92% of total variance with high loading on Al, F, Pb and Si. These metals were predominantly contributed by the water-rock interaction effects and anthropogenic sources. Aluminum was the most abundant element found in the earth's crust [11] and from the result obtained from its analysis, the minimum concentration of aluminum detected in the groundwater samples is 0.01 mg/l with the maximum concentration being 0.09 mg/l. All samples exceeded the desirable limit of Al for drinking water (0.03 mg/l)


except sample 10, but none of the groundwater samples contained Al above the specified maximum contaminant level (0.2 mg/l) [12]. The ranges of fluoride are 0.017–0.358 mg/l. Thus, F concentrations are relatively low in the groundwater (<1.5 mg/l). The concentration of the lead in the groundwater samples ranges from 0.017 to 0.292 mg/l. The groundwater quality standard of lead desirable and maximum permissible limit (WHO) is 0.01 mg/l. All of the groundwater samples are exceeding then WHO desirable and maximum permissible limit of Pb. The concentration of Si in the samples varies from 12.2 to 33.3 mg/l with a mean

**Table 3.** Factor analysis of groundwater data. The significant factors (>1) are shown in bold.

**Total % of variance Cumulative %**

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**Variables Component Communalities**

**1 2 3** Pb −0.74 0.42 0.02 0.64 Fe 0.50 0.66 0.15 0.53 Zn −0.52 0.58 −0.22 0.48 Cu −0.55 0.28 0.69 0.47 Cd −0.08 0.78 −0.24 0.39 Si −0.61 −0.21 0.53 0.44 F −0.88 −0.22 −0.23 0.85 Al −0.81 −0.22 −0.38 0.79

 **3.19 39.92 39.92 1.77 22.08 62.00 1.10 13.70 75.69** 0.69 8.57 84.26 0.63 7.89 92.16 0.30 3.73 95.89 0.24 2.97 98.87 0.09 1.13 100.00

The second factor exhibits 22.08% of the total variance with positive loading on Cd, Fe and Zn. The concentration of the cadmium in the water samples varies from 0.009 to 0.165 mg/l with a mean of 0.066 mg/l. The groundwater quality standard of cadmium desirable and maximum permissible limit is 0.003 mg/l. All samples are exceeding then desirable limit of Cd. The concentration of iron ranges from 0.055 to 0.499 mg/l. The concentrations of Fe in many of the samples are higher than the WHO permitted limit of 0.3 mg/l [12] and the percent

value of 21.6 mg/l.

**Component Eigen values**

**Table 2.** Pearson's correlations matrix for the physicochemical parameters.

Assessment of Heavy Metals Contamination in Groundwater: A Case Study of the South of Setif… http://dx.doi.org/10.5772/intechopen.75734 21



**Table 3.** Factor analysis of groundwater data. The significant factors (>1) are shown in bold.

The first factor shows 39.92% of total variance with high loading on Al, F, Pb and Si. These metals were predominantly contributed by the water-rock interaction effects and anthropogenic sources. Aluminum was the most abundant element found in the earth's crust [11] and from the result obtained from its analysis, the minimum concentration of aluminum detected in the groundwater samples is 0.01 mg/l with the maximum concentration being 0.09 mg/l. All samples exceeded the desirable limit of Al for drinking water (0.03 mg/l)

Remarks: All values are in mg/l except pH, T (°C) and EC (μSiemens/cm). "Min": minimum; "Max": maximum; "SD":

**Min Max Mean SD CV**

EC 830 2730 1451 557 38 T 14 18 16 1.4 8.6 pH 6.9 7.9 7.4 0.3 3.5 Al 0.01 0.09 0.05 0.02 43.69 Cd 0.009 0.165 0.066 0.045 67.646 Cu 0.056 0.43 0.241 0.102 42.248 F 0.017 0.358 0.129 0.111 86.222 Fe 0.055 0.499 0.255 0.116 45.563 Pb 0.017 0.292 0.087 0.069 79.323 Si 12.2 33.3 21.6 7.2 33.2 Zn 0.045 0.276 0.148 0.06 40.466

**EC T pH Pb Fe Zn Cu Cd Si F Al**

EC 1

T −0.36 1

pH 0.33 −0.54 1

Pb 0.32 0.27 0.15 1

Fe −0.46 0.19 −0.42 −0.05 1

standard deviation; "CV" (in %): coefficient of variation.

20 Achievements and Challenges of Integrated River Basin Management

**Table 1.** Statistical summary of physicochemical parameters in groundwater samples.

Zn 0.20 0.31 −0.29 0.54 −0.08 1

Cu 0.04 0.12 0.27 0.50 −0.02 0.31 1

**Table 2.** Pearson's correlations matrix for the physicochemical parameters.

Cd 0.25 0.04 −0.17 0.23 0.37 0.41 0.04 1

Si 0.43 0.06 0.29 0.26 −0.37 0.06 0.49 −0.03 1

F 0.78 −0.05 0.40 0.59 −0.49 0.26 0.28 −0.05 0.41 1

Al 0.72 0.08 0.16 0.44 −0.48 0.28 0.15 0.03 0.36 0.87 1

except sample 10, but none of the groundwater samples contained Al above the specified maximum contaminant level (0.2 mg/l) [12]. The ranges of fluoride are 0.017–0.358 mg/l. Thus, F concentrations are relatively low in the groundwater (<1.5 mg/l). The concentration of the lead in the groundwater samples ranges from 0.017 to 0.292 mg/l. The groundwater quality standard of lead desirable and maximum permissible limit (WHO) is 0.01 mg/l. All of the groundwater samples are exceeding then WHO desirable and maximum permissible limit of Pb. The concentration of Si in the samples varies from 12.2 to 33.3 mg/l with a mean value of 21.6 mg/l.

The second factor exhibits 22.08% of the total variance with positive loading on Cd, Fe and Zn. The concentration of the cadmium in the water samples varies from 0.009 to 0.165 mg/l with a mean of 0.066 mg/l. The groundwater quality standard of cadmium desirable and maximum permissible limit is 0.003 mg/l. All samples are exceeding then desirable limit of Cd. The concentration of iron ranges from 0.055 to 0.499 mg/l. The concentrations of Fe in many of the samples are higher than the WHO permitted limit of 0.3 mg/l [12] and the percent samples above the limit is 39%. The concentration of the zinc ranges from 0.045 to 0.276 mg/l. The groundwater quality standard of zinc desirable limit is 3 mg/l and maximum permissible limit is 10 mg/l, and all samples are lower than the desirable limit [12].

**Figure 2.** FA results in the three-dimensional space: plot of loading of the first three factors.

**Cluster 1**

**Min**

> EC

T pH

Al Cd Cu

F Fe Pb

Si Zn **Table 4.**

Statistical summary of physicochemical parameters in the three clusters.

0.045

0.190

0.133

0.059

44.492

0.089

0.238

0.160

0.056

35.082

0.087

0.276

0.154

0.073

47.516

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12.20

16.70

14.89

1.61

10.80

18.20

23.10

20.85

1.81

8.67

30.60

33.30

31.78

1.02

3.20

0.027

0.101

0.058

0.025

42.274

0.029

0.292

0.102

0.096

94.334

0.017

0.193

0.109

0.073

67.210

0.188

0.373

0.278

0.066

23.576

0.182

0.499

0.304

0.124

40.596

0.055

0.378

0.164

0.130

79.412

0.031

0.128

0.073

0.033

45.940

0.031

0.358

0.133

0.126

94.271

0.017

0.339

0.203

0.137

67.502

0.056

0.364

0.219

0.097

44.034

0.089

0.311

0.196

0.086

43.942

0.213

0.430

0.326

0.089

27.271

0.016

0.165

0.063

0.051

81.045

0.037

0.125

0.076

0.032

41.771

0.009

0.152

0.060

0.057

94.821

0.010

0.060

0.037

0.015

40.278

0.030

0.090

0.057

0.023

41.260

0.040

0.090

0.062

0.023

36.780

7.2

7.8

7.5

0.2

3.1

6.9

7.4

7.2

0.2

2.4

7.3

7.9

7.6

0.2

3.2

14.0

18.0

15.6

1.5

9.7

14.0

17.5

16.6

1.3

7.7

14.0

17.0

15.9

1.3

8.4

950

1540

1164

188

16

830

2730

1463

747

51

1340

2530

1836

489

27

**Max**

**Mean**

**SD**

**CV**

**Min**

**Max**

**Mean**

**SD**

**CV**

**Min**

**Max**

**Mean**

**SD**

**CV**

**Cluster 2**

**Cluster 3**

**Figure 3.** Hierarchical cluster results or dendrogram obtained by CA of the groundwater samples.


samples above the limit is 39%. The concentration of the zinc ranges from 0.045 to 0.276 mg/l. The groundwater quality standard of zinc desirable limit is 3 mg/l and maximum permissible

limit is 10 mg/l, and all samples are lower than the desirable limit [12].

22 Achievements and Challenges of Integrated River Basin Management

**Figure 2.** FA results in the three-dimensional space: plot of loading of the first three factors.

**Figure 3.** Hierarchical cluster results or dendrogram obtained by CA of the groundwater samples.

**Table 4.** Statistical summary of physicochemical parameters in the three clusters. The third factor exhibits 13.7% of the total variance with positive loading on Cu. The concentration of the copper varies from 0.056 to 0.43 mg/l. The groundwater quality standard of copper maximum permissible limit is 2 mg/l. All groundwater samples are less then maximum permissible level of Cu [12].

The second cluster was represented by the wells 1, 4, 7, 9 and 14, and it occupies 33% of the total water samples (mean EC = 1463 μS/cm). This cluster included samples with the highest concentrations of Cd (0.076 mg/l), Fe (0.304 mg/l) and Zn (0.160 mg/l) (**Figure 4(b)**, **(e)**, and **(h)**).

Assessment of Heavy Metals Contamination in Groundwater: A Case Study of the South of Setif…

The third cluster was included samples 2, 15, 16, 17 and 18 (28%), where the mean of EC is 1836 μS/cm. In this cluster, the samples were presented the highest concentrations of Al (0.062 mg/l), Cu (0.326 mg/l), F (0.203 mg/l), Pb (0.109 mg/l) and Si (31.78 mg/l) (**Figure 4(a)**,

The degree of pollution in groundwater samples were assessed employing two methods; degree of contamination (Cdeg) and heavy metal evaluation index (HEI) as reported in the

The quality of groundwater was evaluated by calculating contamination index (Cdeg). The degree of contamination is used as a reference of estimating the extent of metal pollution [17]. This index may be classified into three categories as follows: low (Cdeg < 1), medium (Cdeg = 1–3) and high (Cdeg > 3) [15, 18, 19]. The contamination index was computed from the

> *i*=1 *n*

*CNi*

component, and "*CNi*" is upper permissible concentration of the *i*th component (*N* denotes the

The heavy metal evaluation index gives an overall quality of groundwater with respect to

*i*=1 *<sup>n</sup>* \_\_\_\_\_ *HC HMAC*

where, "*HC*" and "*HMAC*" are the measured value and maximum admissible concentration

The estimated pollution evaluation indices for the selected heavy metals in the three clusters are shown in **Table 5**. In the first cluster, mean values of HEI and Cdeg indices were observed to be 29 and 22 (**Table 5**), respectively, which indicated that the water samples of this cluster were contaminated with low degree of pollution by heavy metals, especially Cd and Pb [19]. The mean values of HEI and Cdeg of the second cluster and the last cluster were respectively

heavy metals [19]. This index was computed using the relationship:

" is contamination factor for the *i*th component, "*CAi*" is analytical value for the *i*th

*Cfi* (1)

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− 1 (2)

(3)

**(c)**, **(d)**, **(f)**, and **(g)**).

literature [15, 16].

following equation:

where, "*Cfi*

"normative value").

**4. Pollution evaluation indices**

*C*deg = ∑

*<sup>C</sup>fi* <sup>=</sup> *<sup>C</sup>*\_\_\_*Ai*

*HEI* = ∑

(MAC) of the *i*th parameter, respectively.

#### **3.2. Cluster analysis**

Cluster analysis (CA) was applied to group objects (cases) into categories or clusters on the basis of similarities within a cluster and dissimilarities between different clusters with respect to distance between objects [13, 14]. Hierarchical agglomerative cluster analysis was performed on the normalized data set using Euclidean distances as a measure of similarity and Ward's method to obtain dendrograms. Three main clusters can be distinguished in the dendrogram shown in **Figure 3**. **Table 4** shows that the increases of electrical conductivity from the first cluster to the last cluster. Cluster analysis confirmed and completed the results obtained by factor analysis.

The first cluster was composed of the wells 3, 5, 8, 10, 11, 12 and 13, and concerns 39% of the total water samples. The mean of electrical conductivity for this cluster is 1164 μS/cm, which presented low concentrations of all heavy metals compared with others clusters (**Figure 4(a)** and **(h)**).

**Figure 4.** Plot of heavy metals in the three clusters.

The second cluster was represented by the wells 1, 4, 7, 9 and 14, and it occupies 33% of the total water samples (mean EC = 1463 μS/cm). This cluster included samples with the highest concentrations of Cd (0.076 mg/l), Fe (0.304 mg/l) and Zn (0.160 mg/l) (**Figure 4(b)**, **(e)**, and **(h)**).

The third cluster was included samples 2, 15, 16, 17 and 18 (28%), where the mean of EC is 1836 μS/cm. In this cluster, the samples were presented the highest concentrations of Al (0.062 mg/l), Cu (0.326 mg/l), F (0.203 mg/l), Pb (0.109 mg/l) and Si (31.78 mg/l) (**Figure 4(a)**, **(c)**, **(d)**, **(f)**, and **(g)**).
