**7.1 Correlations between main pollutants of surface water**

Very strong (0.858 – 0.921) and very significant correlations (P < 0.001) were identified, in 2005, between Cu, Cd, Mg, and Zn pollutants in surface water (Table 1), and according to the average value of the determination coefficient, 87.50% of our data conform to the linear relationship.


\*R2 = 0.875

Table 1. The correlation matrix \*between metallic pollutants of surface water in 2005

Very strong (0.872 – 0.911) and very significant correlations (P < 0.001) were identified between Cu, Cd, Mg, and Zn pollutants in surface water (Table 2), and according to the average value of the determination coefficient, 89.10% of our data conform to the linear relationship.


\*R2 = 0.891

Table 2. The correlation matrix \*between main pollutant components of surface water in 2006


\*R2 = 0.882

Table 3. The correlation matrix \*between main pollutant components of surface water in 2007

In 2007, the relationship between Cu, Cd, Mg, and Zn pollutants in surface water (Table 3) was the same as those reported in previous years of the studied period (2005 – 2009). Between them was calculated very strong (0.858 – 0.921) and very significant correlations (P < 0.001) were identified between and according to the average value of the determination coefficient, 88.20% of our data conform to the linear relationship.

The correlation coefficients emphasized between Cu, Cd, Mg, and Zn pollutants in surface water by 2008 (Table 4), were positive very strong (0.861 – 0.918) and very significant (P < 0.001). The calculated average value of the determination coefficient justifies 88.60% the conformity of our data with the linear relationship.

Similarly with previous years of analyzed period of five years (2005 – 2009), the calculated correlations between the main metallic pollutants (Cu, Cd, Mg, and Zn) of the surface water in the last year of the studied interval of time, 2009, respectively (Table 5), revealed very strong (0.868 – 0.908) and very significant values (P < 0.001). The average value of the determination coefficient, 89.00% of our data conform to the linear relationship.


\*R2 = 0.886

146 Studies on Water Management Issues

In order to measure and establish the relationships between variables representing the main pollutants (nitrogen compounds, phosphates, Cl, S, Pb, Cd, Hg, As, oil products, pesticides) of the monitored groundwater, monitored surface water (Cu, Cd, Mg, and Zn), in Romania

Very strong (0.858 – 0.921) and very significant correlations (P < 0.001) were identified, in 2005, between Cu, Cd, Mg, and Zn pollutants in surface water (Table 1), and according to the average value of the determination coefficient, 87.50% of our data conform to the linear

Issue Cu (mg/L) Cd (mg/L) Mg (mg/L) Zn (mg/L) Cu (mg/L) 1.000 0.858\*\*\* 0.892\*\*\* 0.893\*\*\* Cd (mg/L) 1.000 0.867\*\*\* 0.921\*\*\* Mg (mg/L) 1.000 0.889\*\*\* Zn (mg/L) 1.000

Table 1. The correlation matrix \*between metallic pollutants of surface water in 2005

Very strong (0.872 – 0.911) and very significant correlations (P < 0.001) were identified between Cu, Cd, Mg, and Zn pollutants in surface water (Table 2), and according to the average value of the determination coefficient, 89.10% of our data conform to the linear

Issue Cu (mg/L) Cd (mg/L) Mg (mg/L) Zn (mg/L) Cu (mg/L) 1.000 0.872\*\*\* 0.887\*\*\* 0.897\*\*\* Cd (mg/L) 1.000 0.891\*\*\* 0.911\*\*\* Mg (mg/L) 1.000 0.891\*\*\* Zn (mg/L) 1.000

Table 2. The correlation matrix \*between main pollutant components of surface water in 2006

Table 3. The correlation matrix \*between main pollutant components of surface water in 2007

In 2007, the relationship between Cu, Cd, Mg, and Zn pollutants in surface water (Table 3) was the same as those reported in previous years of the studied period (2005 – 2009). Between them was calculated very strong (0.858 – 0.921) and very significant correlations (P < 0.001) were identified between and according to the average value of the determination

coefficient, 88.20% of our data conform to the linear relationship.

Issue Cu (mg/L) Cd (mg/L) Mg (mg/L) Zn (mg/L) Cu (mg/L) 1.000 0.858\*\*\* 0.892\*\*\* 0.863\*\*\* Cd (mg/L) 1.000 0.867\*\*\* 0.921\*\*\* Mg (mg/L) 1.000 0.889\*\*\* Zn (mg/L) 1.000

during analyzed five years period, the correlation coefficients were calculated.

**7.1 Correlations between main pollutants of surface water** 

**7. Correlations** 

relationship.

\*R2 = 0.875

relationship.

\*R2 = 0.891

\*R2 = 0.882

Table 4. The correlation matrix\* for main pollutant components of surface water data, in 2008


\*R2 = 0.890

Table 5. The correlation matrix\*between main pollutant components of surface water in 2009

#### **7.2 Correlations between main pollutants of groundwater**

In groundwater, by 2005 (Table 6), very strong positive correlations, statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds (0.905; R2 = 0.819), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.922 – 0.793), with an average R2 = 0.797. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cd, As, oil products, pesticides and phosphates, and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and nitrogen compounds (Table 6). Average positive correlations were calculated between Cl and nitrogen compounds, statistically distinct significant (P < 0.01), and significant (P < 0.05) for S, Pb, Hg and nitrogen compounds, respectively (Table 6).

In 2006 (Table 7), too, very strong positive correlations, statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds identified in groundwater (0.912; R2 = 0.831), and between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.923 – 0.791), with an average R2 = 0.821. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.195 – 0.439), and also between S, Cd, Hg, As, oil products, pesticides and nitrogen compounds (0.354 – 0.498) while between Cl and nitrogen compounds was identified a positive (0.528) statistically significant moderate correlation (P < 0.05), and between Pb and nitrogen a statistically distinct significant (P < 0.01) moderate correlation coefficient of 0.583 (Table 7).

Evolution of Water Quality in Romania 149

Phosphates 1.000 0.214 ns 0.182 ns 0.233 ns 0.366 ns 0.322 ns 0.281 ns 0.383ns 0.422 ns Cl 1.000 0.799\*\*\* 0.868\*\*\* 0.858\*\*\* 0.889\*\*\* 0.894\*\*\* 0.905\*\*\* 0.915\*\*\* S 1.000 0.829\*\*\* 0.883\*\*\* 0.799\*\*\* 0.812\*\*\* 0.920\*\*\* 0.899\*\*\* Pb 1.000 0.865\*\*\* 0.913\*\*\* 0.921\*\*\* 0.912\*\*\* 0.798\*\*\* Cd 1.000 0.893\*\*\* 0.837\*\*\* 0.921\*\*\* 0.865\*\* Hg 1.000 0.897\*\*\* 0.909\*\*\* 0.828\*\*\* As 1.000 0.896\*\*\* 0.831\*\*\*

Pesticides 1.000 Table 8. The correlation matrix between main pollutant components of groundwater in 2007

Phosphates 1.000 0.250 ns 0.191ns 0.278 ns 0.314ns 0.322ns 0.273ns 0.389ns 0.412ns Cl 1.000 0.786\*\*\* 0.812\*\*\* 0.845\*\*\* 0.889\*\*\* 0.878\*\*\* 0.909\*\*\* 0.913\*\*\* S 1.000 0.832\*\*\* 0.891\*\*\* 0.799\*\*\* 0.803\*\*\* 0.920\*\*\* 0.886\*\*\* Pb 1.000 0.872\*\*\* 0.921\*\*\* 0.975\*\*\* 0.904\*\*\* 0.796\*\*\* Cd 1.000 0.893\*\*\* 0.835\*\*\* 0.912\*\*\* 0.798\*\*\* Hg 1.000 0.887\*\*\* 0.918\*\*\* 0.825\*\*\* As 1.000 0.895\*\*\* 0.805\*\*\*

Pesticides 1.000 Table 9. The correlation matrix between main pollutant components of groundwater in 2008

In groundwater, by 2008 (Table 9), very strong positive correlations, and statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds (0.925; R2 = 0.856), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.921 – 0.786), with an average R2 = 0.785. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.191 – 0.412), and also between Cd, Hg, As, oil products and nitrogen compounds, with values within the interval 0.315 – 0.423 (Table 9). Average positive correlations were calculated

Phosphates Cl S Pb Cd Hg As Oil

1.000 0.915\*\*\* 0.633\*\* 0.525\* 0.541\* 0.432 ns 0.457 ns 0.322 ns 0.405 ns 0.521\*

1.000 0.914\*\*\*

Phosphates Cl S Pb Cd Hg As Oil

1.000 0.925\*\*\* 0.654\*\* 0.543\* 0.553\* 0.412ns 0.423ns 0.315ns 0.413ns 0.523\*

1.000 0.912\*\*\*

products

products

Pesticides

Pesticides

Issue Nitrogen

Nitrogen compounds

> Oil products

(mg/L)

Nitrogen compounds

> Oil products

(mg/L)

Issue Nitrogen

compounds

compounds


Table 6. The correlation matrix between main pollutant components of groundwater in 2005 (mg/L)


Table 7. The correlation matrix between main pollutant components of groundwater in 2006 (mg/L)

In the same year, 2007, in groundwater (Table 8), very strong positive correlations, statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds (0.915; R2 = 0.837), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.920 – 0.798), with an average R2 = 0.803. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.182 – 0.422), and also between Cd, Hg, As, oil products and nitrogen compounds (0.322 – 0.457) while between S, Pb and nitrogen compounds were identified positive (0.525 and 0.541, respectively) statistically significant moderate correlation (P < 0.05), and between Cl and nitrogen a statistically distinct significant (P < 0.01) moderate correlation coefficient of 0.633 (Table 8).

Phosphates 1.000 0.250 ns 0.191ns 0.278 ns 0.314 ns 0.322 ns 0.273 ns 0.389 ns 0.412ns Cl 1.000 0.793\*\*\* 0.812\*\*\* 0.845\*\*\* 0.889\*\*\* 0.878\*\*\* 0.909\*\*\* 0.913\*\*\* S 1.000 0.832\*\*\* 0.891\*\*\* 0.799\*\* 0.803\*\*\* 0.903\*\*\* 0.886\*\*\* Pb 1.000 0.872\*\*\* 0.923\*\*\* 0.925\*\*\* 0.904\*\*\* 0.796\*\*\* Cd 1.000 0.893\*\*\* 0.835\*\*\* 0.902\*\*\* 0.798\*\*\* Hg 1.000 0.887\*\*\* 0.908\*\*\* 0.825\*\*\* As 1.000 0.895\*\*\* 0.805\*\*\*

Pesticides 1.000 Table 6. The correlation matrix between main pollutant components of groundwater in 2005

Phosphates 1.000 0.195ns 0.254ns 0.259ns 0.385ns 0.364ns 0.228 ns 0.315ns 0.439ns Cl 1.000 0.791\*\*\* 0.812\*\*\* 0.845\*\*\* 0.889\*\*\* 0.878\*\*\* 0.909\*\*\* 0.913\*\*\* S 1.000 0.832\*\*\* 0.891\*\*\* 0.799\*\*\* 0.803\*\*\* 0.913\*\*\* 0.886\*\*\* Pb 1.000 0.872\*\*\* 0.923\*\*\* 0.915\*\*\* 0.914\*\*\* 0.796\*\*\* Cd 1.000 0.893\*\*\* 0.835\*\*\* 0.912\*\*\* 0.798\*\*\* Hg 1.000 0.887\*\*\* 0.918\*\*\* 0.825\*\*\* As 1.000 0.895\*\*\* 0.805\*\*\*

Pesticides 1.000 Table 7. The correlation matrix between main pollutant components of groundwater in 2006

In the same year, 2007, in groundwater (Table 8), very strong positive correlations, statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds (0.915; R2 = 0.837), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.920 – 0.798), with an average R2 = 0.803. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.182 – 0.422), and also between Cd, Hg, As, oil products and nitrogen compounds (0.322 – 0.457) while between S, Pb and nitrogen compounds were identified positive (0.525 and 0.541, respectively) statistically significant moderate correlation (P < 0.05), and between Cl and nitrogen a statistically distinct significant (P < 0.01) moderate

Phosphates Cl S Pb Cd Hg As Oil

1.000 0.905\*\*\* 0.654\*\* 0.543\* 0.553\* 0.412ns 0.423\* 0.315ns 0.413ns 0.523ns

1.000 0.922\*\*\*

Phosphates Cl S Pb Cd Hg As Oil

1.000 0.912\*\*\* 0.528\* 0.432ns 0.583\*\* 0.468ns 0.381ns 0.354ns 0.462ns 0.498 ns

1.000 0.921\*\*\*

products

products

Pesticides

Pesticides

Issue Nitrogen

Nitrogen compounds

> Oil products

(mg/L)

Nitrogen compounds

> Oil products

(mg/L)

Issue Nitrogen

compounds

correlation coefficient of 0.633 (Table 8).

compounds


Table 8. The correlation matrix between main pollutant components of groundwater in 2007 (mg/L)


Table 9. The correlation matrix between main pollutant components of groundwater in 2008 (mg/L)

In groundwater, by 2008 (Table 9), very strong positive correlations, and statistically very significant (P < 0.001) were identified between phosphates and nitrogen compounds (0.925; R2 = 0.856), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.921 – 0.786), with an average R2 = 0.785. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.191 – 0.412), and also between Cd, Hg, As, oil products and nitrogen compounds, with values within the interval 0.315 – 0.423 (Table 9). Average positive correlations were calculated

Evolution of Water Quality in Romania 151

Surface water

I II III IV V VI VII VIII IX X XI XII XIII

Issue Groundwater

I 0.983

I 0.735

II 0.699

III 0.695

IV 0.803

V 0.788

X – Hg; XI – As; XII - oil products; XIII - pesticides

groundwater and wastewater in 2005

VI 0.695

VII 0.743

VIII 0.739

IX 0.788

X 0.803 XI 0.768

XII 0.731

I – Nitrogen compounds; II – Phosphates; III – Cu; IV – Cd; V - Mn; VI – Zn; VII – Cl; VIII – S; IX – Pb;

Table 11. The correlation matrix between main pollutant components of surface water,

XIII 0.744

II 0.857

III 0.899

IV 0.856

V 0.932

VI 0.986

VII 0.956

VIII 0.973

IX 0.956

X 0.888 XI 0.867

XII 0.829

XIII 0.863 Waste water


between Cl and nitrogen compounds (0.654), statistically distinct significant (P < 0.01). Between S, Pb, pesticides and nitrogen compounds were identified average correlation coefficients statistically significant (P < 0.05), with values within the interval 0.523 – 0.553 (Table 9).

Table 10. The correlation matrix between main pollutant components of groundwater in 2009 (mg/L)

The correlation coefficients calculated in 2009 for the groundwater pollutants (Table 10), revealed very strong positive correlations, statistically very significant (P < 0.001) between phosphates and nitrogen compounds (0.917; R2 = 0.841), and also between Cl, S, Pb, Cd, Hg, As, oil products, pesticides (0.921 – 0.795), with an average R2 = 0.783. Weak positive correlations, statistically not significant (P > 0.05) were identified between Cl, S, Pb, Cd, Hg, As, oil products, pesticides and phosphates (0.185 – 0.461), and also between Cd, Hg, As, oil products and nitrogen compounds (0.298 – 0.453), while between Cl and nitrogen compounds, statistically distinct significant (P < 0.01) correlation was found (0.629), and average positive correlations (0.558, and 0.629 respectively), statistically significant (P < 0.05), between S, Pb and nitrogen compounds (Table 9).
