Fig. 3

A correlogram illustrating the relationships between the variables under investigation in water samples. The circles’ color and size correspond to the correlation coefficients. Red color presents negative correlations while blue refers to positive correlations with different shades. Large-sized circles refer to a strong correlation and small- sized circles present a weak correlation. Correlations with p-value greater than 0.05 are deemed insignificant and are indicated by an empty white space.