## 3 Results and Discussion
### Descriptive Analysis of Groundwater Quality Parameters
The concentrations of some mineral compounds such as calcium and magnesium cause the precipitation of these salts. In the Cuernavaca aquifer, calcium was found in concentrations from 3.88 to 121.1 mg/L and a mean value of 41.9 mg/L, while magnesium was found from 3.8 to 50.5 mg/L with a mean value of 19.2 mg/L. The presence of concentrations of these salts (Mg\({}^{2+}\) and Ca\({}^{2+}\)) is due to the geological features of the aquifer. Sodium and potassium were found in a range of 1.92-37.5 and 1.3-6.6 respectively. The mean values for all major cations were within the maximum permissible limit [28]. Bicarbonates were within a range of 48.4-295 mg/L and a mean value of 145.1 mg/L was calculated. It is noteworthy that carbonates were not found in the samples. Sulfates in the Cuernavaca aquifer are between 0.8 and 136 mg/L, which are below the SO\({}_{4}^{2-}\) concentrations reported in other studies [39] and the guidelines recommended by the WHO [28]. Moreover, the chlorides presented a concentration between 8.4 and 78.2 mg/L, while nitrates showed a maximum concentration up to 6.2 mg/L, with a mean value of 3.2 mg/L. Both anions' mean values were also below the WHO maximum allowable values. [PERSON] and [PERSON] [14] suggest that nitrates could be found in groundwaters due to anthropogenic activity. They reported NO\({}_{3}\) concentrations up to 198.17 mg/L in groundwater under the influence of agriculture activities in Nanganur, India. In this study, a high variation in NO\({}_{3}\) concentrations was found between sampling sites, where the highest concentration was found in sampling site 2. Cadmium, chromium, mercury, lead, zinc, and arsenic were also analyzed in this study; however, the concentrations found could be negligible because low concentrations were observed (cadmium \(<\) 0.0002 mg/L; chromium \(<\) 0.00088 mg/L; mercury \(<\) 0.00009 mg/L, lead \(<\) 0.00154 mg/L, zinc \(<\) 0.002 mg/L and arsenic \(<\) 0.00139 mg/L). According to these results, the influence of geogenic sources was evidenced, where leaching and weathering of rocks and the use of pesticides and fertilizers \begin{table}
\begin{tabular}{c c c c c c} \hline
**Parameters** & **Abbreviation** & **Minimum** & **Maximum** & **Mean** & **Standard Deviation** \\ \hline Bicarbonates (mg/L) & HCO\({}^{3-}\) & 48.40 & 294.90 & 145.12 & 79.75 \\ Fecal coliforms (MPN/100 mL) & FC & 1.00 & 2909.00 & 276.62 & 719.15 \\ Total organic carbon (mg/L) & TOC & 0.08 & 2.87 & 0.92 & 0.72 \\ Ammonium (mg/L) & NH\({}_{3}\) & 0.00 & 0.61 & 0.07 & 0.12 \\ Nitrites (mg/L) & NO\({}^{2-}\) & 0.00 & 0.04 & 0.01 & 0.01 \\ Nitrates (mg/L) & NO\({}^{3-}\) & 0.00 & 6.87 & 3.24 & 2.13 \\ Organic Nitrogen (mg/L) & ON & 0.00 & 1.55 & 0.24 & 0.29 \\ Total nitrogen (mg/L) & TN & 0.01 & 7.03 & 3.56 & 2.20 \\ Total phosphorus (mg/L) & TP & 0.00 & 0.40 & 0.15 & 0.09 \\ Total dissolved solids (mg/L) & TDS & 64.64 & 688.00 & 316.01 & 195.16 \\ Electrical conductivity (uS/cm) & EC & 90.00 & 991.00 & 409.79 & 266.25 \\ pH & PH & 6.20 & 8.40 & 7.29 & 0.45 \\ Chlorides (mg/L) & Cl\({}^{-}\) & 8.44 & 78.25 & 23.89 & 20.62 \\ Fluorides (mg/L) & F & 0.04 & 0.97 & 0.32 & 0.19 \\ Silicon oxides (mg/L) & SiO\({}_{2}\) & 30.42 & 91.29 & 67.10 & 13.56 \\ Potassium (mg/L) & K\({}^{+}\) & 1.32 & 7.72 & 3.68 & 1.60 \\ Manganese (mg/L) & Mn & 0.00 & 0.48 & 0.01 & 0.08 \\ Sodium (mg/L) & Na\({}^{+}\) & 1.92 & 40.01 & 18.59 & 9.43 \\ Sulfates (mg/L) & SO\({}_{4}^{2-}\) & 0.82 & 226.38 & 48.41 & 49.98 \\ Calcium (mg/L) & Ca\({}^{2+}\) & 3.87 & 121.10 & 41.93 & 37.57 \\ Magnesium (mg/L) & Mg\({}^{2+}\) & 3.82 & 50.47 & 19.25 & 13.07 \\ Total hardness (mg/L) & TH & 24.60 & 456.80 & 184.46 & 141.14 \\ Water temperature (\({}^{\circ}\)C) & WT & 17.25 & 22.49 & 20.24 & 21.68 \\ \hline \end{tabular}
\end{table} 
Table 2: Range, standard deviation and mean values for water quality parameters in the Cuernavaca aquifer from 2012 to 2019.  
could be recognized as the main driving factors for the hydrochemical and water quality of the aquifer.