## 3 Results and Discussion
### Groundwater Hydrochemistry Assessment
Within the study area, the Na\({}^{+}\) content varied between 15.89 and 295.41 mg/L, with a mean of 65.60 mg/L during the pre-irrigation period and 12.58 to 230.89 mg/L with a mean of 54.71 mg/L during the post-irrigation period (Table 2). In the groundwater of the research region, Ca\({}^{2+}\) is the most prevalent cation ion next to Na\({}^{+}\). Within the research region, the average calcium concentration was 123.59 mg/L during the pre-irrigation period, ranging from 57.40 to 408.60 mg/L, and 124.14 mg/L during the post-irrigation period, ranging from 52.56 to 502.31 mg/L. The permissible level of 100 mg/L for drinking water is exceeded at two sample stations during the pre- and post-irrigation periods [6]. One element that is frequently present in the environment is magnesium. Mg\({}^{2+}\) concentrations were found to range between 12.22 and 115.43 mg/L during the pre-irrigation period, with a mean of 35.76 mg/L, and 13.20 and 105.09 mg/L during the post-irrigation period, with a mean of 31.67 mg/L. In this investigation, K\({}^{+}\) is far less concentrated than Na\({}^{+}\). This may result from K\({}^{+}\)'s propensity to  
Figure 4: Spatial distributions of analytical cations and anions for post-irrigation period in the study area. be reabsorbed throughout groundwater circulation [36]. In the pre- and post-irrigations, it ranges from 0.66 to 189.35 and 0.53 to 161.21 mg/L, respectively. In this region, anions predominate in the groundwater as \(\text{HCO}_{3}{}^{-}>\text{SO}_{4}{}^{2-}>\text{Cl}^{-}>\text{F}^{-}\) throughout both the pre- and post-irrigation periods. \(\text{HCO}_{3}{}^{-}\) levels in pre- and post-irrigation periods ranged from 121.64 to 777.44 and 131.33 to 406.58 mg/L, respectively, with mean values of 308.74 and 281.82 mg/L in the groundwater samples. The dissolution of carbonate minerals from lithological units is the main source of \(\text{HCO}_{3}{}^{-}\) in groundwater. The main sources of sulphate are human activity, fertilizers containing sulphate, and atmospheric deposition [37; 38]. The concentrations of \(\text{SO}_{4}{}^{2-}\) were from 21.59 to 298.38 mg/L during the pre-irrigation period and 20.76 to 275.00 mg/L in the post-irrigation period, with mean values of 103.05 and 97.42 mg/L, respectively. sulphate has a maximum allowable level of 250 mg/L. Four sampling points during the pre-irrigation phase and two sampling points during the post-irrigation period, respectively, do not reach the necessary limit. Sewage waste pollution could be the cause of the elevated Cl\({}^{-}\) values observed in groundwater [39]. Cl\({}^{-}\) concentrations were measured in the pre- and post-irrigation periods, ranging from 15.00 to 314.00 and 16.00 to 342.00 mg/L, with mean values of 75.83 and 71.94 mg/L, respectively. According to WHO guidelines, the content of fluoride in groundwater should not be more than 1.5 mg/L. Fluoride is a necessary trace element for human health. If it goes over this threshold, people may develop thyroid illness or dental and skeletal fluorosis [35]. In the Harran Plain, the fluoride concentrations varied from 0.20 to 2.84 mg/L, with a mean of 0.99 mg/L during the pre-irrigation period, and from 0.15 to 2.05 mg/L, with a mean of 0.79 mg/L in the post-irrigation period. Both pre- and post-irrigation periods exhibit two observation points exceeding 1.5 mg/L. Table 1 indicates that there is no substantial variation in the ion sequences estimated from the mean concentrations of ions in the two periods. The cations are \(\text{Ca}^{2+}>\text{Na}^{+}>\text{Mg}^{2+}>\text{K}^{+}\), while the anions are \(\text{HCO}_{3}{}^{-}>\text{SO}_{4}{}^{2-}>\text{Cl}^{-}>\text{F}^{-}\) in both periods. It suggests that the phytochemical processes and the hydrogeological environment in the research region are mostly unchanged between the two periods [40]. Pre-irrigation mean values for \(\text{Na}^{+}\), \(\text{Mg}^{2+}\), \(\text{K}^{+}\), \(\text{HCO}_{3}{}^{-}\), Cl\({}^{-}\), \(\text{SO}_{4}{}^{2+}\), and \(\text{F}^{-}\) are marginally higher than post-irrigation means values.