The pH of water samples ranges from 8.08 to 8.29 with a mean value of 8.14 in winter (Figure 3A). In summer, the pH values range from 7.64 to 7.98 with a mean value of 7.83 (Figure 3B), indicating that Ismailia Canal water tends to be slightly alkaline. The pH values of Ismailia Canal water are within the range of 6.5–9.0 set by USEPA (2008) for freshwater. Regarding seasonal variation (Figure 4A), the highest pH value, 8.29, is recorded in winter at sampling site 1, while the lowest value, 7.64, is recorded in summer at sampling site 2. However, the variation of pH along the canal shows an increasing trend in summer and a decreasing trend in winter. As shown in Figure 4A, the pH values do not show significant seasonal or spatial variations along the canal. Several studies mention the slightly alkaline nature of Ismailia Canal water (Goher et al., 2014; Abdo and El-Nasharty, 2010; Elhaddad, 2014; Khalil et al., 2012; Yusuf et al., 2018) and attribute this alkalinity to increased photosynthetic activity, which raises the pH. Conversely, the decomposition of organic matter releases acidic gases, lowering the pH of the water (Yusuf et al., 2018).

The total hardness (TH as CaCO₃ in mg/L) of the water samples shows an increasing trend in both winter and summer (Figure 4B). It ranges from 114 to 117 mg/L with a mean value of 116 mg/L in winter (Figure 3E), while in summer, it ranges from 85 to 110 mg/L with a mean value of 94 mg/L (Figure 3F). According to Dhok et al. (2013), Gebresilasie et al. (2021), McGowan (2000), Ramya et al. (2015), Rout and Sharma (2011), and Singh et al. (2021), the water of Ismailia Canal is classified as moderately hard in both winter and summer. As shown in Figure 4B, TH shows significant spatial variation in summer along the canal, while it shows insignificant changes between sampling sites in winter.

The EC of the water samples ranges from 510 to 543 μS/cm with a mean value of 528 μS/cm in winter (Figure 3C). In summer, it fluctuates along the canal (Figure 4C) and ranges from 357 to 476 μS/cm with a mean value of 403 μS/cm (Figure 3D). As shown in Figure 4C, the EC reaches its highest value in winter at sampling site eight and its lowest value in summer at sampling site 5. The TDS ranges from 326 to 347 mg/L with a mean value of 338 mg/L in winter (Figure 3G), while in summer, TDS ranges from 228 to 305 mg/L with a mean value of 258 mg/L (Figure 3H). A similar variation is observed for TDS, with general increasing trends from upstream to downstream, where the highest values are recorded in the downstream reaches of the canal (Figures 4C,D). TDS and EC are relatively higher in winter than in summer, which could be attributed to the lowering of the Ismailia Canal water level during winter, concentrating the dissolved ions. Additionally, the death and decay of microorganisms release different ions into the water. In summer, the water level increases, leading to high dilution and a drop in EC and TDS values (Salem et al., 2019; Abdo and El-Nasharty, 2010; Yusuf et al., 2018; Abdel-Satar et al., 2017; Islam et al., 2015). The average TDS of Ismailia Canal water recorded a little higher values to Damietta Nile Branch (266.25 mg/L, El-Battrawy et al., 2022), lower values in contrast to El-Salam Canal in the Northern East Nile Delta region (852.60 mg/L, El-Amier, et al., 2021) and lower concentrations relative to surface water of Obuasi mining district in Ghana (669 mg/L, Armah et al., 2010).

In winter, the cations K, Na, Mg, and Ca range from 8.48 to 9.0 mg/L, 45.66–50.09 mg/L, 7.48–7.75 mg/L, and 33.41–34.23 mg/L, respectively, with mean values of 8.72, 47.34, 7.58, and 33.87 mg/L, respectively (Figures 5A, C, E, G). In summer, these cations range from 4.32 to 9.33 mg/L, 27.82–48.09 mg/L, 4.37–4.58 mg/L, and 26.9–36.87 mg/L, respectively, with mean values of 8.33, 34.35, 4.48, and 30.28 mg/L, respectively (Figures 5B, D, F, H).

K shows insignificant seasonal changes except at sampling site 4, where its summer value is much lower than its winter value (Figure 6). Na, Ca, and Mg exhibit seasonal variations, with Na and Ca fluctuating along the canal in summer and showing insignificant changes between sites in winter. Mg displays insignificant variation between sites in both seasons. Generally, all cations show increasing trends from upstream to downstream in both winter and summer, except Mg, which slightly decreases in summer (Figure 6B).

The anions Cl, SO₄, HCO₃, CO₃, and NO₃ range in winter from 25.32 to 42.02 mg/L, 31.36–47.86 mg/L, 134.15–167.19 mg/L, 3.13–4.82 mg/L, and 7.92–11.76 mg/L, respectively, with mean values of 33.41, 36.59, 154.95, 4.04, and 9.72 mg/L, respectively (Figures 5I, K, M, O, Q). In summer, these anions range from 22.81 to 38.17 mg/L, 26.68–35.71 mg/L, 81.82–119.84 mg/L, 2.45–3.81 mg/L, and 11.18–12.76 mg/L, respectively, with mean values of 31.23, 31.19, 101.57, 3.02, and 11.91 mg/L, respectively (Figures 5J, L, N, P, R).

All anions show significant seasonal variations except Cl and SO₄, which display similar distribution patterns in both seasons (Figure 6). Generally, all anions increase from upstream to downstream in both winter and summer, except SO₄ and CO₃, which decrease in winter (Figure 6A). HCO₃ fluctuates in summer and shows insignificant spatial changes in winter along the canal. HCO₃ is relatively higher in winter than in summer, possibly due to bacterial decomposition and fermentation of organic matter, which increases during drought periods, producing HCO₃ as a final product, along with the high evaporation rate in summer (Salem et al., 2019; Abdo and El-Nasharty, 2010; Yusuf et al., 2018).

CO₃ and NO₃ display opposite distribution patterns in winter and summer across all sampling sites except sites two and 6. All anions are relatively higher in winter than in summer, except NO₃, which is higher in summer than in winter.

Based on the mean values of cations and anions, cations follow the dominance order Na > Ca > K > Mg in both winter and summer. Anions follow the order HCO₃ > SO₄ > Cl > NO₃ > CO₃ in winter and HCO₃ > Cl > SO₄ > NO₃ > CO₃ in summer.

In the winter season, trace elements such as Al, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, and V are recorded in all samples. Meanwhile, Sb, As, Cr, Pb, Ni, Se, and Tl are recorded in 87.5%, 75%, 50%, 75%, 75%, 50%, and 37.5% of the samples, respectively, and Mo is not detected at all (Figure 7A). In the summer season, trace elements including Al, Cd, Cr, Co, Cu, Fe, Li, Mn, Mo, Ni, Tl, and V are present in all samples. Sb, As, Ba, Be, Pb, and Se are recorded in 87.5%, 12.5%, 25%, 25%, 87.5%, and 75% of the samples, respectively (Figure 7B).

As shown in Figure 8, the trace element concentrations vary along the course of the Ismailia Canal in both winter and summer. Elements such as As (Figures 7A, B), Ba (Figure 8A; Figure 7B), and Cu (Figures 7C, D) have higher concentrations in winter than in summer. Conversely, elements like Cd (Figures 8D, E), Cr (Figure 7A; Figure 8D), Co (Figures 8D, E), Mo (Figure 8D), and V (Figures 8C, D) have higher concentrations in summer than in winter. In most samples, Al, Be, Pb, and Ni have higher concentrations in winter compared to summer. In contrast, Sb, Fe, Li, Mn, Se, and Tl concentrations are higher in summer than in winter (Figures 7, 8).

Seasonal variations in metal concentrations may be attributed to changes in pH, where the canal water has relatively higher pH values in winter than in summer. pH changes can alter the chemical state of many pollutants, affecting their solubility and transport between canal water and bottom sediments (USEPA, 2021). The geology and lithology (Figure 1), as well as human activities such as agricultural practices, urbanization, and industrial activities (Figure 2), influence the inputs of H and OH ions in the water and the level of chemical pollution through rock-water interactions, leakage, leachates, and direct effluent discharges (USEPA, 2021; Li, et al., 2023). Additionally, rainwater and road maintenance works are potential sources of pollution that may result in the accumulation of metals and organic material in the canal water (Geriesh, 1994; Geriesh and El-Rayes, 2001; Ghodeif et al., 2011; Stahl and Ramadan, 2008; Geriesh et al., 2008).

Armah et al. (2010) found that the Obuasi mining area in Ghana contains surface water with elevated concentrations of heavy metals, particularly Hg, Pb, As, Cu, and Cd, exceeding the permissible levels set by the WHO and clearly indicating human impact. El-Amier et al. (2021) indicated that the levels of Fe and Zn in the El-Salam Canal in the Northern East Nile Delta are within acceptable limits for both drinking and irrigation purposes. However, they found that Mn, Pb, Cu, Co, Ni, Cr, and Cd were present at higher concentrations than recommended. The heavy metals in the raw water samples from the Nile River were analyzed by El-Battrawy et al. (2022). Their findings revealed that Copper, Cobalt, and Zinc were not detected in the raw water samples. However, the concentration of Cadmium was measured at 0.021 ± 0.0008 mg/L, Nickel at ±0.047 0.0002 mg/L, and Lead at ± 0.067 0.0005 mg/L, all of which exceeded the permissible limits as per the guidelines provided by WHO (2017). The difference between the water of the Al-Salam Canal and the water of the Nile River, on the one hand, and the water of the Ismailia Canal, on the other hand, in the content and type of pollutants leads to the conclusion that the local environment around the Ismailia Canal, including its industrial, agricultural, urban, and other activity, played a major role in canal water pollution.

Pearson’s correlation analysis (Table 2) is used to determine the relationships between the physicochemical parameters of Ismailia Canal water, with correlation strengths estimated based on Evans (1996) guidelines (McSeveny et al., 2009; Beldjazia and Alatou, 2016).

In the winter season, pH shows a very strong positive correlation with SO₄, a strong positive correlation with CO₃, and strong negative correlations with HCO₃, Al, Co, Cu, and V (Table 2). In the summer, the correlation with SO₄ becomes weak, while its correlation with CO₃ remains very strong but negative. It also retains a strong negative correlation with HCO₃ and shows strong negative correlations with Mg, Al, Cd, and Co, and a strong positive correlation with Cu (Table 2).

Total hardness (TH) in winter shows very strong correlations with K and Ca, and strong correlations with Mg, Al, Ba, and Li (Table 2). In summer, TH correlates very strongly with TDS and Na, and strongly with HCO₃, CO₃, and NO₃, with a perfect correlation with Ca (Table 2).

TDS in winter has very strong correlations with Na, As, and Co, and strong correlations with K and Cl, as well as a strong negative correlation with Sb (Table 2). In summer, TDS shows very strong correlations with Na, Ca, and HCO₃, and strong correlations with CO₃ and NO₃, while the correlation with Cl weakens, and other parameters show insignificant correlations (Table 2).

In winter, K is very strongly correlated with Ca and strongly with Mg. Na shows a strong correlation with Cl, and Mg has a very strong negative correlation with CO₃. Other correlations between cations are less significant (Table 2). In summer, important correlations include very strong and strong correlations between Na and Ca and HCO₃, respectively, a strong negative correlation between Mg and Cl, and strong correlations between Ca and HCO₃ and NO₃ (Table 2).

Among anions in winter, there is a very strong negative correlation between SO₄ and HCO₃, and strong positive and negative correlations between CO₃ and SO₄ and HCO₃, respectively (Table 2). In summer, the only significant correlation is a very strong correlation between HCO₃ and CO₃ (Table 2).

In winter, important correlations between trace elements and cations include K and Co, Na and Sb, As, and Mn (negative for Sb and Mn), Mg and Al and Ba, and Ca and Cd and Li (Table 2). In summer, significant correlations include K and Tl, Na and V (negative), and Mg with Cd, Co, Pb, Li, Mn, and Ni (negative for Pb, Li, and Mn) (Table 2).

For trace elements and anions in winter, significant correlations include a strong negative correlation between Cl and Cr, very strong negative correlations between SO₄ and Al, Cu, and V, a strong correlation between SO₄ and Be, very strong correlation between HCO₃ and Cu, strong correlations between HCO₃ and Al and V, a very strong negative correlation between CO₃ and Al, strong negative correlations between CO₃ and Cu and Fe, and a very strong correlation between NO₃ and As (Table 2). In summer, significant correlations include very strong positive and negative correlations between Cl and Li and Mo, respectively, strong negative correlations between Cl and Cd, Co, Ni, and V, strong negative correlations between SO₄ and Cr, Ni, and V, strong negative correlations between HCO₃ and Sb, Cu, and Mn, strong correlations between CO₃ and As and Cr, a strong negative correlation between CO₃ and Sb, and a strong negative correlation between NO₃ and Ba (Table 2).

Tables 3 shows that correlation relationships among trace elements vary more in summer than in winter. In winter, Al is very strongly correlated with Cu and Fe and strongly with Be, Li, and V. Sb is strongly correlated with As and Li, Ba with Fe and Mn, and Fe with Li and Mn. Other strong correlations include Be-Fe, Cd-Li, Cr-Cu, Co-Ni, Cu-V, and Pb-Se (Table 3). In summer, Al is strongly correlated with Be, Cu, and Ni, As with Cd, Cr, Co, Li, and V, Ba with Co and Fe, Cd with Co, Li, Ni, Pb, Mo, and V, Co with Pb, Mo, Ni, and V, and Li with Ni, V, and Mo. Other strong correlations include Sb-Cr, Be-Mo, Cu-Tl, Fe-Mn, Mo-V, and Ni-V (Table 3).

Cluster analysis is performed on the Ismailia Canal water samples, and Figure 9 shows the dendrograms of the chemical data for winter and summer seasons. Four clusters are obtained in both seasons with similar associations. As shown in Figure 9, TDS forms cluster 1, while NO₃, K, Mg, CO₃, and all the measured trace elements form cluster 2. Cluster three includes Ca, Na, Cl, and SO₄, and HCO₃ forms cluster 4.

In both winter and summer seasons, the major ions Na, Ca, Cl, and SO₄ cluster together, indicating the chemical nature of the canal water (Figures 9A, B). NO₃, K, Mg, CO₃, and all the measured trace elements group together, suggesting water pollution is influenced by human activities and rock weathering processes. HCO₃ is isolated in a separate cluster, highlighting its role in the bacterial decomposition and fermentation of organic matter, with HCO₃ being the final product of these processes, along with the impact of high evaporation rates in summer (Abdo and El-Nasharty, 2010; Salem et al., 2019; Yusuf et al., 2018).

The Spreadsheet for Water Analyses™ (RockWare Aq•QA), is used to construct the Piper trilinear diagram, where ion concentrations are expressed as meq/l, to characterize the water types in the Ismailia Canal (Piper, 1994). As shown in Figure 10A, for the winter season, samples fall in the field of ‘no dominant type’ on the cationic triangle, close to the field of ‘Na(K)-type’. On the anionic triangle, the samples fall in the ‘HCO₃-type’. For the summer season (Figure 10B), most samples fall in the field of ‘no dominant type’ on the cationic triangle, with one sample in the ‘Na(K)-type’ field. On the anionic triangle, most samples fall in the ‘HCO₃-type’ field, with some in the ‘no dominant type’ field, showing a linear trend extending from ‘HCO₃-type’ to ‘no dominant type’.

On the diamond plot for the winter season, samples fall in the field characterized by the Ca(Mg)-HCO₃ water type (Figure 10A). In the summer season, most samples also fall in the Ca(Mg)-HCO₃ water type field, with some samples falling into the mixed water type fields (Figure 10B).

The Gibbs diagram is used to estimate the main processes controlling the surface water chemistry in the Ismailia Canal (Gibbs, 1970). As shown in Figure 11 for both winter and summer seasons, the surface water samples of the Ismailia Canal fall in the area dominated by rock dominance. However, the ratio Na/(Na + Ca) is greater than 0.5 in both winter and summer seasons (Figure 11A), while the ratio Cl/(Cl + HCO₃) is less than 0.5 in both seasons (Figure 11B). This suggests that the chemistry of the Ismailia Canal water might not be solely controlled by rock weathering in its anion composition and/or evaporation in its cation composition (Lu et al., 2015; Chai et al., 2024).