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E r i $E_{r}^{i}$ranges and the average contribution (%) to the ecological risk
| Mn | Zn | Cu | Ni | Co | Pb | Cd | Cr | |
|---|---|---|---|---|---|---|---|---|
| Min. | 0.59 | 0.37 | 1.71 | 5.45 | 0.22 | 0.82 | 52.73 | 0.63 |
| Max | 2.90 | 1.01 | 4.82 | 19.19 | 0.82 | 4.24 | 103.64 | 2.52 |
| Contribution (%) | 1.5 | 0.6 | 3.5 | 10.7 | 0.5 | 2.0 | 80.0 | 1.2 |
Correlation between the elements in water and sediments of the Nile River in the Cairo region
| Water | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Fe | Mn | Zn | Cu | Ni | Co | Pb | Cd | Cr | |
| Fe | 1.00 | ||||||||
| Mn | −0.02 | 1.00 | |||||||
| Zn | −0.30 | −0.24 | 1.00 | ||||||
| Cu | 0.20 | 0.05 | 0.19 | 1.00 | |||||
| Ni | −0.13 | 0.23 | 0.07 | −0.20 | 1.00 | ||||
| Co | −0.29 | 0.13 | 0.27 | −0.09 | 0.75 *Correlation is significant at p < 0.01; n = 32 | 1.00 | |||
| Pb | 0.17 | 0.07 | 0.14 | 0.66 *Correlation is significant at p < 0.01; n = 32 | −0.46 | −0.40 | 1.00 | ||
| Cd | −0.06 | −0.06 | 0.09 | −0.01 | −0.02 | 0.12 | −0.11 | 1.00 | |
| Cr | −0.20 | 0.15 | 0.19 | −0.21 | 0.83 *Correlation is significant at p < 0.01; n = 32 | 0.73 *Correlation is significant at p < 0.01; n = 32 | −0.41 | 0.15 | 1.00 |
Seasonal variation of heavy metals (μg l−1) compared with different criteria and HPI values in the Nile water in the Cairo region
| Autumn | Winter | Spring | Summer | CCME (2007) | WHO (2011) | EWQS (2007) | ||
|---|---|---|---|---|---|---|---|---|
| Fe | Range | 642.0–1090.0 | 775.0–1300.0 | 403.0–862.0 | 196.0–690.0 | 300 | 1000 | 300 |
| Mean±SD | 869.0±169.6 | 1005.8±166.4 | 566.6±142.7 | 433.25±165.13 | ||||
| Mn | Range | 97.81–234.81 | 96.46–287.68 | 90.79–161.5 | 87.33–121.24 | - | 400 | 100 |
| Mean±SD | 152.2±44.7 | 191.7±61.9 | 124.9±25.0 | 97.9±10.5 | ||||
| Ni | Range | 9.54–20.54 | 11.89–26.47 | 9.04–25.41 | 8.45–17.68 | 65 | 70 | 20 |
| Mean±SD | 12.79±3.87 | 16.51±5.32 | 16.48±5.78 | 11.94±3.19 | ||||
| Co | Range | 4.85–20.54 | 6.95–22.63 | 9.51–24.35 | 8.45–21.35 | 1 | - | - |
| Mean±SD | 13.45±5.30 | 14.75±5.30 | 16.39±5.85 | 13.99±4.83 | ||||
| Zn | Range | 22.56–75.48 | 28.91–98.56 | 24.35–36.55 | 18.34–42.18 | 30 | 4000 | 3000 |
| Mean±SD | 38.97±17.34 | 38.97±17.34 | 31.74±4.58 | 29.87±9.49 | ||||
| Cu | Range | 6.45–18.40 | 6.15–19.42 | 7.05–14.12 | 5.12–9.45 | 2 | 2000 | 2000 |
| Mean±SD | 11.71±4.14 | 10.44±4.48 | 10.65±3.10 | 7.47±1.38 | ||||
| Cr | Range | 9.47–17.96 | 8.79–20.68 | 10.69–21.34 | 9.75–16.58 | - | 50 | 50 |
| Mean±SD | 12.28±3.03 | 13.99±3.72 | 14.24±3.84 | 12.42±2.12 | ||||
| Pb | Range | 5.75–12.45 | 4.15–12.15 | 4.01–9.85 | 3.15–18.47 | 2 | 10 | 10 |
| Mean±SD | 9.18±2.18 | 7.26±2.72 | 6.13±1.89 | 9.65±5.60 | ||||
| Cd | Range | 1.98–2.98 | 1.45–2.98 | 1.75–3.15 | 1.98–3.84 | 0.18 according to CCME (2014) | 3 | 3 |
| Mean±SD | 2.35±0.37 | 2.26±0.54 | 2.40±0.55 | 2.79±0.69 | ||||
| HPI according to WHO (2011); | Range | 61.3–96.3 | 46.8–88.7 | 56.6–96.7 | 64.3–104.2 | |||
| HPI according to EWQS (2007); | Range | 64.3–99.0 | 53.3–90.4 | 64.3–96.7 | 66.4–104.1 | |||
Enrichment factor for the studied elements in the Nile River in the Cairo region
| Mn | Zn | Cu | Ni | Co | Pb | Cr | Cd | ||
|---|---|---|---|---|---|---|---|---|---|
| Autumn | Range | 0.35–1.54 | 0.17–0.70 | 0.33–0.65 | 0.78–1.96 | 0.06–0.22 | 0.10–0.38 | 0.15–0.57 | 0.87–2.21 |
| Mean±SD | 0.95±0.34 | 0.38±0.17 | 0.43±0.11 | 1.22±0.47 | 0.14±0.06 | 0.18±0.09 | 0.31±0.14 | 1.54±0.57 | |
| Winter | Range | 0.66–1.82 | 0.44–0.88 | 0.55–0.79 | 1.15–3.03 | 0.13–0.34 | 0.23–0.76 | 0.34–0.99 | 1.76–2.81 |
| Mean±SD | 1.34±0.36 | 0.56±0.15 | 0.65±0.09 | 2.03±0.74 | 0.23±0.08 | 0.46±0.20 | 0.56±0.23 | 2.22±0.42 | |
| Spring | Range | 1.16–2.21 | 0.49–0.91 | 0.53–0.81 | 1.18–2.95 | 0.11–0.35 | 0.23–0.73 | 0.32–0.97 | 2.02–3.35 |
| Mean±SD | 1.57±0.38 | 0.66±0.16 | 0.68±0.11 | 2.06±0.68 | 0.21±0.08 | 0.46±0.18 | 0.58±0.22 | 2.64±0.57 | |
| Summer | Range | 0.58–1.14 | 0.43–0.66 | 0.30–0.73 | 1.44–3.16 | 0.15–0.37 | 0.13–0.37 | 0.29–1.10 | 2.05–3.42 |
| Mean±SD | 0.75±0.16 | 0.52±0.07 | 0.48±0.15 | 2.15±0.61 | 0.24±0.08 | 0.23±0.07 | 0.61±0.27 | 2.79±0.47 | |
Heavy metals distribution (μg g−1) compared with EPA (2006), contamination factor (Cf) and PLI values in the Nile sediment in the Cairo region_
| Metal | Autumn | Winter | Spring | Summer | EPA (2006) | Cf | |
|---|---|---|---|---|---|---|---|
| Fe | Range | 27154–53468 | 18238–25014 | 17548–26481 | 17185–25678 | 20000 | 0.86–2.67 |
| Mean±SD | 38858 ± 9784 | 22774 ± 2166 | 21121 ± 2878 | 19217 ± 2862 | 1.27±0.47 | ||
| Mn | Range | 283.0–1334.0 | 339.0–988.0 | 273.0–456.0 | 512.0–984.0 | 460 | 0.59–2.90 |
| Mean±SD | 849.3 ± 354.4 | 708.0 ± 215.2 | 326.8 ± 58.5 | 754.4 ± 174.4 | 1.43±0.64 | ||
| Zn | Range | 45.00–122.45 | 58.70–120.00 | 46.32–70.00 | 62.40–97.50 | 121 | 0.37–1.01 |
| Mean±SD | 84.44 ± 27.82 | 77.34 ± 19.69 | 60.06 ± 8.54 | 83.66 ± 12.05 | 0.63±0.17 | ||
| Cu | Range | 18.70–30.45 | 19.50–27.89 | 19.85–25.91 | 10.80–20.15 | 31.6 | 0.34–0.96 |
| Mean±SD | 25.49 ± 4.24 | 23.61 ± 2.77 | 22.58 ± 2.20 | 14.31 ± 3.22 | 0.68±0.17 | ||
| Ni | Range | 28.38–87.12 | 27.95–80.52 | 24.75–72.85 | 32.52–67.85 | 22.7 | 1.09–3.84 |
| Mean±SD | 50.44 ± 20.19 | 50.94 ± 19.39 | 47.94 ± 16.75 | 45.06 ± 13.23 | 2.14±0.74 | ||
| Co | Range | 7.19–19.50 | 7.40–20.45 | 5.40–17.85 | 7.56–17.64 | 50 | 0.11–0.41 |
| Mean±SD | 13.06 ± 4.11 | 12.95 ± 4.92 | 11.20 ± 4.00 | 11.27 ± 3.65 | 0.24±0.08 | ||
| Cr | Range | 16.85–54.65 | 18.96–52.56 | 13.67–48.97 | 14.52–47.52 | 43.4 | 0.31–1.26 |
| Mean±SD | 25.27 ± 12.83 | 28.11 ± 12.93 | 26.85 ± 11.37 | 25.44 ± 11.23 | 0.61±0.27 | ||
| Pb | Range | 6.52–18.41 | 9.50–25.12 | 10.00–30.33 | 5.86–11.50 | 35.8 | 0.16–0.85 |
| Mean±SD | 12.12 ± 4.23 | 16.82 ± 4.47 | 18.83 ± 8.18 | 7.85 ± 1.83 | 0.39±0.18 | ||
| Cd | Range | 2.05–3.19 | 1.74–3.21 | 1.86–3.42 | 2.14–3.24 | 0.99 | 1.76–3.45 |
| Mean±SD | 2.75 ± 0.45 | 2.51 ± 0.53 | 2.74 ± 0.50 | 2.62 ± 0.40 | 2.68±0.46 | ||
| PLI | Range | 0.76–1.08 | 0.72–1.05 | 0.73–0.97 | 0.56–0.73 | ||
Geoaccumulation index (I-geo), enrichment factor (EF) and modified contamination factor for elements and contamination levels
| Index | ||||||
|---|---|---|---|---|---|---|
| Geoaccumulation index (I-geo) | Enrichment factor (EF) | Modified contamination degree (mCd) | ||||
| Class no. | I-geo value | Contamination level | EF value | Contamination level | mCd value | Contamination level |
| 0 | I-geo ≤ 0 | practically unpolluted | 1 < EF < 3 | minor enrichment | mCd < 1.5 | nil pollution |
| 1 | 0 < I-geo < 1 | unpolluted to moderately polluted | 3 < EF < 5 | moderate enrichment | 1.5 ≤ mCd < 2 | low pollution |
| 2 | 1 < I-geo < 2 | moderately polluted | 5 < EF < 10 | moderately severe enrichment | 2 ≤ mCd < 4 | moderate pollution |
| 3 | 2 < I-geo < 3 | moderately to heavily polluted | 10 < EF < 25 | severe enrichment | 4 ≤ mCd < 8 | high pollution |
| 4 | 3 < I-geo < 4 | heavily polluted | 25 < EF < 50 | very severe enrichment | 8 ≤ mCd < 16 | very high pollution |
| 5 | 4 < I-geo < 5 | heavily to extremely polluted | EF ≥ 50 | ultra-high | 16 ≤ mCd < 32 | extremely high pollution |
| 6 | I-geo ≥ 5 | extremely polluted | mCd ≥32 | ultra-high pollution | ||
Main characteristics* of the Nile River water in the Cairo region
| Variable | Range | Mean ± SD |
|---|---|---|
| Transparency (cm) | 35–150 | 86.97 ± 25.63 |
| Depth (m) | 1–10 | 4.02 ± 0.82 |
| Dissolved oxygen (DO) (mg l−1) | 4.0–10.26 | 8.02 ± 1.36 |
| pH | 7.32–8.81 | 8.02 ± 0.30 |
| Alkalinity (mg l−1) | 92.0–186.5 | 135.8 ± 25.98 |
| Chloride ion (mg l−1) | 11.0–88.97 | 48.51 ± 21.35 |
Pollution levels according to ER and E r i $\,E_{r}^{i}$values
| Ecological risk levels for single factor pollution | ER scope | Potential ecological risk levels | |
|---|---|---|---|
| Low | ER<150 | Low grade | |
| 40 ≤ | Moderate | 150 ≤ER < 300 | Moderate |
| 80 ≤ | Considerable | 300≤ ER< 600 | Severe |
| 160 ≤ | High | 600 ≤ ER | Serious |
| 320 ≤ | Serious | - | - |