**3.6. Iron**

Soils in the two study sites were observed to have a higher concentration of Fe in the dry season than in the wet season. Soils from Zobe dam catchment and the environs of KTSRM had means of 22, 700 and 555, 16.93 mg/kg; and 18, 266.67 and 58867 mg/kg in dry and wet seasons, respectively (Table 2; Fig 4).

Soil samples collected in the wet season were observed to have a higher concentration of Fe (891.66 and 745.75 mg/kg in Zobe dam catchment and the environs of KTSRM, respectively) than the dry season (360.58 and 277.22 mg/kg in Zobe dam catchment and environs of KTSRM, respectively (Table 2; Fig 4).

Plant species with the highest concentration of Fe in the wet season were *Ipomoea ascarafolia* (115.50 mg/kg) and *Guiera senegalensis* (264.10 mg/kg) for Zobe dam catchment and environs of KTSRM, respectively. In the dry season, *Coldenia procumbens* (184.00 mg/kg) and *Guiera senegalensis* (176.84 mg/kg) were observed to have the highest concentration of Fe Zobe dam catchment and the environs of KTSRM, respectively (Fig 6).

#### **3.7. Manganese**

The mean concentration of Manganese in soils was observed to be higher in the wet season (891.66 and 745.75mg/kg) than in the dry season (360.66 and 277mg/kg) for Zobe dam catch‐ ment and KTSRM respectively.

In plants, *Diospyros piscatoria* (36.5 mg/kg) and *Boscia senegalensis* (102.87 mg/kg) were observed to have the highest Mn concentration during the dry season in Zobe dam catchment and environs of KTSRM, respectively. In the wet season, *Capparis polymopha (*syn*. C. tomentosa)* (80.72 mg/kg) and *Senna siberiana* (190.60 mg/kg) were observed to have the highest concen‐ tration of Mn in Zobe reservoir and KTSRM, respectively (Fig 6).

#### **3.8. Zinc**

Zn concentrations in soils showed a similar pattern with Mn and Fe in Zobe dam catchment during the dry season, being higher in the wet (428.45 mg/kg) than the dry season (263.67 mg/ kg). A reversed trend was observed in the environs of KTSRM, with the concentration being higher in the dry season (693.67 mg/kg) than the wet season (385.00 mg/kg) (Table 2; Fig 4). These observed mean concentrations of Zn were higher than the 200 mg/kg acceptable limit of the WHO.

*Leptadeniahastata* (38.5 mg/kg), *Senna siberiana* (54.84 mg/kg) were observed to have the highest concentration of Zn in the dry season for Zobe dam catchment and the environs of KTSRM, respectively. In the wet season, the highest concentrations of Zn in plant samples were presented by *Capparis polymopha (*syn*. C. tomentosa)* (158.50 mg/kg) and *Senna siberiana* (132.60 mg/kg) (Fig 6). Normal concentrations of Zinc in plants fall between 27 to 150 mg/kg. However, concentrations between 100 to 400 mg/kg may be considered Excessive, while from 70 to 400 mg/kg, as Phytotoxic (Table 4). This is dependent on the plant species in question.

**Fig 6: Concentration (mg/kg) of Fe, Mn and Zn in plants collected from Zobe dam catchment and the environs of Katsina Steel Rolling Mill (KTSRM) and the Dry (a) and Wet (b) Seasons Figure 6.** Concentration (mg/kg) of Fe, Mn and Zn in plants collected from Zobe dam catchment and the environs of Katsina Steel Rolling Mill (KTSRM) and the Dry (a) and Wet (b) Seasons

13

**3.6. Iron**

respectively (Table 2; Fig 4).

708 Environmental Risk Assessment of Soil Contamination

respectively (Table 2; Fig 4).

ment and KTSRM respectively.

**3.7. Manganese**

**3.8. Zinc**

of the WHO.

Soils in the two study sites were observed to have a higher concentration of Fe in the dry season than in the wet season. Soils from Zobe dam catchment and the environs of KTSRM had means of 22, 700 and 555, 16.93 mg/kg; and 18, 266.67 and 58867 mg/kg in dry and wet seasons,

Soil samples collected in the wet season were observed to have a higher concentration of Fe (891.66 and 745.75 mg/kg in Zobe dam catchment and the environs of KTSRM, respectively) than the dry season (360.58 and 277.22 mg/kg in Zobe dam catchment and environs of KTSRM,

Plant species with the highest concentration of Fe in the wet season were *Ipomoea ascarafolia* (115.50 mg/kg) and *Guiera senegalensis* (264.10 mg/kg) for Zobe dam catchment and environs of KTSRM, respectively. In the dry season, *Coldenia procumbens* (184.00 mg/kg) and *Guiera senegalensis* (176.84 mg/kg) were observed to have the highest concentration of Fe Zobe dam

The mean concentration of Manganese in soils was observed to be higher in the wet season (891.66 and 745.75mg/kg) than in the dry season (360.66 and 277mg/kg) for Zobe dam catch‐

In plants, *Diospyros piscatoria* (36.5 mg/kg) and *Boscia senegalensis* (102.87 mg/kg) were observed to have the highest Mn concentration during the dry season in Zobe dam catchment and environs of KTSRM, respectively. In the wet season, *Capparis polymopha (*syn*. C. tomentosa)* (80.72 mg/kg) and *Senna siberiana* (190.60 mg/kg) were observed to have the highest concen‐

Zn concentrations in soils showed a similar pattern with Mn and Fe in Zobe dam catchment during the dry season, being higher in the wet (428.45 mg/kg) than the dry season (263.67 mg/ kg). A reversed trend was observed in the environs of KTSRM, with the concentration being higher in the dry season (693.67 mg/kg) than the wet season (385.00 mg/kg) (Table 2; Fig 4). These observed mean concentrations of Zn were higher than the 200 mg/kg acceptable limit

*Leptadeniahastata* (38.5 mg/kg), *Senna siberiana* (54.84 mg/kg) were observed to have the highest concentration of Zn in the dry season for Zobe dam catchment and the environs of KTSRM, respectively. In the wet season, the highest concentrations of Zn in plant samples were presented by *Capparis polymopha (*syn*. C. tomentosa)* (158.50 mg/kg) and *Senna siberiana* (132.60 mg/kg) (Fig 6). Normal concentrations of Zinc in plants fall between 27 to 150 mg/kg. However, concentrations between 100 to 400 mg/kg may be considered Excessive, while from 70 to 400

mg/kg, as Phytotoxic (Table 4). This is dependent on the plant species in question.

catchment and the environs of KTSRM, respectively (Fig 6).

tration of Mn in Zobe reservoir and KTSRM, respectively (Fig 6).
