Azura-Edo Independent Power Plant Environmental Impact ... - IFC

increased with depth, showing a significant increase at 15 – 30cm (6,250.0 –
61,152 mg/kg) versus 3.4500 – 32,928 mg/kg in the topsoil. Sulphate and
phosphate demonstrated similar patterns in their concentration levels to the
other sampled sites. Among the cations, sodium ion concentrations were
recorded to be the highest during the dry season (1,700.0 – 1,950.0 mg/kg in
the topsoil and 1,500.0 mg/kg in the subsoil), with potassium ions recording
the highest concentrations during the wet season (400.00 – 2,730.0 mg/kg).
The potassium concentration was also found to be of a higher concentration in
the subsoil (1,950.0 – 2,730.0 mg/kg) compared to concentrations observed in
the topsoil (400.00 – 1,650.0 mg/kg).
Hydrocarbon Content. Oil and grease levels were found to be below detection
limits during both seasons, indicating that there is no detectable hydrocarbon
pollution. THC was detected in the soil with a greater concentration range
during the dry season (0.9000 - 21.60 mg/kg), while the THC during the wet
season was 0.4000 – 0.9000 mg/kg. Generally the THC content was higher in
the topsoil. In three out of the four samples collected the THC range were
between 0.6720 – 2.990 g/kg in the topsoil, compared to the THC range in the
subsoil (0.4230 – 0.8600 g/kg, while the fourth sample indicated noticeably
higher THC values, which may be as the result of a spill.
Physico-chemical properties. Sandy loam soil dominates the soil composition
of the area both during the dry and wet seasons (sand percentage in the
topsoil was between 58.220 – 98.240 percent, and between 51.100 – 98.690
percent in the subsoil).. Other particle size distribution pattern (average
values) was calculated during the dry and wet seasons respectively: silt
(8.0400 and 2.1500 percent), and clay (30.270 and 0.63000 percent). The silt
composition across both seasons ranged between 1.1400 – 11.940 and 0.90000 –
6.8800 percent in the top and subsoil respectively. The soil is slightly acidic
with the pH ranging between 5.0300 and 5.7100 and did not vary significantly
across the two depth intervals.
Microbial Analysis. The total heterotrophic bacteria count in the soil ranged
between 70.00 x 10 3 and 450.0 x 10 3 cfu/g across both sampling periods. The
total heterotrophic bacteria count was notably higher in the topsoil (250.0 –
450.0 x 10 3 cfu/g) in comparison to subsoil (70.00 – 210.0 x 10 3 cfu/g). The
mean count was recorded at 293.3 and 205.67x 10 3 cfu/g during the dry and
wet season respectively. Similarly, the total heterotrophic fungi count ranged
between 30.00 x 10 3 and 205.0 x 10 3 cfu/g. The total heterotrophic fungi count
was also higher in the topsoil compared to the subsoil (72.00 – 205.00 and
30.00 – 132.0 x 10 3 cfu/g in the top and subsoil respectively). In contrast to the
other two sites sampled during the dry season, hydrocarbon utilizing bacteria
were only detected in one location (SS3A 0-15 at 15-30 cm) in the dry season
and were not detected during the wet season.
Ihovbor-Evboeka Community
Heavy Metal Composition. Iron had the highest concentration levels during
both the dry and wet season (12,021 – 22,080 and 5,000 – 15,000 mg/kg). In
AZURA EDO IPP
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DRAFT EIA REPORT