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

season and were observably lower during the wet season (20.800– 38.200
mg/kg). Nitrogen concentration generally increased with depth with
concentrations ranging between 2,742.3 – 13, 645 mg/kg in the subsoil, and
2,289.8 – 7,105.0 mg/kg in the topsoil. The reverse was observed for
phosphorus concentration (28.700 – 46,200 and 20.800 – 18, 700 mg/kg in the
top and the subsoil respectively).
Microbial Analysis. The total heterotrophic bacteria (THB) count ranged
between 65.00 x 10 3 and 450.0 x 10 3 cfu/g during both seasons, with a mean
count of 210.6 x 10 3 and 195.5 x 10 3 during the dry and wet seasons
respectively. The THB was generally higher in the topsoil (80.00 – 450.0
mg/kg) compared to the subsoil (65.00 – 320.0 mg/kg). The total
heterotrophic fungi count ranged between 4.000 x 10 3 and 150.0 x 10 3 cfu/g,
which also demonstrated higher levels in the topsoil (20.00 -150.0 mg/kg)
compared to the subsoil (2.000 – 60.00 mg/kg). Coliform was also identified
in the soil samples (1.000 x 10 3 – 175.0 x 10 3 cfu/g) during the dry season
(Annex B). Hydrocarbon-utilising bacteria and fungi were not detected at any
depth intervals in the soil during the dry and wet season.
Portion Directly West of the NIPP Plant
The soil directly west of the NIPP plant does not show evidence of
contamination and demonstrates physico-chemical properties similar to the
other areas sampled.
Heavy Metal Composition. Iron had the highest recorded concentration
amongst the heavy metals analysed both during the dry (7,400.0 - 14,720
mg/kg) and wet season (6,300.0 – 10,500 mg/kg). The nitrogen did not vary
substantially across measured depth intervals (6,300.0 – 14,720 and 7,000.0 –
12,800 mg/kg in the top and subsoil respectively). Nickel had the second
highest concentration in the dry season; however similar to concentrations
observed at the proposed site, nickel recorded one of the lowest
concentrations in the wet season (< 0.15000 mg/kg). The concentration of
nickel did not vary greatly from 0 - 30 cm (17.300 - 19.200 and 14.950 - 18.500
mg/kg in the top and subsoil respectively) Mercury was identified to be
below the detection levels during both seasons and across all depth intervals
sampled (0.05000 mg/kg).
Anion and Cation Analysis. During the dry season, the concentration of
nitrate ranged between 33,768 – 51,408 mg/kg (ranging between 33,768 –
45,528 and 36,288 – 51,408 mg/kg in the top and subsoil respectively). The
nitrate concentrations were lower and also more consistent during the wet
season (2,300.0 – 3,800.0 and 3,600.0 – 4,250.0 mg/kg in the top and subsoil
respectively). Sulphate, phosphate, and chloride concentrations showed
similar patterns to those observed at the proposed site during both seasons.
During the dry season, sodium had the highest concentration levels
particularly in the topsoil (1,625.0 – 2,450.0 mg/kg), however, during the wet
season the concentration of potassium was the highest at 250.00 – 700.00 and
510.00 – 2,000.0 mg/kg in the topsoil and subsoil respectively.
AZURA EDO IPP
4-10
DRAFT EIA REPORT