Groundwater quality

Groundwater remains a vital source of potable water in Benin city, yet its quality is decreasing in most parts of Nigeria. This study assessed the effect of on-site sanitation facility proximity on the physiochemical, total and fecal coliform load of groundwater from selected boreholes in Ikpoba Hill and Sapele Road, Benin City. Water samples are collected from four boreholes located within varying distances (11.8m in Ikpoba Hill to 32m in Sapele Road) from onsite sanitation facilities. In-situ measurements of pH, Electrical conductivity (EC), and total dissolved solids (TDS) were performed using a multifunction water quality meter, while nitrate and ammonia-nitrogen concentrations were determined using spectrophotometric methods. The pH values ranged from 4.3±0.01 in Ikpoba Hill to 5.2±0.5 in Sapele Road, indicating slightly acidic water across all samples. EC and TDS values ranged from (19±0 in Ikpoba Hill - 133±0µS/cm in sapele road) and (9±0 in Ikpoba hill - 66±0 mg/L in Sapele Road), respectively, reflecting low mineralization. Nitrate (0.46±0.11 in Sapele Road – 0.713±0.04 mg/L in Ikpoba Hill) and ammonia-nitrogen (0.85±0.17 in Ikpoba Hill – 1.50±0.77mg/L in Sapele Road). Aside from ammonia-nitrogen, other parameters were below NESREA permissible limits and there were no total or fecal coliforms detected in the samples. The observed differences between the mean physiochemical values were not significant (p>0.05). Aside from borehole C and D, the other boreholes (A and B) were sited well above the minimum distance (15m) from the nearest sanitary facilities (septic tank). It is recommended that sensitization be conducted to enlighten intending property owners with respect to the health implications of improperly siting water sources from onsite sanitation facilities.

Soil, surface water and groundwater samples were collected for physico-chemical, microbial and heavy metal analysis from different locations in Ologbo and environs. Thirteen (13) soil samples including Three controls (Pristine environment) were randomly collected at subsurface depth of 0-30cm, Thirteen surface water samples were collected including three controls and Ten (10) Groundwater samples were collected using random sampling Technique. The samples were collected in order to evaluate the level of pollution/Contamination of the media as a result of petroleum activities, wood industries and other anthropogenic activities within the study area. The results for the groundwater analysis showed pH (5.61-5-78), EC (54.64-65.74), Turbidity (0.05-0.12NTU), Cu (0.38-0.49mg/l), Zn (0.3-0.39mg/l), Cr (0.09-0.16mg/l), Ni (0.64-0.85mg/l), Fe (0.38 2.49mg/l), Mn (0.1-0.15mg/l and Pb (0.01-0.16mg/l). The results for the surface water showed pH (5.71-6.05), turbidity (7.31-13.92NTU), EC (87.11-95.2uS/cm), Zn (0.41-0.45mg/l), Fe (1.24-1.3mg/l), Cu (0.51-0.54mg/l), Cr (0.35-0.38mg/l), Ni (0.09-0.21mg/l) and Pb (0.02- 0.06). These results were compared with world and national standards, and control samples were
collected and used for comparison where needed .The result, of the analyses were further subjected to statistical treatment such as Spearman’s correlation Co-efficient, ANOVA and concentration Factor Analysis, to ultimately ascertain the spatial relationship between sample. The ANOVA results for soil samples indicated a very strong significant difference at (p<0.01)
between control and soil samples for all parameters. Correlation results revealed positive and negative correlation Co-efficient at r (0.01) and r (0.05) indicating strong relationship between them, which probably reflects their source of Contamination. Concentration maps generated for the area showed high concentrations of Lead, Copper and Iron around the central area, increasing towards the southwestern part of the maps. The groundwater flow map showed a 2-way flow direction towards the central part where the major river dividing the map is located. The overall results revealed moderate contamination/pollution of all varieties of samples analyzed and it’s here by recommended that important steps be taken to minimize the negative effects of oil exploration and wood industries in Ologbo.