2 research outputs found
Characterization of Soil and Sediment Parameters of Jisike-Izombe Upper Aquifer System for Assessment of the Potential of Groundwater Pollution
The JES field, an onshore field in the Jisike \u2013 Izombe area of
southeastern Nigeria had a number of oil-producing wells before it was
abandoned over a decade ago. By means of soil/sediment samples
retrieved from three strategically located boreholes around the field,
the subsurface units were delineated and the physical characteristics
of the vadose zone were determined in order to predict the groundwater
pollution potential of the upper aquifer system in the area. Ground
conditions were found to be approximately 1metre (3.043ft) of loamy top
soil overlying about 1.2metres (3.65ft) of clayey laterite which
overlies 19.4 \u2013 24.6metres i.e (60ft \u2013 75ft) of
reddish-brown silty sand, beneath which is medium \u2013 coarse
grained white sand which constitutes the aquifer system with estimated
hydraulic conductivity in the range 1 x 10-1 to 169 x 10-1 mm/sec. Flow
analysis of groundwater indicates a southwesterly flow with the River
Niger as possible discharge zone. The high leaching potentials and high
transmissive properties of the sediments below the clayey laterite
suggests a vulnerability of the aquifer to pollution through vertical
infiltration. However, borehole water quality parameters for the area
show that groundwater quality is not in anyway compromised when
compared to the WHO limits. Rather, it is argued that the groundwater
is naturally well protected by the upper part of the vadose zone where
the clayey lateritic soil with iron oxide cementation of soil particles
provides an appreciable degree of barrier to downward movement of
contaminants. Because of the clayey behavour of the near-surface soils
and their affinity for the retention of contaminants, it is concluded
that the area is not a locus of groundwater pollution