Science Alert
Trends in Applied Sciences Research
  Year: 2011 | Volume: 6 | Issue: 2 | Page No.: 165-173
DOI: 10.3923/tasr.2011.165.173
Assessing Aquifer Vulnerability to Contaminants near Solid Waste Landfill Sites in a Coastal Environment, Port Harcourt, Nigeria
C.N. Ehirim and W. Ofor

2-D resistivity imaging and Vertical Electrical Sounding (VES) surveys were integrated in the study of the aquifer vulnerability to surface contaminants near two solid waste landfill sites in Port Harcourt municipality, Rivers State, Nigeria. Seven vertical electrical soundings and four 2-D resistivity surveys were utilized for the subsurface aquifer characterization. The study was aimed at characterizing a typical Niger Delta coastal aquifer as well as assessing its potential risk to contaminants seepage in terms of the Dar-Zarouk parameters and aquifer transmissivities. The results of interpretation of both data suggests that the study areas are underlain dominantly by sandy formations of varying grain sizes with little clay/shale intercalations at depths. The depth to the aquifers ranges from 23.89 to 73.38 m giving an average of 52.05 m in the study areas. The quantitative assessment of the geoelectric layers showed that the longitudinal conductance (S) of the overburden layers has values ranging from 0.009 Siemens to 0.06 Siemens, while the tranverse resistance (T) of the aquifers varies from 11 to 2.12x102 Ωm2. The low values of the protective capacity of the impermeable overlying materials with high transmissivities of the adjoining aquifer material will make the aquifer highly vulnerable to seepage and migration of contaminants within and around the landfills subsurface layers. With the aid of the 2-D resistivity tomography, two distinct pollutants were mapped and identified within and around the landfills. These are compounds of anomalously high resistivities between 725 and 4419 Ωm suspected to be landfill gases (Ammonia, methane, sulphur (IV) oxide, or carbon (IV) oxide) at depths exceeding 31.4 m and leachate contaminant plumes of low resistivities between 15.6 and 179.0 Ωm at depths between 1.25 m to more than 31.3 m. These revelations suggest that the aquifer has been contaminated and highly vulnerable to surface pollutants in the area.
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06 September, 2015
Sunday Carrick:
Really informative and good paper work, this will help me in my project work