TITLE:
Integrated Geophysical and Geochemical Methods for Environmental Assessment of Municipal Dumpsite System
AUTHORS:
Elijah Adebowale Ayolabi, Adetayo Femi Folorunso, Olusola Titilope Kayode
KEYWORDS:
Dumpsite; Leachate; Electrical Resistivity; Hydrochemical Analysis; Pollution Depth; Heavy Metals;Contaminant Plume
JOURNAL NAME:
International Journal of Geosciences,
Vol.4 No.5,
July
17,
2013
ABSTRACT: Leachate originating from open
refuse dumpsite systems can be delineated through an integration of qualitative
and quantitative methods. This study was designed to examine extent of leachate
and pollution from one of the numerous open refuse dumpsites in Lagos
metropolis. Qualitative assessment was determined using electrical resistivity
tomography (ERT), vertical electrical sounding (VES) and induced polarization
geophysical methods. Both ERT and VES methods revealed persistent low
resistivity (1 - 20 Ωm) of leachate to the depth above 35 m. The two methods were projected to produce
3-D view of the site which shows a NW-SE flow pattern of the leachate and
possibly, the groundwater. IP values observed over the polluted zone was -2.9 - 8 ms, indicating a sandy layer. Quantitative assessment was achieved
by analysis of geochemical substances in the water samples taken from wells and
boreholes in the precinct of the dumpsite. Here, we examine the macroelements,
salts (sulphates, nitrates and chlorides), heavy metals, radioactive metals contents
and physical parameters of the water samples. The analyses reveal the presence
of these substances in the water and their strong correlations justified the
provenance as the same. As part of the quantitative evaluation, physical
parameters (pH, TDS, DO, salinity, total hardness, turbidity, electrical
conductivity EC and temperature) of the water samples were also determined. The
samples pH plotted in the acidic domain unsuitable for human consumption.
Leachate flow direction was generated from the decreasing concentration of
measured parameters (geochemical elements and physicals properties) in NW-SE
direction which agrees with similar flow pattern deduced from ERT results.