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Type of Document Master's Thesis Author Roope, Benjamin Patrick URN etd-12032003-202321 Title Analysis of Elevated Uranium and Impact of the Cotton Industry on Groundwaters in Benin, Africa Degree Master of Science in Environmental Engineering Department Civil Engineering and Geological Sciences Advisory Committee
Advisor Name Title Stephen Silliman Committee Chair Clive Neal Committee Member Jeff Talley Committee Member Keywords
- groundwater
- chemical signatures
- principal component analysis
- benin
- africa
Date of Defense 2003-11-10 Availability unrestricted Abstract By detailing characteristics of groundwater in Benin through elemental signatures,the previous phase of this research sought to better understand the hydrogeology and
spatial distribution of groundwater quality in Benin. Those data indicated elevated
uranium concentrations in two wells in eastern Benin. In the current research effort it
was hypothesized that the uranium present in groundwater is of natural geologic (and not
anthropogenic) origin. It was further hypothesized, based on conversation with Dr. M
Boukari of the University d’Abomey-Calavi, that the cotton agricultural industry has had
some identifiable impact on groundwater quality. In order to provide data to assess both
hypotheses, samples of groundwater, the associated filters, and various precipitation
samples were collected in July 2002, and preserved for analysis. Quantitative elemental
concentrations (elemental signatures) for the samples were acquired using Inductively
Coupled Plasma (ICP) Spectrometry and specific ion probe techniques. These elemental
parameters, in addition to latitude, longitude, temperature, pH, conductivity, and distance
to cotton fields for each sample were compiled into a working matrix. Parameter-
Benjamin Patrick Roope
parameter plots were evaluated using an Exploratory Data Analysis (EDA) technique.
Principle Component Analysis (PCA), Indicator Variable Analysis (IVA) and Cluster
Analysis (CA) were also applied to the data. Conclusions were drawn about the
characteristics of groundwater samples based on a full statistical perspective gained for
each of the data sets. The results from the application of the EDA, IVA, and PCA
methods support the stated hypothesis that the source of uranium in groundwater samples
is geology-related. Records indicative of elevated concentrations of uranium in surface
water in the eastern part of the country that predate allegations of human dumping also
support the case. However, the same applied methods and similar literature searches
provided little support of the assertion that groundwater is being contaminated by cotton
farming (made by the second hypothesis). Although the major elements Ca and Na were
noted at elevated concentrations near cotton fields, they were not definitively linked to
agricultural practices or the use of pesticides. Future work will help identify the specific
geologic formation(s) responsible for elevated uranium concentrations, and to
subsequently conceive a remediation plan. Future work will also concentrate on
conclusively determining the source of the elevated Ca and Na around cotton fields
through soil sampling and testing.
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