AbstractThe Ogoniland axis of Rivers State, Niger Delta (Nigeria) is a heavily hydrocarbon-contaminated region, due to prolonged oil spillages and petrochemical activities on-going in the area. UNEP (2011) issued an environmental impact assessment report on the state of oil pollution in
Ogoniland which highlighted the severe problem of hydrocarbon contaminated groundwater and surface waters, which in turn profoundly impacts upon regional ecosystems and drinking water resources. Despite the acknowledged severity of surface and groundwater contamination in this area,
understanding of (a) hydrocarbon migration and exposure pathways, and (b) practical methods of managing the impact of hydrocarbon-derived contaminants is limited.
This research has therefore investigated the distribution and concentrations of key hydrocarbon (and trace and major element) contaminants in groundwater and surface waters around major oil and petrochemical sites in Ogoniland; examined potential contaminant migration pathways between groundwater, surface water, and drinking water resources; and assessed the potential application of practical, more sustainable, water remediation or management methods, with particular emphasis on low-cost adsorption and enhanced natural attenuation approaches.
Field sampling identified gross contamination of surface and groundwater by phenol, with measured concentrations of 10.90-350mg/l exceeding the ATSDR (2008) phenol limit in drinking water of 0.03mg/l by several orders of magnitude. Laboratory core flooding studies were applied to examine contaminant migration and attenuation in simulated Ogoniland soils and to assess potential contaminant transfer pathways. The feasibility of the practical application of adsorbent-based remediation methods, based on testing of low-cost carbonaceous adsorbents, was examined in terms of the utility of these adsorbents (a) in reducing contaminant transfer to local receptors, (b) for local community use, and (c) for providing broader sustainability benefits to the local population. Commercial activated carbons were shown to be highly effective adsorbents for phenol removal (and removal of other contaminants of concern), although biochar adsorbents (based on Miscanthus grass, softwood, and rice husk) were less effective bulk adsorbents. Despite the relatively low adsorption efficiency of biochars observed here, however, their low-cost and potential for on-site (i.e., local) production suggest that they may still have application in combined, large area, soil improvement and contaminant risk management strategies. Commercial activated carbons, due to their higher cost, may find a potential demand at the point of water use but are unlikely to be effective community-level tools for large area application.
|Date of Award
|Andrew Cundy (Supervisor) & David Nash (Supervisor)