ABSTRACT
Petroleum hydrocarbon spill on land pollutes soil and reduces its ecosystem. Hydrocarbon transport in the soil is aided by several biological, physical, and chemical processes. However, pore characteristics play a major role in the distribution within the soil matrix. Restoring land use after spills necessitates remediation using cost-effective technologies. Several remediation technologies have been demonstrated at different scales, and research is ongoing to improve their performances towards the reduction of treatment costs. The process of removing the contaminants in the soil is through one or a combination of containment, separation, and degradation methods under the influence of biological, physical, chemical, and electrically-dominated processes. Generally, performance improvement is achieved through the introduction of products/materials and/or energy. Nevertheless, the technologies can be categorized based on effectiveness period as short, medium, and long term. The treatment cost of short, medium, and long-term technologies are usually in the range of $39 - 331/t (/tonne), $22 - 131/t, and $8 - 131/t, respectively. However, the total cost depends on other factors such as site location, capital cost, and permitting. This review compiles cost-saving strategies reported for different techniques used in remediating petroleum hydrocarbon polluted soil. We discuss the principles of contaminant removal, performance enhancing methods, and the cost-effectiveness analysis of selected technologies.
ABSTRACT
In recent times, disasters and risk management have gained significant attention, especially with increasing awareness of the risks and increasing impact of natural and other hazards especially in the developing world. Vulnerability, the potential for loss of life or property from disaster, has biophysical or social dimensions. Social vulnerability relates to societal attributes which has negative impacts on disaster outcomes. This study sought to develop a spatially explicit index of social vulnerability, thus addressing the dearth of research in this area in sub-Saharan Africa. Nineteen variables were identified covering various aspects. Descriptive analysis of these variables revealed high heterogeneity across the South West region of Nigeria for both the state and the local government areas (LGAs). Feature identification using correlation analysis identified six important variables. Factor analysis identified two dimensions, namely accessibility and socioeconomic conditions, from this subset. A social vulnerability index (SoVI) showed that Ondo and Ekiti have more vulnerable LGAs than other states in the region. About 50% of the LGAs in Osun and Ogun have a relatively low social vulnerability. Distribution of the SoVI shows that there are great differences within states as well as across regions. Scores of population density, disability and poverty have a high margin of error in relation to mean state scores. The study showed that with a geographical information system there are opportunities to model social vulnerability and monitor its evolution and dynamics across the continent.
