Petroleum hydrocarbons contamination of the environment associated with exploration, development and production operations is a common feature in oil producing nations around the world, especially in a developing country like Nigeria where the incidence of facilities sabotage, operational failures, accidental discharges, pipeline vandalization and leakages, bunkering and artisanal refining is very common. Apart from poor governance systems, poor corporate social responsibility (CSR) of multinational oil companies (MOCs), poor environmental regulation of the petroleum industry, the inability of the political elite to effectively manage petroleum hydrocarbon-derived revenue, loss of petroleum hydrocarbons resource revenue to corruption and theft, petroleum hydrocarbons contamination of the total environment (air, soil, water and biota) have impacted negatively on the human health and wellbeing of oil producing communities in the Nigeria's Niger Delta region. Findings from several studies have revealed variable negative impacts of petroleum hydrocarbons toxicity on the human health (including exposed populations), the natural environment and other ecological receptors. Over the past fifty-five years, the oil producing host communities in the Nigeria's Niger Delta region have experienced a wide range of environmental pollution, degradation, human health risks, deterioration of our cultural heritage items and socio-economic problems as a result of various activities associated with petroleum exploration, development and production. Petroleum hydrocarbons contamination of surface water and groundwater is a notable environmental and human health problem in the oil producing communities and there are several water quality issues in the Nigeria's Niger Delta region. This review examines some of the water quality issues and human health implications of petroleum hydrocarbons contamination of controlled water sources (surface-water and groundwater) in the oil producing host communities in the Nigeria's Niger Delta region. It will further highlight some of the problems of petroleum hydrocarbons contamination and/or pollution of marine environments associated with unsustainable practices of petroleum industry in the region.

Petroleum exploration and production in the Nigeria's Niger Delta region and export of oil and gas resources by the petroleum sector has substantially improved the nation's economy over the past five decades. However, activities associated with petroleum exploration, development and production operations have local detrimental and significant impacts on the atmosphere, soils and sediments, surface and groundwater, marine environment and terrestrial ecosystems in the Niger Delta. Discharges of petroleum hydrocarbon and petroleumderived waste streams have caused environmental pollution, adverse human health effects, socioeconomic problems and degradation of host communities in the 9 oil-producing states in the Niger Delta region. Many approaches have been developed for the management of environmental impacts of petroleum production-related activities and several environmental laws have been institutionalized to regulate the Nigerian petroleum industry. However, the existing statutory laws and regulations for environmental protection appear to be grossly inadequate and some of the multinational oil companies operating in the Niger Delta region have failed to adopt sustainable practices to prevent environmental pollution. This review examines the implications of multinational oil companies operations and further highlights some of the past and present environmental issues associated with petroleum exploitation and production in the Nigeria's Niger Delta. Although effective understanding of petroleum production and associated environmental degradation is importance for developing management strategies, there is a need for more multidisciplinary approaches for sustainable risk mitigation and effective environmental protection of the oilproducing host communities in the Niger Delta.

This chapter provides a clear insight into microbial degradation of petroleum hydrocarbons in contaminated soil that have emerged from the growing body of bioremediation research and its applications in practice. Understanding the biodegradability of several classes of petroleum contaminants is of critical importance for developing bioremediation strategies for risk mitigation. In situ (biostimulation, bioaugmentation, phytoremediation) and ex situ (biopiling, bioreactors, composting, land farming, ) bioremediation strategies and their applications are also described.

Global flaring and venting of petroleum-associated gas is a significant source of greenhouse gas emissions and airborne contaminants that has proven difficult to mitigate over the years. In the petroleum industry, poor efficiency in the flare systems often result in incomplete combustion which produces a variety of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and inorganic contaminants. Over the past fifty years, gas flaring and venting associated with petroleum exploration and production in the Nigeria's Niger Delta has continue to generate complex consequences in terms of energy, human health, natural environment, socioeconomic environment and sustainable development. In some oil-producing host communities, most flaring and ventingsystems are located in close proximity to residential areas and/or farmlands; and the resultant emissions potentially contribute to global warming as well as somelocal and/or regional adverse environmental impacts.There are emerging facts in an attempt to understand the effect of flaring and venting practices and the complex interactions of thermal pollution, organic and inorganic contaminants emission in the environment. This review discusses environmental contamination, adverse human health consequences, socioeconomic problems, degradation of host communities and other associated impacts of flaring and venting of associated gas in the petroleum industry in the Niger Delta. Effective understanding of the overall impact of associated gas flaring and venting in the petroleum industry is important for effective management of the energy resources, environmental risk mitigation, implementation of good governanceand sustainable development.

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