www.noia.org/website/article.asp?id=129
edu Executive Summary There is little argument that liquid petroleum (crude oil and the products refined from it) plays a pervasive role in modern society. As recently as the late 1990s, the average price of a barrel of crude oil was less than that of a take-out dinner. Yet a fluctuation of 20 or 30 percent in that price can influence automotive sales, holiday travel decisions, interest rates, stock market trends, and the gross national product of industrialized nations, whether they are net exporters or importers of crude oil. A quick examination of world history over the last century would reveal the fundamental impact access to crude oil has had on the geopolitical landscape. Yet its sheer magnitude makes understanding the true extent of the role of petroleum in society difficult to grasp. Furthermore, widespread use of any substance will inevitably result in intentional and accidental releases to the environment. The frequency, size, and environmental consequences of such releases play a key role in determining the extent of steps taken to limit their occurrence or the extent and nature of mitigation efforts taken to minimize the damage they cause. Consequently, the United States and other nations engaged in strategic decisionmaking regarding energy use spend a significant amount of time examining policies affecting the extraction, transportation, and consumption of petroleum. In addition to the geopolitical aspects of energy policymaking, the economic growth spurred by inexpensive fuel costs must be balanced against the environmental consequences associated with widespread use of petroleum. Petroleum poses a range of environmental risks when released into the environment (whether as catastrophic spills or chronic discharges). In addition to physical impacts of large spills, the toxicity of many of the individual compounds contained in petroleum is significant, and even small releases can kill or damage organisms from the cellular- to the population-level. Compounds such as polycyclic aromatic hydrocarbons (PAH) are known human carcinogens and occur in varying proportions in crude oil and refined products. Making informed decisions about ways to minimize risks to the environment requires an understanding of how releases of petroleum associated with different components of petroleum extraction, transportation, and consumption vary in size, frequency, and environmental impact. In recognition of the need for periodic examinations of the nature and effect of petroleum releases to the environment, various governments have commissioned a variety of studies of the problem over the last few decades. Within the United States, federal agencies have turned to the National Research Council on several instances to look at the issue. One of the most widely quoted studies of this type was completed in 1985 and entitled Oil in the Sea: Inputs, Fates, and Effects. The report that follows was initially requested by the Minerals Management Service (US) in 1998. Financial support was obtained from the Minerals Management Service, the US Geological Survey, the Department of Energy, the Environmental Protection Agency, National Oceanic and Atmospheric Administration, the US Coast Guard, the US Navy, the American Petroleum Institute, and the National Ocean Industries Association. Although originally envisioned as an update of the 1985 report, this study goes well beyond that effort in terms of proposing a clear methodology for determining estimates of petroleum inputs to the marine environment. In addition, the geographic and temporal variability in those inputs and the significance of those inputs in terms of their effect on the marine environment are more fully explored. Like the 1985 report, this report covers theoretical aspects of the fate and effect of petroleum in the marine environment. This current effort, however, benefited tremendously by the existence of more systematic databases and the voluminous field and laboratory work completed since the early 1980s, work largely stimulated by the Exxon Valdez oil spill in Prince William Sound, Alaska. PETROLEUM INPUTS TO THE SEA An examination of reports from a variety of sources, including industry, government, and academic sources, indicate that although the sources of petroleum input to the sea are diverse, they can be categorized effectively into four major groups, natural seeps, petroleum extraction, petroleum transportation, and petroleum consumption. Natural seeps are purely natural phenomena that occur when crude oil seeps from the geologic strata beneath the seafloor to the overlying water column. Recognized by geologists for decades as indicating the existence of potentially economic reserves of petroleum, these seeps release vast amounts of crude oil annually. Yet these large volumes are released at a rate low enough that the surrounding ecosystem can adapt and even thrive in their presence. Petroleum extraction can result in releases of both crude oil and refined products as a result of human activities associated with efforts to explore for and produce petroleum. The nature and size of these releases is highly variable, but is restricted to areas where active oil and gas exploration and development are under way. Petroleum transportation can result in releases of dramatically varying sizes, from major spills associated with tanker accidents such as the Exxon Valdez, to relatively small operational releases that occur regularly. Petroleum consumption can result in releases as variable as the activities that consume petroleum. Yet, these typically small but frequent and widespread releases contribute the overwhelming majority of the petroleum that enters the sea due to human activity. Based on analysis of data from a wide variety of sources, it appears that collectively these four categories of sources add, each year on average, about 260,000 metric tonnes (about 76,000,000 gallons) of petroleum to the waters off North America. Annual worldwide estimates of petroleum input to the sea exceed 1,300,000 metric tonnes (about 380,000,000 gallons). Although these are imposing figures, they are difficult to interpret in terms of their ecological significance, as they represent thousands or tens of thousands of individual releases whose combined effect on the environment is difficult to clearly establish. Regional or worldwide estimates of petroleum entering the environment are useful only as a first order approximation of need for concern. Sources of frequent, large releases are rightfully recognized as areas where greater effort to reduce petroleum pollution should be concentrated, despite the fact that not every spill of equal size leads to the same environmental impact. This study, as did the 1975 and 1985 NRC reports, attempts to develop a sense of what the major sources of petroleum entering the marine environment are, and whether these sources or the volume they introduce, have changed through time. Thus, this report not only attempts to quantify the amount released each year, but makes an effort to examine the geographic distribution and nature of releases of petroleum to the marine environment, as well as the processes that can mitigate or exacerbate the effect of these releases on the environment. Where appropriate, comparisons of estimates of petroleum pollution among studies over the last 25 years provide the basis needed to explore the performance for prevention efforts implemented during that time. Natural Seeps Natural seepage of crude oil from geologic formations below the seafloor to the marine environment off North America is estimated to exceed 160,000 tonnes (47,000,000 gallons), and 600,000 tonnes (180,000,000 gallons) globally, each year. Natural processes are therefore, responsible for over 60 percent of the petroleum entering North American waters, and over 45 percent of the petroleum entering the marine environment worldwide. Oil and gas extraction activities are often concentrated in regions where seeps form. Historically, slicks of oil from seeps have been attributed to releases from oil and gas platforms, and vice versa. In North America, the largest and best known natu...
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