Big spills 137

Routine maintenance

Up in smoke Offshore drilling Natural seeps

Down the drain

Routine maintenance

Down the drain


FIGURE 6-2 The annual input of petroleum hydrocarbons into marine environments annually in millions of gallons: Big spills, major oil tanker and oil well accidents; Routine maintenance, bilge cleaning and other discharges from oil tankers and other large ships; Down the drain, used automobile engine oil, runoff from land of municipal and industrial waste; Up in smoke, hydrocarbons from vehicle exhaust and other sources that are rained out in the oceans; Offshore drilling, Spill from offshore oil wells; Natural seeps, oil seeping into the oceans from natural, underground sources. Redrawn from oil_pollution/html.

are the effects of the slowly degraded petroleum residues on aquatic life. Automobile emissions, on the other hand, cause atmospheric problems. Much spilled oil also enters the atmosphere by evaporation, but the problems associated with oil spills and automobile emissions are sufficiently different to warrant separate discussion in this chapter. The additional environmental problems of the surfactants, polymers, and pesticides synthesized from petroleum are discussed in subsequent chapters.

It is estimated that the crude oil input into the sea is 7 x 108 gal/year worldwide (Figure 6-2). The sources of the oil, with the exception of delivery from the atmosphere, are discussed in the subsequent sections of this chapter. The atmospheric input is too diverse and ill defined to permit a clear delineation of all the sources.

Natural oil seeps led to the discovery of many of the major oil fields in the world. The first oil well in the United States was drilled in Titusville, Pennsylvania, because oil was observed seeping into the Oil River at that point. These oil seeps may be responsible for local environmental problems, but often the rate of seepage is so slow that the oil is effectively dispersed by environmental

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