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Oil in the Sea III: Inputs, Fates, and Effects
FIGURE 2-12 Average, annual input (1990-1999) of petroleum hydrocarbons (kilotonnes) for the Canadian Arctic.
Effort to reduce the frequency and size of such spills should continue to be undertaken.
Alaska was divided into two regions, divided by the Aleutian Islands. Inputs to these regions are presented in Table 2-9 and Figure 2-16, showing dramatically different sources and loads for coastal and offshore waters. Surprisingly, aircraft dumping is estimated to be one of the largest sources of oil into offshore areas, and inputs from spills from non-tank vessels are small but one-two orders of magnitude greater than spills from tankers. In coastal waters, seeps in south-central Alaska are responsible for over 40 percent of the calculated inputs3 during the reporting period (1990-1999; Table 2-9).
As discussed in Chapter 3 and Appendix I, erosion of organic rich source rocks can yield petroleum-bearing sediment in locally significant amounts. However, this material is largely bound within sediment particles, thus suggesting it is largely not biologically available.