a“Regions” refers to 17 zones or regions of North American waters for which estimates were prepared.
bCargo washing is not allowed in U.S. waters, but is not restricted in international waters. Thus, it was assumed that this practice does not occur frequently in U.S. waters (see Chapter 3 and Appendix E).
cEstimated loads of less than 10 tonnes per year reported as “trace”
dWorld-wide populations of recreational vessels were not available (see Chapter 3 and Appendix F).
eInsufficient data were available to develop estimates for this class of vessels (see Chapter 3 and Appendix E).
1.Totals may not equal sum of components due to independent rounding.
2. Generally assumes an average specific volume of oil at 294 gallons per tonne (7 barrels per tonne). Where the specific commodity is known, the following values are applied when converting from volume to weight:
Gasoline: 333 gallons per tonne
Light Distillate: 285 gallons per tonne
Heavy Distillate: 256 gallons per tonne
Crude Oil: 272 gallons per tonne
3. Numbers reported to no more than 2 significant figures using rules: http://web.mit.edu/10.001/Web/Course_Notes/Statistics_Notes/Significant_Figures.html#SignificantFigures