B
Definitions and Conversions

Definitions

a.Petroleum hydrocarbons focused upon in this analysis

For the purposes of estimating the input of petroleum hydrocarbons to marine environment, some consideration was given to the nature of this complex group of compounds. The estimates included here are intended to be as inclusive as possible (see individual sections for greater explanation of how various classes of hydrocarbons were treated); however, the committee found it practical and pragmatic to focus its attention on liquid petroleum compounds of higher molecular weights (i.e., methane, ethane, and other compounds lighter than C6 are not included in the calculated estimates).

b.North American waters and specific regions of study

In analyzing oil-input data from all sources around North America, the committee determined that there would be some value to compiling that data according to certain discrete geographic boundaries, based primarily on the influence of major estuaries and marine water circulation patterns in each area. To the extent possible, boundaries selected also recognize the operational boundaries between various U.S. Coast Guard offices. This should enable more efficient comparison of inputs between regions around the United States as an aid in focusing control efforts.

Boundaries were established as follows around the North American coast:

  1. Nearshore: from the shore along the coastline seaward 3 miles to the demarcation line between state and federal waters, except in estuaries (bays, sounds, river mouths, etc.), where input data will be collected inland to include all tidally affected waters (i.e., to the extent those waters remain navigable to ocean-going commercial, self-propelled vessels).

  2. Offshore: from the 3-mile demarcation line out to the outer limit of the Economic Exclusion Zone (EEZ) generally 200 miles from shore.

c.Units Used and Conversion Factors

Lateral boundaries were also established to distinguish between regions around the coast based on political boundaries (between Canada, the United States, and Mexico) and between certain Coast Guard operational unit boundaries within the United States based on major estuaries within those boundary areas (see Figure 1-7 and Table B-1).

Barrels × 42 = US gallons

Liters × 0.264 = US gallons

Cubic meters × 264.2 = US gallons

Cubic feet × 7.481 = US gallons

Liters × 0.0009 = Tonnes* (note tonnes = metric tons)

Tonnes × 294 = US gallons*

U.S. gallons × 0.0034 = Tonnes*

*  

Note: The gallon is a volume measurement. The tonne is a weight measurement. For truly precise conversions between gallons and tonnes, it is important to take into account that equal volumes of different types of oil differ in their densities. The specific gravity (sp gr), or density in relation to pure water is generally less than 1.0. Specific gravity of petroleum products varies from about 0.735 for gasoline to about 0.90 for heavy crude to 0.95 for Bunker C (No. 6 fuel). In some cases the oil is even heavier than water, especially with some of the heavy No. 6 fuels. These oils can sink. The



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Oil in the Sea III: Inputs, Fates, and Effects B Definitions and Conversions Definitions a.Petroleum hydrocarbons focused upon in this analysis For the purposes of estimating the input of petroleum hydrocarbons to marine environment, some consideration was given to the nature of this complex group of compounds. The estimates included here are intended to be as inclusive as possible (see individual sections for greater explanation of how various classes of hydrocarbons were treated); however, the committee found it practical and pragmatic to focus its attention on liquid petroleum compounds of higher molecular weights (i.e., methane, ethane, and other compounds lighter than C6 are not included in the calculated estimates). b.North American waters and specific regions of study In analyzing oil-input data from all sources around North America, the committee determined that there would be some value to compiling that data according to certain discrete geographic boundaries, based primarily on the influence of major estuaries and marine water circulation patterns in each area. To the extent possible, boundaries selected also recognize the operational boundaries between various U.S. Coast Guard offices. This should enable more efficient comparison of inputs between regions around the United States as an aid in focusing control efforts. Boundaries were established as follows around the North American coast: Nearshore: from the shore along the coastline seaward 3 miles to the demarcation line between state and federal waters, except in estuaries (bays, sounds, river mouths, etc.), where input data will be collected inland to include all tidally affected waters (i.e., to the extent those waters remain navigable to ocean-going commercial, self-propelled vessels). Offshore: from the 3-mile demarcation line out to the outer limit of the Economic Exclusion Zone (EEZ) generally 200 miles from shore. c.Units Used and Conversion Factors Lateral boundaries were also established to distinguish between regions around the coast based on political boundaries (between Canada, the United States, and Mexico) and between certain Coast Guard operational unit boundaries within the United States based on major estuaries within those boundary areas (see Figure 1-7 and Table B-1). Barrels × 42 = US gallons Liters × 0.264 = US gallons Cubic meters × 264.2 = US gallons Cubic feet × 7.481 = US gallons Liters × 0.0009 = Tonnes* (note tonnes = metric tons) Tonnes × 294 = US gallons* U.S. gallons × 0.0034 = Tonnes* *   Note: The gallon is a volume measurement. The tonne is a weight measurement. For truly precise conversions between gallons and tonnes, it is important to take into account that equal volumes of different types of oil differ in their densities. The specific gravity (sp gr), or density in relation to pure water is generally less than 1.0. Specific gravity of petroleum products varies from about 0.735 for gasoline to about 0.90 for heavy crude to 0.95 for Bunker C (No. 6 fuel). In some cases the oil is even heavier than water, especially with some of the heavy No. 6 fuels. These oils can sink. The

OCR for page 189
Oil in the Sea III: Inputs, Fates, and Effects     volume that a particular weight of oil takes up varies with temperature and atmospheric pressure. The conversion factor of 294 gallons per tonne is derived from an average specific gravity of 0.83, which corresponds to an API gravity or degree API of 39. Note that API gravity and specific gravity are inversely proportional as per the formulae below. The 294 gallons/tonne conversion unit is also convenient because it happens that 294 gallons = 7 barrels. API = (141.5/sp gr) − 131.5 sp gr = 141.5/(API + 131.5) TABLE B-1 Descriptions of Coastal Zones as Defined by This Study Zone Description A Bounded by a line drawn northerly 0º true along the U.S./Canada border in the Arctic and a line bearing northerly 0º true from Lancaster Island in Canada (includes Arctic Canada west of Hudson Bay). B Bounded by a line bearing northerly 0º true from Lancaster Island in Canada and a line bearing easterly 90º true from the northern boundary of Newfoundland, Canada (includes Hudson Bay east to the Maritime Provinces in Canada). C Bounded by a line bearing easterly 90º true from the northern boundary of Newfoundland, Canada, and a line drawn easterly along the U.S./ Canada border as follows: a line drawn 90º true from the shore along 44º11’12” N to 67º16’46” W; thence southwest to 42º53’14” N, 67º44’35” W; thence southeast to 42º31’08” N, 67º28’05” W; thence southeast to 40º27’05” N, 65º41’59” W. D Bounded by a line drawn easterly along the U.S./Canada border and a line bearing due east 90º true from the shore at the Virginia/North Carolina border (34º59.8’ N) to the offshore extent of the EEZ [includes US Coast Guard Marine Safety Offices (MSOs) Portland, Maine; Boston; Providence; Long Island Sound, Connecticut; New York; Philadelphia; Baltimore; and Hampton Roads, Virginia]. E Bounded by a line bearing due east 90º true from the shore at the Virginia/North Carolina border (34º59.8’ N) to the offshore extent of the EEZ and by a line bearing 227º true drawn from 26º00’ N latitude and 81º30’ W longitude to the offshore extent of the EEZ (includes MSOs Charleston, Savannah, Jacksonville, and Miami). F Bounded by a line bearing 227º true drawn from 26º00’ N latitude and 81º30’ W longitude to the offshore extent of the EEZ and a line from the Mississippi coast at 89º10’ W bearing southeasterly to 29º10’ N, 88º00’ W; thence southerly bearing 180º true to the offshore extent of the EEZ (includes MSOs Tampa Bay and Mobile). G Bounded by a line from the Mississippi coast at 89º10’ W bearing southeasterly to 29º10’ N, 88º00’ W; thence southerly bearing 180º true to the offshore extent of the EEZ and a line drawn along the U.S./Mexico boarder in Texas bearing 90º true to the offshore extent of the EEZ (includes MSOs New Orleans and Morgan City, Louisiana; and Port Arthur, Houston and Corpus Christi, Texas). H Includes Mexican offshore waters on the east coast of Mexico that are south of a line bearing 90º true from the U.S./Mexico border to the outermost extent of the EEZ and north of a line bearing 90º true from the Mexico/Belize border to the outermost extent of the EEZ. I Includes the areas of both the Commonwealth of Puerto Rico and the Territory of the U.S. Virgin Islands to the offshore extent of the EEZ (includes MSO San Juan). J Includes Mexican offshore waters on the west coast of Mexico that are south of a line bearing 270º true from the U.S./Mexico border to the outermost extent of the EEZ and north of a line bearing 270º true from the Mexico/Guatemala border to the outermost extent of the EEZ. K Includes a line along the U.S./Mexico border in California to the offshore extent of the EEZ and a line drawn from the intersection of 34º58’ N latitude and the California coastline bearing 229º true to the offshore extent of the EEZ (includes MSOs San Diego and Los Angeles/Long Beach). L Includes a line drawn from the intersection of 34º58’ N latitude and the California coastline bearing 229º true to the offshore extent of the EEZ and a line drawn along the 42º00’ N latitude from the shore to the offshore extent of the EEZ (includes MSO San Francisco). M Includes a line drawn along the 42º00’ N latitude from the shore to the offshore extent of the EEZ and a line drawn along the international boundary between the United States and Canada at the entrance to the strait of Juan de Fuca to the offshore extent of the EEZ (includes MSOs Portland, Oregon, and Puget Sound, Washington). O Includes a line drawn along the international boundary between the United States and Canada at the entrance to the strait of Juan de Fuca to the offshore extent of the EEZ (48º29’38.11” N, 124º43’34.69” W to 48º29’38.11” N, 125º00’00” to 48º04’00”N, 126º10’35” W) and a line along the international boundary bearing 270º true between the United States and Canada at the Dixon entrance to the offshore extent of the EEZ (includes all marine waters in western Canada.) N Includes Hawaii, American Samoa, Johnston Atoll, Palmyra Atoll and Kingman Reef, Wake Island, Jarvis Island, Howland and Baker Islands, Guam, the Commonwealth of Northern Mariana Islands, and the Trust Territory of the Pacific Islands. P Includes a line drawn along the international boundary bearing 270º true between the United States and Canada at the Dixon entrance to the offshore extent of the EEZ and a line drawn along the northern edge of the Aleutian Island chain to the offshore extent of the EEZ (includes MSO Southeast Alaska and a portion of MSO Western Alaska). Q Includes a line drawn along the northern edge of the Aleutian Island chain to the offshore extent of the EEZ and a line drawn northerly 0º true along the U.S./Canada border in the Arctic.