TABLE 3-2 Average, Annual Releases (1990-1999) of Petroleum by Source (in thousands of tonnes)

 

North America

Worldwide

 

Best Est.

Regionsa

Min.

Max.

Best Est.

Min.

Max.

Natural Seeps

160

160

80

240

600

200

2000

Extraction of Petroleum

3.0

3.0

2.3

4.3

38

20

62

Platforms

0.16

0.15

0.15

0.18

0.86

0.29

1.4

Atmospheric deposition

0.12

0.12

0.07

0.45

1.3

0.38

2.6

Produced waters

2.7

2.7

2.1

3.7

36

19

58

Transportation of Petroleum

9.1

7.4

7.4

11

150

120

260

Pipeline spills

1.9

1.7

1.7

2.1

12

6.1

37

Tank vessel spills

5.3

4.0

4.0

6.4

100

93

130

Operational discharges (cargo washings)

nab

na

na

na

36

18

72

Coastal Facility Spills

1.9

1.7

1.7

2.2

4.9

2.4

15

Atmospheric deposition

0.01

0.01

tracec

0.02

0.4

0.2

1

Consumption of Petroleum

84

83

19

2000

480

130

6000

Land-based (river and runoff)

54

54

2.6

1900

140

6.8

5000

Recreational marine vessel

5.6

5.6

2.2

9

ndd

nd

nd

Spills (non-tank vessels)

1.2

0.91

1.1

1.4

7.1

6.5

8.8

Operational discharges (vessels ≥100 GT)

0.10

0.10

0.03

0.30

270

90

810

Operational discharges (vessels<100 GT)

0.12

0.12

0.03

0.30

nde

nd

nd

Atmospheric deposition

21

21

9.1

81

52

23

200

Jettisoned aircraft fuel

1.5

1.5

1.0

4.4

7.5

5.0

22

Total

260

250

110

2300

1300

470

8300

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).

NOTES:

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

Council (NRC, 1975; NRC, 1985) and new information on the natural seepage of crude oil into the marine environment (detailed in Appendix C). Not considered in the new or previous studies is the contribution to the marine environment of hydrothermally-derived petroleum at oceanic spreading axes (see summary by Kvenvolden and Simoneit, 1990). Although it is clear that hydrothermal petroleum occurs in the sea, the rates of seepage are unknown, but are believed to be very small, and therefore are not included in the new global assessment.

In 1975, the estimated worldwide rate of natural seepage of oil into the marine environment ranged widely from 200,000 to 6,000,000 tonnes per year, with a “best estimate” of 600,000 tonnes per year. These rates were based on a comprehensive global survey incorporating extensive geological considerations, but used extrapolations from only a few known seeps. In 1985, little new information had become available, and estimates of individual oil-seep rates had not changed significantly. Thus a revised estimate of the global seepage rate was calculated based on assumptions concerning the amount of crude oil known to be present that could seep over reasonable periods of geologic time. This theoretical approach was first developed by Kvenvolden and Harbaugh (1983) and incorporated into NRC (1985). The



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