vided among coastal pipelines, tanker spills, and coastal facilities. These sources reflect the large petroleum industry of the region that involves all phases of oil and gas exploration, production, and transportation.

Spills from pipelines and tank vessels into the Western Gulf of Mexico release about 1,600 tonnes into both offshore and coastal areas, thus continued efforts by the transportation industries is needed to reduce the threat posed by such spills. In addition to the direct threat posed from spills, the elevated inputs of petroleum hydrocarbon (both as TPH and as PAH) due to human activities within the Mississippi River watershed and along the Gulf Coast, especially that load entering the coastal zone from land-based sources, suggests that sensitive marine communities in these areas are at a significant risk from chronic releases and the long-term, sublethal exposure associated with them. As discussed earlier, the ultimate effect of this exposure remains an area of important scientific research, but greater understanding and monitoring of nonpoint sources of petroleum pollution is needed in these areas.

Pacific Seaboard of North America and Hawaii

The total average annual input of petroleum hydrocarbons to the Pacific seaboard of North America (including Hawaii) on a regional basis, is relatively low. This area, the largest of the five discussed, receives roughly 31,000 tonnes of petroleum hydrocarbons from all sources each year (less than 10 percent on the total annual load to North American waters; Table 2-8, Figure 2-15). The dominant source of petroleum hydrocarbons to the coastal zone is from consumption related activities, and as expected, these loads show marked correlation to the distribution of human population and the degree of urbanization. In addition, the heavy use of recreational marine vessels in some regions results in substantial loads of petroleum hydrocarbons, accounting for nearly 50 percent of the calculated load for waters off California. Offshore, inputs are much smaller, with the significant exception of offshore Southern California. Here the extensive system of natural seeps off Coal Oil Point release approximately 20,000 tonnes of crude petroleum to the marine environment each year (accounting for nearly two thirds of the total load received by coastal and offshore waters of the Pacific seaboard, including Hawaii).

The load from consumption-related activities to coastal waters off more densely populated coastal regions of western North America may represent a significant risk to natural resources in these areas, depending on local oceanographic conditions (see Chapter 4) and the nature of the biota. This risk may be even more significant if these ecosystems should prove sensitive to chronic exposure to certain toxins found in petroleum hydrocarbons (such as PAH; see Chapter 5). Spills, although infrequent compared to some regions, can still be significant, especially if they occur at important periods of biologic activity or in particularly important locations.

TABLE 2-5 Average Annual Input (1990-1999) of Petroleum Hydrocarbons (tonnes) for the Canadian Arctic

ZONE (Coastal)

 

A

B

Sum Seepsa

 

na

na

 

Platforms

na

na

 

Atmospheric

na

na

 

Produced

na

na

Sum Extractionb

 

na

na

 

Pipelines

na

na

 

Tank vessel

na

tracec

 

Coastal facilities

na

na

 

Atmosphericd

trace

trace

Sum Transportation

trace

trace

 

Land-based

tracee

660

 

Recreational vessels

ndf

nd

 

Vessels >100GT (spills)

0g

0

 

Vessel >100GT (op discharge)

trace

trace

 

Vessel <100GT (op discharge)

trace

trace

 

Atmospheric

2000

1300

 

Aircrafth

na

na

Sum Consumption

2000

2000

ZONE (Offshore)

 

A

B

Sum Seepsa

 

na

na

 

Platforms

na

na

 

Atmospheric

na

na

 

Produced

na

na

Sum Extraction

 

na

na

 

Pipelines

na

na

 

Tank vessel

na

na

 

Atmosphericd

trace

trace

Sum Transportationb

trace

trace

 

Land-basedi

na

na

 

Recreational vesselsj

na

na

 

Vessels >100GT (spills)

na

trace

 

Vessel >100GT (op discharge)

trace

trace

 

Vessel <100GT (op discharge)

trace

trace

 

Atmospheric

220

230

 

Aircraft

20

50

Sum Consumption

240

270

Grand Total

2300

2300

Sum of Anthropogenic

2300

2300

aNo known seeps in these regions

bNo known oil and gas production in these regions

cEstimated loads of less than 10 tonnes per year reported as “trace”

dSmall number of tankers carrying fuel to coastal areas assumed

ePristine waters in this region assumed to carry some fraction of petroleum bearing sediment eroded from exposed sources rocks (see Chapter 3 and Appendix I)

fPopulations of recreational vessels were not available for these regions (see Chapter 3 and Appendix F)

gNo spills from vessels greater than 100 GT were reported in these regions for the reporting period (see Chapter 3 and Appendix E)

hPurposeful jettisoning of fuel not allowed within 3 nmiles of land (see Chapter 3 and Appendix E)

iLand-based inputs are defined in this study as being limited to the coastal zone (see Chapter 3 and Appendix I)

jRecreational vessels are defined in this study as being limited to operations within 3 miles of the coast (see Chapter 3 and Appendix F)



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