Transcript seeps - Cynthia Cudaback

Beach hazard in Santa Barbara:
Tarry feet!
Seep: natural spring of oil and gas
USGS
USGS
La Brea tar pits
USGS
Roasting marshmallows over a gas seep in Humboldt County
USGS
asphaltum
seep near Santa Barbara
Most local seeps are underwater, right near campus
UCSB studies of natural gas & oil seeps
Motivation: air pollution
• 88% of gas from seeps is methane
• rises as bubbles to water surface
• contributes to atmospheric ozone
• hydrocarbons from seeps: 24 tons/day,
• cars & trucks: 22 tons/day (a few years ago)
Ongoing studies:
• mapping
• measuring emissions
• effect of oil production
• biology near seeps
Gas bubbles
Surface oil slick
UCSB Geology
July, 1995
False color sonar image
Blue streaks show
gas bubbles from seep
UCSB Geology
UCSB
Large oil slicks from natural seeps: swirled around by eddies
facts about the seeps near Coal Oil Point
Where it is:
• region is 18 km2, 3 km offshore
• water depths 20-60m
• reservoir is 1500 m below sea floor
• contains 150 million gallons of oil
What comes out:
• 100 barrels oil /day (4100 gallons)
• 40 tons methane gas /day
• seepage varies with tides and seasons
• underwater methane plumes extend 12 km
Seepage is reduced
by oil drilling!
Things the oil industry would like you to remember:
• Oil seeps put 37,000 barrels of oil into environment each year
• Since 1980, industry has spilled only 800 barrels total
• Oil drilling reduces pressure on, and flow from, seeps
• Gas from seeps causes air pollution
• Industry is catching gas from seeps
Things the oil industry would like you to forget:
• Oil spill in 1969 was 80,000 barrels
• Oil spills are all at once in one place
• Seeps are spread out in space and time
• Processing oil causes air pollution
• Driving cars causes air pollution
How much beach can 80,000 barrels of oil cover?
Use dimensional analysis.
80,000 barrels * 41 gal/barrel * 3.8 liters/gal * 1000 cm3/liter = 1.25*1010 cm3
If that oil spreads over 25 km of beach (here to Summerland)
In a band 10 m wide, how thick is the layer?
1.25*1010 cm3 / 25*105 cm / 1000 cm = 5 cm
Biology around oil seeps
• Patchy distribution
most critters rarely exposed to fresh (toxic) oil
weathered oil is tar
• Increased microbial production
more oil-eating bacteria found near bottom
• Exposure level studies
different critters like different levels
• Adaptation
maybe individuals, but not multi-generation
• Chemosynthetic organisms
depend on bacteria for food
species of clams, mussels, snails, tubeworms
Oil Leases
(SB Independent 6/13/2002 and SB News Press 6/26/99)
36 undeveloped leases extended thru 2003
Estimated 1 billion (1,000,000,000) barrels oil
State wants to review any development of these leases
Federal Government buys some leases
Florida: $275 million, feds buying, Gov. Jeb Bush happy
California: $2,000 million, feds say CA likes oil, Gov. Davis unhappy
What should we do?
Where does SB Channel tar come from?
•Primarily from natural oil seeps in SB Channel
•Special “tents” are placed over some of these to recover
oil and gas!
•Major source of air pollution here is from these oil
seeps!