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Pollution from the Ocean

Researchers from the University of California, Santa Barbara (UCSB), have found that natural seep gases and liquid petroleum emerge from fissures on the ocean floor of the Southern California Bight.    Being less dense than water, the seep gases rise to the surface as bubble plumes in the Santa Barbara Channel and enter the atmosphere, significantly contributing to air pollution in Santa Barbara County (see http://www.crseo.ucsb.edu/iog/seeps.htm for details).    The UCSB researchers and others have also noted that the liquid oil component of this hydrocarbon seepage tends to accumulate in slicks at the sea-surface, as well as form tar balls that can end up on beaches, and even your feet!     Thus, this liquid oil seepage is an important contributor to marine pollution.    However, to date it has been difficult to quantify where and when these slicks are found due to their relatively small size and ephemeral nature.   

Fortunately, we have found that Synthetic Aperture Radar (SAR) satellite imagery can be used to identify these slicks and map their spatial and seasonal extent.    Further, SAR images can be used to examine how long the slicks persist and under what wind conditions they are visible, as well as describe channel conditions that lead to the dispersal of the oil, or worse, its accumulation and/or shoreward transport.    This SAR image shows a natural oil slick in the Santa Barbara Channel; it also demonstrates that small-scale eddies (see the CIRCULATION page) can impact the distribution of this oil.   

This SAR image also covers part of the Santa Barbara Channel.    This large oil slick shows little apparent effect from eddy current circulation.

Natural oil seepage is also found in Santa Monica Bay, but to a much lesser extent than that observed in the Santa Barbara Channel.    Much as it would appear in a glass of water, oil dampens small waves on the surface, reducing sea-surface roughness and leading to darker regions on the SAR images (areas of reduced backscatter).    These images and others like them are part of an ongoing effort by JPL and UCSB researchers to quantify liquid oil seepage in the Southern California Bight and assess its potential environmental impact.

Offshore wells sometimes leak liquid petroleum onto the ocean surface.   Such oil spills, if large in area, can be tracked by satellite imaging just like natural oil slicks from the ocean floor.

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