Floating tar balls are a product of weathering of crude oil in the marine environment. They have been found to be prevalent in the world ocean, particularly in the 1960s and 1970s before stricter controls on petroleum transport and handling were in effect. Much of the early research on the occurrence and composition of pelagic tar balls was conducted in the North Atlantic Ocean. Research and time-series assessments in the Sargasso Sea since that time have documented that floating tar balls sampled by neuston nets in the open ocean and washed up on shorelines have declined in the past two decades.
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