By: Franyi Sarmiento, Ph.D., Inspenet, June 24, 2022
Oil slicks (microscopic ephemeral layers of hydrocarbons floating on the ocean surface) can be of natural or anthropogenic origin. In some cases, hydrocarbons may seep naturally from seafloor oil deposits. Others can be attributed to oil spills from ships, offshore oil/gas infrastructure and coastal currents.
Due to their transient nature and the large extent of the ocean surface, monitoring marine oil slicks, especially those caused by human activities, has been difficult. Therefore, estimates of the contribution of natural versus anthropogenic sources are poorly known and highly variable. The contributions of natural seepage to oil slicks, for example, range from 10% in the 1980s to 46% in 1990-1999, and the contribution of anthropogenic sources is even more difficult to determine.
A basic understanding of global oil slicks is important for ocean conservation and policy.
Using more than 560,000 synthetic aperture radar (SAR) images taken by Sentinel-1A/1B satellites between 2014 and 2019, Yanzhu Dong’s team at Nanjing University in China created a map of 450,000 oil slicks in oceans around the world.
SAR (a remote sensing method widely used in oil spill monitoring) enabled Dong and his colleagues to identify and catalog the static and persistent sources of marine oil slicks.
The authors of the study found a cumulative oil slick area of approximately 1.5 million square kilometers, more than twice the area of France.
Dong and colleagues identified a very uneven distribution of the spots. The vast majority were located within 100 miles of the coasts and along maritime routes.
From their analysis, Dong and his colleagues estimate that the vast majority of marine oil slicks (94%) have their origin in human activity. The remaining 6% is attributable to natural sources. This means that the proportion of marine oil pollution caused by human activity has been significantly underestimated.
The study is entitled “Chronic oiling in global oceans”. And it has been published in the academic journal Science.
Source AAAS and NCYT Amazings: https://noticiasdelaciencia.com/art/44472/las-fuentes-de-la-contaminacion-marina-por-petroleo
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