Pollution reaches unprecedented scale and oceans are among the main victims of this dangerous human action. Oceans end up as collectors of most of the world’s garbage. In this case, a team of scientists discovered how mercury, the toxic metal, is spread in the oceans at increasing levels. The Industrial Revolution is a reference point for many pollution studies. Because mercury is produced both naturally and by humans, the first Industrial Revolution is an important landmark in establishing how much is produced by each side. Ocean mercury pollution is at alarming levels.
Woods Hole Oceanographic Institution (WHOI), Wright State University, Observatoire Midi-Pyréneés in France, and the Royal Netherlands Institute for Sea Research have gathered scientists undertaking a research on the level of mercury in the oceans. It is the first time that a direct calculation of mercury levels was pursued. Twelve sampling cruises collected materials for a total period of eight years.
Other scientists have recently looked at the level of plastic pollution in the oceans. Surprisingly, they found that the level is lower than expected, but that is a not the full story.
Ocean mercury pollution measured for the first time
Researchers lead by WHOI marine chemist Carl Lamborg looked at the samples and compared them with phosphates levels, because the substance interacts with the environment similarly to mercury.
The results of the analysis showed that deeper waters, bellow 3.300 feet, have higher levels of mercury. The deep waters did not make contact with the atmosphere since the beginning of the Industrial Revolution, so they reveal the impact of human production of mercury. By using carbon dioxide as a tracer, the team discovered that 60.000 to 80.000 tons of mercury lie in the oceans. Shallow waters are the most affected by pollution, showing triple levels of mercury compared to what was found more than two centuries ago.
Unfortunately, the ocean waters surrounding the pols is among the most affected, because of how ocean currents circulate. Moreover, other regions which did not produce mercury through industrial activities are among the most affected. Scientists warn that the next 50 years of industrial activity might double the amount of ocean mercury pollution at shallow depths. Right now, the most worrying prospect is that we do not know how marine life is influenced by the changing levels of the toxic metal.
The research results will be published soon in Nature journal.