Leaded gasoline, once a mainstay at gas stations worldwide, has slowly been phased out of use starting in the 1970s. However, this did not prevent toxic lead from the substance to make its way into the Indian Ocean, a new research shows.
Scientists from the Cambridge-based Massachusetts Institute of Technology
(MIT) have recently conducted a new investigation in the area, diving to collect samples at various locations across the ocean.
They focused their attention on corals. These organisms grow annual density bands, which retain the chemical characteristic of the water in which they formed. Each year has its individual record, and these density bands can be counted just like tree rings can.
Researchers were thus able to reconstruct the history of lead concentrations in the Indian Ocean. They also tracked back the origins of the gasoline that tainted these waters in the first place.
Lead gasoline was phased out because it damaged the catalytic converters on automobiles, but also because scientific studies have shown that it can cause significant neurological and cardiovascular damage in humans and other animals.
About 185 countries have already renounced the fuel, with six others bound to do the same within the next two years or so. Even though the producing of this substance has decreased considerably, its effects can still be felt in the environment at great intensity.
In the new study, MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS) professor of geochemistry Ed Boyle reconstructed the history of anthropogenic (man-made) lead in the Indian Ocean for the past 50 years.
Details of the investigation will be presented this week in Montreal, Canada, at the Goldschmidt Geochemistry Conference. MIT postdoctoral researchers Jong-Mi Lee and Intan Nurhati, and graduate student Yolanda Echegoyen-Sanz, were also part of the research team.
One of the main conclusions of the research has been that the Indian Ocean now features lead concentrations higher than what is found in either the Atlantic or the Pacific, which are widely considered to be the most polluted oceans in the world.
“It is an indication of the human footprint on the planet that essentially all the lead in the oceans now is from human activities. It’s very hard to find a trace of the lead that’s there naturally,” Boyle adds.
“Lead was phased out much later in South Asia, so conditions there are more like they were 20 years ago in the North Atlantic. Studying the Indian Ocean now can tell us something about conditions in the Atlantic Ocean before lead measurements were made,” Anderson concludes.