LONDON, Sept. 28 (Xinhua) -- By analyzing the lead pollution in the North Atlantic, researchers have found evidence that leaded petrol emissions had declined over the past few decades, according to a study published Wednesday in the journal Nature Communications.
Over the last 100 years, the North Atlantic Ocean has been heavily affected by high levels of lead pollution from the industrialized regions of North America and Europe.
The primary source of this pollution has been lead emitted from car engines and other combustion engines. Starting in the 1970s, countries have introduced a series of policies to eliminate lead additives from combustion engines.
Scientists are particularly keen to monitor levels of lead from natural sources, such as windblown dust, and lead from man-made sources, such as burning coal, to determine the impact of industrialization on the planet and levels of pollution.
An international team of researchers analyzed the chemistry of seawater samples collected from across the tropical North Atlantic in 2010 and 2011.
The results showed that up to 50 percent of the lead came from natural sources, reflecting a decrease in the amount of lead pollution emitted from combustion engines.
But this finding is confined to a specific area of the ocean, which is expected to receive particularly high inputs of natural lead, and that continuing pollution from sources such as coal-burning and smelting processes are still overwhelming natural lead elsewhere in the Atlantic ocean, according to the researchers.
The proportion of lead from human activities and naturally occurring sources in the surface of oceans reflects the extent of environmental lead pollution, and that is why the finding is encouraging.
"It demonstrates how effective policies to phase out leaded petrol have been", said one of the study authors Dr Luke Bridgestock from Imperial College London.
"The big catch though is that lead pollution from other sources is still high, overall remaining dominant over naturally occurring lead in the oceans," said Bridgestock.