News & AnalysisOceanography

Chemical Atlas Shows Where Seas Are Tainted—And Where They Can Bloom

Science  07 Mar 2014:
Vol. 343, Issue 6175, pp. 1070
DOI: 10.1126/science.343.6175.1070

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Summary

The new atlas, which shows the distribution of important trace metals and other substances, is the first product of GEOTRACES, a $300 million international effort. It draws on careful measurements from more than 30,000 seawater samples drawn from nearly 800 locations. One map, for example, shows the distribution of minute trace levels of the toxic metal lead, once a major component of gasoline. In the Atlantic Ocean, GEOTRACES researchers show that lead-tainted water that was once at the surface has now sunk some 1000 meters, creating a kind of time capsule recording past pollution. But the map also shows that contamination in continuing, with relatively high trace levels entering the Atlantic from the Indian Ocean, which is bordered by nations where cars still burn leaded gasoline. Overall, however, lead levels in the Atlantic have been dropping since the United States and Europe banned leaded gasoline decades ago, and the levels pose no threat to humans or wildlife.