A study from a USC-led research team has found that emissions from coal-fired power plants in China are fertilizing the North Pacific Ocean with a metal nutrient that is important for marine life and may change the ocean’s ecosystem.
“Certain metal deposits could help some marine life thrive while harming other life,” said Seth John, the study’s lead author and an assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “There are inevitable tradeoffs when the ocean water’s chemistry changes.”
The study, published last Thursday in the Proceedings of the National Academy of Sciences, showed that smoke from power plants carries iron and other metals to the surface waters of the North Pacific Ocean as westerly winds blow emissions from Asia to North America.
Peak measurements show that up to nearly 60% of the iron in one vast swath of the northern part of the ocean emanates from smokestacks, according to researchers.
John said it has “long been understood that burning fossil fuels alters Earth’s climate and ocean ecosystems by releasing carbon dioxide into the atmosphere,” and noted that the study showed that fossil fuel burning has the side effect of releasing iron and metals into the atmosphere that carry thousands of miles and deposit in the ocean where they can impact marine ecosystems.
The research team measured metals in surface seawater, focusing on a remote part of the Pacific Ocean that is downwind of industrial emissions in east Asia and hundreds of miles north of Hawaii and about midway between Japan and California.
The peak iron concentrations found are about three times greater than background ocean measurements, and elevated lead concentrations coincided with the iron “hot spots,” according to the study.
“When we collected samples in the ocean, we found that the iron isotope and lead isotope `fingerprints’ from seawater matched those of anthropogenic pollution from Asia,” said Paulina Pinedo-Gonzalez, a USC post-doctoral scientist and study author who is now at the Lamont-Doherty Earth Observatory at Columbia University.
Researchers said the study has important implications for marine life, with the North Pacific lacking iron, a key micronutrient, noting that an influx of metals and other substances can help build the foundation for a new ecosystem.
“Microscopic iron-containing particles released during coal burning impacts algae growth in the ocean, and therefore the entire ecosystem for which algae form the base of the food chain,” John said. “In the short term, we might think that iron in pollution is beneficial because it stimulates the growth of phytoplankton, which then take carbon dioxide out of the atmosphere as they grow to offset some of the carbon dioxide released during the initial burning process.”
But he added that “it’s totally unsustainable as a long-term geoengineering solution because of the deleterious effects of pollution on human health. Thus, the take-home message is perhaps a better understanding of an unintended side effect of coal burning and the ways in which that can impact ocean ecosystems thousands of miles away.”
The study’s authors also include Nicholas J. Hawco of USC, Randelle M. Bundy and E. Virginia Armbrust of the University of Washington; Michael J. Follows of MIT; B.B. Cael of National Oceanography Center of the United Kingdom; and Angelicque E. White, Sara Ferron and David M. Karl of the University of Hawaii at Manoa.
The research was supported by the Simons Foundation.
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