They state that peak measurements showed that up to nearly 60% of the iron in one vast swath of the northern part of the ocean emanates from smokestacks.
“It has long been understood that burning fossil fuels alters Earth’s climate and ocean ecosystems by releasing carbon dioxide into the atmosphere,” Seth John, senior author of the study and professor at the University of Southern California, said in a media statement. “This work shows fossil fuel burning has a side effect: the release of iron and metals into the atmosphere that carry thousands of miles and deposit in the ocean where they can impact marine ecosystems.”
According to John, certain metal deposits could help some marine life thrive while harming other life.
To carry out this research, the scientist and his colleagues measured metals in surface seawater. They focused on a remote part of the Pacific Ocean, hundreds of miles north of Hawaii and about midway between Japan and California. The region is downwind of industrial emissions in east Asia.
In May 2017, they boarded a research vessel and took water samples along a north-south transect at latitudes between 25 degrees and 42 degrees north. They found peak iron concentrations in about the middle, which corresponded with a big wind event over east Asia one month before. The peak iron concentrations were about three times greater than the background ocean measurements.
The researchers also found that elevated lead concentrations coincided with the iron hot spots. Other research has shown that most of the lead at the ocean surface comes from manmade sources, including cement plants, coal-fired power plants and metal smelters.
Similarly, this new study concluded that the metals in the seawater samples they took bear telltale traces of Chinese industrial sources.
Since the North Pacific notably lacks iron, the scientists say that an influx of metals and other substances can help build the foundation for a new ecosystem. However, this situation must be interpreted as a ‘good news, bad news’ outcome for Earth.
“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 explained. “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. However, it’s totally unsustainable as a long-term geoengineering solution because of the deleterious effects of pollution on human health.”