As the saying goes, what goes up should come down—and, because it seems, lots of what runs up comes down into the world’s oceans. Iron particles, launched by human industrial activities, are one instance of a pollutant that goes into the environment and ultimately settles into the ocean. Now, new analysis means that human-emitted iron is accumulating in the ocean in much larger quantities than scientists previously estimated. And it might also be dissolving into the water more easily than suspected.
The results are still unclear, but they are worth investigating, scientists say. Iron is likely one of the key nutrients that tiny phytoplankton organisms in the ocean need to thrive. In areas where its ranges are limited, including more iron to the water may give plankton a hike, potentially altering both marine food webs and the ocean’s carbon uptake.
Actually, this phenomenon is the basis for a controversial geoengineering concept that some scientists have proposed to tackle climate change. Known as “iron fertilization,” the idea entails including iron to certain remote regions of the ocean where iron nutrients are usually limited. Doing so may promote the growth of phytoplankton, which naturally sucks up carbon dioxide.
Now, the new research would appear to counsel that people could already be engaging in a type of inadvertent iron fertilization campaign. But whether it is having any significant effect on marine ecosystems or carbon storage continues to be unknown.
Scientists have long recognized that dust from the Sahara, swept by winds into the sea, tends to be rich in iron and accounts for quite a lot of the iron particles that wind up in the Atlantic Ocean. Iron input from anthropogenic sources, like the burning of fossil fuels and other industrial activities, is believed to be comparatively much decrease.
The new research investigated the difficulty by chemically analyzing iron samples from the North Atlantic. Aerosols from dust and from human sources tend to have slightly different chemical fingerprints, associated with the ratio of iron isotopes they contain.