That concept has made headlines with a recent study by researchers at the University of Hawai’i at Mānoa. Their findings showed dramatic shifts in iron sources in the South Pacific Ocean over the last 93 million years. This study points out just how important iron is to marine ecosystems. It plays a role in regulating the growth of phytoplankton, which are used to sequester atmospheric carbon dioxide.
Iron, an essential nutrient for many forms of marine life. It stimulates phytoplankton productivity, which in turn render them as important mediators of carbon cycling. These tiny organisms take in carbon dioxide, contributing to the global balance of the gas in our atmosphere. Iron limits phytoplankton production in a huge swath of the Pacific Ocean. This limitation renders the region a central area of interest for comprehending oceanic and climatic processes.
According to this research, hydrothermal sources of iron may have been the primary contributors to the South Pacific—at least initially. But around 30 million years ago, dust started to be more important and became the main iron supplier. This transition mirrors the extreme changes in geologic and atmospheric conditions that took place over hundreds of millions of years.
Over the past 93 million years, we found that five primary sources of iron have influenced the South Pacific Ocean: dust, iron from far off ocean sources, two distinct hydrothermal sources, and volcanic ash,” said Logan Tegler, one of the researchers involved in the study. He continued, “These sources changed through time as the environments of the sites slowly moved to a greater distance from mid-ocean ridges.
As it stands, the South Pacific is regarded as an iron-poor region. There’s one big shocker that Tegler’s findings reveal. Even with this special designation, modern dust deposition in this region is greater than it has been at any time in the last 90 million years. Contemporary dust deposition in the South Pacific is one of the lowest in the world. Perhaps most surprisingly, our results indicate that the South Pacific is now experiencing the most dust inputs in at least 90 million years. Even more amazing given its reputation as an iron-poor region! He continued.
Scientists analyzed iron isotopes from three sediment cores taken from the deep sea. This analysis enabled them to reveal the deep historical pattern of oceanic iron. Their findings underscore the importance of understanding how essential nutrients like iron have shaped ocean ecosystems and climate over millions of years.
Tegler further described how human activity is inadvertently boosting iron input to the oceans, such as through industrial emissions of iron and biomass burning. Learning from historical disruptions of the iron cycle is key to anticipating, preventing, and ameliorating their harmful consequences.