translated from Spanish: Researchers reveal that the distribution of iron in icebergs is different from what was thought

Iron is an essential micronutrient for all living organisms. In the oceans, this metal is extremely scarce and its contribution acts as a natural fertilizer increasing marine productivity. The growth of microalgae consumes carbon dioxide (CO2), produces 50% of the oxygen that is breathed on the planet and may be limited by the amount of iron in seawater.
Although this metal is very abundant in the Earth’s crust, in the oceanic areas its presence is scarce. Particularly in the Southern Ocean, its concentration is even lower, as the Antarctic Circumpolar Current and the west winds prevent terrestrial inputs from other areas, while Antarctic ice retains it on the continent.
Glacier ice iron
A new study published in the prestigious journal Nature Communications revealed that iron is not evenly distributed in icebergs, as scientific literature had assumed for decades due to lack of evidence. After four years of work and analysis of the glacial ice of 207 points of the Arctic, Patagonia and Antarctica, it was determined that approximately 90% of the metal is concentrated in only 4% of the samples analyzed.
Scientists from the Helmholtz Centre for Ocean Research Kiel (GEOMAR) in Germany and two Chilean institutions participated in the research: the High Latitudes Marine Ecosystem Dynamic Research Center (IDEAL) of the Universidad Austral de Chile ( UACh) and the Pontifical Catholic University of Valparaiso (PUCV). With the data obtained they created the world’s largest database of iron concentration in icebergs.
“This work shows that the effect of icebergs on ocean productivity depends largely on where the sediments and iron-rich layers are located, and how their distribution and abundance changes according to the variation of ice sheets” Explained the study leader, GEOMAR chemist and IDEAL Center researcher Dr. Mark Hoopwood.
Relationship between iron and ice masses
To date, the scientific community has used the “average” to estimate the effect of icebergs on ocean fertilization. However, the researchers found that this approach is not correct.
“Our records show that the relationship between iron and ice masses is much more complex than thought. Historically, scientists have used the ‘medium’ concentration of this metal in icebergs to analyze its fertilizing effect. However, thanks to this research we realized that this was not a valid tool, because as the glaciers are defrosted, their properties change. In the future we must see where the sediment comes from in the icebergs,” said the opographer Dr. Juan Hufer, a PUCV academic and researcher at the IDEAL Center.
The study marks a milestone for models used in the future, especially in a climate change context, in which it is predicted that the flow of glacial ice to the oceans will continue to increase over the next few years.
As a result, the amount of fertilization of icebergs – particularly in the Southern Ocean – is also thought to continue to grow. However, it will probably do so to a lesser extent than had been thought before, given that thanks to this study it is known that the fertilizing effect and the flow of glacial ice are not directly and simply related.
“The great importance of this study is that the relationship between the fertiliser effect of glaciers and the productivity of surrounding marine systems is different from what we thought. Glaciers are home to iron, a productivity limiting micronutrient, affecting the composition and extent of primary producers in marine systems,” concludes the oceanographer and director of the IDEAL Center, Dr. Humberto González.

Original source in Spanish