Soot or Black Carbon (BC) is the reminiscence of incomplete combustion of fossil fuels, biofuels, and biomass. This emission often tends to contain aerosol which can be extremely harmful to the aquatic environment. BC contributes to the acceleration of sea ice melting in the Arctic. Scientists from all over the world are trying to figure out strategies to change this situation.
Aron Stubbins, a professor of marine and environmental sciences at Northeastern University, along with a team of researchers are trying to establish how rivers transport BC into the ocean. The study was published in Nature Communications which showed how the carbon dwelling in the rivers does not match with that in the oceans.
He concluded that, due to the long journey from rivers to oceans and the continuous exposure to sunlight, the black carbon goes through some changes. It causes the black carbon to quickly transform into carbon dioxide which entraps the heat, thus controlling Earth’s climate. Stubbins says, “It’s a lot of carbon, we want to understand how it cycles to understand if it will ever end up in the atmosphere as carbon dioxide.”
To study more about the difference between the black carbon in rivers and oceans, Stubbins started testing both of them individually. They found a water body deep enough to carry out the test, moreover, it was situated offshore as well. The team took samples from the North Pacific and North Atlantic oceans and also included rivers like the Amazon, the Congo, and other major rivers. This test was led by Sasha Wagner, a former researcher at Northeastern and an assistant professor of earth and environmental sciences at Rensselaer Polytechnic Institute in Troy, New York
Stubbins noticed that the black carbon present in the ocean’s samples were quite similar to that of the ocean, yet different. He was able to spot those differences with stable carbon isotopes. They are generally used to trace the origin of a substance found in nature. It determined that the carbon dioxide became carbon-12, the most abundant carbon, after being absorbed by air and plants.
He says, “By looking at the isotopes of black carbon, we found that black carbon in the oceans is not from the same source as the black carbon in rivers.” However, still, a question remains unanswered: “Where did the black carbon dissolve in the ocean come from?” To answer this, he concludes in a very hopeful tone, saying, “Maybe somewhere in there there’s a clue for the source of this material.”
Subarna Basu