The progressive increase in atmospheric carbon dioxide levels since the beginning of the industrial era also has repercussions on surface ocean waters by absorbing part of this anthropogenic CO2. If on the one hand, the oceans contribute to mitigating global warming by capturing part of this atmospheric carbon dioxide, on the other hand, the sea is becoming more acid because there is more and more dissolved CO2, which causes negative effects for organisms with carbonated shells, skeletons, shells, etc., species some of which are of economic interest. These effects described in numerous scientific works occur in the water column, but what happens at the bottom where part of the carbon “sequestered” by organisms accumulates, as do the rest of the shells or skeletons, in the form of calcium carbonate, when the organisms die? “That is where the importance of sediments lies, because in them we can measure how much organic carbon and carbonate they contain and we can measure how their concentration has changed over time, even over a few centuries. That is, we can measure the concentration that existed before the industrial era and how much it has varied throughout it, up to the present day.” This is how Guillermo Francés, professor and researcher at the Department of Marine Geosciences and Territorial Planning at the University of Vigo, explains the importance of, when calculating carbon cycle flows, not restricting ourselves solely to the water column, as occurs in most studies carried out, but rather introducing into the calculation the part that “still a minority, it is not negligible”, goes to the sediments or, eventually, that the sediments are returning to the ocean.
Although, as Francés details, “sediments allow estimates to be made about primary productivity and the circulation of water masses (the two large groups of variables that intervene in the carbon cycle) in the recent past, and also, for current times, they allow the concentrations in the most superficial sediment to be related to what is happening at different depths in the water column”, the comprehensive study, which in addition to the water column also considers sediments, is something absolutely new, at least in the North Atlantic. Hence the importance of the BOCATS campaign that begins this Friday, June 17 and will last until early August and in which research and technical staff from the University of Vigo, the CSIC Marine Research Institute in Vigo and Ifremer will sail aboard the oceanographic vessel Sarmiento de Gamboa from Vigo to Reykjavik. During that period the researchers, as well as the technical staff, will take measurements of various oceanographic variables at approximately 126 points along a transect of the North Atlantic between Vigo and Greenland (OVIDE section), to then navigate south to the Reykjanes Ridge and continue the transect (RREX section) following the orientation of this submarine mountain range until it ends in Iceland.
University researchers focused on the study of sediments
Along with Guillermo Francés, Irene Alejo, Víctor Pelayo and Susa Álvarez complete the representation of the University of Vigo in the BOCATS campaign, which is developed within the framework of the project of the same name, acronym for Biennial Observation of Carbon, Acidification, Transport and Sedimentation in the North Atlantic, Observación bienal do carbono, acidificación, transporte e sedimentación no Atlántico Norte, a project financed by MINECO with more than 158,000 euros (not including the campaign) and led by the researcher from the Department of Oceanography of the CSIC’s Institute of Marine Research in Vigo, Fiz Fernández.
“The BOATS campaign aims to evaluate the transport of water, salt, heat, natural and anthropogenic carbon, other biogeochemical tracers and determine carbon fluxes between the water column and the ocean floor sediment”, explains Guillermo Francés in relation to the campaign, which in the case of researchers from the University of Vigo is focused on the study of ocean floor sediments in order to establish changes on a centennial scale in the speed of bottom currents and accumulation rates of calcium carbonate and organic carbon. “The advantage of this study is that the sedimentary data will be acquired at the same points where the bottom water is characterized, which will allow us to establish relationships between the current sedimentary record and the physical-chemical properties of the water mass in direct contact with the bottom”, highlights the researcher from the Department of Marine Geosciences and Territorial Planning.
In the case of the OVIDE section, there have been measurements of the water column repeated every two years since 2002, but this will be the first time that a comprehensive analysis of the water column and sediments has been carried out. On the other hand, the water column of the RREX section was measured for the first time last year, but no sediments were measured on that occasion. “As far as Fiz Fernández and I can remember, we are not aware of any study of this type in such an extensive area of the ocean, with so many measurement points, at different depths and in different bottom water masses. It is true that something similar has been done in some very restricted sectors, but it has nothing to do with what we propose”, explains Guillermo Francés.
Source DUVI
