Dissolved organic matter (DOM) is an important component of the global carbon cycle. However, achieving sufficient knowledge of its global distribution, particularly in the ocean, remains a challenge. The Brazil-Malvinas Confluence (BMC) is of particular interest to this respect, as subantarctic and subtropical waters of very different characteristics meet in the BMC. Further, the BMC is an important site for the returning Atlantic Meridional Overturning Circulation (AMOC), largely setting the latitudinal rate of transfer of key properties. Dissolved organic carbon (DOC), nitrogen (DON) and phosphorus (DOP) tend to accumulate, especially in the upper waters, becoming a significant component of the return of carbon and nutrients and influencing the nutrient balance of the North Atlantic. Therefore, a good knowledge of the distribution of DOC, DON and DOP in the BMC region is very relevant. Here, we report hydrographic data and DOC, DON and DOP concentrations obtained from two cruises across the BMC. We found, in the upper 1000 m of the region, a range of 36-125 µmol·kg^-1 DOC, 0.2-26 µmol·kg^-1 DON and 0.1-2 µmol·kg^-1 DOP. We performed an inverse optimum multi-parameter (OMP) analysis with the aim of estimating the changes in the dissolved organic carbon and nutrient concentrations of the different water types, hence providing a better context for studying the distribution and transformation of DOM along the BMC system.

Primary Presenter: Pol Rojas, Universitat de Barcelona, Barcelona, Spain (polrojas@ub.edu)

Authors:

Pol Rojas Sanchez, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain  (polrojas@ub.edu)

Carles Guallar, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain  ()

Patricia De La Fuente, Departament d’Oceanografia Física i Tecnològica, Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain  ()

Dorleta Orúe-Echevarría, Departament d’Oceanografia Física i Tecnològica, Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain  ()

Mikhail Emelianov, Departament d’Oceanografia Física i Tecnològica, Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain  ()

Celia Marrasé, Departament d’Oceanografia Física i Tecnològica, Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain  ()

Josep L. Pelegrí, Departament d’Oceanografia Física i Tecnològica, Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain  ()

Montserrat Vidal, Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Barcelona, Spain  ()