Xosé Antón Álvarez Salgado¹, Victor Martinez-Vicente², Gemma Kulk³, Angus Laurenson², Andrey Kurekin², Daniel Clewley², Elin Meek², Jon White², Tiit Kutser⁴, Kaire Toming⁴, Roberto Sabia⁵, Javier Alonso Concha⁶ and Steve Groom², (1)Organic Geochemistry Lab, CSIC Institute of Marine Research, Vigo, Spain, (2)Plymouth Marine Laboratory, Plymouth, United Kingdom, (3)Earth Observation Science & Applications, Plymouth Marine Laboratory, Plymouth, United Kingdom, (4)Estonian Marine Institute, University of Tartu, Tartu, Estonia, (5)European Space Agency, Frascati, Italy, (6)European Space Research Institute, European Space Agency, Frascati, Italy