Jack Middelburg was trained as a biogeologist/geochemist and worked from 1992-2009 at the Netherlands Institute of Ecology. Since 2009 he holds the geochemistry chair at Utrecht University and an excellent chair at MARUM, University of Bremen (since 2019). He has a very wide scientific interest, from inorganic geochemistry via biogeochemistry to ecology, from elemental-cycles oriented to organisms-oriented studies, from weathering of rocks to deep-sea pore-waters, from laboratory studies and field observations to numerical modelling, from global scale down to nanometer scale, and through the use of reductionistic as well as holistic and explorative approaches. He has been elected member of the Royal Netherlands Academy of Arts and Sciences, Academia Europaea and European Academy of Sciences, is Fellow of the EAG/Geochemical Society and is recipient of various awards, including ASLO's Hutchinsons award in 2016 and the EGU's Vernadsky award in 2017. He has authored an open access text book Ocean Carbon Biogeochemistry and is scientific director of the Netherlands Earth System Science Centre.