Royal Netherlands Institute for Sea Research
Royal Netherlands
Institute for Sea Research
Phone number
+31 (0)222 369 410
Ocean Systems (OCS)
Senior Scientist
  • Trace Metals
  • Marine biogeochemical cycles
  • Chemical oceanography
  • ICP-MS
  • Role of metals in marine ecosystems

Dr. Rob Middag

Senior Scientist

Research interest & specialisation

My research focusses on the role of metals in marine ecosystems. Though often solely regarded as toxins, metals are required as nutrients for the growth of all organisms. Metals form the reactive centres of enzymes, enabling these to perform biochemical functions, such as oxygen-transport or photosynthesis. As such, trace metals are central to the health of individual organisms as well as entire ecosystems. On the other hand, elevated concentrations of metals can have detrimental effect to individual organisms as well as ecosystems and this double sided nature of metals is what inspires my research. Specific research foci:
    •    Determination of trace elements in seawater samples to establish drivers (trace nutrients) or stressors in marine ecosystems. Especially in the (sub)Antarctic regions, trace metal availability regulates primary production. The role of iron is well established, but the role of other metals is becoming more evident as well.
    •     Development and application of ICP-MS based and flow injection methods for the analysis of trace elements in sea water to expand our capabilities to determine levels of trace nutrient levels, contaminants as well as tracers of ocean processes.
    •    Trace metal clean bio assays to assess trace nutrient stress.
    •    Ultra clean sampling of open ocean regions for trace elements; to get reliable data on trace elements and their functions in ecosystems, utmost care must be taken during sampling and sample handling to avoid contamination. 


Linked news

Wednesday 08 April 2020
A rapidly changing Arctic: Shelf sediments, freshwater runoff from rivers brings more carbon, nutrients to North Pole
A new study by researchers at Woods Hole Oceanographic Institution (WHOI) and their international colleagues, among which several NIOZ researchers, found that freshwater runoff from rivers and continental shelf sediments are bringing significant…
Friday 23 August 2019
Phytoplankton, the base of the ocean’s food-chain, can influence climate
A recent study, conducted by researchers from Dalhousie University and NIOZ researcher Rob Middag has been published in Nature Communications. They examined the effects of low iron and manganese, an element often found in minerals in combination with…
Friday 01 June 2018
3 Vidi-beurzen voor NIOZ-onderzoekers | 3 Vidi grants for NIOZ researchers
[Scroll down for English version] De Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) heeft aan drie ervaren NIOZ-onderzoekers een Vidi-financiering van 800.000 euro toegekend. Hiermee kunnen zij de komende vijf jaar een eigen,…
Thursday 16 March 2017
Sea Acceptance Test Confirms Quality of NIOZ ‘Pristine’ Ultra Clean CTD
In March 2017, a Sea Acceptance Test (SAT) of the ‘Pristine’ Ultra Clean CTD-system (UCC) was successfully carried out on board of the South Korean research vessel ‘Isabu’, sailing from Guam in the Pacific Ocean near the Mariana-trench. This system…
Monday 06 February 2017
Kleine wezens, groot effect op het oceaanleven
Kiezelwieren zijn klein maar o zo belangrijk voor het zeeleven in de Zuidelijke Oceaan: door hun enorme biomassa bepalen ze de verdeling van voedingsstoffen en sporenelementen rond Antarctica. Een internationale groep onderzoekers toont dit aan in…

Linked blogs

Monday 11 February 2019
Antarctic expedition FePhyrus II
Wat hebben ijzer en virus-infecties in Antarctica met elkaar te maken? We zijn op expeditie in de Zuidelijke Oceaan en de Weddellzee om dit uit te zoeken. Volg onze avonturen in de winter van 2018/2019 via deze blog! ~~~~ English version below ~~~~
Wednesday 21 February 2018
Antarctic expedition FePhyrus
Wat hebben ijzer en virus-infecties in Antarctica met elkaar te maken? We zijn op expeditie in de kustgebieden van West-Antarctica om dit uit te zoeken. Volg onze avonturen in de winter van 2017/2018 via deze blog! ~~~~ English version…
Friday 18 August 2017
Expedition STRATIPHYT-17
An ad-hoc cruise where an interdisciplinary team will build on earlier obtained knowledge during the STRATIPHYT project, but where we will also investigate new ideas, and collect samples for others that cannot join the cruise. The team consists of 3…

NIOZ publications

  • 2020
    Ardiningsih, I.; Krisch, S.; Lodeiro, P.; Reichart, G.-J.; Achterberg, E.P.; Gledhill, M.; Middag, R.; Gerringa, L.J.A. (2020). Natural Fe-binding organic ligands in Fram Strait and over the northeast Greenland shelf. Mar. Chem. 224: 103815.
    Menzel Barraqueta, J.-L.; Samanta, S.; Achterberg, E.P.; Bowie, A.R.; Croot, P.; Cloete, R.; De Jongh, T.; Gelado-Caballero, M.D.; Klar, J.K.; Middag, R.; Loock, J.C.; Remenyi, T.A.; Wenzel, B.; Roychoudhury, A.N. (2020). A first global oceanic compilation of observational dissolved aluminum data with regional statistical data treatment. Front. Mar. Sci. 7: Article 468.
    Middag, R.; De Baar, H.J.W.; Bruland, K.W.; van Heuven, S.M.A.C. (2020). The distribution of nickel in the west-Atlantic Ocean, its relationship with phosphate and a comparison to cadmium and zinc. Front. Mar. Sci. 7(article 105).
  • 2019
    George, E.; Stirling, C.H.; Gault-Ringold, M.; Ellwood, M.J.; Middag, R. (2019). Marine biogeochemical cycling of cadmium and cadmium isotopes in the extreme nutrient-depleted subtropical gyre of the South West Pacific Ocean. Earth Planet. Sci. Lett. 514: 84-95.
    Grand, M.M.; Laes-Huon, A.; Fietz, S.; Resing, J.A.; Obata, H.; Luther, G.W.; Tagliabue, A.; Achterberg, E.P.; Middag, R.; Tovar-Sanchez, A.; Bowie, A.R. (2019). Developing autonomous observing systems for micronutrient trace metals. Front. Mar. Sci. 6: 35.
    Hartland, A.; Zitoun, R.; Middag, R.; Sander, S.; Laferriere, A.; Saeed, H.; De Luca, S.; Ross, P.M. (2019). Aqueous copper bioavailability linked to shipwreck-contaminated reef sediments. NPG Scientific Reports 9(1): 13 pp.
    Middag, R.; de Baar, H.J.W.; Bruland, K.W. (2019). The relationships between dissolved zinc and major nutrients phosphate and silicate along the GEOTRACES GA02 transect in the west Atlantic Ocean. Global Biogeochem. Cycles 33(1): 63-84.
    Wu, M.; McCain, J.S.P.; Rowland, E.; Middag, R.; Sandgren, M.; Allen, A.E.; Bertrand, E.M. (2019). Manganese and iron deficiency in Southern Ocean Phaeocystis antarctica populations revealed through taxon-specific protein indicators. Nature Comm. 10: 3582.
  • 2018
    Arrigo, K.R.; van Dijken, G.L.; Alderkamp, A.-C.; Erickson, Z.K.; Lewis, K.M.; Lowry, K.E.; Joy-Warren, H.L.; Middag, R.; Nash-Arrigo, J.E.; Selz, V.; van de Poll, W. (2017). Early Spring Phytoplankton Dynamics in the Western Antarctic Peninsula. JGR: Oceans 122(12): 9350–9369.
    Baltar, F.; Gutiérrez-Rodríguez, A.; Meyer, M.; Skudelny, I.; Sander, S.; Thomson, B.; Nodder, S.; Middag, R.; Morales, S.E. (2018). Specific effect of trace metals on marine heterotrophic microbial activity and diversity: Key role of iron and zinc and hydrocarbon-degrading bacteria. Front. Microbiol. 9: 3190.
    Dulaquais, G.; Waeles, M.; Gerringa, L.J.A.; Middag, R.; Rijkenberg, M.J.A.; Riso, R. (2018). The biogeochemistry of electroactive humic substances and its connection to iron chemistry in the North East Atlantic and the western Mediterranean Sea. Journal of Geophysical Research-Oceans 123(8): 5481-5499.
    Middag, R.; van Heuven, S.M.A.C.; Bruland, K.W.; de Baar, H.J.W. (2018). The relationship between cadmium and phosphate in the Atlantic Ocean unravelled. Earth Planet. Sci. Lett. 492: 79-88.
    Rolison, J.M.; Sterling, C.H.; Middag, R.; Gault-Ringold, M.; George, E.; Rijkenberg, M.J.A. (2018). Iron isotope fractionation during pyrite formation in a sulfidic Precambrian ocean analogue. Earth Planet. Sci. Lett. 488: 1-13.
    Rusiecka, D.; Gledhill, M.; Milne, A.; Achterberg, E.P.; Annett, A.L.; Atkinson, S.; Birchill, A.; Karstensen, J.; Lohan, M.; Mariez, C.; Middag, R.; Rolison, J.M.; Tanhua, T.; Ussher, S.; Connelly, D. (2018). Anthropogenic signatures of lead in the Northeast Atlantic. Geophys. Res. Lett. 45(6): 2734-2743.
    Schlitzer,R.; Anderson,R.F.; Dodas,E.M.; Lohan,M.; Geibert,W.; Tagliabue,A.; Bowie,A.; Jeandel,C.; Maldonado,M.T.; Landing,W.M.; Cockwell,D.; Abadie,C.; Abouchami,W.; Achterberg,E.P.; Agather,A.; Aguliar-Islas,A.; van Aken,H.M.; Andersen,M.; Archer,C.; Auro,M.; de Baar,H.J.; Baars,O.; Baker,A.R.; Bakker,K.; Basak,C.; Baskaran,M.; Bates,N.R.; Bauch,D.; van Beek,P.; Behrens,M.K.; Black,E.; Bluhm,K.; Bopp,L.; Bouman,H.; Bowman,K.; Bown,J.; Boyd,P.; Boye,M.; Boyle,E.A.; Branellec,P.; Bridgestock,L.; Brissebrat,G.; Browning,T.; Bruland,K.W.; Brumsack,H.-J.; Brzezinski,M.; Buck,C.S.; Buck,K.N.; Buesseler,K.; Bull,A.; Butler,E.; Cai,P.; Mor,P.C.; Cardinal,D.; Carlson,C.; Carrasco,G.; Casacuberta,N.; Casciotti,K.L.; Castrillejo,M.; Chamizo,E.; Chance,R.; Charette,M.A.; Chaves,J.E.; Cheng,H.; Chever,F.; Christl,M.; Church,T.M.; Closset,I.; Colman,A.; Conway,T.M.; Cossa,D.; Croot,P.; Cullen,J.T.; Cutter,G.A.; Daniels,C.; Dehairs,F.; Deng,F.; Dieu,H.T.; Duggan,B.; Dulaquais,G.; Dumousseaud,C.; Echegoyen-Sanz,Y.; Edwards,R.L.; Ellwood,M.; Fahrbach,E.; Fitzsimmons,J.N.; Russell Flegal,A.; Fleisher,M.Q.; van de Flierdt,T.; Frank,M.; Friedrich,J.; Fripiat,F.; Fröllje,H.; Galer,S.J.G.; Gamo,T.; Ganeshram,R.S.; Garcia-Orellana,J.; Garcia-Solsona,E.; Gault-Ringold,M.; George,E.; Gerringa,L.J.A.; Gilbert,M.; Godoy,J.M.; Goldstein,S.L.; Gonzalez,S.R.; Grissom,K.; Hammerschmidt,C.; Hartman,A.; Hassler,C.S.; Hathorne,E.C.; Hatta,M.; Hawco,N.; Hayes,C.T.; Heimbürger,L.-E.; Helgoe,J.; Heller,M.; Henderson,G.M.; Henderson,P.B.; van Heuven,S.; Ho,P.; Horner,T.J.; Hsieh,Y.-T.; Huang,K.-F.; Humphreys,M.P.; Isshiki,K.; Jacquot,J.E.; Janssen,D.J.; Jenkins,W.J.; John,S.; Jones,E.M.; Jones,J.L.; Kadko,D.C.; Kayser,R.; Kenna,T.C.; Khondoker,R.; Kim,T.; Kipp,L.; Klar,J.K.; Klunder,M.; Kretschmer,S.; Kumamoto,Y.; Laan,P.; Labatut,M.; Lacan,F.; Lam,P.J.; Lambelet,M.; Lamborg,C.H.; Le Moigne,F.A.C.; Le Roy,E.; Lechtenfeld,O.J.; Lee,J.-M.; Lherminier,P.; Little,S.; López-Lora,M.; Lu,Y.; Masque,P.; Mawji,E.; Mcclain,C.R.; Measures,C.; Mehic,S.; Barraqueta,J.-L.M.; van der Merwe,P.; Middag,R.; Mieruch,S.; Milne,A.; Minami,T.; Moffett,J.W.; Moncoiffe,G.; Moore,W.S.; Morris,P.J.; Morton,P.L.; Nakaguchi,Y.; Nakayama,N.; Niedermiller,J.; Nishioka,J.; Nishiuchi,A.; Noble,A.; Obata,H.; Ober,S.; Ohnemus,D.C.; van Ooijen,J.; O'Sullivan,J.; Owens,S.; Pahnke,K.; Paul,M.; Pavia,F.; Pena,L.D.; Peters,B.; Planchon,F.; Planquette,H.; Pradoux,C.; Puigcorbé,V.; Quay,P.; Queroue,F.; Radic,A.; Rauschenberg,S.; Rehkämper,M.; Rember,R.; Remenyi,T.; Resing,J.A.; Rickli,J.; Rigaud,S.; Rijkenberg,M.J.A.; Rintoul,S.; Robinson,L.F.; Roca-Martí,M.; Rodellas,V.; Roeske,T.; Rolison,J.M.; Rosenberg,M.; Roshan,S.; Rutgers van der Loeff,M.M.; Ryabenko,E.; Saito,M.A.; Salt,L.A.; Sanial,V.; Sarthou,G.; Schallenberg,C.; Schauer,U.; Scher,H.; Schlosser,C.; Schnetger,B.; Scott,P.; Sedwick,P.N.; Semiletov,I.; Shelley,R.; Sherrell,R.M.; Shiller,A.M.; Sigman,D.M.; Singh,S.K.; Slagter,H.A.; Slater,E.; Smethie,W.M.; Snaith,H.; Sohrin,Y.; Sohst,B.; Sonke,J.E.; Speich,S.; Steinfeldt,R.; Stewart,G.; Stichel,T.; Stirling,C.H.; Stutsman,J.; Swarr,G.J.; Swift,J.H.; Thomas,A.; Thorne,K.; Till,C.P.; Till,R.; Townsend,A.T.; Townsend,E.; Tuerena,R.; Twining,B.S.; Vance,D.; Velazquez,S.; Venchiarutti,C.; Villa-Alfageme,M.; Vivancos,S.M.; Voelker,A.H.L.; Wake,B.; Warner,M.J.; Watson,R.; van Weerlee,E.; Alexandra Weigand,M.; Weinstein,Y.; Weiss,D.; Wisotzki,A.; Woodward,E.M.S.; Wu,J.; Wu,Y.; Wuttig,K.; Wyatt,N.; Xiang,Y.; Xie,R.C.; Xue,Z.; Yoshikawa,H.; Zhang,J.; Zhang,P.; Zhao,Y.; Zheng,L.; Zheng,X.-Y.; Zieringer,M.; Zimmer,L.A.; Ziveri,P.; Zunino,P.; Zurbrick,C. (2018). The GEOTRACES Intermediate Data Product 2017. Chem. Geol. 493: 210-223.
  • 2017
    de Baar, H.J.W; van Heuven, S.; Middag, R. (2017). Ocean Biochemical Cycling and Trace Elements, in: Encyclopedia of Geochemistry. Encyclopedia of Earth Sciences Series, : pp. 1-21; Chapter 356-1.
    de Baar, H.J.W; van Heuven, S.M.A.C.; Middag, R. (2017). Ocean Salinity, Major Elements, and Thermohaline Circulation, in: Encyclopedia of Geochemistry. Encyclopedia of Earth Sciences Series, : pp. 1-7; Chapter 120-1.
    De Baar, H.J.W.; van Heuven, S.M.A.C.; Abouchami, W.; Xue, Z.; Galer, S.J.G.; Rehkämper, M.; Middag, R.; van Ooijen, J. (2017). Interactions of dissolved CO2 with cadmium isotopes in the Southern Ocean. Mar. Chem. 195: 105-121.
    Rolison, J.M.; Stirling, C.H.; Middag, R.; Rijkenberg, M.J.A. (2017). Uranium stable isotope fractionation in the Black Sea: Modern calibration of the 238U/235U paleo-redox proxy. Geochim. Cosmochim. Acta 203: 69–88.
    van Hulten, M.; Middag, R.; Dutay, J.-C.; de Baar, H.; Roy-Barman, M.; Gehlen, M.; Tagliabue, A.; Sterl, A. (2017). Manganese in the west Atlantic Ocean in the context of the first global ocean circulation model of manganese. Biogeosciences 14: 1123-1152.
    Vance, D.; Little, S.H.; de Souza, G.F.; Khatiwala, S.; Middag, R. (2017). Silicon and zinc biogeochemical cycles coupled through the Southern Ocean. Nature Geoscience 10(3): 202-206.
  • 2015
    Middag, R.; Séférian, R.; Conway, T.M.; John, S.G.; Bruland, K.W.; de Baar, H.J.W. (2015). Intercomparison of dissolved trace elements at the Bermuda Atlantic Time Series station. Mar. Chem. 177(Part 3): 476–489.
    Middag, R.; van Hulten, M.M.P.; van Aken, H.M.; Rijkenberg, M.J.A.; Gerringa, L.J.A.; Laan, P.; de Baar, H.J.W. (2015). Dissolved aluminium in the ocean conveyor of theWest Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography. Mar. Chem. 177(Part 1): 69–86.
    Rijkenberg, M.J.; de Baar, H.J.W.; Bakker, K.; Gerringa, L.J.A.; Keijzer, E.; Laan, M.; Laan, P.; Middag, R.; Ober, S.; van Ooijen, J.; Ossebaar, S.; van Weerlee, E.M.; Smit, M. (2015). “PRISTINE”, a new high volume sampler for ultraclean sampling of trace metals and isotopes. Mar. Chem. 177(Part 3): 501–509.
  • 2014
    Abouchami, W.; Galer, S.J.G.; de Baar, H.J.W.; Middag, R.; Vance, D.; Zhao, Y.; Klunder, M.; Mezger, K.; Feldmann, H.; Andreae, M.O. (2014). Biogeochemical cycling of cadmium isotopes in the Southern Ocean along the Zero Meridian. Geochim. Cosmochim. Acta 127: 348-367.
    Dulaquais, G.; Boye, M.; Middag, R.; Owens, S.; Puigcorbe, V.; Buesseler, K.; Masqué, P.; De Baar, H.J.W.; Carton, X. (2014). Contrasting biogeochemical cycles of cobalt in the surface western Atlantic Ocean. Global Biogeochem. Cycles 28(12): 1387-1412.
    Klunder, M.B.; Laan, P.; de Baar, H.J.W.; Middag, R.; Neven, I.; Van Ooijen, J. (2014). Dissolved Fe across the Weddell Sea and Drake Passage: impact of DFe on nutrient uptake. Biogeosciences 11(3): 651-669.
    Rijkenberg, M.J.A.; Middag, R.; Laan, P.; Gerringa, L.J.A.; van Aken, H.M.; Schoemann, V.; de Jong, J.T.; de Baar, H.J.W. (2014). The Distribution of Dissolved Iron in the West Atlantic Ocean. PLoS One 9(6): e101323 1-14.
    van Hulten, M.M.P.; Sterl, A.; Middag, R.; de Baar, H.J.W.; Gehlen, M.; Dutay, J.-C.; Tagliabue, A. (2014). On the effects of circulation, sediment resuspension and biological incorporation by diatoms in an ocean model of aluminium. Biogeosciences 11: 3757-3779.
  • 2013
    Middag, R.; de Baar, H.J.W.; Klunder, M.B.; Laan, P. (2013). Fluxes of dissolved aluminum and manganese to the Weddell Sea and indications for manganese co-limitation. Limnol. Oceanogr. 58(1): 287-300.
    van Hulten, M.M.P.; Sterl, A.; Tagliabue, A.; Dutay, J.-C.; Gehlen, M.; de Baar, H.J.W.; Middag, R. (2013). Aluminium in an ocean general circulation model compared with the West Atlantic Geotraces cruises. J. Mar. Syst. 126: 3-23.
    Xue, Z.; Rehkämper, M.; Horner, T.J.; Abouchami, W.; Middag, R.; van de Flierd, T. ; de Baar, H.J.W. (2013). Cadmium isotope variations in the Southern Ocean. Earth Planet. Sci. Lett. 382: 161–172.
  • 2012
    Klunder, M.B.; Laan, P.; Middag, R.; de Baar, H.J.W.; Bakker, K. (2012). Dissolved iron in the Arctic Ocean: Important role of hydrothermal sources, shelf input and scavenging removal. J. Geophys. Res. 117.
    Middag, R.; de Baar, H.J.W.; Laan, P.; Huhn, O. (2012). The effects of continental margins and water mass circulation on the distribution of dissolved aluminum and manganese in Drake Passage. J. Geophys. Res. 117.
    Roeske, T.; Rutgers van der Loeff, M.; Middag, R.; Bakker, K. (2012). Deep water circulation and composition in the Arctic Ocean by dissolved barium, aluminium and silicate. Mar. Chem. 132: 56-67.
  • 2011
    Abouchami, W.; Galer, S.J.G.; de Baar, H.J.W.; Alderkamp, A.C.; Middag, R.; Laan, P.; Feldmann, H.; Andreae, M.O. (2011). Modulation of the Southern Ocean cadmium isotope signature by ocean circulation and primary productivity. Earth Planet. Sci. Lett. 305(1-2): 83-91.
    Klunder, M.B.; Laan, P.; Middag, R.; de Baar, H.J.W.; van Ooijen, J.C. (2011). Dissolved iron in the Southern Ocean (Atlantic sector). Deep-Sea Res., Part 2, Top. Stud. Oceanogr. 58(25-26): 2678-2694.
    Middag, R.; de Baar, H.J.W.; Laan, P.; Cai, P.H.; van Ooijen, J.C. (2011). Dissolved manganese in the Atlantic sector of the Southern Ocean. Deep-Sea Res., Part 2, Top. Stud. Oceanogr. 58(25-26): 2661-2677.
    Middag, R.; de Baar, H.J.W.; Laan, P.; Klunder, M.B. (2011). Fluvial and hydrothermal input of manganese into the Arctic Ocean. Geochim. Cosmochim. Acta 75(9): 2393-2408.
    Middag, R.; van Slooten, C.; de Baar, H.J.W.; Laan, P. (2011). Dissolved aluminium in the Southern Ocean. Deep-Sea Res., Part 2, Top. Stud. Oceanogr. 58(25-26): 2647-2660.
    Rutgers van der Loeff, M.; Cai, P.H.H.; Stimac, I.; Bracher, A.; Middag, R.; Klunder, M.B.; van Heuven, S.M.A.C. (2011). 234Th in surface waters: Distribution of particle export flux across the Antarctic Circumpolar Current and in the Weddell Sea during the GEOTRACES expedition ZERO and DRAKE. Deep-Sea Res., Part 2, Top. Stud. Oceanogr. 58(25-26): 2749-2766.

Linked projects

FePhyrus_Iron limitation and viral lysis, phytoplankton caught between a rock and a hard place
Rob Middag
Netherlands Organization for Scientific Research
Project duration
1 May 2017 - 30 Apr 2021
Trace metals & the Artic-Atlantic gateway in a changing world
Rob Middag
Netherlands Organization for Scientific Research - Veni/Vidi/Vici
Project duration
15 Nov 2018 - 31 Oct 2023