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Dr. Loes J.A. Gerringa

ROYAL NETHERLANDS INSTITUTE

FOR SEA RESEARCH

 

Postal address:

P.O. Box 59,

NL-1790 AB Den Burg (Texel)

The Netherlands

 

Visiting address:

Landsdiep 4

NL-1797 SZ ’t Horntje (Texel)

The Netherlands

 

Phone:

(+31) (0)222-369300

Fax:

(+31) (0)222-319674

Dept. BCO

E-mail: Loes.Gerringa@nioz.nl

Phone: (+31) (0)222-369439

 

 

Education

 

1972-1981            

14/9/1990            

 

Physical geography, University of Amsterdam. Masters in soil weathering.

PhD University of Groningen "Speciation of trace metals in relation to degradation of organic matter in marine sediment slurries".

 

Experience

 

 

 

01/03/1981 - 01/09/1985

Project manager at the National Institute of Public Health and Environmental Protection (RIVM)

 

01/09/1985 - 01/03/1990

PhD position, Netherlands Institute for Sea Research (NIOZ)

 

01/05/1990 - 01/04/1996

Scientist at the Netherlands Institute for Ecology (NIOO), Centre for Estuarine and Coastal Ecology.

 

15/04/1996 - 01/04/1999

Scientist (part time 0.4) at NIOZ.

 

01/06/1999 - 01/01/2003 

Post doc (part time 0.5, NWO, NAAP, grant nr 85120004), at NIOZ

 

01/09/2003 - 01/01/2006

Post doc (part time 0.5,) at NIOZ

 

01/06/2006 - now

Post doc (part time 0.5,) at NIOZ (NEBROC)

 

 

Research interest

 

Interdisciplinary work concerning bio availability of metals for biota, phytoplankton in particular

 

The last 5 years my work focuses on the chemistry of iron (Fe) and the availability of Fe for large Antarctic diatoms.

 

The inorganic solubility of Fe in seawater is very low and in spite of all efforts, the speciation of Fe in seawater is far from known. In large parts of the oceans growth of phytoplankton is limited by Fe. The biological availability of Fe depends on the physical-chemical speciation of Fe, which is extremely complex and dynamic.

 

Nowadays it is realized dissolved Fe actually consists of four physico-chemical pools: organically complexed Fe(III) i.e. [FeL], inorganic Fe(III) i.e. [FeIII'], reduced Fe i.e. [Fe(II)] and colloidal Fe. Please be aware that latter colloidal pool also consists of various chemical fractions, i.e.  being partly organically complexed and/or reduced.  Until now it has proven to be impossible to ascribe the biological availability of dissolved Fe to one (or more) of these physical-chemical distinguished pools.

 

Overview current research

 

Since 1994 it is known that more than 99% of the dissolved Fe in seawater is complexed with dissolved organic ligands. These ligands increase the solubility of Fe enormously, but decrease the fraction of inorganic (ionic Fe and Fe-hydroxides) Fe dramatically. Thus the inorganic fraction is far too low to be the sole source of Fe for phytoplankton. Since the organic fraction of Fe(III) is by far the largest pool, it seems the most logic supply of Fe to the phytoplankton cell.

 

Since kinetics appear to play a key role in the uptake process any disturbance in the reactions can influence the bio-availability of Fe species and thus the response of the phytoplankton. One of the disturbances in the natural ocean causing disequilibrium in the Fe chemistry is photo-reduction. It is known is that biological Fe uptake is enhanced by photo-reduction.

 

Photo-reduction is related to light intensity, and to the wavelength of the solar spectrum. A recent project (financed by NAAP, NWO) proved that in the water column especially the UV-A and PAR are responsible for photo-reduction of Fe species. We have recently documented the effect of different organic ligands on photo-reduction. The penetration depth of the UV-B and UV-A part of the solar light is small, and during the nights no photo-reduction can take place. Fe (II) formed by photo-reduction may contribute to support algal growth, but cannot be the main source, especially not in the open ocean. (Rijkenberg et al., 2004-2008; Gerringa et al., 2004, 2007)

 

Part of this research resulted in the thesis PhD of Micha Rijkenberg (MJA Rijkenberg, 2005, Photochemistry and organic complexation of iron, interactions in the Southern Ocean. University of Groningen, 222 pp.)

 

During the KEOPS cruise, January and February 2005, the area SE of the Kerguelen Archipelago in the Indian sector of the Southern Ocean was studied to investigate the effect of the Archipelago on the Fe concentration and its organic speciation in the surrounding waters (Blain et al., 2007; Gerringa et al., 2008).

 

Ongoing research, part of the GEOTRACES program, funded by N.W.O., IPY (International Polar Year), is not only focused on the area near Antarctica but also on the arctic seas (2007-2011). The mission of the GEOTRACES program is:

To identify and quantify processes that control the distribution of key trace elements and isotopes in the ocean, and their sensitivity to changing environmental conditions.

 

Trace elements serve important roles as regulators of ocean processes including marine ecosystem dynamics and carbon cycling. The role of iron is well known as the key limiting micronutrient in the Southern Ocean. Understanding the biogeochemical cycling of these micronutrients requires knowledge of their diverse sources and sinks as well as their transport and chemical form in the ocean.

Two expeditions of the Polarstern are part of GEOTRACES, an Arctic expedition (ARK XXII-2 Aug-Sept 2007) and an Antarctic expedition (ANT XXIV-3 in Febr-April 2008).

 

 My part of GEOTRACES program is to study the physical and chemical speciation of dissolved Fe in the polar oceans. Charles-Edouard Thuroczy is one of the PhD students hired on IPY Geotraces and together we are investigating this part of he program.

We study along the lines of two distinct approaches, which may seem to be dis-concordant at first glance, but in my view need to be addressed both, in a concerted action, in order to make real progress at all. These two approaches are:

 

  1. Determine the distribution of dissolved (<0.2 micron filtrate) Fe in seawater between one (or more) operationally defined colloid size class(es), and the remaining soluble (<smallest size cutoff ultrafiltration) pool which is deemed to consist mostly of organic Fe(III) complexes to be determined by 'classical' CLE voltammetry. Overall this is the more or less (quasi-)equilibrium approach.
  2. Assess the kinetic reactivity of various physico-chemical species (Fig. 1)in the overall dissolved Fe pool  by a suite of carefully designed kinetic experiments, in order to quantify the key rate constants of conversion reactions between physical-chemical species. Overall this is the kinetic approach.

 

Publications (of the last 10 years)

 

De Baar, H.J.W., L.J.A. Gerringa, P.Laan, K.R Timmermans, 2008. Efficiency of carbon removal per added iron in ocean fertilization. Mar Ecol Prog Ser., 364: 269-282.

 

Gerringa, L.J.A., S. Blain, P. Laan, G. Sarthou,  M.J.W. Vedlhuis, CPD Brussaard,  E. Viollier.  K.R. Timmermans, 2008. Fe-containing dissolved organic ligands near the Kerguelen Archipelago in the Southern Ocean (Indian sector). Deep Sea Res. II, 55, 606-621.

 

Rijkenberg, M.J.A., L.J.A. Gerringa, K.R. Timmermans, A.C. Fischer, K.J. Kroon, A.G.J. Buma, H.Th. Wolterbeek and H.J.W. de Baar, 2008. Marine diatoms enhance the reactive iron pool by modification of iron‑binding ligands and stimulation of iron‑photoreduction. Mar Chem. 109, 29-44.

 

Blain, S., B. Quéguigiener, L. Armand, S. Belviso, B. Bombled, L. Bopp, A. Bowie, C. Brunet, C. Brussaard, F. Carlotti, U. Christaki, A. Corbière, I. Durand, F. Ebersbach, J-L. Fuda, N. Garcia, L. Gerringa, B. Griffiths, C. Guigue, C. Guillerm, S. Jacquet, C. Jeandel, P. Laan, D. Lefèvre, C. Lomonaco, A. Malits, J. Mosseri, I. Obernosterer, Y-H. Park, M. Picheral, P. Pondaven, T. Remenyi, V. Sandroni, G. Sarthou, N. Savoye, L. Scouarnec, M. Souhaut, D. Thuiller, K. Timmermans, T. Trull, J. Uitz, P. van-Beek, M. Veldhuis, D. Vincent, E. Viollier, L. Vong, T. Wagener, 2007. The effect of natural iron fertilization on carbon sequestration in the Southern Ocean. Nature, vol 446, 1070-1075.

 

Gerringa, L.J.A., M.J.A. Rijkenberg, H.Th. Wolterbeek, T. Verburg, M. Boye, H.J.W. de Baar, 2007. Kinetic study reveals weak Fe-binding ligand, which affects the solubility of Fe in the Scheldt estuary. Mar Chem., 103, 30-45.

 

Gerringa, L.J.A., M.J.W. Veldhuis, K.R. Timmermans, G. Sarthou, H.J.W. de Baar, 2006. Co-variance of dissolved Fe-binding ligands with biological observations in the Canary Basin. Mar Chem., 102, 276-290.

 

Fischer A.C., Wolterbeek H.Th., Kroon J.J., Gerringa L.J.A., Timmermans K.R., Elteren J.T. van,. Teunissen T , 2006 On the use of iron radio-isotopes to study iron speciation kinetics in seawater: A column separation and off-line counting approach. Sci of the total environment, 362, 242-258.

 

Rijkenberg, M.J.A., Gerringa, L.J.A., Carolus, V.E., Velzeboer, I.,de Baar, H.J.W., 2006. Enhancement and inhibition of iron photoinhinition by individual ligands in open ocean seawater. Geochim, Cosmochim Acta, 70, 2790-2805.

 

Rijkenberg, M.J.A., Gerringa, L.J.A., Velzeboer, I.,  Timmermans, K.R.,  Buma, A.G.J.,  de Baar, H.J.W.,  2006: Iron-binding ligands in Ducth estuaries are not affected by UV induced photochemical degradation. Mar. Chem., 100, 11-23.

 

Rijkenberg, M.J.A., Fischer, A.C., Kroon, J.J., Gerringa, L.J.A., Timmermans, K.R., Wolterbeek, H.Th., de Baar, H.J.W. , 2005. The influence of UV irradiation on the photoreduction of iron in the Southern Ocean. Marine Chemistry, 93, 119-129.

 

Rijkenberg, M.J.A., Gerringa, L.J.A., Neale, P.J., Timmermans, K.R., Buma, A.G.J., de Baar, H.J.W, 2004 . UVA variability overrules UVB ozone depletion effects on the photoreduction of iron in the Southern Ocean. J Phys Res Lett, 31, L24310. doi:10.1029/2004GL020829.

 

Schulz, K.G., Zondervan, I., Gerringa, L.J.A., Timmermans, K.R., W. Veldhuis, Riesebell, U. 2004. Effect of trace metal availability on coccolithophorid calcification. Nature, 430, 673-676

 

Gerringa, L.J.A., M.J.A. Rijkenberg, K.R. Timmermans, A.G.J. Buma, 2004. The influence of UV radiation on hydrogen peroxide formation in the Atlantic Ocean near the equator. J Sea Res , vol. 51-1, 3-10.

 

Visser, F.,  L.J.A. Gerringa, S.J. van der Gaast, H.J.W de Baar and K.R. Timmermans, 2003. The role of reactivity and iron content of aerosol dust on growth rates of two Antarctic diatom species. J. Phycol. 39 (6): 1085-1094.

 

Rijstenbil, J.W., L.J.A. Gerringa, 2002. Interactions of algal ligands, metal complexation and availability and cell responses of the marine planktonic diatom Ditylum brightwellii, throughout a gradual increase of copper to toxic levels. Aquatic Toxicology 56: 115-131.

 

Gerringa, L.J.A., H.J.W. de Baar, R.F. Nolting, H.Paucot, 2001. The influence of salinity on the solubility of Zn and Cd sulphides in the Scheldt estuary. J.Sea Res., 46, 201-211.

 

Timmermans, K.R., M.S. Davey, B. van der Wagt, J. Snoek, R.J. Geider, M.J.W. Veldhuis, L.J.A. Gerringa, H.J.W. de Baar, 2001. Co-limitation by iron and light of Chaetoceros brevis, C. dichaeta and C. calcitrans (bacillariophyceae). Mar. Ecol. Prog. Ser., 217: 287-297.

 

Timmermans, K.R., R. J. Snoek, L.J.A. Gerringa , H. J.W. de Baar, 2001. Not all eukaryotic algea can interreplace cobalt and zinc: Chaetoceros calcitrans (Bacillariophyceaea) versus Emiliania huxleyi (Haptophyceae). Limnol. Oceanogr. 46 (3): 699 - 704.

 

Timmermans, K.R., L.J.A. Gerringa, H.J.W. de Baar, B. van der Wagt, M.J.W. Veldhuis, J.T.M. de Jong, P.L.Croot, M. Boye, 2001. Growth rates of large and small Southern Ocean diatoms in realtion to availability of iron in natural seawater. Limnol. Oceanogr. 46, 260-266.

 

Gerringa, L.J.A., H.J.W. de Baar, K.R. Timmermans, 2000. A comparison of iron limitation of phytoplankton in natural oceanic waters and laboratory media conditioned with EDTA. Mar. Chem. 68, 335-346.

 

Nolting, R.F., W. Helder, H.J.W. de Baar, L.J.A. Gerringa, 1999. Contrasting behaviour of trace metals in the Scheldt estuary in 1978 compared to recent years. J. Sea Res., 42, 275-290.

 

Gerringa, L.J.A., H. Hummel, T.C.W. Moerdijk-Poortvliet, 1999. Vertical gradients for particulate Cu fractions in estuarine water over tidal flats. Hydrobiologia 405: 149-161

 

Nolting, R.F., Gerringa, L.J.A., Swagerman, M.J.W., Timmermans, K.R., de Baar, H.J.W., 1998. Fe III speciation in the High Nutrient, Low Chlorophyll Pacific region of the Southern Ocean. Mar. Chem. 62, 335-352.