Mariëtte Wolthers

Currently at:
Department of Chemistry
University College London
20 Gordon Street
London, WC1H 0AJ, United Kingdom

Room: 205
Tel: +44 (0)20 7679 7465
Fax: +44 (0)20 7679 7463
e-mail: m.wolthers_at_ucl.ac.uk
HTTP: UCL Departmental website

Also at:
Department of Earth Sciences
Faculty of Geosciences
Utrecht University
Princetonplein 5, Room W116

P.O. Box 80021
3508 TA Utrecht
The Netherlands
Tel: +31-(0)30 253 5042
Fax: +31-(0)30 253 5302







Curriculum vitae: Download pdf

2012-present Advanced NERC Fellow at the Department of Chemistry, University College London, U.K. and Associate Researcher at Department of Earth Sciences-Geochemistry, Utrecht University.
2010-2012 Visiting scientist at the Department of Chemistry, University College London
2007-2012 VENI Research Fellow at the Department of Earth Sciences, Utrecht University, the Netherlands
2006 Postdoctoral researcher at Stratigraphy and Paleontology, Faculty of Geosciences, Utrecht University, the Netherlands
2003-2005 Postdoctoral researcher, jointly at then Laboratoire de Geophysique Interne et Tectonophysique (LGIT), Grenoble University, France, and Department of Earth Sciences–Geochemistry, Faculty of Geosciences, Utrecht University, the Netherlands
1997-2003 PhD research at Utrecht University in association with the School of Earth and Ocean Sciences, Cardiff University, U.K.
Thesis advisors: Prof. C.H. van der Weijden, Prof. D. Rickard, Dr. P.R. van der Linde
Thesis defended on March 31st 2003.
1992-1997 M.Sc in Geology at the Faculty of Earth Sciences, Vrije Universiteit, Amsterdam, The Netherlands




Research interests


Mineral surface–water chemistry, crystal growth, biomineralisation, carbonate minerals, iron sulphide geochemistry, nanoparticle properties, geochemistry-fauna interactions.

My main research focus is on carbonate mineral surface reactivity, with and without impurity ions, and during growth. The ultimate aim of my work is obtain a fundamental mechanistic understanding of the processes leading to the uptake of trace metals in calcite during biomineralisation. My approach is both experimental and theoretical; the tools I use to study carbonate minerals and other earth materials range from atomic scale computational chemistry and macroscale geochemical modelling to sophisticated analyses techniques such as synchrotron-based spectroscopy.

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Grants and awards, selection


2012 NERC Advanced Fellowship, hosted by the Department of Chemistry, University College London, U.K. (salary and research money for 5 years).
2010 Royal Society International Joint Project, collaboration with the group of Prof. Nora de Leeuw, Department of Chemistry, University College London (travel and subsistence grant for 2 years, bi-directional).
2008 British Council Partnership Programme in Science, collaboration with the group of prof. Nora de Leeuw, Department of Chemistry, UCL (travel and subsistence grant for 3 visits, NL to UK).
2007-2009 NWO Van Gogh grant, collaboration with Dr. Annette Hofmann , UFR des Sciences de la Terre, Lille University, France (travel and subsistence grant 2 years, bi-directional)
2006 NWO Starting Fellowship (VENI, salary and research money, for ~4 years)
For a complete funding ID, check my curriculum vitae





PhD research


Geochemistry and environmental mineralogy of the iron–sulphur–arsenic system
Why study the geochemistry and environmental mineralogy of the iron-sulphur-arsenic system? In the minds of most people, "arsenic" and "poison" are almost synonyms. It has been available to dissatisfied spouses and the politically ambitious for thousands of years, a cheap and effective solution to many of the awkward situations that develop in human affairs (quote from Penrose, 1974). Presently, arsenic is recognised as one of the most serious inorganic contaminants in drinking water on a worldwide basis. An alarming example of arsenic problems in groundwater is Bangladesh, where many of the recently installed millions of drinking water wells contain high concentrations of arsenic (Smedley and Kinniburgh, 2002). These wells withdraw water from suboxic aquifers. The processes behind the effectively high arsenic mobility in this and other suboxic and anoxic environments are poorly understood (Smedley and Kinniburgh, 2002; Harvey et al., 2002). Knowledge of such processes is essential to understand and predict the behaviour of arsenic in these environments. The solubility of arsenic oxides and sulphides is relatively high under a wide range of pH and redox conditions. The most important process reducing arsenic mobility in the environment is sorption onto other, less soluble, oxides and sulphides. Iron oxides and sulphides are ubiquitous phases in sedimentary environments. While arsenic sorption onto iron oxides has been studied intensively over the past few years, its sorption onto Fe(II) sulphides has not been widely investigated.

The scope of the thesis is to study arsenic sorption onto disordered mackinawite, FeSam, and the association of As with Fe(II) sulphides during the formation of pyrite, FeS2. At ambient temperatures and pressures, several iron-sulphide phases can be formed. However, in anoxic sulphidic environments at pH values higher than 5, pyrite is the most stable and ubiquitous phase formed. Generally, pyrite formation is preceded by the precipitation of metastable disordered mackinawite. Since, in sedimentary settings, arsenic is present as dissolved As(III) or As(V), the behaviour of both As(V) and As(III) in the presence of FeSam and during the reaction to pyrite is studied.

As a background to the thesis, a brief overview of the literature on (disordered) mackinawite, pyrite and arsenic is provided in Chapter 1. In Chapters 2 and 3, the bulk characteristics, crystallinity and surface properties of synthetic FeSam are determined. The constructed surface model is applied in Chapter 4 to experimental arsenic sorption data. In Chapter 5, the behaviour of arsenic during the transformation of FeSam to pyrite is studied in batch experiments and results are interpreted in relation to the sorption reactions proposed in Chapter 4. Subsequently, pyrite formation in the presence of As(III) at concentrations approaching those in ambient environments is explored in Chapter 6, using a continuous-flow reaction system. Lastly, Chapter 7 is the synthesis of the thesis, in which conclusions are discussed and environmental implications of the study considered.
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Publications


International refereed journals and refereed books:

(20) Wolthers M., D. Di Tommaso, Z. Du and N.H de Leeuw, 2013. Variations in calcite growth kinetics with surface topography: Molecular Dynamics simulations and process-based growth kinetics modelling. Accepted for publication in CystEngComm, DOI: 10.1039/C3CE40249E.

(19) Slomp C.P., Mort H.P., Jilbert T., Reed D.C., Gustafsson B.G., Wolthers M., 2013. Coupled dynamics of iron and phosphorus in sediments of an oligotrophic coastal basin and the impact of anaerobic oxidation of methane. PLoS ONE [E], 8(4).

(18) Wit J., de Nooijer L.J., Wolthers M., Reichart G.J., 2013. The effect of salinity on incorporation of Mg and Na in foraminiferal calcite. Biogeosciences Discuss. 10, 6039-6063.

(17) Wolthers M., D. Di Tommaso, Z. Du and N.H de Leeuw, 2012. Calcite surface structure and reactivity: molecular dynamics simulations and macroscopic surface modelling of the calcite-water interface. Physical Chemistry Chemical Physics 14, 15145-15157. DOI: 10.1039/C2CP42290E.

(16) Ruiz-Hernandez S.E., Grau-Crespo R., Almora-Barrios N., Wolthers M., Rabdel Ruiz-Salvador A., Fernandez N. and de Leeuw N.H., 2012. Mg/Ca partitioning between aqueous solution and aragonite. Chemistry - A European Journal 18, 9828-9833. DOI: 10.1002/chem.201200966.

(15) Wolthers M., Nehrke G., Gustafsson J.-P. and Van Cappellen P., 2012. Calcite growth kinetics: Modeling the effect of solution stoichiometry. Geochim. Cosmochim. Acta 77, 121-134. DOI: 10.1016/j.gca.2011.11.003.

(14) Li, Z., Hofmann, A., Wolthers, M., Thomas, P., 2012. Reversibility of cadmium sorption to calcite revisited. J. Colloid Interf. Sci. 368, 434-442. DOI: 10.1016/j.jcis.2011.09.085.

(13) Mettler S., Wolthers M., Charlet L., von Gunten U., 2009. Sorption and catalytic oxidation of Fe(II) at the surface of calcite. Geochim. Cosmochim. Acta 73, 1826-1840. DOI: 10.1016/j.gca.2009.01.003.

(12) Wolthers M., Charlet L., Van Cappellen P., 2008. The surface chemistry of divalent metal carbonate minerals; a critical assessment of surface charge and potential data using the charge distribution multi-site ion complexation model. Am. J. Sci. 308, 905-941. DOI: 10.2475/08.2008.02.

(11) Wolthers M., Butler I., Rickard D., 2007. Influence of arsenic on iron sulfide transformations. Chem. Geol. 236, 217-227. DOI: 10.1016/j.chemgeo.2006.09.010.

(10) De Nooijer L.J., Reichart G.J., Duenas-Bohorquez A., Wolthers M., Ernst S.R., Mason P.R.D., Van Der Zwaan G.J., 2007. Copper incorporation in foraminiferal calcite: Results from culturing experiments. Biogeosciences 4, 493-504.

(9) Chakraborty S., Wolthers M., Chatterjee D., Charlet L., 2007. Adsorption of Arsenite and Arsenate on muscovite and biotite mica. J. Colloid Interf. Sci. 309, 392-401. DOI: 10.1016/j.jcis.2006.10.014.

(8) Wolthers M., Charlet L., Tournassat C., 2006. Surface chemistry of bentonite: an additive model applied to uranyl sorption. In: Surface Complexation Modelling (Ed. J. Lützenkirchen), Interface Science and Technology, 11, Elsevier Ltd as an Academic Press imprint, 539-554.

(7) Wolthers M., Charlet L., Van der Weijden C.H., Van der Linde P.R., Rickard D., 2005. Arsenic mobility in the ambient sulphidic environment: sorption of Arsenic (V) and Arsenic (III) onto disordered mackinawite. Geochim. Cosmochim. Acta 69 (14), 3483-3492. DOI: 10.1016/j.gca.2005.03.003 .

(6) Wolthers M., Charlet L., Van der Linde P.R., Rickard D., Van der Weijden C.H., 2005. The surface chemistry of disordered mackinawite (FeS). Geochim. Cosmochim. Acta 69 (14), 3469-3481. DOI: 10.1016/j.gca.2005.01.027.

(5) Wolthers M., Butler I.B., Rickard D., Mason P.R.D., 2005. Arsenic incorporation into pyrite at ambient environmental conditions: a continuous-flow experiment. In: Advances in Arsenic Research: Integration of Experimental and Observational Studies and Implications for Mitigation (Eds. P. A. O'Day, D. Vlassopoulos, X. Ming, L. G. Benning), American Chemical Society (ACS) Symposium Series 915, pp 60-76. DOI: 10.1021/bk-2005-0915.ch005.

(4) Charlet L., Chakraborty S., Varma S., Tournassat C., Wolthers M., Chatterjee D. Roman Ross G., 2005. Adsorption and heterogeneous reduction of arsenic at the phyllosilicate-water interface. In: Advances in Arsenic Research: Integration of Experimental and Observational Studies and Implications for Mitigation (Eds. P. A. O'Day, D. Vlassopoulos, X. Ming, L. G. Benning), ACS Symposium Series 915, pp 41-59. DOI: 10.1021/bk-2005-0915.ch004.

(3) Wolthers M., Charlet L., Van Cappellen P., 2004. The surface chemistry of carbonates, a new approach. In: Water-Rock Interaction 2004 (Wanty, R.B., Seal II, R.R., eds.) pp 781-784, Taylor and Francis Group, London.

(2) Wolthers M., Van der Gaast S.J., Rickard D., 2003. The structure of disordered mackinawite. Am. Mineral. 88, 2007-2015. or PDF with subscription.

(1) Wolthers M., Charlet L., van der Weijden C.H., 2003. Arsenic sorption onto disordered mackinawite as a control on the mobility of arsenic in the ambient sulphidic environment. J. Phys. IV France 107, pp 1377–1380. DOI: 10.1051/jp4:20030558.


Outreach activities:

In 2011, I lectured within the Darwin Summer School. Furthermore, I have written several reports with the aim to translate scientific knowledge for end-users such as drinking water companies and waste storage managers:

Wolthers M., 2005. Reactivity of bentonite: an additive model applied to uranyl sorption. ANDRA report D.RP.0LGT.05.002, 27 p.
Wolthers M., 2004. Advances in the development of a mixed-component surface model for radionuclide sorption onto bentonite MX-80. ANDRA report D.RP.0LGT.04.003, 26p.
Wolthers M., 2004. Radionuclide immobilization by sorption onto bentonite MX-80: the development of a mixed-component surface model. ANDRA report D.RP.0LGT.04.001, 19 p.
Wolthers M., 2003. Radionuclide immobilization by bentonite, describing the role of accessory minerals with a mixed-component surface model. ANDRA report D.RP.0LGT.03.003, 24 p.
Wolthers M., 2003. Radionuclide immobilization by sorption onto bentonite MX-80; the role of accessory minerals. ANDRA report D.RP.0LGT.03.001, 15 p.
Wolthers M., Passier H.F., 2002. Wat is pyriet? Chapter 2 of the Pyrite Workgroup CD-ROM pp 8-14.


Abstracts (published, selection):

Wolthers M., Nehrke G., Van Cappellen P., 2010. Calcite growth rate and solution composition.Geochim. Cosmochim. Acta 74, Supplement 1, p A1139.
Wolthers M., Charlet L., Van Cappellen P., 2009. Carbonate mineral surface charge and potential reevaluated. Abstr. Papers A.C.S., GEOC 77.
Wolthers M., Van Cappellen P., Charlet L., 2007. Surface charge and potential of carbonate minerals. Geochim. Cosmochim. Acta 71, Supplement 1, p A1125.
Wolthers M., Charlet L., Tournassat C., 2006. Surface chemistry of bentonite: an additive model applied to uranyl sorption. In: Surface Complexation Modelling (Ed. J. Lützenkirchen), Interface Science and Technology, volume 11, Elsevier Ltd as an Academic Press imprint, 539-554.
Wolthers M., Rickard D., Charlet L., 2006. Structure and reactivity of FeS. Abstr. Papers A.C.S., GEOC 107.
Wolthers M., Charlet L., Van Cappellen P., 2004. The surface chemistry of carbonates, a new approach. In: Water–Rock Interaction 2004 (Wanty, R.B., Seal II, R.R., eds.) 781–784, Balkema, Leiden.
Rickard D., Wolthers M., Van der Gaast S. J., Butler I., Luther G., Griffiths A., Oldroyd A., 2003. Clusters and iron(II) monosulfide. Abstr. Papers A.C.S. 225, U912.





Invited Presentations


(10) Wolthers, M. , 2012. Building Biominerals. Monthly meeting of the London Palaeoclimate Group, Imperial College, London, U.K..

(9) Wolthers, M. , Nehrke G., Van Cappellen P., 2011. Calcite growth rate and solution composition. C-Seminar cycle of the AWI, Bremerhaven, Germany.

(8) Wolthers M., Charlet L., Van Cappellen P., 2010. Carbonate mineral surface chemistry: a surface structural model. Invited replacement of keynote lecture, Goldschmidt conference 2010, Knoxville, U.S.A.

(7) Wolthers M., Charlet L., Van Cappellen P., 2009. Carbonate mineral surface charge and potential reevaluated. American Chemical Society Meeting , Salt Lake City, U.S.A., March 2009.

(6) Wolther M., Mineral surface reactivity of iron sulphides and divalent metal carbonates. Seminar Series, Institut für Nukleare Entsorgung, Forschungszentrum Karlsruhe, Karlsruhe, Germany, May 2008.

(5) Wolthers M., Langezaal A.M. , Meysman F. , van Lith Y. , Ernst S. , Van der Zwaan G.J. 2007. Microhabitat distribution of benthic foraminifera. Darwin Days, The Netherlands, April 2007.

(4) Wolthers M., Rickard D., Charlet L., 2006. Structure and reactivity of FeS. American Chemical Society Fall Meeting, San Fransisco, U.S.A., September 2006.

(3) Wolthers M., Charlet L., Van Cappellen P., 2004. The surface chemistry of carbonates. Talk within the C-Seminar cycle of the Alfred Wegener Institute, Bremerhaven, Germany, September 2004.

(2) Wolthers M., 2004. Mackinawite surface chemistry. Journée scientifique de l'IMBG 'Le soufre et les métaux: Importance dans les sciences de l'univers et du vivant.' Grenoble, France, March 2004.

(1) Wolthers M., Rickard D., van der Weijden C.H., 2000. Arsenic incorporation into pyrite at low temperature. Talk at the meeting of the Kring Aardse Materialen of the Royal Geological and Mining Society of the Netherlands KNGMG, Utrecht, the Netherlands, December 2000.




©Mariëtte Wolthers
This webpage, initially developed in HTML Kit, was last updated March 2013.