Mariette Wolthers

Mariette Wolthers
Utrecht University | UU · Department of Earth Sciences

Ph.D.

About

92
Publications
15,850
Reads
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2,564
Citations
Introduction
My main research focus is on the interaction between water and minerals. I investigate mineral nucleation, growth, dissolution and surface reactivity, with and without impurity ions. My approach is both experimental and theoretical; the tools I use to study earth materials range from atomic scale computational chemistry and macroscale geochemical modelling to sophisticated analyses techniques such as synchrotron-based spectroscopy.
Additional affiliations
August 1999 - July 2000
Cardiff University
Position
  • PhD
Description
  • Visiting PhD student
March 2006 - October 2012
Utrecht University
Position
  • Research Associate
Description
  • Veni, NWO Starting Research Fellow
December 2019 - December 2023
Utrecht University
Position
  • Professor (Associate)
Education
September 1997 - March 2003
Utrecht University
Field of study
  • Geochemistry
September 1992 - August 1997
Vrije Universiteit Amsterdam
Field of study
  • Petrology/Isotope Geology

Publications

Publications (92)
Article
Until recently the influence of solution stoichiometry on calcite crystal growth kinetics has attracted little attention, despite the fact that in most aqueous environments calcite precipitates from non-stoichiometric solution. In order to account for the dependence of the calcite crystal growth rate on the cation to anion ratio in solution, we ext...
Article
Full-text available
Minerals form in natural systems from solutions with varying ratios of their lattice ions, yet non‐stoichiometric conditions have generally been overlooked in investigations of new formation (nucleation) of ionic crystals. Here, we investigated the influence of cation:anion ratio in the solution on the initial steps of nucleation by studying positi...
Article
Full-text available
The impact of solution stoichiometry on formation of BaSO4 (barite) crystals and the development of surface charge was investigated at various predefined stoichiometries (raq = 0.01, 0.1, 1, 10, and 100, where raq = {Ba²⁺}:{SO42–}). Synthesis experiments and zeta potential (ζ-potential) measurements were conducted at a fixed initial degree of super...
Article
Full-text available
The impact of solution stoichiometry, upon formation of BaSO4 crystals in 0.02 M NaCl suspensions, on the development of particle size was investigated using dynamic light scattering (DLS). Measurements were performed on a set of suspensions prepared with predefined initial supersaturation, based on the quotient of the constituent ion activity prod...
Article
Full-text available
In order to use classical molecular dynamics to complement experiments accurately, it is important to use robust descriptions of the system. The interactions between biomolecules, like aspartic and glutamic acid, and dissolved ions are often studied using standard biomolecular force-fields, where the interactions between biomolecules and cations ar...
Article
Full-text available
Drinking water softening has primarily prioritized public health, environmental benefits, social costs and enhanced client comfort. Annually, over 35 billion m³ of water is softened worldwide, often utilizing three main techniques: nanofiltration, ion exchange and seeded crystallization by pellet softening. However, recent modifications in pellet s...
Article
Full-text available
Calcium carbonate (CaCO3) dissolution is an integral part of the ocean's carbon cycle. However, laboratory measurements and ocean alkalinity budgets disagree on the rate and loci of dissolution. In situ dissolution studies can help to bridge this gap, but so far published studies have not been utilized as a whole because they have not previously be...
Poster
Full-text available
Since the 1980’s in the Netherlands, drinking water softening has focused on robustness. However, in more recent years, significant changes were made in the water softening treatment process. These changes include the type of pellet material, NaOH application, targeted total hardness and the acid addition. Yet, these changes have not led to the des...
Article
Full-text available
Carbon dioxide entering and acidifying the ocean can be neutralized by the dissolution of calcium carbonate, which is mainly found in two mineral forms. Calcite is the more stable form and is often found in deep‐sea sediments, whilst aragonite is more soluble and therefore rarely preserved. Recent research shows aragonite may account for a much lar...
Article
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The significance of iron sulphide (FeS) formation extends to "origin of life" theories, industrial applications, and unwanted scale formation. However, the initial stages of FeS nucleation, particularly the impact of...
Article
Full-text available
The impact of solution stoichiometry on the nucleation and growth of BaSO4 was studied by measuring solution transmittance and subsequent fitting to a crystallization model. Our results show that a large excess of either Ba²⁺ or SO42– ions inhibits both the nucleation and growth of BaSO4. However, for a small excess of Ba²⁺, the growth is enhanced....
Data
Supporting data to: Seepma, S.Y.M.H., Kuipers, B.W.M., Wolthers, M., (2023). Impact of Solution {Ba2+}:{SO42–} on Charge Evolution of Forming and Growing Barite (BaSO4) Crystals: A ζ─ Potential Measurement Investigation. ACS omega, 8(46), 43521-43537.
Poster
Full-text available
Since the 1980’s in the Netherlands, drinking water softening is applied on the basis of robustness. However, in more recent years, significant changes have been made at the drinking water softening location of Weesperkarspel, which is responsible for providing drinking water to Schiphol and Amsterdam. A few of those examples are the exchange of pe...
Article
Full-text available
Enhanced recycling of phosphorus as ocean deoxygenation expanded under past greenhouse climates contributed to widespread organic carbon burial and drawdown of atmospheric CO 2 . Redox-dependent phosphorus recycling was more efficient in such ancient anoxic marine environments, compared to modern anoxic settings, for reasons that remain unclear. He...
Article
Full-text available
In the open ocean, calcium carbonates are mainly found in two mineral forms. Calcite, the least soluble, is widespread at the seafloor, while aragonite, the more soluble, is rarely preserved in marine sediments. Despite its greater solubility, research has shown that ara-gonite, whose contribution to global pelagic calcification could be at par wit...
Article
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Amino acids and polycyclic aromatic hydrocarbons (PAHs) belong to the range of organic compounds detected in meteorites. In this study, we tested empirically and theoretically if PAHs are precursors for amino acids in carbonaceous chondrites, as previously suggested. We conducted experiments to synthesize amino acids from fluoranthene (PAH), with a...
Article
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Iron mono-sulphides, or pyrrhotites, are minerals present in the Earth's crust and mantle as well as major magnetic constituents of several classes of meteorites, thus are of interest to a wide range of disciplines including geology, geophysics, geochemistry, and material science. Despite displaying diverse magnetic properties as a results of iron...
Preprint
Full-text available
In the open ocean, calcium carbonates are mainly found in two mineral forms. Calcite, the least soluble, is widespread at the seafloor, while aragonite, the more soluble, is rarely preserved in marine sediments. Despite its greater solubility, research has shown that aragonite, which could contribute between 10 and 90% to pelagic calcium carbonate...
Article
Full-text available
Pore network model simulation (PNM) is an important method to simulate reactive transport processes in porous media and to investigate constitutive relationships between permeability and porosity that can be implemented in continuum-scale reactive-transport modelling. The existing reactive transport pore network models (rtPNMs) assume that the init...
Article
Magnesium hydroxide is a commodity chemical, produced in almost pure form from seawater through precipitation. Even though Li brines contain high concentrations of Mg²⁺ cations, the precipitation of Mg(OH)2 from them is not common. Rather it is typically coprecipitated with other salts and becomes a waste. The crystallization of chemical-grade Mg(O...
Article
Recent measurements on the dissolution rate of nano- and micron-scale rough calcite surfaces have shown lateral variations in dissolution rate, which can be quantified using rate spectra. This study uses numerical simulations to investigates the hydrodynamic processes during such experiments to explore whether hydrodynamic effects can explain the o...
Article
Full-text available
Metal sulphides constitute cheap, naturally abundant, and environmentally friendly materials for energy storage applications and chemistry. In particular, iron (II) monosulphide (FeS, mackinawite) is a material of relevance in theories of the origin of life and for heterogenous catalytic applications in the conversion of carbon dioxide (CO2) toward...
Poster
Full-text available
When calcium carbonate (CaCO3) crystals form in aqueous environments, the building blocks—calcium and carbonate ions—come together in the solid in an ideal 1:1 ratio. In contrast, the natural and industrial solutions in which they form, contain widely diverging ionic ratios. What is the impact of these non-ideal ionic ratios on the crystals that fo...
Article
Full-text available
Magnesium (Mg2+) is one of the most common impurities in calcite and is known to have a non-linear impact on the solubility of magnesian calcites. Using molecular dynamics (MD), we observed that Mg2+ impacts overall surface energies, local free energy profiles, interfacial water density, structure and dynamics and, at higher concentrations, it also...
Article
Full-text available
The effect of stoichiometry on the new formation and subsequent growth of CaCO3 was investigated over a large range of solution stoichiometries (10–4 < r(aq) < 10⁴, where r(aq) = {Ca(2+)}:{CO3(2–)}) at various, initially constant degrees of supersaturation (30 < Ωcal < 200, where Ωcal = {Ca(2+)}{CO3(2–)}/K(sp)), pH of 10.5 ± 0.27, and ambient tempe...
Article
During the so-called Messinian Salinity Crisis (MSC: 5.97-5.33 Myr ago), reduced exchange with the Atlantic Ocean caused the Mediterranean to develop into a “saline giant” wherein ∼1 million km³ of evaporites (gypsum and halite) were deposited. Despite decades of research it is still poorly understood exactly how and where in the water column these...
Article
Full-text available
Injection of CO2 into carbonate rocks causes dissolution and alters rock transport properties. The extent of the permeability increases, due to the increased pore volume and connectivity, strongly depends on the regimes of transport and dissolution reactions. Identification of these regimes and their parametrization at the microscopic scale is requ...
Article
Full-text available
The dehydration of cations is generally accepted as being the rate-limiting step in many processes. Molecular dynamics (MD) can be used to investigate the dynamics of water molecules around cations, and two different methods exist to obtain trajectory-based water dehydration frequencies. Here, these two different post-processing methods (direct met...
Poster
Full-text available
In Earth Sciences and Geoengineering, knowledge on crystal formation mechanisms is crucial to: (1) quantify fluxes in biogeochemical cycles, (2) timing and rate of different geological processes, (3) physical and chemical conditions during crystal formation and prevent scaling, (4) evaluate crystal origin and quality and use that as a proxy for pal...
Article
Multiple sulfur isotope variability in Archean sedimentary rocks provides constraints on the composition of the Earth’s earliest atmosphere. The magnitude and sign of mass-independent anomalies reflect not only atmospheric processes, but also transformations due to the Archean marine sulfur cycle prior to preservation into sedimentary pyrite. The p...
Article
The trace elemental composition of foraminiferal shell calcite is known to reflect the environment in which the shell was precipitated. Whereas conservative elements incorporated in foraminiferal shell carbonate reflect factors such as temperature (Mg), carbonate chemistry (B) and salinity (Na), the nutrient type elements (Ba, Cd, and possibly Zn)...
Article
It is becoming increasingly clear that the rate of crystal growth, even at constant saturation, varies with pH, ionic strength, and solution stoichiometry. Here, we contribute to the limited data set on experimentally obtained calcite step velocities from solutions with strictly controlled parameters. We measured growth on obtuse and acute edges in...
Article
During mineral growth and dissolution, material (in the form of atoms, molecules, complexes, or clusters) is transported through water to or from the mineral surface. Even in a solution that is at equilibrium with respect to a given mineral, there is transport to and from the surface. Although this equilibrium transport is in balance over large sca...
Article
Full-text available
Expanding hypoxia in the Baltic Sea over the past century has led to the development of anoxic and sulfidic (euxinic) deep basins that are only periodically ventilated by inflows of oxygenated waters from the North Sea. In this study, we investigate the potential consequences of the expanding hypoxia for manganese (Mn) burial in the Baltic Sea usin...
Article
Full-text available
Conditions of low oxygen, as well as strong fluctuations in dissolved oxygen concentrations, can substantially affect marine benthic communities. An early assessment of the status of a community after such an event is of fundamental ecological importance and may help to inform management measures. This paper investigates the response of a foraminif...
Article
The effects of pH and phosphate on the precipitation of calcium carbonate polymorphs from aqueous solution were investigated. Experiments were carried out at near-freezing temperature and two different pH conditions (pH 13.4 and 9.0). At each pH condition, solutions having different concentrations of CaCl2 and NaHCO3 were mixed to achieve Ca/CO3 ra...
Article
Full-text available
The construction of a permanent astronomical time scale for the Paleocene tuned to stable 405-kyr eccentricity is hampered by uncertainties in the number of eccentricity-related cycles between the Cretaceous-Paleogene (K/Pg) boundary and the Early Late Paleocene Event (ELPE) situated just below the Selandian-Thanetian boundary. Here we re-examine a...
Article
Although [Ni(S2CNBui2)2] is stable at high temperatures in a range of solvents, solvothermal decomposition occurs at 145 °C in oleylamine to give pure NiS nanoparticles, while in n-hexylamine at 120 °C a mixture of Ni3S4 (polydymite) and NiS results. A combined experimental and theoretical study gives mechanistic insight into the decomposition proc...
Conference Paper
Full-text available
Independent reconstruction of seawater inorganic carbon chemistry parameters (pH, [DIC], alkalinity) is necessary to understand the behavior of ocean chemistry and, thereby, unravel relationships between atmospheric CO2 and Earth’s climate. These parameters are tightly linked, allowing reconstruction of the complete inorganic carbon system based on...
Article
Full-text available
Expanding hypoxia in the Baltic Sea over the past century has led to anoxic and sulfidic (euxinic) deep basins that are only periodically ventilated by inflows of oxygenated waters from the North Sea. In this study, we investigate the consequences of the expanding hypoxia for manganese (Mn) burial in the Baltic Sea using a combination of pore water...
Article
Full-text available
Salinity and temperature determine seawater density, and differences in both thereby control global thermo- haline circulation. Whereas numerous proxies have been calibrated and applied to reconstruct temperature, a direct and independent proxy for salinity is still missing. Ideally, a new proxy for salinity should target one of the direct constitu...
Article
Full-text available
It is generally accepted that cation dehydration is the rate-limiting step to crystal growth from aqueous solution. Here we employ classical molecular dynamics simulations to show that the water exchange frequency at structurally distinct calcium sites in the calcite surface varies by about two orders of magnitude. The decrease in water exchange fr...
Article
Full-text available
Studies of phosphorus (P) dynamics in surface sediments of lakes and coastal seas typically emphasize the role of coupled iron (Fe), sulfur (S) and P cycling for sediment P burial and release. Here, we show that anaerobic oxidation of methane (AOM) also may impact sediment P cycling in such systems. Using porewater and sediment profiles for sites i...
Article
Full-text available
An in situ XAS study of the solvothermal decomposition of iron and nickel dithiocarbamate complexes was performed in order to gain understanding of the decomposition mechanisms. This work has given insight into the steps involved in the decomposition, showing variation in reaction pathways between the iron and nickel dithiocarbamates, and the non-i...
Article
Full-text available
Salinity and temperature determine seawater density and differences in both thereby control global themohaline circulation. Whereas numerous proxies have been calibrated and applied to reconstruct temperature, a direct and independent proxy for salinity is still missing. Ideally, a new proxy for salinity should target one of the direct constituents...
Article
Full-text available
Calcite-water interactions are important not only in carbon sequestration and the global carbon cycle, but also in contaminant behaviour in calcite-bearing host rock and in many industrial applications. Here we quantify the effect of variations in surface structure on calcite surface reactivity. Firstly, we employ classical Molecular Dynamics simul...
Article
We have calculated the concentrations of Mg in the bulk and surfaces of aragonite CaCO(3) in equilibrium with aqueous solution, based on molecular dynamics simulations and grand-canonical statistical mechanics. Mg is incorporated in the surfaces, in particular in the (001) terraces, rather than in the bulk of aragonite particles. However, the total...
Article
The effect of sorption and coprecipitation of Fe(II) with calcite on the kinetics of Fe(II) oxidation was investigated. The interaction of Fe(II) with calcite was studied experimentally in the absence and presence of oxygen. The sorption of Fe(II) on calcite occurred in two distinguishable steps: (a) a rapid adsorption step (seconds–minutes) was fo...
Article
The Charge Distribution MUltiSite Ion Complexation or CD-MUSIC modeling approach is used to describe the chemical structure of carbonate mineral-aqueous solution interfaces. The new model extends existing surface complexation models of carbonate minerals, by including atomic scale information on the surface lattice and the adsorbed water layer. In...
Article
Full-text available
A partition coefficient for copper (D<sub>Cu</sub>) in foraminiferal calcite has been determined by culturing individuals of two benthic species under controlled laboratory conditions. The partition coefficient of a trace element (TE) is an emperically determined relation between the TE/Ca ratio in seawater and the TE/Ca ratio in foraminiferal calc...
Article
Arsenite and arsenate sorption was studied on two silt-sized phyllosilicates, namely muscovite and biotite, as a function of solution pH (pH 3-8 for muscovite, and 3-11 for biotite) at an initial As concentration of 13 microM. The amount of arsenic adsorbed increases with increasing pH, exhibiting a maximum value, before decreasing at higher pH val...
Article
The association of arsenate, As(V), and arsenite, As(III), with disordered mackinawite, FeS, was studied in sulfide-limited (Fe:S = 1:1) and excess-sulfide (Fe:S = 1:2) batch experiments. In the absence of arsenic, the sulfide-limited experiments produce disordered mackinawite while the excess-sulfide experiments yield pyrite with trace amounts of...
Article
Compacted bentonite is a major packing and storage material, because of its extremely low hydraulic conductivity. This chapter presents an additive mixed-component model to describe the surface complexation of radionuclides in the bentonite MX-80. The chapter provides an overview of the mineralogy and the surface sites. The surface chemistry of sel...
Article
Pyrite was synthesized in the presence of arsenite, As(III), at concentrations approaching those in ambient environments, under controlled, monitored, anoxic conditions in a continuous-flow reaction system at pH 6 and 25°C. During the continuous pyrite growth in these experiments, a continued uptake of arsenic by pyrite was observed. No unequivocal...