ORCID Profile
0000-0002-1825-782X
Current Organisation
Universiteit Utrecht
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Publisher: Mineralogical Society of America
Date: 20-09-2011
DOI: 10.2138/AM.2011.3779
Publisher: Proceedings of the National Academy of Sciences
Date: 10-04-2017
Abstract: We document organic matter encapsulated in rock clasts from a oceanic serpentinite mud volcano above the Izu–Bonin–Mariana subduction zone (Pacific Ocean). Although we cannot pinpoint the exact origin of the organic matter, chemical analysis of the constituents resembles molecular signatures that could be produced by microbial life deep within or below the mud volcano. Considering the known temperature limit for life, 122 °C, and the subduction zone forearc geotherm where such mud volcanoes are located, we estimate that life could exist as deep as ∼10,000 m below the seafloor. This is considerably deeper than other active serpentinizing regions such as midocean ridges and could have provided sheltered ecosystems for life to survive the more violent phases of Earth’s history.
Publisher: American Chemical Society (ACS)
Date: 22-07-2013
DOI: 10.1021/ES401188J
Abstract: Magnesite growth in chloride and sulfate-rich solutions has been examined at 90 °C in situ using phase-shift interferometry (PSI) and ex situ using atomic force microscopy (AFM) to evaluate the feasibility of cosequestering SO2 and CO2 in Mg-rich rocks. Although sulfate may assist desolvation at the magnesite surface, evidence for enhanced growth was only found at specific surface sites. The overall growth rates fit with those observed for chloride experiments in similarly saturated solutions. Thus, the formation of Mg-SO4 ion pairs in solution, which lowers the supersaturation with respect to magnesite, will have the dominant effect during sequestration. Lowering the activity of Mg(2+) ions in solution also inhibited the nucleation of other hydrated Mg-carbonate phases. As no evidence was found for sulfate incorporation into the growing magnesite, the presence of sulfate in solution will be detrimental to CO2 sequestration and is not expected to be cosequestered. The PSI data also emphasize the variability of reactivity over the surface and how this changes as a function of solution saturation and composition.
Publisher: American Chemical Society (ACS)
Date: 27-07-2010
DOI: 10.1021/ES9038193
Abstract: Large-scale olivine carbonation has been proposed as a potential method for sequestering CO(2) emissions. For in situ carbonation techniques, understanding the relationship between the formation of carbonate and other phases is important to predict the impact of possible passivating layers on the reaction. Therefore, we have conducted reactions of olivine with carbonated saline solutions in unstirred batch reactors. Altering the reaction conditions changed the Mg-carbonate morphology. We propose that this corresponded to changes in the ability of the system to precipitate hydromagnesite or magnesite. During high-temperature reactions (200 degrees C), an amorphous silica-enriched phase was precipitated that was transformed to lizardite as the reaction progressed. Hematite was also precipitated in the initial stages of these reactions but dissolved as the reaction proceeded. Comparison of the experimental observations with reaction models indicates that the reactions are governed by the interfacial fluid composition. The presence of a new Mg-silicate phase and the formation of secondary products at the olivine surface are likely to limit the extent of olivine to carbonate conversion.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-10281
Abstract: Every year about 10-14 million m3 of sediments are dredged in the Port of Rotterdam (PoR) as part of harbor maintenance.& Approximately 10% of these sediments are stored in a confined disposal facility (CDF) Slufter due to high levels of toxic metals (cadmium, zinc, mercury, lead, etc.) and persistent organic pollutants, whereas over 90% of the sediments that are not contaminated are currently being relocated to the sea. Whilst the majority of these sediments have the potential to be used in nature-based environmental management projects, there are concerns that the oxidation of these sediments will release greenhouse gases and contaminants to the environment.The idea of spreading ground olivine in terrestrial and coastal environments to capture CO2 is becoming increasingly popular due to the urgency to combat climate change. This technique (termed artificially enhanced olivine weathering, EOW) capitalizes on the natural process of olivine weathering that encourages gaseous CO2 to transform into dissolved bicarbonate ions (HCO3-). & In addition, the dissolution of olivine increases soil water pH and allows precipitation of secondary minerals (e.g. Fe oxyhydroxides) that can immobilize toxic metals through adsorption and co-precipitation mechanisms. As a result, EOW could be a promising geo-engineering solution for sediment management at PoR and reduce the negative environmental impacts associated with dredging. However, the specific controls on the drawdown of CO2 and toxic metal dynamics via silicate weathering are not well constrained.Through laboratory experiments and field trials, we aim to investigate whether the addition of various commercial olivine-rich mineral mixtures (Greensand, Sibelco sand, etc.) can transform the dredged material from the PoR into a sustainable resource. Several bulk sediment and intact core s les, representing the majority of sediment supplied to the Slufter, were collected from the fluvial stretch of the PoR area. Laboratory batch experiments using artificial seawater were conducted for 90 days (at 1 bar and 12oC) with (1) only fine-grained (10 & #8211 30 & #956 m) Greensand containing ~62 weight-% forsteritic olivine, 2) only fluvial harbor sediment, and 3) mixtures of Greensand and fluvial harbor sediment. Our results show that olivine dissolution caused significant increases in alkalinity, dissolved inorganic carbon (DIC), and seawater-pH. Nickel concentrations in the aqueous phase remained below the environmental standards in most of the experiments and only slightly exceeded the standard value in experiments with the highest solid/liquid ratio. Furthermore, the mobilization of toxic metals like Zn and Mn from the harbor sediment to the solution was limited in the olivine-sediment mixed experiments, most likely due to adsorption with olivine or with precipitated byproducts of olivine dissolution. Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS) analysis of the reacted olivine s les shows the presence of Ca carbonates precipitation but no clear evidence of Mg carbonates or secondary Mg silicate phases (in contrast to results from thermodynamic calculations using PHREEQC). & #173 Overall, these preliminary laboratory findings indicate that EOW applications in PoR are likely to be viable from an environmental geochemical point-of-view, but further testing in long-term experiments and field trials planned in the project will provide a more accurate assessment.
Publisher: Elsevier BV
Date: 11-2010
Publisher: MDPI AG
Date: 10-10-2016
DOI: 10.3390/MIN6040104
Publisher: Elsevier BV
Date: 07-2014
Publisher: Elsevier BV
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CC02312D
Abstract: The presence of water in the Earth has long been an enigma. However, computer modelling techniques have shown that the adsorption of water onto the fractal surfaces of interplanetary dust particles, which are present in the planetary accretion disk, is sufficiently strong to provide a viable origin of terrestrial water.
Publisher: American Chemical Society (ACS)
Date: 07-07-2014
DOI: 10.1021/CG500495A
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Helen King.