Project: In situ nucleation and growth kinetics of carbonates and oxalates with inhibitors

The aim pf this project is to derive molecular level knowledge regarding the effect and role of inhibitors on the formation of calcium carbonates and oxalates. You will employ state-of-the-art synchrotron-based scattering and diffraction techniques combined with high-resolution imaging and quantify the kinetics and mechanisms of the nucleation and growth of these phases in the absence and presence of inhibitors and as a function of changing pH, saturation and T conditions. As part of the training, opportunities for research secondments to other MINSC partners as dictated by the research programme are strongly encouraged.

You are expected to publish research papers and to present your research at national and international meetings, and interface with other MINSC fellows and partner teams. You will have a PhD in Geochemistry/Mineralogy, Inorganic Chemistry, or Material Sciences preferably including experience in aspects of synchrotron-based scattering and diffraction. You should have a demonstrated publication record, excellent communication skills, the ability to work as part of a team, and good laboratory experimental skills related to mineral synthesis and characterization.

EU eligibility criteria: You must not have resided in the UK for more than 12 months in the last 3 years. You cannot have more than 5 years of research experience since the completion of your Mastersdegree (including the time required to complete a PhD).

For further clarifications please send a CV to Liane G. Benning for final eligibility checks (l.g.benning@leeds.ac.uk). 

Salary: Fixed at €61,971 per year, plus additional Marie Curie mobility allowances, which will be paid in Sterling using an appropriate conversion rate. 

Closing Date: 1 September 2012

University Grade 7 (£30,122 - £35,938 p.a.)

Informal enquiries may be made to Professor Liane G. Benning, tel +44 (0)113 343 5220, email l.g.benning@leeds.ac.uk.

Closing Date: 01 October 2012

Non funded PhD position in Biogeochemistry: but see info about eligibility and funding possibilities

Metals, Minerals and Microbes: Fate of Heavy-Metals in the Critical Zone
Supervisor: Liane G. Benning  and Caroline Peacock

The critical zone is the heterogeneous, near surface environment in which complex interactions involving rock, sediment, soil, water, air, and living organisms regulate the natural habitat.  In this zone, the fate and mobility of heavy-metals is controlled by reactions between microbes, minerals and organic matter.  These reactions determine heavy-metal concentrations in surface- and ground-waters and are the dominant control on the migration, or retardation, of toxic heavy-metals.

Although, we can in part predict heavy-metal concentrations in the critical zone using models that describe heavy-metal reactions, the development of such models requires new, fundamental and quantitative understanding of the interactions between metal-mineral-microbes at the molecular level.

To date, the vast majority of our understanding concerning the interaction of heavy-metals with minerals is derived from laboratory studies using abiotic mineral phases.  It is increasingly recognised, however, that bacteria are ubiquitous in the critical zone and minerals precipitated in the presence of, and/or through the metabolic action of, bacteria are likely the dominant mineral forms in the near surface.  These biominerals are complex composites of bacterial cells intermixed with mineral phases, and, crucially, show significantly different reactivity towards heavy-metals compared to their abiotic counterparts.

In order to accurately predict heavy-metal concentrations and the migration of heavy-metal contamination in freshwaters we must have models that include the interaction of these metals with bacteria and bacterially produced biominerals.   Current models do not adequately account for metal-microbe and metal-biomineral interactions and might significantly under- or over-estimate heavy-metal concentrations in surface- and ground-waters.

In this project we will characterize for the first time the fundamental reactions between key toxic heavy-metals and i) ubiquitous iron- and manganese-oxidizing freshwater bacteria and ii) their iron and manganese biomineralization products.  This new information will then be used to develop the first thermodynamic and kinetic models to incorporate metal-microbe and metal-biomineral interaction.

The student will be at the forefront of a new and exciting research field combining experimental biogeochemistry and geomicrobiology with contaminant hydrology to help understand heavy-metal pollution in the near-surface environment.

Methodology:  The student will help design a series of innovative laboratory experiments to i) culture Fe- and Mn-oxidizing freshwater bacteria and synthesise Fe and Mn (hydr)oxides precipitated in the presence of, and through the metabolic action of, these microbes, and ii) characterize and quantify the uptake and release of key toxic heavy-metals by the bacteria and bacterially-produced biominerals.  We will investigate metal-microbe-biomineral interactions under different environmental conditions relevant to the near-surface environment (e.g., pH, temperature, oxic/anoxic).  We will use state-of-the-art, molecular-level X-ray Absorption Spectroscopy using synchrotron light to determine for the first time the precise mechanism of heavy-metal uptake and release.  Using our experimental results and our molecular-level data we will develop some of the first thermodynamic and kinetic models capable of robustly predicting heavy-metal concentrations in natural freshwaters and soils.

Training: The student will receive training in state-of-the-art mineralogical, biogeochemical, geomicrobiological, experimental and analytical techniques and computational geochemical modelling.  In addition, the student will be trained in a wide variety of key transferable skills within the SOEE Graduate School.

Opportunity for Travel: The student will travel with their supervisors to international synchrotron research sources including 

1. Fortin D. and Langley S. (2005) Formation and occurrence of biogenic iron-rich minerals. Earth Sci. Rev. 72, 1–19.
2. Read-Daily B.L. and Fein J.B. (2009) An X-ray absorption spectroscopy study of Cd binding to a bacterial consortia. Geochim. Cosmochim. Acta 73, 4311- 4325.
3. Peacock C.L. and Sherman D.M. (2004) Copper (II) sorption onto goethite, hematite and lepidocrocite: A surface complexation model based on ab inito molecular geometries and EXAFS spectroscopy. Geochim. Cosmochim. Acta 68, 2623- 2637.
4. Yee, N; Benning, LG; Phoenix, VR; Ferris, FG (2004) Characterization of metal-cyanobacteria sorption reactions: A combined macroscopic and infrared spectroscopic investigation. Environ. Sci. Technol. 38, 775-782.
5. Tobler, D.J., Stefánsson, A., and Benning L.G. (2008) In-situ grown silica sinters in Icelandic geothermal areas. Geobiology: 6, 481–502.