PhD studentship Deep Critical Zone Microbe-Mineral Feedbacks at University of Bristol

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Start Date: 
Tuesday, November 24, 2015 - 00:00

Project description

Co-supervised by Dr. Heather L. Buss and Prof. Alexandre M. Anesio. Project enquiries - Email: h.buss@bristol.ac.uk

Microbial communities at the rock-soil interface are key players in soil formation and nutrient cycles. In many soil environments, nutrients and energy substrate (e.g., organic carbon) are recycled by organisms living in the upper 50-100 cm of the soil, leaving little, if any, to infiltrate to depths below the rooting zone. In such environments, microbial communities at depth are highly dependent on chemolithoautotrophic primary producers: microorganisms that utilise energy derived from inorganic geological sources to produce biomass. Effectively, these are rock-eating bacteria. The biomass produced by these microorganisms becomes an energy source for organisms that utilise other metabolic processes. The production of essential mineral nutrients (e.g., P, Mg, Ca, K) and micronutrients (e.g., Zn, Cu, Mo, Cr) and the creation of new soil fundamentally depends on the physical and chemical breakdown of bedrock by weathering.

In addition to exploiting the energy and nutrients provided by weathering minerals, subsurface soil microorganisms also chemically alter environments they inhabit, impacting subsequent geochemical weathering reactions. Thus, perturbations to the diversity or functioning of the microbial community at depth have major implications for soil production, fertility, and the ecosystem services provided by soils. Predicting the impacts of environmental change (be they natural or anthropogenic) on the sustainability of soil resources and ecosystem services will require quantitative understanding of the coupled biogeochemical processes that produce and transform soil and soil nutrients. Despite this need, only a few attempts (e.g., Buss et al., 2005) have been made to quantitatively describe the coupled geochemical and biological processes at the “nexus of weathering and biology”: the rock-soil interface. This PhD studentship research project will work directly at this nexus.

In collaboration with the Czech Geological Survey and international critical zone observatory networks (www.czen.org, criticalzone.org, www.soiltrec.eu) we will collect and analyse microbiological and geochemical data from the rock-soil interface of 3 different bedrock types at the Slavkov Critical Zone Observatory (Slavkov CZO) in the Czech Republic. We will use these data to estimate energy transfer and biomass production of the different microbial groups and communities based on the different energy sources available and the microbial growth rates (estimated as functions of mineral weathering rates). This project will enable a quantitative assessment of geomicrobiological processes in soils and their vulnerabilities to environmental change, providing fundamental new insights into the role of microorganisms in the earliest stages of chemical weathering and soil development.

See attached announcement for more information.  

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