Dr Anirban Basu, Department of Earth Sciences, Royal Holloway University of London (RHUL)
Dr Javier Cuadros, Department of Earth Sciences, Natural History Museum (NHM)
Dr Anne Jungblut, Department of Life Sciences, Natural History Museum
One of the most important questions related to the critical zone research and long-term climate stability is how biology influences weathering. This PhD project investigates a crucial question of Earth’s biogeochemistry: do microorganisms accelerate rock weathering or slow it down under environmentally relevant conditions? Because microorganisms have been extracting nutrients and energy from rocks for ~3.7 billion years there is a mutual life-lithosphere modification, which is not yet well-explored. Very slow weathering observed at the field scale contradicts the idea of microbially enhanced rapid weathering from experimental studies. Therefore, it is important to test the hypothesis that microbial biofilms around minerals inhibit weathering by regulating the transport and loss of weathering products. Knowing the metabolic diversity of microbial communities, grain-scale interactions between microbial communities and minerals, and the weathering intensity is important to link the roles of biological agents to erosion and climatic change.
Gran Canaria (Canary Islands) is a natural laboratory providing two essential constraints for the project – 1) volcanic rocks of homogeneous composition and the same age, and 2) large differences of rainfall inducing large differences of microbial development in soils. This PhD project will apply cutting-edge chemical, mineralogical, isotopic and microbiology techniques and bioinformatics to determine the relationship between soil weathering rates, atmospheric precipitation and microbial communities and assess how microorganisms modify weathering intensities. U series isotopic disequilibrium (234U/238U) in porewater/stream water and soils will be used to independently constrain the weathering intensity.
The student will obtain training in field work and sample collection in Gran Canaria. They will receive training in X-ray diffraction, wet chemical analysis methods, molecular, microbiology techniques and bioinformatics (environmental DNA, high throughput sequencing, microbial community structure analysis, metagenomics and phylogenetic interference) at NHM. They will also receive training in clean lab techniques and isotopic measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) at RHUL. They will gain highly interdisciplinary quantitative geochemical skills integrating mineralogical, microbial, chemical and isotopic data.
A good background in Earth Sciences, preferably with some knowledge of chemistry and biology.