PhD project offered by the IMPRS-gBGC in July 2022

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Incorporation of oxygen measurements in soil studies

Boaz Hilman , Susan Trumbore , Gerd Gleixner , Thorsten Schäfer , Marion Schrumpf

Project description

How we understand soil respiration is restricted by the available measurement methods. A new measurement that might help to separate the various processes contributing to soil C cycling is oxygen (O2) uptake. The ratio between CO2 production and O2 uptake (the apparent respiratory quotient, ARQ) is primarily derived from the chemistry of the respiratory substrate. However, ARQ values for SOM microbial decomposition are mysteriously lower than expected by the expected substrates. The low ARQ values are probably the result of additional soil processes, like non-respiratory O2 uptake related with oxidative break-down of polymers and abiotic oxidation of reduced species. The oxygen-richer substrates in roots and roots-rhizosphere respiration result in higher ARQ values than SOM decomposition. Thus, ARQ has the potential to provide valuable information about variations in respiration sources in the belowground and about soil processes that are poorly quantified to date. The successful candidate will perform detailed soil incubations including amendment of isotopically labeled molecules and assays of soil oxidative enzymes in order to resolve the drivers of SOM-decomposition ARQ. In further stages of the PhD temporal variations in roots respiration and exudation will be studied. The PhD project will include field work and lab experiments using various measurements, e.g. ARQ, δ13C, radiocarbon, and molecular traces.

Requirements

Applications to the IMPRS-gBGC are open to well-motivated and highly-qualified students from all countries. Prerequisites for this PhD project are:
  • A Master's degree in (bio(geo)chemistry, environmental science, geosciences, physics, atmospheric science, (micro)meteorology, (geo-)ecology, geography, remote sensing, biology, computer science, mathematics, chemistry, soil science, mineralogy, hydrology) or other disciplines related to environmental sciences
  • Lab skills
    • Gas measurements (for example Raman, GC-MS, LC-MS, high resolution MS, isotopes measurements/radiocarbon)
    • Soil methods
  • Computational skills
    • Programming skills (such as IDL, Matlab, R, Python or Julia)
    • Statistics
  • Interest in soil and plant biogeochemistry
  • Excellent oral and written communication skills in English, knowledge of German and is an asset

The Max Planck Society seeks to increase the number of women in those areas where they are underrepresented and therefore explicitly encourages women to apply. The Max Planck Society is committed to increasing the number of individuals with disabilities in its workforce and therefore encourages applications from such qualified individuals.

Soil respiration chamber (© Boaz Hilman)
Soil respiration chamber (© Boaz Hilman)


>> more information about the IMPRS-gBGC + application