NERC GW4+ DTP PhD Studentship: Unravelling the influence of soil erosion on carbon dynamics in the terrestrial and aquatic domains of agricultural catchments

University of Exeter - College of Life and Environmental Science

Unravelling the influence of soil erosion on carbon dynamics in the terrestrial and aquatic domains of agricultural catchments.

Main supervisor: Dr Jeroen Meersmans (Geography, University of Exeter)

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus six Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Met Office, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/

Intensified agricultural practices, since the Green Revolution (1950s), have increased rates of soil erosion considerably, driving significant lateral fluxes of carbon and nutrients through the landscape. However, the role of erosion on the net C balance is still unclear: on the one hand when soil is detached and transported during erosional processes soil organic carbon (SOC) will be exposed to the microbial communities and be consumed more easily, but on the other hand some of this eroded SOC will finally be buried and stabilized in depositional areas situated at footslope positions and/or in aquatic ecosystems. Furthermore, nutrients transported in association with SOC may enhance NPP in aquatic ecosystems and change their net C exchange with the atmosphere. Hence, unravelling the exact contribution of erosion on the global C cycle is needed to better understand, and improve projections of, the status of soil’s many vital ecosystem services that are linked to SOC, and the impact of land use on climate.

The PhD candidate will study the effects of erosion on SOC dynamics by monitoring in detail both the quantity and quality of SOC and C input as well as mineralization on experimental cropland sites in Cornwall and Devon. More precisely, below and aboveground biomass, SOC depth distribution and soil respiration rates will be measured at different slope positions representing different erosional and/or depositional environments. The student will also monitor C metabolism in fluvial and lacustrine environments, using O2 optodes and benthic chambers, to get a handle on the relative rates of C remineralisation across the aquatic-terrestrial continuum. Furthermore, special attention will be given on the implications for food and water quality security by focusing on the associated within-catchment variability in crop productivity and impacts on ecological health and sustainability of the aquatic environment.

In this project advanced equipment will be used, such as radionuclide detectors to measure soil erosion rates, soil CO2 flux chambers and O2 optodes to monitor remineralisation rates in aquatic environments. This will allow the PhD candidate to develop excellent research skills. After linking the detailed soil erosion, C input and mineralization data, the ultimate aim of this PhD studentship is to conduct a novel 3D spatio-temporal model, which will allow refining existing regional SOC estimates. This research is genuinely novel in that it combines both terrestrial and aquatic biogeochemistry to track the fate of C through catchments. It therefore has major potential to yield numerous publications in high impact journals and to establish a platform for developing a successful career in science.

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Type / Role:

PhD

Location(s):

South West England