Evaluating sources of sediment carbon of marine sediments

Evaluating sources of sediment carbon of marine sediments

Evaluating sources of sediment carbon of marine sediments

Lead Supervisor: Prof Gregory Price

Location: University of Plymouth, School of Geography, Earth, and Environmental Sciences

Duration: 6 weeks

Suitable undergraduate degrees: Earth Sciences or Environmental Sciences

Project background

Marine sediments represent one of the largest pools of organic matter and provide a long-term sink for CO2. Thus, they are a vital system of the global carbon cycle and Earths climate. A large fraction of the organic carbon that is buried in marine sediments originates from the terrestrial biosphere. In addition, organic carbon can be transported to marine sediments by other means including the weathering of ancient organic carbon in rocks and the resuspension of already-deposited carbon. Although accounting for a small part of the total global ocean area, marginal seas are an important carbon sink. Despite this importance, sources of carbon into marginal seas are less well constrained. For example, with respect to highly productive seagrass meadows, the amount and rate of organic carbon accumulating in seagrass sediments often exceeds the amount of carbon produced by seagrass (Greiner et al. 2016). This implies that there may be other inputs that contribute to carbon stocks in seagrass sediments. Stable carbon isotope analysis is a useful tool for determining the different carbon source contributions to sediments.

Our approach to assess variation in potential sources of carbon is to collect a range of samples from a number of estuaries along the Devon and Cornwall coast in southwest England. Within each estuary, locations to be sampled include freshwater, upper estuary and lower estuary. Field sampling and analytical methods will follow standard procedures. A comprehensive collection of organic material is envisaged including suspended particulate matter, coarse particulate organic matter, macrophytes and algae, saltmarsh plants (e.g., Spartina) and the more extensive surrounding terrestrial vegetation (grasses, bushes and trees) from areas adjacent to each estuary.

Samples will be identified, rinsed in deionized water (to remove any inorganic carbon) and dried at 40°C and then analysed for stable carbon (and nitrogen) isotopes, using a on a Thermo Scientific Delta V Advantage.  After data acquisition, the successful candidate will have the opportunity to process and interpret their data to understand different carbon source contributions to sediments.

Training in fieldwork, sample preparation and isotopic analysis will be provided by Prof Price and Drs Fisher and Davies. Training in data interpretation will be provided by all supervisors.

The successful candidate will join our vibrant and active research group of students, postdocs, and faculty from the University of Plymouth, which meets regularly in-person. The results of this project will form parts of a peer-reviewed publication. For further information, interested students can contact Prof. Gregory Price (g.price@plymouth.ac.uk).

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