Cycling of dissolved and particulate organic matter in the ocean west of the Antarctic Peninsula

• Main Author: Dittrich, Ribanna
• Other Authors: Henley, Sian, Ganeshram, Raja, Cowie, Greg, Ngwenya, Bryne, Natural Environment Research Council (NERC)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: The University of Edinburgh 2020
• Subjects: Antarctica; biogeochemistry; stable isotopes; organic chemistry; dissolved organic matter; West Antarctic Peninsula; Antarctic; The Antarctic; Antarctic Peninsula; Austral; Rothera; Rothera Research Station; Antarc*; Sea ice
• Online Access: https://hdl.handle.net/1842/37132; https://doi.org/10.7488/era/433

Dissolved organic matter (DOM) in the oceans stores as much carbon as the atmosphere for thousands of years. However, our understanding of production, transformation and removal processes of DOM is still incomplete. At the West Antarctic Peninsula (WAP), rapid warming led to increased atmospheric and oceanic temperatures during the second half of the 20th century with reduced sea-ice cover and increased glacial melting. The WAP supports a productive ecosystem with intense primary production during the austral spring and summer when solar radiation is high and sea ice cover is reduced. Research on dissolved organic matter in this region is scarce. Concentrations of DOM here are low compared to lower latitudes but reasons for this remain unclear and the cycling of DOM is not fully understood. Because of the recent climate change in this region, its geographical distance from anthropogenic sources and the distinct seasonality of the ecosystem’s productivity, the WAP represents an ideal location to study processes involved in autochthonous DOM dynamics. This thesis integrates a suite of biogeochemical and physical data to develop an understanding of dissolved organic carbon (DOC) and nitrogen (DON) cycling at the WAP. Samples have been collected for spatial analysis with the U.S. led Palmer Longterm Ecological Research Program (PAL LTER) cruise team in 2017 and samples for temporal analysis are available from the UK’s Rothera Research Station as part of the Rothera Time Series (RaTS) from 2013 to 2016. In combination with other available physical, biogeochemical and biological data, processes driving the distribution and cycling of DOM over a range of spatial and temporal timescales are investigated. The temporal analysis from the RaTS data found DOC production occurring alongside particulate organic carbon production contrasting earlier studies where DOM production was found to occur later with a time lag of a few days to weeks. This thesis shows that DOC is produced and released directly by phytoplankton while DON ...