Characterisation and Availability of Organic Nitrogen within the Marine Environment |
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Phillippa Curtis-Jackson1, Martha Gledhill2, Mark Fitzsimons1 |
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Petroleum & Environmental Geochemistry Group, School of Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, UK, PL4 8AA |
| 2 | Marine Chemistry Group, School of Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, UK, PL4 8AA |
Download: Poster as an A4 pdf file. |
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Dissolved organic nitrogen (DON) is largely uncharacterised, despite the fact that its concentrations often exceed those of dissolved inorganic nitrogen (DIN) species by several orders of magnitude, within estuaries and rivers (Seitzinger & Sanders, 1997; Perakis & Hedin, 2002). This is mainly due to analytical challenges associated with the qualitative determination of DON, with its array of molecules of different sizes and functionality. However, its characterisation is key to a complete understanding the aquatic nitrogen cycle.
The release of DON by phytoplankton, after assimilation of DIN, is potentially a very important process in the marine nitrogen cycle. Recent studies on the composition of marine DON suggest that most of the higher molecular weight fraction is in the amide form. However, little is known regarding the composition of the quantitatively dominant low molecular weight (LMW) fraction of DON and, therefore, its reactivity and bioavailability.
This project aims to characterise the LMW fraction (< 1000 Da) of DON released by a phytoplankton monoculture during its growth cycle under semi-axenic conditions. Aqueous culture samples were extracted at key stages during the growth cycle and bulk DON and its fractions were determined using high temperature catalytic oxidation and LC-MS. Provisional results and ideas for future work are presented.
Download the complete poster as an A4 pdf file.