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Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England

Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England
Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England
Nitrogen loadings to coastal waters have increased over the last century, resulting in deterioration in water quality. In this study we investigated the distributions and seasonality of dissolved organic nitrogen (DON), and its relationship to total dissolved nitrogen (TDN), for two anthropogenically influenced estuarine systems in southwest England. Concentrations of DON in both estuaries were generally < 80 ?M. DON showed non-conservative distributions, resulting from external and internal inputs and in situ reactivity. DON contributed 38 ± 22% (range 4–79%, Yealm) and 36 ± 17% (range 4–84%, Plym) to the TDN pool, with lower values generally observed in the fresher samples relative to the more saline samples. DON was a larger fraction of the TDN pool during the summer and autumn relative to winter and spring, indicating the influence of bacterioplankton release on nitrogen cycling in the estuaries. Ammonification and nitrification were observed in the estuaries, processes which were reproduced in incubation experiments using bioreactors. The bioreactor experiments showed that 12% h? 1 of the DON flux from the River Plym may be available to bacteria, indicating significant removal of DON during the residence time of the water in the estuary (a few days). The bioavailable nature of the DON means that this N fraction significantly adds to the eutrophication burden of the receiving coastal waters, and therefore cannot be ignored in environmental assessments.

Nitrogen, DON, TDN, DOC, Estuaries, Bioavailability
0304-4203
153-164
Badr, E-S.A.
dd4aeb21-d2aa-4537-a061-2587b7658c67
Tappin, A.
d69bc1a4-e8da-47d3-a8f9-808cbae396b7
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Badr, E-S.A.
dd4aeb21-d2aa-4537-a061-2587b7658c67
Tappin, A.
d69bc1a4-e8da-47d3-a8f9-808cbae396b7
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9

Badr, E-S.A., Tappin, A. and Achterberg, E.P. (2008) Distributions and seasonal variability of dissolved organic nitrogen in two estuaries in SW England. Marine Chemistry, 110 (3-4), 153-164. (doi:10.1016/j.marchem.2008.04.007).

Record type: Article

Abstract

Nitrogen loadings to coastal waters have increased over the last century, resulting in deterioration in water quality. In this study we investigated the distributions and seasonality of dissolved organic nitrogen (DON), and its relationship to total dissolved nitrogen (TDN), for two anthropogenically influenced estuarine systems in southwest England. Concentrations of DON in both estuaries were generally < 80 ?M. DON showed non-conservative distributions, resulting from external and internal inputs and in situ reactivity. DON contributed 38 ± 22% (range 4–79%, Yealm) and 36 ± 17% (range 4–84%, Plym) to the TDN pool, with lower values generally observed in the fresher samples relative to the more saline samples. DON was a larger fraction of the TDN pool during the summer and autumn relative to winter and spring, indicating the influence of bacterioplankton release on nitrogen cycling in the estuaries. Ammonification and nitrification were observed in the estuaries, processes which were reproduced in incubation experiments using bioreactors. The bioreactor experiments showed that 12% h? 1 of the DON flux from the River Plym may be available to bacteria, indicating significant removal of DON during the residence time of the water in the estuary (a few days). The bioavailable nature of the DON means that this N fraction significantly adds to the eutrophication burden of the receiving coastal waters, and therefore cannot be ignored in environmental assessments.

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More information

Published date: 16 June 2008
Keywords: Nitrogen, DON, TDN, DOC, Estuaries, Bioavailability

Identifiers

Local EPrints ID: 52463
URI: https://eprints.soton.ac.uk/id/eprint/52463
ISSN: 0304-4203
PURE UUID: def35098-f7e3-4621-81fa-ad7af0329d15

Catalogue record

Date deposited: 30 Jun 2008
Last modified: 13 Mar 2019 20:42

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