Browse by author
Lookup NU author(s): Robert Spencer, Dr Guenther Uher
In order to evaluate the respiration-photosynthesis dynamics in two contrasting North Sea estuaries, pH, temperature, alkalinity, chlorophyll-a (chl-a), and isotopic ratios of dissolved inorganic carbon (δ13CDIC) and dissolved oxygen (δ18ODO) were measured in the Tyne (July 2003) and Tweed (July 2003 and December 2003) estuaries. Using a concentration-dependent isotope mixing line, δ13CDIC values in the Tweed (July 2003) demonstrated mostly conservative behaviour across the estuary, reflecting mixing between riverine and marine sources, although some samples were slightly more 13C-enriched than predicted δ13CDIC values. Low pCO2 (less than 2 times atmospheric pressure) and 18O-depleted δ18ODO signatures below equilibrium with the atmosphere provided further evidence for net autotrophy in the Tweed estuary in summer 2003. Conversely, in the Tyne during the summer and in the Tweed during the winter higher pCO2 (up to 6.5 and 14.4 times atmospheric partial pressure in the Tweed and Tyne, respectively), slightly 13C-depleted δ13CDIC and 18O-enriched δ18ODO values indicated heterotrophy as the dominant process. The relatively large releases of CO2 observed during these two estuarine surveys can be attributed to significant oxidation of terrigenous organic matter (OM). This study therefore demonstrates the usefulness of combined δ18ODO and δ13CDIC isotopes in examining the relationship between respiration-photosynthesis dynamics and the fate of terrestrially derived OM during estuarine mixing. © 2008 Elsevier Ltd. All rights reserved.
Author(s): Ahad J, Barth J, Ganeshram R, Spencer R, Uher G
Publication type: Article
Publication status: Published
Journal: Estuarine, Coastal and Shelf Science
Year: 2008
Volume: 78
Issue: 4
Pages: 685-693
Print publication date: 30/07/2008
ISSN (print): 0272-7714
ISSN (electronic): 1096-0015
Publisher: Elsevier
URL: http://dx.doi.org/10.1016/j.ecss.2008.02.006
DOI: 10.1016/j.ecss.2008.02.006
Altmetrics provided by Altmetric
