Abstract
The spatial and seasonal dynamics of surface water fluxes of the greenhouse gases (GHG) CO2, CH4, and
N2O were quantified in the Tay estuary, Scotland, on seven sampling occasions every 3 months during
2009/2010. This estuary is a relatively pristine river-dominated macrotidal estuary system of a type that
is sparsely represented in global GHG flux studies. Significant spatial and temporal variability in GHG
fluxes were measured, with similar spatial dynamics to that of other European estuaries. Greatest
temporal and spatial variability in gas saturations were found for CH4, which was higher in the summer,
with peaks in saturation occurring in the freshwater upper estuary and sharply decreasing in the midestuary
mixing zone. Concentrations of CO2 and N2O were also generally higher in the upper to middle
estuary in summer, although seasonality was less pronounced. Estimated air-sea fluxes also displayed
significant spatial and temporal variability. Total annual CO2 emissions were greatest in the middle estuary
zone (13.8 106 kg C yr 1), and lowest in the upper estuary (1.52 106 kg C yr 1). Seasonally, the
highest CO2 emissions integrated across the estuary were in spring and autumn, with the lowest in
winter. Total annual CH4 emissions were also highest in the middle estuary (0.05 106 kg C yr 1) and
lowest in the upper estuary (0.01 106 kg C yr 1), whereas total N2O emissions, whilst highest in the
middle estuary (2344 kg N yr 1), were lowest in the outer estuary ( 435 kg N yr 1). Emissions of CH4
and N2O were substantially higher in the summer than any other season and lowest emissions were
found in winter. The estimated annual exchange of both CO2 and N2O is substantially lower than those
reported in other European macrotidal estuaries.
© 2014 Elsevier Ltd. All rights reserved.
Original language | English |
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Pages (from-to) | 62 - 73 |
Number of pages | 12 |
Journal | Estuarine, Coastal and Shelf Science |
Volume | 153 |
DOIs | |
Publication status | First published - 2015 |
Bibliographical note
52740014Keywords
- Biogeochemistry
- Carbon dioxide
- Emissions
- Estuaries
- Methane
- Nitrous oxide
- Tay Estuary
- Water quality