CO2 Input Dynamics and Air–Sea Exchange in a Large New England Estuary

Christopher W Hunt,Douglas Vandemark,Joseph E Salisbury

doi:10.1007/s12237-013-9749-2

Christopher W Hunt, Douglas Vandemark + Show 1 more

Open Access

https://doi.org/10.1007/s12237-013-9749-2

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Abstract

Repeated surveys of the Kennebec estuary, a macrotidal river estuary in Maine, USA, between 2004 and 2008 found spatial and temporal variability both in sources of carbon dioxide (CO2) to the estuary and the air–sea flux of estuary CO2. On an annual basis, the surveyed area of the Kennebec estuary had an area-weighted average partial pressure of CO2 (pCO2) of 559 μatm. The area-weighted average CO2 flux to the atmosphere was 3.54 mol C m−2 year−1. Overall, the Kennebec estuary was an annual source of 7.2 × 107 mol CO2 to the atmosphere. Distinct seasonality in estuarine pCO2 was observed, with shifts in the seasonal pattern evident between lower and higher salinities. Fluxes of CO2 from the estuary were elevated following two summertime storms, and inputs of riverine CO2 outweighed internal estuarine CO2 inputs in nearly all months. River and estuarine inputs of CO2 represented 68 and 32 % of the total CO2 contributions to the estuary, respectively. This study examines the variability of CO2 in a large New England estuary, and highlights the comparatively high contribution of CO2 from riverine sources.

Highlights

MethodsStudy Site The Kennebec estuary is located along the central Maine (USA) coast (Fig. 1)
The flux of water through estuaries represents a relatively small portion of the global water budget, and the surface area of estuaries is small relative to the surface area of the coastalCommunicated by Alberto Vieira BorgesC
Surveys of Kennebec estuary pressure of CO2 (pCO2) were conducted over a wide range of river flow conditions (Fig. 2)

Summary

Methods

Study Site The Kennebec estuary is located along the central Maine (USA) coast (Fig. 1). It is supplied with freshwater from two large adjacent rivers: the more western Androscoggin and the eastern Kennebec. The combined Kennebec and Androscoggin river system, which drains 24,389 km, represents one of the largest freshwater inputs to the Gulf of Maine system. A temperature offset was observed between the sea surface temperature measured by the continuous-flow SBE-45 and that measured at the water surface by a SBE-37 thermosalinograph deployed as part of a profiling package. The oxygen percent saturation was calculated according to Sea-bird Electronics Application Note 64 (Sea-bird Electronics 2013)

Results

Discussion

Conclusion