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Abstract

In the present paper we report partial pressure of CO 2 (pCO 2 ) data obtained off the Belgian coast during 24 cruises. The temporal and spatial resolution of this data set allows us to discuss satisfactorily seasonal and inter-annual variability of pCO 2 in the study area. The dynamics of pCO 2 are described using two approaches: fixed reference stations and area survey cruises. The air-water fluxes of CO 2 in the Scheldt estuarine plume and in the outerplume region are estimated quantitatively, showing that these areas correspond respectively to a net annual source and sink of atmospheric CO 2 . The annually integrated air-water fluxes for the Scheldt estuarine plume range between +1.1 and +1.9 mol m −2 year −1 as a function of the formulation of the exchange coefficient of CO 2 . The annual net emission of CO 2 from the estuarine plume to the atmosphere is estimated to be between +2.3 to +4.0 Gmol year −1 which represents 17 to 29% of the estimate reported in the literature for the Scheldt inner estuary.

Sniffle: a step forward to measure in situ CO2 fluxes with the floating chamber technique

“…Our fluxes fit within the range in the European coastal environment, observed by Borges et al (2006), and globally, observed by Laruelle et al (2010) and Chen et al (2013). For example, air-sea CO 2 fluxes observed in the Scheldt Estuary (Zeebrugge, Belgium) after spring bloom, a system that is similar to Jade Bay, ranged from 2.0 × 10 -3 to 6.9 × 10 -3 mmol m -2 min -1 (Borges and Frankignoulle, 2002). Overall, the comparability of our pCO 2 data and fluxes to other studies indicates that Sniffle is a powerful tool for determining ocean carbon budgets.…”

A comparison of CO2 dynamics and air‐water fluxes in a river‐dominated estuary and a mangrove‐dominated marine estuary

“…Even in the lower reaches of the Hugli, fCO 2 (water) rarely went below~600 μatm. However, the magnitudes documented in polluted estuaries like the Rhine (∼25,000 μatm [Kempe, 1982]) and the Scheldt (∼15,200 μatm [Borges and Frankignoulle, 2002]) was much higher than observed in the present study. The monthly discharge in the Hugli Estuary, with discharge data taken from Rudra [2014], exhibited a statistically significant correlation (R 2 = 0.71, p < 0.05) with the monthly mean fCO 2 (water) values observed for all four stations of the Hugli Estuary.…”

Response to Comment on "Enhanced Open Ocean Storage of CO 2 from Shelf Sea Pumping"

“…Despite loss of CO 2 to the atmosphere, the overall system still acts as a net annual sink of CO 2 and exports DIC into the deep ocean. Thus, the high pCO 2 values at the shelf Eup to 1200 parts per million (ppm); see figure 1 in (5)^are intrinsic to this saltmarsh-dominated margin system and akin to the pCO 2 (up to 750 ppm) observed in the Scheldt River plume (8). Only if all the salt marshes were dammed off could the SAB shelf component be presented as a system on its own.…”