[en] The partial pressure of carbon dioxide (pCO2) in surface waters and related atmospheric exchanges were measured in nine European estuaries. Averaged fluxes over the entire estuaries are usually in the range of 0.1 to 0.5 mole of CO2 per square meter per day. For wide estuaries, net daily fluxes to the atmosphere amount to several hundred tons of carbon (up to 790 tons of carbon per day in the Scheldt estuary). European estuaries emit between 30 and 60 million tons of carbon per year to the atmosphere, representing 5 to 10% of present anthropogenic CO2 emissions for Western Europe.
Disciplines :
Aquatic sciences & oceanology
Author, co-author :
Frankignoulle, Michel; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Abril, Gwenaël; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Borges, Alberto ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Bourge, Isabelle; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Canon, Christine; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Delille, Bruno ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Libert, Emile; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Theate, Jean-Marie; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie chimique
Language :
English
Title :
Carbon Dioxide Emission from European Estuaries
Publication date :
16 October 1998
Journal title :
Science
ISSN :
0036-8075
eISSN :
1095-9203
Publisher :
American Association for the Advancement of Science, Washington, United States - District of Columbia
Volume :
282
Issue :
5388
Pages :
434-6
Peer reviewed :
Peer Reviewed verified by ORBi
Name of the research project :
BIOGEST
Funders :
UE - Union Européenne [BE] F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
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F = K α ΔP, where F is the flux in mol m-2 s-1, K is the exchange coefficient in m s-1, α is the CO2 solubility coefficient in mol m-3 atm-1, and ΔP is the CO2 gradient through the interface [pCO2(water)-pCO2(air)] in atmospheres. An exchange coefficient of 2 × 10-5 m s-1 (that is, 8 cm hour-1) (2, 22, 23) was used for a Schmidt number Sc = 600 (24), which is a typical value for a moderately turbulent river (25).
Atmospheric exchanges of CO2 were measured using the direct floating chamber method (26) adapted for operation in estuarine environments (2). The chamber was set up on a lagrangian system in order to avoid creation of turbidity due to estuarine current and to follow the same water mass. Measurements were typically carried out each 2.5 salinity step through the whole estuary. Wind speed is usually low in investigated areas (0 to 5 m s-1), and the exchange coefficient K (27) is mainly determined by the turbulence of the water column. Calculated values of K, from measured flux and CO2 gradient (27), is in good agreement with those reported for rivers (25). It should be pointed out that, if wind becomes predominant, actual efflux would be higher than our estimate.
We thank the crews and technicians who were involved in the numerous cruises, R. Wollast and two anonymous referees for helpful comments on a previous version of this manuscript, and A. Pollentier, J. Backers, and A. Peliz for providing salinity and temperature data. Funded by the Fonds National de la Recherche Scientifique (FNRS, Belgium), with which the senior author is a research associate, and the European Union [Marine Science and Technology (MAST) and Environment and Climate programs]. This is a contribution to the European Land Ocean Interactions Studies (ELOISE) Programme (publication number 037) in the framework of the Biogas Transfer in Estuaries (BIOGEST) project carried out under contract ENV4-CT96-0213.
