The internal consistency of the North Sea carbonate system

• Published in: Journal of Marine Systems
• Main Authors: Salt, Lesley A., Thomas, Helmuth, Bozec, Yann, Borges, Alberto, Baar, Hein J. W. De
• Other Authors: FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: Carbon dioxide; North Sea; Life sciences; Aquatic sciences & oceanology; Sciences du vivant; Sciences aquatiques & océanologie; North Atlantic
• Online Access: https://orbi.uliege.be/handle/2268/192405; https://orbi.uliege.be/bitstream/2268/192405/1/salt_et_al_2016.pdf; https://doi.org/10.1016/j.jmarsys.2015.11.008

peer reviewed Abstract In 2002 (February) and 2005 (August), the full suite of carbonate system parameters (total alkalinity (AT), dissolved inorganic carbon (DIC), pH, and partial pressure of \{CO2\} (pCO2) were measured on two re-occupations of the entire North Sea basin, with three parameters (AT, DIC, pCO2) measured on four additional re-occupations, covering all four seasons, allowing an assessment of the internal consistency of the carbonate system. For most of the year, there is a similar level of internal consistency, with \{AT\} being calculated to within ± 6 μmol kg− 1 using \{DIC\} and pH, \{DIC\} to ± 6 μmol kg− 1 using \{AT\} and pH, pH to ± 0.008 using \{AT\} and pCO2, and pCO2 to ± 8 μatm using \{DIC\} and pH, with the dissociation constants of Millero et al. (2006). In spring, however, we observe a significant decline in the ability to accurately calculate the carbonate system. Lower consistency is observed with an increasing fraction of Baltic Sea water, caused by the high contribution of organic alkalinity in this water mass, not accounted for in the carbonate system calculations. Attempts to improve the internal consistency by accounting for the unconventional salinity–borate relationships in freshwater and the Baltic Sea, and through application of the new North Atlantic salinity–boron relationship (Lee et al., 2010), resulted in no significant difference in the internal consistency.