Scientia Marina, Vol 74, No S1 (2010)

Anthropogenic CO2 in the Azores region

Fiz F. Pérez
Instituto de Investigacións Mariñas (CSIC), Spain

Javier Arístegui
Facultad de Ciencias del Mar, Campus Universitario de Tafira, Spain

Marcos Vázquez-Rodríguez
Instituto de Investigacións Mariñas (CSIC), Spain

Aida F. Ríos
Instituto de Investigacións Mariñas (CSIC), Spain


The AZORES-I cruise was conducted in August 1998, spanning the length of three latitudinal large-scale sections at 22, 28 and 32ºW. The oceanic carbon system was oversampled by measuring total alkalinity, total inorganic carbon and pH. It is thus possible to estimate anthropogenic CO2 (CANT) and to investigate its relationship with the main water masses that are present. C CANT is calculated using the latest back-calculation techniques: φCTº and TrOCA methods. Although the two approaches produce similar vertical distributions, the results of the TrOCA method show higher CANT variability and produce higher inventories than those of the φCTº method. The large proportion of Mediterranean Water found in the northern part of the study area is the main cause of the observed increase northwards of C CANT inventories. Changes in C CANT inventories between 1981 and 2004 are evaluated using data from the TTO-NAS, OACES-93 and METEOR-60/5 cruises. According to the φCTº and TrOCA approaches, the average long-term rates of C CANT inventory change are 1.32±0.11 mol C m-2 y-1 (P=0.008) and 1.18±0.16 mol C m-2 y-1 (P=0.018), respectively. During the 1993-1998 a significant increase in the C CANT storage rate was detected by the φCTº method. It is thought that this stems directly from the enhanced Labrador Seawater formation after the increased advection observed at the time.


anthropogenic CO2; CO2 uptake; water masses; Mediterranean Water; Labrador Seawater

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