Mixing analysis of nutrients, oxygen and inorganic carbon in the Canary Islands region

We show the distribution of nutrients, oxygen, total dissolved inorganic ca rbon (C-T) and total alkalinity (A(T)) along three sections close to the Ca nary Islands, between 18 degreesW and the African coast during Meteor 37/2 cruise (January 1997). From the thermohaline properties of Eastern North At lantic Central Water (ENACW), Mediterranean Water (MW), Antarctic Intermedi ate Water (AAIW) and North Atlantic Deep Water (NADW), a mixing model has b een established based on the water mass description. It can explain most of the variabilities found in the distribution of the chemical variables, inc luding the carbon system, and it is validated through the use of conservati ve chemical variables like 'NO.' From nutrients, oxygen, A(T) and C-T, the chemical characterisation of the water masses was performed by calculating the concentration of these variables in the previously defined thermohaline end-members. The relative variation of nutrient concentrations, resulting from the regeneration of organic matter, was estimated. Close to the Africa n shelf-break, a poleward undercurrent conveying as much as a 11% of AAIW w as observed only in the southern section (28.5 degreesN). From the chemical and thermohaline properties of the end-members, a comparison with data fro m other oceanic regions was made in respect to conservative chemical variab les ('NO'). In addition, a north-south gradient in the ventilation pattern of water masses is observed from the residuals of the model. (C) 2001 Elsev ier Science B.V. All rights reserved.