Nutrients in porewater of sediment profile 12923-005

Total carbonate (Ct) concentrations were determined on-board ship during Discovery 222 (leg A) nd 226 cruises, using colourmetric methods (Johnsson et al., 1987) with a precision of 0.2% RSD (n=10) using a sample loop of 4ml. During Discovery 231, 236 and Meteor 42/2 cruises a newly developed system (based on infrared detection of (CO2) were used for determination of total carbonate (Goyet and Snover, 1993; OSullivan and Millero, 1998). The precision of this method was also 0.2% RSD (n=10) using a sample loop of 4ml. Samples were filtrated through disposable sterile cellulose acetate filters (0.45µm) and stored refrigerated in polyethylene vials (rinsed in MQ-water) until analysis on-board.