Atlantic Meridional Transect cruise AMT28 (JR18001) micro-molar nutrient measurements from CTD bottle samples collected in 2018.

This dataset consists of measurements of micromolar nutrient concentrations made on samples collected during the Atlantic Meridional Transect programme cruise 28 (AMT28 JR18001) on the RRS James Clark Ross, between 23rd September and 29th October 2018. The cruise track was between Harwich, UK and Stanley, Falkland Islands (Malvinas), and passed through both north and south Atlantic gyres. This dataset contributes to the AMT time-series of core oceanographic measurements along a north-south transect of the Atlantic Ocean. Samples were collected twice daily at all sampled CTDs (Total of 62) at selected depths, usually from samples in the upper 500m, but down to maximum depths of 1000-4000m during some casts. A CTD rosette with 24 x 20L Niskin bottles was deployed. Nutrient samples were drawn into 30 ml polypropylene screw-capped centrifuge tubes. The tubes and caps were cleaned with 10 percent HCl and rinsed 2-3 times with sample before filling. Samples were either analysed within 1-3 hours after sample collection or stored overnight in the fridge, allowing sufficient time for all samples to reach room temperature. The analyses were for Nitrate+Nitrite, Nitrite, Phosphate, and Silicate. The main nutrient analyser was a Seal Analytical continuous-flow AutoAnalyzer 3 (AA3). The methods used are described by Gordon et al (1992), Hager et al. (1972), and Atlas et al. (1971). Details of modification of analytical methods used in this cruise are also compatible with the methods described in the nutrient section of the GO-SHIP repeat hydrography manual (Hydes et al. 2010).