IMIS

Atlantic Meridional Transect cruise AMT30 (DY157) micro-molar nutrient measurements from CTD bottle samples collected in 2023.

This dataset consists of measurements of micromolar nutrient concentrations made on samples collected during the Atlantic Meridional Transect programme cruise 30 (AMT30 DY157) on the RRS Discovery, between 20th February and 30th March 2023. The cruise track, between Port Stanley, Falkland Islands, and Southampton, UK, passed through both north and south Atlantic Oceans and through the central gyre of the South Atlantic. This dataset contributes to the AMT time-series of core oceanographic measurements along a south-north transect of the Atlantic Ocean. Samples were collected on a daily basis at all sampled CTDs (total of 56) and depths (according to GO-SHIP protocols), with samples taken to a depth maximum of 500 m at most CTDs. A CTD rosette with 24 x 20L OTE (Ocean Test Equipment) bottles was used for sampling. Samples were analysed within 2-3 hours of collection for nitrate+nitrite, nitrite, phosphate and silicate using a 4-channel SEAL Analytical AAIII segmented flow, colorimetric, auto-analyser. The analytical methods used were Brewer and Riley (1965) for nitrate, Grasshoff (1976) for nitrite, and Kirkwood (1989) for phosphate and silicate. Established, proven analytical protocols were used and clean sampling and handling techniques were employed, all following International GO-SHIP nutrient protocols (Becker et al., 2020). Certified Nutrient reference materials from KANSO Ltd, Japan (Batch BU), were used during the cruise to ensure good quality control and reliable analytical results.