Atlantic Meridional Transect cruise AMT21 (D371) micro-molar nutrient measurements from CTD bottle samples collected in 2011.

This dataset consists of measurements of micromolar nutrient concentrations made on samples collected during the Atlantic Meridional Transect programme cruise 21 (AMT21 D371) on the RRS Discovery, between 29th September and 13th November 2011. The cruise track was between Avonmouth, UK and Punta Arenas, Chile, 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 74) at selected depths, usually from samples in the upper 500m, but down to a maximum depth of 1000m for some casts. A CTD rosette with 24 x 20L Niskin bottles was deployed. Samples were sub-sampled into acid-clean 60 ml HDPE (Nalgene) sample bottles. Analysis for nutrients was completed within 1-2 hours of sampling in all cases. Clean handling techniques were employed to avoid contamination of the samples. The nutrient analyser was a 5-channel Bran and Luebbe AAIII segmented flow autoanalyser. The analyses were for Nitrate+Nitrite, Nitrite, Phosphate, and Silicate. The analytical chemical methodologies used were according to Brewer and Riley (1965) for nitrate, Grasshoff (1976) for nitrite and Kirkwood (1989) for phosphate and silicate.