Temperature, salinity, alkaline phosphatase activity, phytoplankton abundance, chlorophyll a, inorganic nutrients, dissolved organic phosphorus, and dissolved zinc concentrations from towed fish surface samples in the subtropical North Atlantic during summer 2017 on cruise GApr08/JC150.

This dataset includes chlorophyll a, dissolved organic phosphorus (DOP), alkaline phosphatase activity (APA), and phytoplankton abundance data obtained from unfiltered seawater samples, inorganic nutrients (phosphate, nitrate, nitrite, ammonium), and dissolved zinc concentrations from seawater samples filtered through 0.45/0.2 µm acetate membrane cartridge filters (Sartobran-300, Sartorius), and concurrent temperature and salinity values. The 130 water samples were collected from a depth of 3 m using acid-washed PVC tubing attached to a towed FISH sampler on board the RRS James Cook during cruise JC150 (GEOTRACES cruise GApr08), between the 27 June and 8 August 2017. The temperature and salinity measurements were made by the ship's underway sensor package. The cruise took place in the subtropical North Atlantic. Chlorophyll a was measured using a Turner 10AU field fluorometer. DOP was quantified as the difference in Dissolved Inorganic Phosphorus (DIP) concentrations before and after persulfate oxidation measured by a Bran and Luebbe QuAAtro 5-channel autoanalyser. APA samples were spiked with synthetic fluorogenic substrate MUFP (4-methylumbeliferyll-phosphate), incubated for up to 12 hours, and measured using a Turner 10AU field fluorometer. Phytoplankton cell abundance (Synechococcus, Prochlorococus, Picoeukaryotes and low and high DNA content bacteria) were determined using flow cytometry. Inorganic nutrients were measured at the nanomolar level using flow colorimetric techniques with 2 metre liquid waveguides. Dissolved zinc was obtained via acidification and the use of flow-injection analysis with fluorimetric detection. Data were collected to determine the importance of zinc on the phytoplankton community growth, as part of the Natural Environment Research Council (NERC) Discovery Science grant - Zinc, Iron and Phosphorus Co-Limitation in the Ocean (ZIPLOc), grant references NE/N001079/1 and NE/N001125/1.