Seawater carbonate chemistry dataset collected during the Tara Pacific Expedition 2016-2018

The Tara Pacific expedition (2016-2018) sampled coral ecosystems around 32 islands in the Pacific Ocean, and sampled the surface of oceanic waters at 249 locations, resulting in the collection of nearly 58,000 samples. The expedition was designed to systematically study corals, fish, plankton, and seawater, and included the collection of samples for advanced biogeochemical, molecular, and imaging analysis. Here we provide results of carbonate chemistry for seawater samples collected during the expedition at the offshore and inshore sampling stations as well as at coral sampling sites (a few meters from studied colonies). The sampling protocol was described by Gorsky et al. (2019). Briefly, unfiltered seawater was collected once a week during the cruise and poisoned with Hg2Cl2 before to be stored on TARA board (356 samples). Like for TARA-Ocean expedition (Picheral et al, 2014) Total Alkalinity (TA) and Total Inorganic Carbon (TC) were measured at the SNAPO-CO2 facility at LOCEAN laboratory (Paris, France) and analyzed simultaneously by potentiometric titration derived from the method developed by Edmond (1970) using a closed cell. Calibrated Certified Reference Material (CRM, Dickson et al, 2007) were regularly analyzed (CRM Batches 155, 173 and 182). Analytical accuracy of the TA and TC concentrations is ±3 µmol.kg-1. Additional parameters of the carbonate system were calculated with CO2SYS.m v3.1.1 (Feb 2021: https://github.com/jonathansharp/CO2-System-Extd) using measured TA-TC data, in-situ seawater salinity and temperature measured at each seawater sampling, and local phosphate and silicate concentrations as inputs.