The data set comprises trace metal and isotope data from the GEOTRACES programme. The data set incorporates the core GEOTRACES parameters for example, Iron (Fe), Aluminum (Al), Zinc (Zn), Manganese (Mn), Cadmium (Cd), Copper (Cu), delta 15 Nitrogen, delta 13 Carbon, Thorium (Th) isotopes, Protactinium(Pa) isotopes, Lead (Pb) isotopes, Neodymium (Nd) isotopes and aerosols, These data are also supported by ancillary measurements. GEOTRACES is global in scope and consists of ocean sections complemented by regional process studies. The ocean sections are designed to cross regions that provide the most information about sources, sinks and internal cycling of trace elements and isotopes (TEIs). The programme started in 2006, with the first International Polar Year - GEOTRACES cruise, and aims to study all major ocean basins over the next decade. Advances in clean sampling protocols and analytical techniques provide an unprecedented capability for measurement of a wide range of TEIs. All measurements collected for GEOTRACES will use ultra clean techniques as many of the countries involved have built specialist winches, wires and conductivity-temperature-depth (CTD) units specifically for this programme. SAFe standards (standards developed following the Sampling and Analysis of Fe (SAFe) cruise) and GEOTRACES inter-calibration protocols provide quality control.The GEOTRACES programme builds on the data collected during the Geochemical Ocean Section Study (GEOSECS) in the 1970s. The potential afforded by advances in sampling protocol and analytical techniques had not been realized since then, largely because of a lack of coordinated research. The GEOTRACES programme includes scientists from approximately 30 nations, although the key countries are the UK, Germany, France, Spain, Sweden, Netherlands, USA, Canada, New Zealand, Australia, Japan, India and China.

The Iodide in the ocean project brings together marine and atmospheric scientists in order to address uncertainties in the marine iodine flux and associated ozone sink. Specifically, it aims to quantify the dominant controls on the sea surface iodide distribution and improve parameterisation of the sea-to-air iodine flux and of ozone deposition. It contains data from a combination of laboratory experiments, field measurements and ocean and atmospheric modelling from three cruises as well as worldwide sea surface measurements from 1967-2018 from published manuscripts, published and unpublished data supplied by the originators themselves or provided by repositories. Iodide, iodate and total iodine concentrations were measured on three cruises: BOBBLE, June to July 2016 in the Bay of Bengal, Sagar-Kanya33 in September 2016 in the Arabian Sea and ISOE9 in January to February 2017 in the Indian and Southern Oceans. Samples were taken from Niskin bottles on conductivity-temperature-depth (CTD) profilers. Laboratory experiments consisted of phytoplankton cultures to measure rates of iodate incorporation and iodide production. This work was carried out by Lucy Carpenter (PI), Claire Hughes (Co-PI) , Liselotte Tinel, and Helmke Hepach at York University, Mark Evans (Co-PI) at the University of Edinburgh. It was funded by the NERC Discovery Science project Iodide in the ocean: distribution and impact on iodine flux and ozone loss (parent grant reference NE/N009983/1 with child grants NE/N009444/1 and NE/N01054X/1 led by Stephen Ball and David Stevens respectively).