Dissolved and total water column 210Po and 210Pb from samples collected on Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018

This project is part of the international GEOTRACES program, which was created to allow a comprehensive, coordinated study of trace elements and isotopes (TEIs) in the oceans. This project uses the radionuclide pair 210Pb and its grand-daughter, 210Po, to provide important biogeochemical rate information pertinent to the trace elements and isotopes (TEIs) measured during the US GEOTRACES Meridional Transect in the Pacific from Alaska to Tahiti in late 2018. Many processes in the ocean cannot be directly observed and, as such, tracers such as 210Po and 210Pb can be used to provide important constraints on their rates and pathways. 210Po (half-life = 138 d) and 210Pb (half-life = 22.3 y) decay on timescales that are useful to study 1) atmospheric deposition of trace elements, 2) scavenging of particle-reactive trace elements, 3) export of particulate organic carbon (POC) from the photic zone, and 4) the fate of hydrothermal plumes dispersed from the mid-ocean ridge system. The present data set primarily includes measurements of 210Po and 210Pb on filtered water samples (i.e., \"dissolved\" activities) collected with CTD casts. Surface water samples were collected separately and were unfiltered, so represent \"total\" activities. Particulate samples also were collected using in situ pumps and those data are reported separately.