Dataset: Dissolved elemental mercury (Hg) from samples collected by the ship’s underway system during Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from Sept-Oct 2018

This dataset reports dissolved elemental mercury (Hg) concentration measured continuously while the ship is moving, but not while on station, with samples taken from the ship's underway sampling system.

Samples are collected with 10 minute integration and the data submitted is the average concentration and standard deviation for each day while the ship is moving. The water is supplied by the ship's underway sampling system and the analytical methods rely on the equilibration of Hg-free air bubbled through the water, which is collected and analyzed using an automated Tekran 2357X air sampling system. The water concentration is calculated based on the air concentration assuming equilibrium and using Henry's Law (Mason et al., 2017; DiMento et al., 2019). The automated analyzer that detects the elemental Hg is automatically calibrated with an in situ permeation tube but was also calibrated manually each week during the cruise with a manual injection.

This parameter, because of the nature of its collection, was not assigned GEOTRACES sample numbers. The sampling depth is that of the ship's inlet system, which varies somewhat but is around 5 m on average so these are surface water samples.

Dissolved elemental Hg is reported in units of fmol/L.
Detection limit = 0.4
Spike recovery (%) = 98.2±4.3