Dataset: Dissolved Nutrient Analyses for CTD water rosette samples and AUV Sentry/SUPR samples in the hydrothermal plumes emanating from the Main Endeavor region of the Juan de Fuca Ridge collected from R/V Atlantis cruise AT50-15 from Aug 28 to Sep 15 2023

Samples were collected in two different ways with two different instruments and these methods are identified in the data file. One method collected whole water samples as vertical profiles with a trace metal grade water rosette. The other method collected water samples with AUV Sentry equipped with a SUPR in situ sample collection system.

Samples collected with CTD water rosette were collected as whole water and filtered through 0.2 um Sterivex PES filters on deck and frozen until analysis.

Samples collected with AUV Sentry/SUPR sampler were filtered in situ through 0.2 um SUPR PES filters and the filtrate was subsampled for nutrient aliquots in a shipboard laboratory and frozen until analysis. These samples were collected in horizontal surveys as the AUV flew a gridded survey through plume depths. The AUV samples were collected while the AUV was in motion and since they were also filtering for particulate material for separate analyses, the associated water samples are an integrated mixture of waters from segments of the survey line and not point samples.

The coverage for either modes of collection are variable as we were targeting hydrothermal plume anomalies. All nutrient samples were analyzed for dissolved silicate, orthophosphate, nitrate, nitrite, and ammonium in seawater by standard methods for oceanographic nutrient samples at the UC San Diego Oceanographic Data Facility (Becker et al. 2019).