Dataset: Sinking Organic Particle fluxes and stable C isotopes (collected with sediment traps) from the Eastern Tropical North Pacific on cruises SKQ201617S, RR1805, and KM1920 (2017–2019)

 Free floating, unpoisoned surface tethered sediment traps were used to quantify fluxes of sinking particles during three cruises in the Eastern Tropical North Pacific Oxygen Deficient Zone: 1) at St P1 (20.1ºN 106.2ºW)  in January 2017 from the R/V Sikuliaq on cruise SKQ201617S, 2) at St P1 and St P2 (16.9ºN 107ºW) in April 2018 from the R/V Revelle on cruise RR1805, and 3) at St P2 and St P3 (21.8°N  109.9°W) in October 2019 from the R/V Kilo Moana on cruise KM1920.

Trap depths ranged between 50 m and 965 m, and trap deployments ranged between 21 and 91 hours with deeper traps deployed for longer. Traps were deployed in arrays of two traps per line except in 2019 when they were deployed as 4 per trap line. In 2017 and 2018, two types of traps were deployed: 1) in shallow waters (<150 m), traps with a solid plastic cone top (0.46 m² opening area) were used, 2) in deep waters (>150 m), net traps (1.24 m² opening area) modeled from (Peterson et al., 2005) were used. For both types of trap, the cod end had bottoms that were open during deployment and during an 8 hour equilibration period at the target depth performed to remove oxygen contamination. Cod ends were closed with a gate valve, using a pre-programmed electronic dissolving link (burn wire) system controlled by an onboard Arduino microcontroller to start collection at the correct depth, and a second gate valve that closed the top of the cod end before retrieval. The aspect ratio, or height/trap mouth diameter, of the net traps was 2.5 while the aspect ratio of the cone traps was 0.6. These two types of traps have been shown to collect material with similar efficiency when normalized by opening area (Cram et al., 2022). No salt solution was used with these traps and no poisons were used in any chamber. For 2019, cone traps were modified to add a 36 inch tall canvas cylinder to the top of the cone to increase its aspect ratio to 1.7, but the opening area was still 0.46 m². All other aspects of the trap were the same as described above. 

Some trap deployments functioned as simple sediment traps, and some deployments were combined trap and in situ incubators. The combined trap incubators consisted of upper and lower chambers. The material used to calculate fluxes reported here was collected from the upper chamber and was not incubated.  Sinking material was collected in the lower incubation chamber, then isolated by closed a gate valve and injected with ¹⁵N-NO₂^- . While the incubation occurred (in situ), sinking material was collected in an upper chamber that never encountered the spiked material. However, we do not report d¹⁵N natural stable isotopes for the sediment trap material here due to proximity to the incubation. 

After every deployment, sediment trap material was filtered onto pre-combusted GF-75 filters (0.3 µm nominal pore size). To conform to community standards, zooplankton carcasses were not included in the measurements of carbon and nitrogen flux. Samples were stored frozen. Filter samples (particles only) were wafted with HCl overnight to remove carbonate, dried at 40°C, packed into silver foil cups. Samples from 2017 were sent to the University of Washington Isolab facility in the Department of Earth and Space Sciences (Seattle, WA) for C and N analysis utilizing an Costech elemental analyzer attached to an isotope ratio mass spectrometer (ThermoFinnegan MAT 253). Samples from 2018 and 2019 were sent to UC Davis Stable Isotope Facility (Davis, CA), where they used an elemental analyzer (Elementar Vario EL Cube) attached to an isotope ratio mass spectrometer (Isoprim VisION) for C and N analysis.