Sinking Organic Particle fluxes and stable C isotopes (collected with sediment traps) from the Eastern Tropical North Pacific on the R/V Sikuliaq cruise SKQ201617S in January 2017

Abstract

Fluxes of sinking organic carbon and nitrogen and the isotopic composition of organic carbon were obtained from free floating, unpoisoned surface tethered sediment traps at St P2 (16.5°N 107°W) in the Eastern Tropical North Pacific Oxygen Deficient Zone in January 2017. These traps were deployed from the R/V Sikuliaq on cruise SKQ201617S. Trap depths ranged between 69 m and 965 m, and trap deployments ranged between 21 and 91 hours with deeper traps deployed for longer. The Oxygen Deficient Zone extended from 105 m to 820 m at this station. Two types of traps were deployed: 1) in shallow waters (150 m), net traps (1.24 m2 opening area) 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. 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. 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. Filter samples (particles only) were wafted with HCl overnight to remove carbonate and sent to the University of Washington Isolab facility in the Department of Earth and Space Sciences (Seattle, WA) for C and N analysis. These data were collected to improve our understanding of sinking fluxes of organic matter in the offshore Oxygen Deficient Zone, and to see whether Oxygen Deficient Zones reduce organic matter attenuation Megan Duffy, Jacquelyn Neibauer, and Allan Devol and Rick Keil from the University of Washington deployed these sediment trap systems. Clara Fuchsman and Megan Duffy analyzed the data.

For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/948735