Suspended Organic Particle concentration and stable C and N isotopes from the Eastern Tropical North Pacific in April 2018 (R/V Roger Revelle RR1805) and October 2019 (R/V Kilo Moana KM1920)

Abstract

Suspended Organic Particle Carbon and Nitrogen concentrations and stable C and N isotopes were obtained from the Eastern Tropical North Pacific on the R/V Revelle cruise RR1805 in April 2018 and the R/V Kilo Moana cruise KM1920 in October 2019. R/V Revelle cruise RR1805 sampled two stations in 2018: St P2 (16.9ºN 107ºW) and St P1 (20.3 °N 106.1°W). These two stations included an anoxic Oxygen Deficient Zone from 105-820 m for St P2 and 68-800 m for St P1. The R/V Kilo Moana cruise KM1920 sampled two stations in 2019: St P2 (16.9°N 107°W) and St P3 (21.8°N 109.9°W). These two stations included an anoxic Oxygen Deficient Zone from 110-820 m for St P2 and 160-650 m for St P3. St P3 is at the Northern Edge of the Oxygen Deficient Zone. St P2 is offshore in the core of the Oxygen Deficient Zone, and St P1 is on the continental slope.

During both cruises, water for bulk suspended particulate organic C and N analyses was obtained from Niskin bottles on a CTD rosette and vacuum-filtered it onto pre-combusted GF/F filters. Samples were wafted with HCl to remove carbonate and sent to the UC Davis Stable Isotope Facility (Davis, CA) for C and N analysis utilizing an elemental analyzer attached to an isotope ratio mass spectrometer.

The samples were obtained to determine whether organic matter concentrations increased and isotopic composition changed at the secondary chlorophyll maximum in the Oxygen Deficient Zone and at the zooplankton/forage fish vertical migration depth in the Oxygen Deficient Zone. St P2 and St P1 had a secondary chlorophyll maximum and St P3 did not.

Samples were collected and data were analyzed by Clara Fuchsman of Horn Point Laboratory, a part of the University of Maryland Center for Environmental Science.

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/948637