Size fractionated organic C and N concentrations and stable isotopes from the Eastern Tropical North Pacific on the R/V Kilo Moana cruise KM1920 in October 2019

Abstract

Size fractionated Organic Particle Carbon and Nitrogen concentrations and stable C and N isotopes from the Eastern Tropical North Pacific were obtained from the R/V Kilo Moana on cruise KM1920 in the Eastern Tropical North Pacific at two stations in October 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.

For size fractionated particulate organic C and N analyses, water was obtained from Niskin bottles on a CTD rosette, by opening the bottom of the Niskin bottle. Water was gravity filtered through stacked mesh with the following pore sizes: 500 um, 180 um, 53 um, 20 um, and 5 um. Each fraction was resuspended off the mesh and vacuum filtered it onto pre-combusted GF/C filters (nominal pore size 1.2 um). 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 particle size to carbon and nitrogen relationships for models, while gaining insights into the origins of particulate organic matter in the Oxygen Deficient Zone.

Samples were collected by Jacob Cram of Horn Point Laboratory (University of Maryland Center for Environmental Science) and his lab members.

Filters were prepped in the lab, 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/948682