In Situ Experimentation to Determine the Impact of Sinking Particles on Dentrification and Anammox in Suboxic Waters

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Studies have suggested that remineralization of particulate organic matter is linked to nitrogen loss processes, namely denitrification and anammox, which together represent the largest uncertainties in the nitrogen cycle of the ocean. Unfortunately, no direct evidence has been gathered to relate sinking particle dynamics to nitrogen cycling in suboxic zones. To remedy this oversight, scientists from the University of Washington plan to carry out in-situ experiment with a novel drifting trap-incubation system capable of incubating water with and without sinking particles and simultaneously measure organic matter remineralization with isotopic pairing experiments to determine nitrogen cycling. The novel incubators, coupled with the enhanced isotopic labeling approach, will yield the first in situ rate measurements for these processes in the Eastern Tropical North and South Pacific. In addition, the researchers plan to do metabolomic profiling to evaluate the concentrations and turnover of metabolically important compounds used in the various nitrogen pathways, as well as proteomic evaluation of the production and abundance of enzymes pertinent to specific nitrogen pathways. In terms of the broader impacts, this study will lead to the development of a new research tool that can help further our knowledge of the nitrogen cycle. The scientists will work with the University of Washington's Centers for Ocean Sciences Education Excellence-Ocean Learning Communities Program and the Society for the Advancement of Chicanos and Native Americans in Science Program to create a dual-language website aimed at explaining the research to be carried out to undergraduates both in the United States, as well as Mexico and Peru. One graduate student and two undergraduate students would be supported and trained as part of this project.