CHEMICAL CHARACTERIZATION OF DISSOLVED ORGANIC MATTER AT THE LAND-OCEAN CONTINUUM IN A CHILEAN PATAGONIA FJORD

In the central Chilean Patagonia, the Martínez-Baker Channel system links terrestrial water inputs with the southeast Pacific Ocean. This system is surrounded by the Pascua, Huemules, and Baker rivers—the latter being Chile’s largest by volume—and the Jorge Montt and Steffen glaciers and fjords. Ocean forcing is driving the rapid retreat of both tidewater glaciers. For the first time, dissolved organic matter (DOM) fractions from this unique transitional aquatic environment have been characterized to the molecular level. During Spring 2024, samples were collected at eleven locations across the Martínez-Baker Channel system at multiple depths aboard the scientific vessel Sur-Austral. In addition to total dissolved organic carbon measurements, the fluorescent fraction of DOM was analyzed via excitation-emission matrix spectroscopy. DOM was further isolated using solid-phase extraction and analyzed by high-resolution liquid chromatography tandem mass spectrometry in positive and negative mode electrospray ionization. A cheminformatics workflow was used to process chromatographic data and assess the chemical composition at a molecular and structural level. This study aims to provide insights into the transformation and fate of terrestrial carbon transported to the ocean. Understanding how these inputs shape the marine ecosystem at the land-ocean continuum is crucial, especially as climate forcing is rapidly altering the environment.

Presentation Preference: Poster

Primary Presenter: Lucia Cancelada, University of California San Diego (lcancela@ucsd.edu)

Authors:

Lucia Cancelada, Scripps Institution of Oceanography and Chemistry & Biochemistry department, University of California San Diego  (lcancela@ucsd.edu)

Marcelo Gutiérrez, Departamento de Oceanografía and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (magutier@udec.cl)

Camila Fernández, Departamento de Oceanografía and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción and CNRS, UMR 7621, LOMIC, Observatoire Océanologique de Banyuls-sur-Mer  (camilafernandez@oceanografia.udec.cl)

Valentina Valdés-Castro, Departamento de Oceanografía and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (valentinavaldes@oceanografia.udec.cl)

Paulina Montero, Centro de Investigación en Ecosistemas de la Patagonia (CIEP) and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (pmontero@ciep.cl)

Giovanni Daneri, Centro de Investigación en Ecosistemas de la Patagonia (CIEP) and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (gdaneri@ciep.cl)

Cristóbal Castillo-Ilabaca, Departamento de Oceanografía and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (ccastilloi@udec.cl)

Benjamin Granzow, Scripps Institution of Oceanography, University of California San Diego  (bgranzow@ucsd.edu)

Pieter Dorrestein, Collaborative Mass Spectrometry Innovation Center and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego  (pdorrestein@ucsd.edu)

Silvio Pantoja-Gutiérrez, Departamento de Oceanografía and Centro de Investigación Oceanográfica COPAS COASTAL, Universidad de Concepción  (spantoja@udec.cl)

Lihini Aluwihare, Scripps Institution of Oceanography, University of California San Diego  (laluwihare@ucsd.edu)