Dissolved organic matter composition and photochemical transformations in the northern North Pacific Ocean

Patricia M. Medeiros, Michael Seidel, Leanne C. Powers, Thorsten Dittmar, Dennis A Hansell, William L. Miller

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

The composition and photochemical transformations of dissolved organic matter (DOM) in the northern North Pacific Ocean were investigated at the molecular level using ultrahigh resolution mass spectrometry and geochemical tracers. Analyses included vertical profiles and experiments in which deep sea DOM was exposed to sunlight and incubated in the dark. The composition of the deep sea DOM was found to be approximately uniform and enriched with highly unsaturated compounds, with highly aromatic compounds, and with polycyclic aromatics. Surface DOM had a significantly different composition, being enriched with both highly unsaturated and with unsaturated aliphatic compounds potentially due to the addition of photodegradation products and phytoplankton inputs. Deep sea DOM composition is transformed by photoreactions, becoming more similar to surface DOM. The influence of photochemistry extends beyond the photic zone, presumably because of vertical export of DOM previously modified at the surface.

Original languageEnglish (US)
Pages (from-to)863-870
Number of pages8
JournalGeophysical Research Letters
Volume42
Issue number3
DOIs
StatePublished - Feb 16 2015

Keywords

  • dissolved organic matter
  • FT-ICR MS
  • molecular composition
  • North Pacific Ocean
  • photochemistry

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

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