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Dissolved organic matter composition and photochemical transformations in the northern North Pacific Ocean
Author(s) -
Medeiros Patricia. M.,
Seidel Michael,
Powers Leanne C.,
Dittmar Thorsten,
Hansell Dennis A.,
Miller William L.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062663
Subject(s) - dissolved organic carbon , composition (language) , environmental chemistry , photic zone , phytoplankton , organic matter , deep sea , photodegradation , oceanography , chemistry , photochemistry , environmental science , geology , nutrient , photocatalysis , organic chemistry , philosophy , linguistics , catalysis
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.