Dissolved organic carbon export and subsequent remineralization in the mesopelagic and bathypelagic realms of the North Atlantic basin

Craig A. Carlson, Dennis A. Hansell, Norman B. Nelson, David A. Siegel, William M. Smethie, Samar Khatiwala, Meredith M. Meyers, Elisa Halewood

Research output: Contribution to journalArticle

152 Scopus citations

Abstract

Dissolved organic carbon (DOC) data are presented from three meridional transects conducted in the North Atlantic as part of the US Climate Variability (CLIVAR) Repeat Hydrography program in 2003. The hydrographic sections covered a latitudinal range of 6°S to 63°N along longitudes 20°W (CLIVAR line A16), 52°W (A20) and 66°W (A22). Over 3700 individual measurements reveal unprecedented detail in the DOC distribution and systematic variations in the mesopelagic and bathypelagic zones of the North Atlantic basin. Latitudinal gradients in DOC concentrations combined with published estimates of ventilation rates for the main thermocline and North Atlantic Deep Water (NADW) indicate a net DOC export rate of 0.081PgCyr-1 from the epipelagic zone into the mesopelagic and bathypelagic zones. Model II regression and multiple linear regression models applied to pairwise measures of DOC and chlorofluorocarbon (CFC-12) ventilation age, retrieved from major water masses within the main thermocline and NADW, indicate decay rates for exported DOC ranging from 0.13 to 0.94γmolkg-1yr-1, with higher DOC concentrations driving higher rates. The contribution of DOC oxidation to oxygen consumption ranged from 5 to 29% while mineralization of sinking biogenic particles drove the balance of the apparent oxygen utilization.

Original languageEnglish (US)
Pages (from-to)1433-1445
Number of pages13
JournalDeep-Sea Research Part II: Topical Studies in Oceanography
Volume57
Issue number16
DOIs
StatePublished - Aug 1 2010

Keywords

  • AOU
  • CFC
  • Carbon export
  • DOC
  • NADW

ASJC Scopus subject areas

  • Oceanography

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