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Title: Meridional fluxes of dissolved organic matter in the North Atlantic Ocean

Abstract

Using bio-optical estimates of gelbstoff and a few platinum measurements of dissolved organic carbon (DOC{sub pt}), a budget of the meridional flux of DOC and dissolved organic nitrogen (DON) across 36{degrees}25{prime}N in the North Atlantic is constructed from previous inverse models of water and element transport. Distinct southward subsurface fluxes of dissolved organic matter (DOM) within subducted shelf water, cabelled slope water, and overturned basin water are inferred. Within two cases of a positive gradient of DOC{sub pt} between terrestrial/shelf and offshore stocks, the net equatorward exports of O{sub 2} and DOC{sub pt} from the northern North Atlantic yield molar ratios of 2.1 to 9.1, compared to the expected Redfield O{sub 2}/C ratio of 1.3. In the first case, 63% of the apparent oxygen utilization demands of the water column may be met by DOC, instead of only 14% in the second scenario, preserving a role for falling particles in the sea. With a DOC/DON ratio of 10, the larger net southward export of DON across 36{degrees}25{prime}N balances the postulated net northward input of 1.7 x 10{sup 3} kg NO{sub 3} s{sup {minus}1} of unutilized nitrate within the Gulf Stream. Without an enhanced supply of DOM from the shelves, amore » zero seaward gradient of DOM in the third case suggests that none of the poleward nitrate flux is returned southward as DON, but instead a net poleward flux of DON prevails as well. The authors present estimates are confounded, however, by the seasonal and multiyear variability of sinking processes in the North Atlantic. Future active and passive remote sensors, field programs, and simulation models must now discriminate between particulate and dissolved components of surface color signals to verify the importance of both continental margins and DOM in global biogeochemical cycles. 98 refs., 4 figs., 4 tabs.« less

Authors:
; ;  [1]
  1. Univ. of South Florida, St. Petersburg, FL (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
68038
DOE Contract Number:  
FG05-85ER60285
Resource Type:
Journal Article
Journal Name:
Journal of Geophysical Research
Additional Journal Information:
Journal Volume: 97; Journal Issue: C10; Other Information: PBD: 15 Oct 1992
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; SOLUTES; OCEANIC CIRCULATION; MASS TRANSFER; ORGANIC NITROGEN COMPOUNDS; CARBON COMPOUNDS; ATLANTIC OCEAN; NORTHERN HEMISPHERE

Citation Formats

Walsh, J J, Carder, K L, and Mueller-Karger, F E. Meridional fluxes of dissolved organic matter in the North Atlantic Ocean. United States: N. p., 1992. Web. doi:10.1029/92JC01177.
Walsh, J J, Carder, K L, & Mueller-Karger, F E. Meridional fluxes of dissolved organic matter in the North Atlantic Ocean. United States. doi:10.1029/92JC01177.
Walsh, J J, Carder, K L, and Mueller-Karger, F E. Thu . "Meridional fluxes of dissolved organic matter in the North Atlantic Ocean". United States. doi:10.1029/92JC01177.
@article{osti_68038,
title = {Meridional fluxes of dissolved organic matter in the North Atlantic Ocean},
author = {Walsh, J J and Carder, K L and Mueller-Karger, F E},
abstractNote = {Using bio-optical estimates of gelbstoff and a few platinum measurements of dissolved organic carbon (DOC{sub pt}), a budget of the meridional flux of DOC and dissolved organic nitrogen (DON) across 36{degrees}25{prime}N in the North Atlantic is constructed from previous inverse models of water and element transport. Distinct southward subsurface fluxes of dissolved organic matter (DOM) within subducted shelf water, cabelled slope water, and overturned basin water are inferred. Within two cases of a positive gradient of DOC{sub pt} between terrestrial/shelf and offshore stocks, the net equatorward exports of O{sub 2} and DOC{sub pt} from the northern North Atlantic yield molar ratios of 2.1 to 9.1, compared to the expected Redfield O{sub 2}/C ratio of 1.3. In the first case, 63% of the apparent oxygen utilization demands of the water column may be met by DOC, instead of only 14% in the second scenario, preserving a role for falling particles in the sea. With a DOC/DON ratio of 10, the larger net southward export of DON across 36{degrees}25{prime}N balances the postulated net northward input of 1.7 x 10{sup 3} kg NO{sub 3} s{sup {minus}1} of unutilized nitrate within the Gulf Stream. Without an enhanced supply of DOM from the shelves, a zero seaward gradient of DOM in the third case suggests that none of the poleward nitrate flux is returned southward as DON, but instead a net poleward flux of DON prevails as well. The authors present estimates are confounded, however, by the seasonal and multiyear variability of sinking processes in the North Atlantic. Future active and passive remote sensors, field programs, and simulation models must now discriminate between particulate and dissolved components of surface color signals to verify the importance of both continental margins and DOM in global biogeochemical cycles. 98 refs., 4 figs., 4 tabs.},
doi = {10.1029/92JC01177},
journal = {Journal of Geophysical Research},
number = C10,
volume = 97,
place = {United States},
year = {1992},
month = {10}
}