TY - JOUR
T1 - Biogenic Nitrogen Gas Production at the Oxic-Anoxic Interface in the Cariaco Basin, Venezuela
AU - Montes, Enrique
AU - Altabet, M. A
AU - Muller-Karger, Frank E
AU - Scranton, M. I
AU - Thunell, R.
AU - Benitez-Nelson, C.
AU - Lorenzoni, Laura
AU - Astor, Y. M
PY - 2013/1/1
Y1 - 2013/1/1
N2 - Excess nitrogen gas (N2xs) was measured in samples collected at six locations in the eastern and western sub-basins of the Cariaco Basin, Venezuela, in September 2008 (non-upwelling conditions) and March 2009 (upwelling conditions). During both sampling periods, N2xs concentrations were below detection in surface waters, increasing to ∼ 22 μmol N kg-1 at the oxic-anoxic interface ([O2] ∼ 4 μmol kg-1, ∼ 250 m). Below the oxic-anoxic interface (300-400 m), the average concentration of N2xs was 24.7 ± 1.9 μmol N kg-1 in September 2008 and 27.5 ± 2.0 μmol N kg-1 in March 2009, i.e., N2xs concentrations within this depth interval were ∼ 3 μmol N kg-1 higher (p < 0.001) during the upwelling season compared to the non-upwelling period. These results suggest that N-loss in the Cariaco Basin may vary seasonally in response to changes in the flux of sinking particulate organic matter. We attribute the increase in N2 xs concentrations, or N-loss, observed during upwelling to: (1) higher availability of fixed nitrogen derived from suspended and sinking particles at the oxic-anoxic interface and/or (2) enhanced ventilation at the oxic-anoxic interface during upwelling.
AB - Excess nitrogen gas (N2xs) was measured in samples collected at six locations in the eastern and western sub-basins of the Cariaco Basin, Venezuela, in September 2008 (non-upwelling conditions) and March 2009 (upwelling conditions). During both sampling periods, N2xs concentrations were below detection in surface waters, increasing to ∼ 22 μmol N kg-1 at the oxic-anoxic interface ([O2] ∼ 4 μmol kg-1, ∼ 250 m). Below the oxic-anoxic interface (300-400 m), the average concentration of N2xs was 24.7 ± 1.9 μmol N kg-1 in September 2008 and 27.5 ± 2.0 μmol N kg-1 in March 2009, i.e., N2xs concentrations within this depth interval were ∼ 3 μmol N kg-1 higher (p < 0.001) during the upwelling season compared to the non-upwelling period. These results suggest that N-loss in the Cariaco Basin may vary seasonally in response to changes in the flux of sinking particulate organic matter. We attribute the increase in N2 xs concentrations, or N-loss, observed during upwelling to: (1) higher availability of fixed nitrogen derived from suspended and sinking particles at the oxic-anoxic interface and/or (2) enhanced ventilation at the oxic-anoxic interface during upwelling.
UR - https://digitalcommons.usf.edu/msc_facpub/1065
U2 - 10.5194/bg-10-267-2013
DO - 10.5194/bg-10-267-2013
M3 - Article
VL - 10
JO - Biogeosciences
JF - Biogeosciences
ER -