TY - JOUR
T1 - Isotopic fractionation of dissolved ammonium at the oxygen‐hydrogen sulfide interface in anoxic waters
AU - Velinsky, David J.
AU - Fogel, Marilyn L.
AU - Todd, James F.
AU - Tebo, Bradley M.
PY - 1991/4
Y1 - 1991/4
N2 - The δ15N of dissolved ammonium was determined in three anoxic marine basins: Black Sea, Saanich Inlet, B.C., Canada, and Framvaren Fjord, Norway. In each basin, the δ15N‐NH4+ was greatest near the 02/H2S interface, with δ15N as high as +21‰. The depth distributions of NH4+ and δ15N‐NH4+ for Black Sea and Framvaren Fjord were examined with a one‐dimensional, steady‐state, vertical advection‐diffusion model to calculate the isotope fractionation during the consumption of NH4+ by bacteria. Isotope enrichments, ϵ, for Black Sea were between 5 and 15 ‰, whereas in Framvaren Fjord ϵ ranged from 20 to 30 ‰. These differences are related mainly to the ambient concentration of NH4+. Biosynthetic uptake of NH4+ rather than nitrification was responsible for the fractionation. The δ15N‐NH4+ in Saanich Inlet appears related to in‐situ regeneration of NH4+ with little isotopic fractionation between dissolved and particulate nitrogen (PN).
AB - The δ15N of dissolved ammonium was determined in three anoxic marine basins: Black Sea, Saanich Inlet, B.C., Canada, and Framvaren Fjord, Norway. In each basin, the δ15N‐NH4+ was greatest near the 02/H2S interface, with δ15N as high as +21‰. The depth distributions of NH4+ and δ15N‐NH4+ for Black Sea and Framvaren Fjord were examined with a one‐dimensional, steady‐state, vertical advection‐diffusion model to calculate the isotope fractionation during the consumption of NH4+ by bacteria. Isotope enrichments, ϵ, for Black Sea were between 5 and 15 ‰, whereas in Framvaren Fjord ϵ ranged from 20 to 30 ‰. These differences are related mainly to the ambient concentration of NH4+. Biosynthetic uptake of NH4+ rather than nitrification was responsible for the fractionation. The δ15N‐NH4+ in Saanich Inlet appears related to in‐situ regeneration of NH4+ with little isotopic fractionation between dissolved and particulate nitrogen (PN).
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U2 - 10.1029/91GL00344
DO - 10.1029/91GL00344
M3 - Article
AN - SCOPUS:0025955903
SN - 0094-8276
VL - 18
SP - 649
EP - 652
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 4
ER -