Nitrogen isotopic composition of sinking particles from the southern Bay of Bengal: Evidence for variable nitrogen sources
Daniela Unger
Petra Schäfer
Venugopalan Ittekkot
Birgit Gaye
Abstract
An 8-year record of N fluxes and δ15N of sinking particles from the deep southern Bay of Bengal, northern Indian Ocean, is presented. Fluxes and δ15N vary between ∼0.1 and 3 mg m−2 day−1 and ∼2‰ and 8‰, respectively. The seasonal variation is determined mainly by oceanographic processes coupled to the Indian monsoon system. The annual pattern of δ15N is characterized by minima during spring intermonsoon (∼March–May), when nutrient inputs to the euphotic zone should be low because of stratification, and lighter nitrate/particulate matter is expected to be advected from the central Bay. Highest δ15N are associated with peak fluxes during southwest monsoon (∼June–September), when the southern Bay comes under the influence of the SW monsoon current, which appears to advect particulate matter with distinctly higher δ15N. The impact of this process, however, varies interannually under the influence of factors such as ENSO and the Indian Dipole Mode. Weakened advection leads to relatively low N fluxes and reduced δ15N. The data highlight the necessity of multi-annual studies to comprehend the natural variability of a system.
Unger D., Schäfer P., Ittekkot V. and Gaye B. (2006) Nitrogen isotopic composition of sinking particles from the southern Bay of Bengal: Evidence for variable nitrogen sources. 53(10): 1658-1676. 10.1016/j.dsr.2006.07.004
@article{Unger2006,
Title = {Nitrogen isotopic composition of sinking particles from the southern Bay of Bengal: Evidence for variable nitrogen sources},
Author = {Unger, Daniela and Schäfer, Petra and Ittekkot, Venugopalan and Gaye, Birgit},
Editor = {},
Year = {2006},
Pages = {1658-1676},
Volume = {53},
Doi = {10.1016/j.dsr.2006.07.004},
Abstract = {An 8-year record of N fluxes and δ15N of sinking particles from the deep southern Bay of Bengal, northern Indian Ocean, is presented. Fluxes and δ15N vary between ∼0.1 and 3 mg m−2 day−1 and ∼2‰ and 8‰, respectively. The seasonal variation is determined mainly by oceanographic processes coupled to the Indian monsoon system. The annual pattern of δ15N is characterized by minima during spring intermonsoon (∼March–May), when nutrient inputs to the euphotic zone should be low because of stratification, and lighter nitrate/particulate matter is expected to be advected from the central Bay. Highest δ15N are associated with peak fluxes during southwest monsoon (∼June–September), when the southern Bay comes under the influence of the SW monsoon current, which appears to advect particulate matter with distinctly higher δ15N. The impact of this process, however, varies interannually under the influence of factors such as ENSO and the Indian Dipole Mode. Weakened advection leads to relatively low N fluxes and reduced δ15N. The data highlight the necessity of multi-annual studies to comprehend the natural variability of a system.},
}
TY - JOUR
AU - Unger, Daniela
AU - Schäfer, Petra
AU - Ittekkot, Venugopalan
AU - Gaye, Birgit
TI - Nitrogen isotopic composition of sinking particles from the southern Bay of Bengal: Evidence for variable nitrogen sources
PY - 2006
SP - 1658-1676
VL - 53
DO - 10.1016/j.dsr.2006.07.004
AB - An 8-year record of N fluxes and δ15N of sinking particles from the deep southern Bay of Bengal, northern Indian Ocean, is presented. Fluxes and δ15N vary between ∼0.1 and 3 mg m−2 day−1 and ∼2‰ and 8‰, respectively. The seasonal variation is determined mainly by oceanographic processes coupled to the Indian monsoon system. The annual pattern of δ15N is characterized by minima during spring intermonsoon (∼March–May), when nutrient inputs to the euphotic zone should be low because of stratification, and lighter nitrate/particulate matter is expected to be advected from the central Bay. Highest δ15N are associated with peak fluxes during southwest monsoon (∼June–September), when the southern Bay comes under the influence of the SW monsoon current, which appears to advect particulate matter with distinctly higher δ15N. The impact of this process, however, varies interannually under the influence of factors such as ENSO and the Indian Dipole Mode. Weakened advection leads to relatively low N fluxes and reduced δ15N. The data highlight the necessity of multi-annual studies to comprehend the natural variability of a system.
ER -
