¹⁵N enrichment in the surface Particulate Organic Nitrogen of the north-eastern Arabian Sea from the middle to the waning phase of the winter monsoon: possible causes

S. Kumar (1, 2) , R. Ramesh (1)

1 Planetary and Geosciences Division [Ahmedabad]
2 Environmental Sciences Research Centre

A temporal increase of ~5? in the average nitrogen isotopic composition (?¹⁵N_PON) of surface particulate organic nitrogen was observed in the open north-eastern Arabian Sea during January to late February-early March 2003, despite the presence of T. erithraeum (up to ~11%), a diazotroph that fixes atmospheric N₂, in the latter period. Hydrographic conditions and residence time of nitrate in the water column suggested that this increase could be a combined effect of denitrification in the subsurface layer and inefficient utilization of nitrate entrained in the water column during January.

Domaines: Océan, Atmosphère

S. Kumar, R. Ramesh. ¹⁵N enrichment in the surface Particulate Organic Nitrogen of the north-eastern Arabian Sea from the middle to the waning phase of the winter monsoon: possible causes. Ocean Science Discussions, 2007, 4 (1), pp.245-264. ⟨hal-00298465⟩