|Atmospheric dry deposition of inorganic and organic nitrogen to the Bay of Bengal: Impact of continental outflow|Srinivas, B.; Sarin, M.M.; Sarma, V.V.S.S. (2011). Atmospheric dry deposition of inorganic and organic nitrogen to the Bay of Bengal: Impact of continental outflow. Mar. Chem. 127(1-4): 170-179. dx.doi.org/10.1016/j.marchem.2011.09.002
In: Marine Chemistry. Elsevier: Amsterdam. ISSN 0304-4203, more
Bay of Bengal; Inorganic nitrogen; Organic nitrogen; Continental outflow; Air–sea deposition
|Authors|| || Top |
- Srinivas, B.
- Sarin, M.M.
- Sarma, V.V.S.S.
The continental outflow from south and south-east Asia, persisting during January to March, dominates the widespread dispersal of pollutants over tropical Bay of Bengal. With a view to assess the impact of anthropogenic sources on surface ocean biogeochemistry, concentrations of water-soluble inorganic and organic nitrogen (NInorg, NOrg), their spatial variability and dry-deposition fluxes have been studied in two size fractions (PM2.5 and PM10) collected during Jan-2009 from the MABL of Bay of Bengal. The mass concentration of NInorg (NH4+ + NO3-, range: 18 to 565 nmol m- 3) dominates the total soluble nitrogen (NTot = NInorg + NOrg,) in the fine mode (PM2.5), and occurs mainly as NH4+ (range: 16 to 561 nmol m- 3). The mass-ratio of NInorg in PM2.5 to PM10 centers around 0.85, suggesting that contribution of coarse mode NO3- is relatively insignificant. The dominant contribution of NInorg (as NH4+) to NTot is also evident based on the data from earlier cruises (Feb–Mar-2001, Feb-2003 and Mar–Apr-2006) conducted in the Bay of Bengal. Water-soluble NOrg also dominates the fine fraction and accounts for no more than 40% of NTot, with relatively high concentrations along coastal regions. A significant linear relationship among NOrg, NH4+, nss-K+ and EC (p-value < 0.001) suggest their common source from biomass burning emissions and large-scale application of fertilizers (urea). The dry-deposition flux of nitrogen (NInorg + NOrg) to the Bay of Bengal ranges from 2 to 167 µmol m- 2 d- 1. The upper estimate of N-deposition is somewhat comparable with the model based fluxes, and can support up to 13% of the Primary Production in the Bay of Bengal.