Atmospheric outflow of nutrients to the Bay of Bengal: Impact of anthropogenic sources

作者：Srinivas Bikkina; Sarin M M^*; Sarma V V S S

来源：Journal of Marine Systems, 2015, 141: 34-44.

DOI：10.1016/j.jmarsys.2014.07.008

• Atmospheric outflow
• Nutrients
• Indo-Gangetic Plain
• Bay of Bengal
• Biomass burning
• Emissions
• Organic nitrogen
• Soluble phosphorous
• Soluble iron

The air-sea deposition of nutrients (N, P and Fe) to the oceanic regions located downwind of pollution sources in south and south-east Asia is gaining considerable attention in the present-day scenario of climate change. We report here a case study on the atmospheric outflow of nutrients from the Indo-Gangetic Plain (IGP) to the Bay of Bengal (BoB). Air mass back trajectories suggest conspicuous downwind transport of chemical constituents from the IGP to the BoB during the late NE-monsoon (January-April); thus, representing BoB as one of the unique oceanic regions influenced by anthropogenic sources over a short span of 3-4 months. During the course of this study (November'09-March'10), nutrient (NO3-, NH4+, N-Org, PO43- and Fe-ws) concentrations in the atmospheric outflow show pronounced temporal variability. The inorganic nitrogen (NH4+-N: similar to 90% of N-Inorg) dominates the total soluble nitrogen (N-Tot). Although the contribution of organic nitrogen is not significant, the mass ratio of N-Org/N-Tot in the outflow varied from 0.07 to 0.40. The abundances of P-Inorg and Fe-ws varied from 0.4 to 4.8 nmol m(-3) and 0.2 to 0.6 nmol m(-3), respectively. The high abundance of K+ and significant (P-value < 0.05) correlation with P-Inorg and Fe-ws suggest their significant contribution from biomass burning emissions (BBEs). The characteristic mass ratios of nutrients (N-Inorg/N-Tot: 0.92 +/- 0.13, N-Org/N-Tot: 0.21 +/- 0.11, and P-Inorg/nss-Ca2+: 0.35 +/- 0.23) in the IGP-outflow show striking similarity with those reported over the BoB. These results have implications to further increase in the atmospheric deposition of nutrients and their impact on biogeochemistry of surface Bay of Bengal.

• 出版日期2015-1