Atmospheric deposition of N, P and Fe to the Northern Indian Ocean: Implications to C- and N-fixation

This study presents the first data set on atmospheric input of N, P and Fe to the Northern Indian Ocean. Based on the chemical analysis of ambient aerosols, collected from the marine atmospheric boundary layer (MABL) during the continental outflow (January–April), we document that dry-deposition flu...

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Bibliographic Details
Published in:The Science of the total environment 2013-07, Vol.456-457, p.104-114
Main Authors: Srinivas, Bikkina, Sarin, M.M.
Format: Article
Language:English
Subjects:
Aerosols
Air Pollutants - analysis
Air–sea deposition of nutrients
Applied sciences
Arabian Sea
Atmospheric pollution
Bay of Bengal
C-fixation
Carbon Cycle
chemical analysis
Dispersed sources and other
dry deposition
Environmental Monitoring
Exact sciences and technology
Indian Ocean
Iron - analysis
N-fixation
Natural water pollution
Nitrogen - analysis
Nitrogen Fixation
Ocean surface biogeochemistry
Phosphorus - analysis
Pollution
Pollution sources. Measurement results
Seawater - chemistry
Seawaters, estuaries
solubility
temporal variation
Water treatment and pollution
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Summary:This study presents the first data set on atmospheric input of N, P and Fe to the Northern Indian Ocean. Based on the chemical analysis of ambient aerosols, collected from the marine atmospheric boundary layer (MABL) during the continental outflow (January–April), we document that dry-deposition fluxes (μmolm−2 d−1) of N (2–167), P (0.5–4.8) and Fe (0.02–1.2) to the Bay of Bengal are significantly higher compared to those over the Arabian Sea [N: 0.2–18.6; P: 0.3–0.9; Fe: 0.001–0.015]. Using atmospherically derived P and Fe, C-fixation (1.1Pgyr−1) in the Bay of Bengal is dominated by anthropogenic sources. In contrast, C-fixation (0.03Pgyr−1) in the Arabian Sea is limited by P and Fe. This is attributed to the poor fractional solubility of atmospheric mineral dust transported to the Arabian Sea. However, N-fixation by diazotrophs in the two oceanic regions is somewhat similar (0.5Tgyr−1). Our estimate of N-deposition (0.2Tgyr−1) to the Northern Indian Ocean is significantly lower compared to model results (~800–1200mg-Nm−2yr−1≈5.7–8.6Tgyr−1 by Duce et al. (2008); ~4.1Tgyr−1 by Okin et al. (2011); ~0.8Tgyr−1 by Kanakidou et al. (2012)). An overestimate of N-deposition by models could arise due to inappropriate parameterization of temporal variability associated with the continental outflow spread over only four months. •First data set on air–sea deposition of N, P and Fe to the Northern Indian Ocean•Deposition fluxes are significantly higher over the Bay of Bengal.•Atmospheric supply of nutrients is comparable with the riverine input.•N-fixation rates in the Arabian Sea and Bay of Bengal are comparable.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2013.03.068