• Influence of phytoplankton pigment composition and primary production on pCO$_{2}$ levels in the Indian Ocean

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    • Keywords


      Dissolved inorganic carbon; pCO$_{2}$; biological pump; phytoplankton composition; Indian Ocean.

    • Abstract


      The tropical Indian Ocean is a net sink for the carbon dioxide (CO$_{2}$) in the atmosphere and phytoplankton production plays a crucial role in CO$_{2}$ fixation and determines the direction of CO$_{2}$ flux at the sea-to-air interface. In order to assess the influence of phytoplankton composition and primary production on pCO$_{2}$ levels in the Indian Ocean, sampling was conducted at 25 stations during the spring intermonsoon period under the auspices of the Indian GEOTRACES program. The pCO$_{2}$ was significantly correlated with salinity due to the discharge of low pCO$_{2}$ water by major rivers to the Bay of Bengal (BoB). The stronger negative correlation observed between pCO$_{2}$ and major phytoplankton marker pigments, net primary production and oxygen saturation levels suggesting significant influence of biological processes on pCO$_{2}$ levels in the Indian Ocean. This study indicates that pCO$_{2}$ levels are strongly modulated by biological processes than hitherto hypothesized as solubility pump in the Indian Ocean.


      $\bullet$ Surface pCO$_{2}$ levels are undersaturated in the Indian Ocean compared to atmosphere, except Arabian Sea.

      $\bullet$ Oligotrophic conditions prevailed in the entire tropical Indian Ocean.

      $\bullet$ Picophytoplankton (cyanobacteria) is the dominant phytoplankton in the Indian Ocean.

      $\bullet$ Significant relation between phytoplankton groups and pCO$_{2}$ indicates strong biological control on surface pCO$_{2}$.

    • Author Affiliations



      1. CSIR-National Institute of Oceanography, 176 Lawsons Bay Colony, Visakhapatnam, India.
      2. Academy of Scientific and Innovative Research (AcSIR), Dona Paula, Goa, India.
      3. Present address: National Centre for Sustainable Coastal Management, Chennai, India.
    • Dates

  • Journal of Earth System Science | News

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      Posted on July 25, 2019

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