Summary of Abstract Submission

Abstract Submission No. IO50-02-0016PresentationPoster

IMPACT OF UPWELLING ON INORGANIC CARBON CYCLING IN THE EASTERN ARABIAN SEA

Hema Naik*1, Michelle Fernandes1, P. Rashith1, Damodar Shenoy 1, S. W. A. Naqvi1

1 CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, India

ABSTRACT :

The eastern boundary of the Arabian Sea experiences weak upwelling during the Southwest Monsoon (SWM). The upwelled water is derived from the perennial mesopelagic oxygen deficient zone that is characterized by low pH. Effect of upwelling on carbon cycling has not been investigated in this region so far. We carried out high-precision measurements of pH and Total Alkalinity (TA) on two cruises undertaken during June-July and September-October 2014, corresponding to the early and late phases of upwelling. Off the continental margin, water becomes undersaturated with respect to aragonite at depths as shallow as 250 m. Upwelling led to prevalence of low pH in surface waters (7.98-8.03) in June-July that decreased further to 7.86-7.89 on the latter cruise. The computed average pCO2 increased from 438 ľatm to 602 ľatm, whereas aragonite saturation (Ώ) declined from 3.62 to 2.58. These results demonstrate the vulnerability of this region to future changes in upwelling intensity, eutrophication and ocean acidification.