East India Coastal Current controls the dissolved inorganic carbon in the coastal Bay of Bengal

Sarma, V. V. S. S.; Kumari, V R; Srinivas, T. N. R.; Krishna, M. S.; Ganapathi, P.; Murty, V. S. N.

doi:10.1016/j.marchem.2018.07.010

Cited by 29 publications

(20 citation statements)

References 53 publications

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“…The biological production in the BoB is modulated to a large extent by physical processes such as seasonal upwelling, cyclones and heavy rainfall, bringing nutrients to the photic zone (Maneesha et al ., 2011; Sarma et al ., 2018). The freshwater blanket due to high fluvial discharge in the BoB leads to a strong near‐surface density stratification (Gopalakrishna and Sastry, 1985; Shetye et al ., 1996) and a shallow mixed layer.…”

Section: Study Areamentioning

confidence: 99%

Indian monsoon variability during the last 46 kyr: isotopic records of planktic foraminifera from southwestern Bay of Bengal

Gautam

Narayana

Kumar

et al. 2020

J Quaternary Science

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The Indian monsoon carries large amounts of freshwater to the northern Indian Ocean and modulates the upper ocean structure in terms of upwelling and productivity. Freshwater‐induced stratification in the upper ocean of the Bay of Bengal is linked to the changes in the Indian monsoon. In this study, we test the usefulness of δ18O and δ13C variability records for Globigerina bulloides and Orbulina universa to infer Indian monsoon variability from a sediment core retrieved from the southwestern Bay of Bengal encompassing the last 46 kyr record. Results show that the northeast monsoon was dominant during the Last Glacial Maximum. Remarkable signatures are observed in the δ18O and δ13C records during the Marine Isotope Stage (MIS) 3 to MIS‐1. Our study suggests that Indian monsoon variability is controlled by a complex of factors such as solar insolation, North Atlantic climatic shifts, and coupled ocean–atmospheric variability during the last 46 kyr.

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Section: Study Areamentioning

confidence: 99%

Indian monsoon variability during the last 46 kyr: isotopic records of planktic foraminifera from southwestern Bay of Bengal

Gautam

Narayana

Kumar

et al. 2020

J Quaternary Science

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“…(2012); Sarma, Viswanadham, et al. (2012) observed low DIC, TA, pCO 2 , and high pH in the Ganges river (Glacial river) than in peninsular rivers (Sarma, Krishna, et al., 2012; Sarma, Viswanadham, et al., 2012) and, fluctuations in river discharges can exert a strong influence on the distribution of inorganic carbon system in the coastal BoB (Sarma et al., 2018).…”

Section: Resultsmentioning

confidence: 99%

Elevated Acidification Rates Due to Deposition of Atmospheric Pollutants in the Coastal Bay of Bengal

Sridevi

Krishna

Srinivas

et al. 2021

Geophysical Research Letters

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Absorption of atmospheric CO 2 is lowering the pH of surface-ocean at the rate of 0.0015 ± 0.0005 units per year (Bates et al., 2014;Sutton et al., 2017) in the global ocean. The rate of acidification is reported as higher in the coastal than offshore region due to the proximal multiple human activities that modify the carbonate equilibria (e.g., Cai et al., 2011). Deposition of sulfate and nitrate aerosols, formed from fossil fuel and biomass burning, may further decrease pH of surface ocean (Doney et al., 2007;Mackenzie, 1995;Schlesinger, 1997).The Bay of Bengal (BoB or northeastern Indian Ocean) is the best suited region to study impact of atmospheric aerosols deposition on surface ocean acidification due to its proximity to populated areas, this region is under the influence of multitude human activities of the world's most populated region (Boblme, 2014). Zhang and Reid (2010) reported higher levels of aerosol optical depth (AOD) over the BoB and the rate of increase is the highest compared to elsewhere in the world. Recently Yadav et al. (2021) estimated higher rate of increase in anthropogenic aerosols over the northwestern and western coastal BoB (0.006-0.01/yr respectively) between 2001 and 2019 than earlier report (Zhang & Reid, 2010). Based on atmosphere-ocean couple model, Doney et al. (2007) found that atmospheric deposition of pollutants in the open sea region of BoB is decreased pH of surface-ocean by 0. 003 between 1990003 between and 2000003 between . Sarma et al. (2015 reported rapid increase in acidification in the western coastal BoB, based on data collected during 1991 and 2011, due to deposition of atmospheric pollutants. Since this study is based on two snapshot measurements, it is unclear the longterm variability in pH and potential reasons responsible for its variability. In order to examine the influence of atmosphere-ocean interactions on long-term variability in ocean acidification, time-series observations were conducted between 2007 and 2018 in the BoB. Based on this data, we would like to evaluate the (a) rate of acidification in the coastal BoB, (b) long-term variability in composition of atmospheric aerosols, and (c) impact of deposition of atmospheric pollutants on coastal water pH through laboratory experiments.

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“…3a) and strong inverse relationship with SSS (r 2 ¼ 0.86; p < 0.001; Fig. 3b) as freshwater from Ganges river is relatively high compared to seawater (Sarma et al, 2012a(Sarma et al, , 2018. Since warming of surface ocean in the northern BoB occurs due to salinity stratification, higher warming associated with low saline water.…”

Section: Multiple Linear Regression (Mlr) Approachmentioning

confidence: 94%

“…Dandapat et al (2020 found that modification of salinity has significant impact on stratification and heat flux in the BoB. As noticed by Sarma et al (2018), the decrease in salinity increases pH and decreases pCO 2 levels, therefore, increase in river discharge may decrease OA and pCO 2 levels. The main objective of this work is to evaluate impact of warming, melt-driven freshening and atmospheric dust deposition on pCO 2 and OA in the BoB.…”

Section: Introductionmentioning

confidence: 95%

“…Since discharge peaks during monsoon, pCO 2 levels decrease in the BoB resulting in linear relationship between salinity and pCO 2 levels (Kumar et al, 1996;Sarma et al, 2012a). Based on monthly time-series observations, Sarma et al (2018) reported positive correlation between the observed salinity and pCO 2 and inverse relation with pH in the coastal BoB. They further noticed that the variability in pCO 2 along the coastal BoB is governed by direction of East India Coastal Currents (EICC) that brings in low salinity waters influenced by Ganges discharge during October -January period resulting in high pH, and low pCO 2 , and contrasting to that noticed during February-May due to change in direction of EICC.…”

Section: Introductionmentioning

confidence: 99%

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Role of river discharge and warming on ocean acidification and pCO<sub>2</sub> levels in the Bay of Bengal

Sridevi

Sarma

2021

Tellus B: Chemical and Physical Meteorology

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Shifts in surface ocean pCO 2 and pH are important controls governing global climate. Based on the linear relationship of observed surface pH and pCO 2 with sea surface temperature (SST), sea surface salinity (SSS) and Chlorophyll-a (Chl-a) multiple linear regression equations were developed. Based on remote sensing SST, Chl-a and model-derived SSS, pH and pCO 2 data were derived from 1998 to 2015. Overall warming of BoB is noticed at the rate of 0.004 to 0.03 C/y whereas cooling is found in the northwestern BoB during winter and spring seasons associated with an increase in atmospheric dust. Decrease in SSS is noticed during all seasons due to melting of Himalayan ice cover associated with increase in fresh water flux due to increase in atmospheric temperature. Increase in pH is observed in the eastern and southern Bay during all seasons associating with warming and decrease in salinity. In contrast, decrease in pH (À0.001 y À1 ) and pCO 2 increase (þ0.1 to þ0.7 matm y À1 ) is noticed in the western and head Bay during winter and spring seasons due to deposition of atmospheric pollutants. This study suggests that increase in freshwater input due to melting of Himalayan ice cover and deposition of atmospheric pollutants are dominant controlling factors on surface ocean pH and pCO 2 in the BoB between 1998 and 2015 and this region is acting as a stronger sink for the atmospheric CO 2 in the present than that in the past two decades. The global coastal regions are significantly influenced by river discharge and atmospheric deposition of pollutants and they are not part of the global models leading to ill-reproduction of seasonal variability in pH and pCO 2 . Inclusion of these processes may improve prediction of pH and pCO 2 in the regions heavily influenced by discharge/deposition from land and atmosphere.

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East India Coastal Current controls the dissolved inorganic carbon in the coastal Bay of Bengal

Cited by 29 publications

References 53 publications

Indian monsoon variability during the last 46 kyr: isotopic records of planktic foraminifera from southwestern Bay of Bengal

Indian monsoon variability during the last 46 kyr: isotopic records of planktic foraminifera from southwestern Bay of Bengal

Elevated Acidification Rates Due to Deposition of Atmospheric Pollutants in the Coastal Bay of Bengal

Role of river discharge and warming on ocean acidification and pCO<sub>2</sub> levels in the Bay of Bengal

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