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Role of river discharge and warming on ocean acidification and pCO2 levels in the Bay of Bengal Cover

Role of river discharge and warming on ocean acidification and pCO2 levels in the Bay of Bengal

Tellus B: Chemical and Physical Meteorology
Volume 73 (2021): Issue 1
By:  and    
Open Access
|Jan 2021
Figures & tables

Figures & Tables

Fig. 1.

The map showing the station locations of the data used for construction of multiple regression equations for the Bay of Bengal. The data collected during different periods and years are given in different colors indicated in the box. The locations of discharge by different rivers are shown. The boxes 1, 2, 3, 4 and 5 represent head bay (HB), western bay (WB), central bay (CB), and eastern bay (EB), respectively.

Table 1.

Cruise name, region, period and reference where data were published of the data collected in the Bay of Bengal.

Cruise nameArea of samplingYear and month of samplingPublication referenceSK63Western BoBMarch 1991Kumar et al. (1996)I09NCentral and eastern BoBFebruary–March 1995Sabine et al. (2000)I01ESouthern BoBSeptember–October, 1995Sabine et al. (1999, 2000)I09N_RCentral and eastern BoBApril, 2007UnpublishedSN42Western BoBJuly 2010Sarma et al. (2012a)SSK12Western coastal BoBMarch 2011UnpublishedSSK14Western coastal BoBApril 2011UnpublishedSK304Central BoB and Andaman SeaApril 2013UnpublishedRR1315Central BoBOctober 2013UnpublishedSK311Central BoBApril 2014UnpublishedSSD01Central BoB and Andaman SeaJune 2015UnpublishedSSK90Western BoBApril 2016UnpublishedI09N_RRCentral and eastern BoBApril 2016UnpublishedSSK118Western and Central BoBMar–April 2018Sarma et al. (2019) SN142Western and Central BoBJune 2019UnpublishedBOBOACentral Bay of BengalNov 2013–presentUnpublished
Fig. 2.

Mean (standard deviation) of measured (a) SST, (b) SSS, (c) Chl-a, (d) DIC, (e) pH and (f) pCO2 are depicted with reference to year of collection in the Bay of Bengal.

Fig. 3.

The relationship of pH with (a) SST, (b) SSS and (c) Chl-a and relationship of pCO2 with (d) SST, (e) SSS and (f) Chl-a in the Bay of Bengal. The color code of the figure is given in the box.

Fig. 4.

Seasonal mean rate of increase (positive) or decrease (negative) of pH (in 10−3) during (a) winter, (b) spring, (c) summer and (d) fall monsoons in the Bay of Bengal. The region within the thick contour lines shows 90% significant level.

Table 2.

Mean values of SST, SSS, AOD, Chl-a, pH and pCO2 and rate of change between 1998 and 2015 in the selected regions in the Bay of Bengal (EB: 11–13°N; 95–97°E; WB: 15–17°N; 84–86°E; HB: 20–22°N; 88–90°E; CB: 14–16°N; 89–91°E).

ParameterSeasonMeanSlope (/year)p-valueEBWBCBHBEBWBCBHBEBWBCBHBSST (°C)DJF28.1226.8127.1124.97+0.020−0.011+0.012−0.0040.240.390.490.69MAM29.6229.0129.0128.24+0.034−0.015+0.002+0.0100.110.250.700.55JJAS28.5228.9528.7429.14+0.029+0.019+0.025+0.0580.100.130.070.00ON28.6628.6928.8628.57+0.047+0.005+0.021−0.0210.010.630.060.25SSS (psu)DJF31.3132.8832.3928.90−0.041−0.017+0.022+0.0530.070.390.200.40MAM31.9233.1832.4331.90−0.027−0.018−0.0033−0.0130.080.200.730.64JJAS31.4933.3032.9825.61−0.017+0.004+0.0020−0.0040.440.740.740.58ON30.5032.0032.6322.38−0.029−0.010−0.0011+0.0810.470.720.850.36Chl (mg/m3)DJF0.200.250.181.55−0.001−0.0002−0.0004+0.0600.620.410.540.42MAM0.180.160.151.84−0.001−0.001−0.0008−0.0380.420.520.180.46JJAS0.190.250.162.33−0.001−0.002−0.0003−0.0160.350.460.430.40ON0.190.260.161.88+0.001+0.008+0.0015−0.0150.410.150.350.37AOD (at 550 nm)DJF0.310.360.270.58+0.001+0.008+0.0052+0.0170.550.000.020.00MAM0.360.470.360.63+0.005+0.009+0.0066+0.0120.070.020.040.00JJAS0.340.490.410.57−0.001+0.005+0.0015+0.0100.690.280.650.29ON0.270.330.250.44+0.001+0.010+0.0033+0.0160.770.000.280.00pHDJF8.087.998.017.99+0.0018−0.001+0.0001−0.00110.050.210.700.48MAM8.138.078.098.06+0.0020−0.001+0.0002−0.00020.050.200.740.57JJAS8.098.078.078.27+0.0019+0.001+0.0019+0.00140.070.190.120.45ON8.128.098.088.29+0.0028+0.001+0.0009−0.00250.010.370.200.20pCO2 (µatm)DJF377473447472−1.9+0.1−0.1+1.30.060.620.680.47MAM328387368408−2.1+0.7−0.2+0.20.050.330.740.59JJAS362391392196−2.0−0.7−1.9−1.60.100.450.130.47ON334371377168−2.9−0.3−0.9+2.40.010.580.150.36
Fig. 5.

Seasonal mean rate of increase (positive) or decrease (negative) of pCO2 (µatm) during (a) winter, (b) spring, (c) summer and (d) fall monsoons in the Bay of Bengal. The region within the thick contour lines shows 90% significant level.

Fig. 6.

Mean concentrations of SST, SSS, Chl-a, AOD, and derived pH, and pCO2 from MLR model (Eqs. (1) and (2)) in the EB, WB, CB and HB regions.

Fig. 7.

Variability in monthly mean SST in the (a) Eastern Bay, (b) Western Bay, (c) Central Bay and (d) Head Bay between 1998 and 2015. The rate of change in SST is given in each figure.

Table 3.

Comparison of climatological mean pH and pCO2 estimated by different models in selected regions in the Bay of Bengal.

RegionSeasonTakahashiSOCATPresent studyLauvset et al. (2015)Present studypCO2 (µatm)pHNorthern BoB (85–90°E; 14–18°N)DJF342347 ± 2440 ± 158.095 ± 0.0278.018 ± 0.015MAM347357 ± 2391 ± 118.040 ± 0.0078.006 ± 0.010JJAS351356 ± 2367 ± 138.052 ± 0.0118.091 ± 0.013ON348355 ± 2365 ± 188.054 ± 0.0018.092 ± 0.018Western BoB (80–85°E; 10–14°N)DJF352354 ± 2447 ± 7NaN8.013 ± 0.008MAM356365 ± 3402 ± 10NaN8.016 ± 0.010JJAS356363 ± 1365 ± 13NaN8.094 ± 0.012ON353358 ± 1377 ± 15NaN8.081 ± 0.015Southern BoB (85–90°E; 2–6°N)DJF360366 ± 1439 ± 4NaN8.022 ± 0.004MAM369372 ± 1366 ± 88.055 ± 0.0098.094 ± 0.008JJAS366370 ± 2403 ± 128.069 ± 0.0038.057 ± 0.011ON361366 ± 2433 ± 12NaN8.028 ± 0.011Eastern BoB (90–95°E; 6–10°N)DJF359358 ± 2434 ± 78.076 ± 0.0058.025 ± 0.006MAM360369 ± 1369 ± 15NaN8.112 ± 0.015JJAS359362 ± 2387 ± 16NaN8.072 ± 0.015ON353354 ± 2429 ± 118.097 ± 0.0038.030 ± 0.011

[i] NaN denotes no data available (Takahashi et al., 2014; Bakker et al., 2016; Lauvset et al., 2015). The reference year for both pCO2 climatology and present study are 2005.

DOI: https://doi.org/10.1080/16000889.2021.1971924 | Journal eISSN: 1600-0889
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Language: English
Page range: 1971924 - 1971924
Published on: Jan 1, 2021
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services
Keywords:
ocean acidification,
pH,
pCO2,
atmospheric dust,
climate change

© 2021 B. Sridevi, V. V. S. S. Sarma, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 73 (2021): Issue 1
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