Outwelling of total alkalinity and dissolved inorganic carbon from the Hooghly River to the adjacent coastal Bay of Bengal

• Published in: Environmental monitoring and assessment Vol. 193; no. 7; p. 415
• Main Authors: Ghosh, Jayashree, Chakraborty, Kunal, Chanda, Abhra, Akhand, Anirban, Bhattacharya, Trishneeta, Das, Sourav, Das, Isha, Hazra, Sugata, Choudhury, S. B., Wells, Mark
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-07-2021; Springer Nature B.V
• Subjects: Acidification; Alkalinity; Atmospheric Protection/Air Quality Control/Air Pollution; Biogeochemistry; Brackishwater environment; Carbon; Carbon budget; Carbon dioxide; Carbon dioxide flux; Coastal dynamics; Dissolved inorganic carbon; Dissolved oxygen; Dynamics; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Environmental science; Estuaries; Estuarine dynamics; Fluctuations; Fluxes; Freshwater; Inland water environment; Mass balance; Monitoring/Environmental Analysis; Ocean dynamics; Oceans; Organic loading; Organic matter; Oxygen; Seasonal variability; Seasonal variation; Seasonal variations; Tropical climate; Water temperature; Bay of Bengal; Dissolved inorganic carbon flux; Coastal Bay of Bengal; LOICZ box model; Total alkalinity flux; Hooghly estuary
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-021-09191-y

The seasonal variability of the lateral flux of total alkalinity (TAlk) and dissolved inorganic carbon (DIC) of the tropical Hooghly estuary is analyzed in this work. In situ observations of water temperature, salinity, dissolved oxygen, TAlk, and pH were measured in four different stations of the Hooghly estuary. It was measured once every month during 2015–2016, and subsequently, DIC was estimated. A carbon budget was constructed to quantify carbon flows through the freshwater-marine continuum of the Hooghly estuary, and plausible impacts on the adjacent coastal ocean, the northern Bay of Bengal, were examined. The biogeochemical mass balance box model was used to compute the seasonal flow of carbon flux, and subsequently, the annual budgeting of lateral fluxes of TAlk and DIC to the adjacent coastal ocean was carried out. The net annual TAlk and DIC flux from the Hooghly estuary to the adjacent coastal ocean were 4.45 ± 1.90 × 10
11
 mol and 4.59 ± 1.70 × 10
11
 mol, respectively. The net annual DIC flux of the Hooghly estuary is about 30 to 60 times higher than surface area integrated air–water CO
2
flux, which is an indication of promoting acidification in the adjacent coastal ocean. The present study indicates that the lateral DIC flux has increased substantially in the Hooghly estuary during the last two decades. The increase in inorganic carbon load in the Hooghly estuary due to the enhanced discharge of inorganic and organic matter load in the upper reaches of the estuary led to this increase in lateral DIC flux. The results strongly establish the need of having such regional studies for better understanding the estuarine carbon dynamics, and its role in controlling the adjacent coastal ocean dynamics.