Approximation of submarine groundwater discharge and allied nutrient fluxes to the Bay of Bengal, India using nutrient mass balance

The magnitude of terrestrial (fresh) and recirculated (saline) submarine Groundwater Discharge (SGD) derived nutrient fluxes were estimated to transact parallel in Coleroon estuary from surface water, pore water, and groundwater samples. The dissolved nutrients fluxes observed were 1656.0 μ mol day −1 for Dissolved Inorganic Nitrogen (DIN), 127.4 μ mol day −1 for dissolved inorganic phosphate (DIP), and 534.4 μ mol day −1 for dissolved silica (DSi), suggesting sources due to fertilizers, ion exchange, and degree of weathering irrespective of tides and sampling locations. Groundwater supplied nutrients were higher than streams, rivers, and pore water, other water bodies supplied nutrients. Location A recorded a higher Redfield ratio (4274.3) and was found declining towards the coast which suggests anoxic seawater mixing with oxic groundwater, and lower ratio recorded in location C groundwater samples (1.5) suggests anoxic aquifers due to salinization. Mass balance calculated net nutrient production was 1656.0 µ mol day −1 for DIN, 127.4 µ mol day −1 for DIP, and 534.4 µ mol day −1 for DSi, suggesting SGD as sources for algal blooms and hypoxia.