An investigation of submarine groundwater discharge and related fluxes in parts of the southeast coast of India: Combined radon and nutrients mass balance approach

Submarine groundwater discharge (SGD) delivers significant nutrients from inland to oceans. Nevertheless, SGD-related nutrient fluxes have been unnoticed in the Cuddalore coast of Tamil Nadu, Bay of Bengal, exposed to thoughtful environmental issues. The present attempt was to assess SGD-aided radon and nutrient fluxes. Groundwater samples were collected and analyzed for pH, electrical conductivity, total dissolved solids, salinity, radon, nitrogen, phosphorous, and silica. The radon in groundwater samples lies between 0.1 and 7.9, with an average of 2.2 Bq L⁻¹. The SGD flux calculated from radon mass balance ranges from 0.11 to 15.03, with an average of 3.42 m d⁻¹. The SGD-associated dissolved nutrients were 4292.0, 184.0, and 1442.2 µ mol L⁻¹ d⁻¹ for dissolved inorganic nitrogen, dissolved inorganic phosphate, and dissolved silica, respectively. The quantum of SGD and accompanying nutrient fluxes were prejudiced by precipitation, hydraulic gradient, and aquifer environments like oxic and anoxic.