Quantification of submarine groundwater discharge (SGD) using radon, radium tracers and nutrient inputs in Punnakayal, south coast of India

The present study focused on the estimation of submarine groundwater discharge (SGD) and the effects of nutrient fluxes due to the SGD process. The parameters of SGD such as magnitude, character, and nutrient flux in Punnakayal region of South East coast of India were evaluated using multiple tracers of groundwater inputs in 2019. It was found that the elevated values for the tracers in the study area, displayed a gradational change in the values as move from estuarine part to the offshore. Simultaneous occurrence of fresh and saline SGD is observed on the study sites. Also, indicated that the SGD fluxes ranged from 0.04 to 0.12 ​m3 ​m−2 ​d−1 ​at the estuary and 0.03–0.15 ​m3 ​m−2 ​d−1 ​at the groundwater site. A substantially increased value for 222Rn activities is distinguished in the estuary to values over 312 dpm L−1. Nutrient embellishments were generally greatest at locations with substantial meteoric elements in groundwater; however, the recirculation of saltwater through the geological formation could provide a way of transferring terrestrially-derived nutrients to the coastal zone at many places. [Display omitted] •SGD fluxes ranged from 0.04 to 0.12 ​m3 ​m−2 ​d−1 ​at the estuary and 0.03–0.15 ​m3 ​m−2 ​d−1 ​at the groundwater site.•SGD driven nutrient fluxes may play an important role for nutrient recycling.•High level of tracers showing a gradual change from the estuary to the offshore.