Hydrogeochemistry and magnitude of SGD in the Bay of Puck, southern Baltic Sea

Abstract

Summary This work reports the hydrogeochemistry of submarine groundwater discharge (SGD) in the Bay of Puck, southern Baltic Sea. To understand the seasonal and spatial variability of SGD, groundwater and seawater-based SGD samples were collected in several sites in November 2017, March 2018, May 2018 and July 2018. Additionally, a vertical, one-dimensional, advection-diffusion model was used to estimate SGD in each site. The obtained results ranged from to 1.8 × 10−7 L cm−2 s − 1 to 2.8 × 10−7 L cm−2 s − 1 and depended on both: short-timescale factors (wind direction and monthly precipitation) and long-timescale factors (total precipitation and large-scale sea level variations). The calculated rates were further extrapolated to the entire Bay of Puck and ranged from 16.0 m3 s − 1 to 127.7 m3 s−1. The estimated SGD fluxes were significantly higher than results including only the freshwater component of SGD. In the Baltic Sea the importance of SGD, as a source of water and accompanying chemical substances, is still neglected, however, the present findings indicate that locally SGD can be higher than rivers runoff.