Temperature, salinity and oxygen concentration in the water column of the Gdańsk Basin (southern Baltic Sea) in summer 2023

Temperature, salinity and dissolved oxygen data were collected with Sea-Bird instruments (SBE 25plus Sealogger and SBE 43) during a cruise aboard the RV Oceanograf (owned by the University of Gdańsk) from July 28 to August 5, 2023. Data were acquired from 5 stations located in the Gdańsk Basin (southern Baltic Sea). Station depths were 52 m for MET2, 82 m for MET1-MP and MET1-REF, 89 m for MET1-BH and 103 m for ZGG. The MET1-BH station is a small but very active pokmark with strong and concentrated methane outflow, and MET1-MP is an extensive pokmark with diffuse gas outflow. MET2 is shallow gas regular accumulation in close proximity to the coast. The MET-REF and ZGG station represents anaerobic sediment with no signs of gas accumulation in the upper layers. The purpose of the study was to determine whether hydrochemical conditions in the water column vary as methane is released from the sediment.