Nutrient and total dissolved carbon (TOC) concentrations as well as pH in the water column in the Gdańsk Basin (southern Baltic Sea) in summer 2023

Description

Concentration of nutrients and total dissolved carbon (TOC) and pH was analyzed in the water column of five stations located in the Gdańsk Basin (southern Baltic Sea). Samples were collected during a cruise aboard the RV Oceanograf (owned by the University of Gdańsk) from July 28 to August 5, 2023. 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 pH and nutrient concentrations in the water column change as a result of methane from the sediment.

Steps to reproduce

Water samples (at specific depths) were collected using a Niskin bottle rosette (SBE32 12 Position Carousel System from Sea-Bird Sci.). The pH in the water column was measured using a pH probe (SBE 18, Sea-Bird Sci.). Nutrient concentrations were determined using standard spectrophotometric methods immediately after sample collection. Samples for determination of total organic carbon (TOC) were acidified with HCl to pH=2 and stored in a refrigerator before analysis in the land-based laboratory. TOC was analyzed using a high-temperature catalytic combustion and NDIR detection on a Vario TOC Cube (Elementar GmbH).

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