The CO2 system dynamics in the vicinity of the Vistula River mouth (the southern Baltic Sea): A baseline investigation

The CO2 system dynamics in coastal areas strongly controlled by river outflow is largely understudied. In this study, the influence of a large, continental, carbonate-rich river on the carbonate system was seasonally examined in the vicinity of the Vistula River Mouth. Three parameters describing the CO2 system were investigated: the partial pressure of carbon dioxide (pCO2), total alkalinity (TA), and pH, together with salinity, temperature, oxygen concentration, calcium cation (Ca2+), particulate inorganic carbon (PIC), and inorganic carbon (IC) in sediments. TA varied from 1700 mu mol kg 1 in the brackish water of the Gda ' nsk Bay to 3475 mu mol kg 1 in the Vistula River plume, highlighting the difference between the two end-members. Highest pCO2 was observed in October (855 mu atm) and lowest in May (148 mu atm). Oxygen concentration was negatively correlated to pCO2 in all seasons, suggesting that both were inversely controlled by the net ecosystem production (NEP). The pH seasonal variation was significant with a range of 0.72 unit. The calcium carbonate saturation (O) varied from 0.8 to 8.5 for calcite and from 0.5 to 8.5 for aragonite, both displaying O < 1 in February 2018. This study shows the importance of ecosystem metabolism and TA end-member variability (3138-3631 mu mol kg 1), for controlling pH in the vicinity of the Vistula River Mouth. In addition, we present data on PIC, supporting possible deposition of inorganic forms of carbon to the sediments near the Vistula River Mouth.

Automated summary

The study highlights the importance of ecosystem metabolism and TA end-member variability in controlling pH near the Vistula River Mouth, providing data on possible deposition of inorganic forms of carbon to sediments near the river mouth.