Spatial greenhouse gas dynamics, physical and biogeochemical properties of surface water, Baltic Sea, Finland, Aug⁠ – ⁠Sep 2023

Nicolas-Xavier Geilfus, Alf Norkko, Anna Villnäs, Bruno Delille

The dataset provides measured physical and biogeochemical parameters of coastal surface seawater, including partial pressure of CO₂ and seawater concentrations of CH₄ and N₂O, in southwestern Finland, the Baltic Sea, from August to September 2023.

Greenhouse gas (GHG) dynamics in shallow-water estuaries remain relatively scarce even though they are active sources of greenhouse gases (CO₂, CH₄, and N₂O). Shallow coastal ecosystems are highly heterogeneous, with strong physical, biogeochemical, and biological gradients that affect carbon cycling. However, large uncertainties persist due to limited measurements.

The data are based on a spatial campaign in which 21 sites were visited, spanning diverse soft-sediment habitats along a salinity gradient. The study was conducted to investigate coastal heterogeneity in greenhouse gas dynamics.

MarinePelagic biogeochemistryGreenhouse gas dynamicsCO₂CH₄Coastal ecosystemsBaltic SeaCoastClimSpatial campaign 2023

Name

Version

Citation

References

Geilfus N-X, Delille B, Villnäs A, Norkko A (2025) Spatial heterogeneity of GHG dynamics across an estuarine ecosystem. [preprint] https://doi.org/10.5194/egusphere-2025-5068

Data description

This dataset is used in publication by Geilfus et al. (2026).

The data are provided in one csv spreadsheet file.

coastclim-geilfus-2026-spatial-ghg-1.csv

Number of variables: 24
Number of cases/rows: 21
Missing data code: NaN
Delimiter: Semicolon
Encoding: UTF-8

Variables

• date Sampling date in the format of yyyy-mm-dd
• site Site ID number (1-21)
• latitude Latitude coordinates in decimal degrees
• longitude Longitude coordinates in decimal degrees
• water_depth Seawater depth in meters
• temperature Seawater temperature in degrees Celcius, °C
• salinity Salinity, psu
• o2_saturation Oxygen saturation in the seawater in percent, %
• chla Chlorophyll-a concentration in the water, µg/l
• turb Turbidity in the seawater, FTU
• cdom Colored dissolved organic matter, µg/l
• xCO2 Dry mole fraction of CO₂, ppm
• xCH4 Dry mole fraction of CH₄, ppb
• CO2_atm Atmospheric concentration of CO₂, ppm
• CH4_atm Atmospheric concentration of CH₄, ppm
• temp_eq Temperature at equilibrium in degrees Celcius, °C
• ta Total alkalinity, µmol/kg
• dic Dissolved inorganic carbon, µmol/kg
• pCO2 Surface water pCO₂, µatm
• pCH4 Surface water concentration of CH₄, nmol/l
• N2O Surface water concentration of N₂O, nmol/l
• fCO2 Air-sea CO₂ flux, mmol/m2/day
• fCH4 Air-sea CH₄ flux, mmol/m2/day
• wind_speed Wind speed in m/s

Comments

Method

Physical and biogeochemical properties of surface seawater, including the partial pressure of dissolved CO₂, and CH₄ concentration, were measured in situ using a custom-built flow-through system. It consists of a double showerhead equilibrator associated with a infrared gas analyser (IRGA, LI-COR, LI-7810) for GHG measurements. GHG measurements are coupled with measurements from a thermosalinograph (SeaBird, TSG045), a fluorometer for chlorophyll a (chl-a), turbidity, and phycocyanin concentrations (Chelsea, TriLux), a fluorometer for coloured dissolved organic matter (CDOM, Chelsea, UviLux), and an optode for dissolved oxygen concentration and saturation (Aanderaa 4531).

CoastClim

This is a contribution from the Centre for Coastal Ecosystem and Climate Change Research. CoastClim is a multidisciplinary strategic partnership between Stockholm University and the University of Helsinki, that evaluates the links between coastal biodiversity, carbon cycling, and climate feedbacks.

Funding

This study was supported by the Jane and Aatos Erkko Foundation (AN, NXG), Walter and Andrée de Nottbeck Foundation405 (NXG), and the Sophie von Julin’s Foundation (AN, AV) and utilized research infrastructure facilities at Tvärminne Zoological Station, University of Helsinki, as part of FINMARI (Finnish Marine Research Infrastructure Consortium). This project has received infrastructure funding from the European Union - NextGenerationEU instrument and is funded by the Research Council of Finland under grant number 345495. CH₄ and N₂O measurements were supported by GreenFeedBack RIA (Greenhouse gas fluxes and earth system feedback) funded by the European Union’s HORIZON research and innovation program under grant410 agreement N°101056921. Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor the granting authority can be held responsible for them.

Project

CoastClim

Publisher

Bolin Centre Database

License

Creative Commons Attribution 4.0 International License (CC BY 4.0)

First name

Nicolas-Xavier

Last name or organisation

Geilfus

Email address

nicolas-xavier.geilfus@helsinki.fi

Address

Tvärminne Zoological Station; University of Helsinki

Postal code

FI-10900

City

Hanko

Country

Finland

GCMD science keyword

Earth science > Oceans > Aquatic sciences

GCMD location

Continent > Europe > Northern Europe > Scandinavia > Finland

Dataset language

English

Begin date

2023-08-16

End date

2023-09-12

DOI

Time