Methane and nitrous oxide concentration with isotopic observations in the land-sea continuum of the Baltic Sea

This dataset contains surface water observations from rivers and coastal waters, as well as groundwater observations from beach aquifers, collected along the Baltic Sea coastline during May and August 2024. The dataset includes measurements of greenhouse gases and stable carbon isotopes. It serves as a companion dataset to the previously published “Hydrogeochemical and isotopic observations in the Baltic Sea system” (DOI: 10.5281/zenodo.15792010) with more hydrogeochemical parameters.