The subterranean estuary (STE) has been recognised as a reactive biogeochemical zone at the groundwater–seawater interface in coastal areas. In this study, we collected sediments from different seasons (April 2021 [storm season) and September 2021 [dry season]) from Mobile Bay, USA. Shallow sediment cores (up to 2 m) were recovered using a Geoprobe coring system (Model 5410, Geoprobe Systems, Inc.). We conducted controlled laboratory experiments using these sediments and subjected them to various nitrate inputs (Storm/Dry 2-4, GW1-2), saline solutions (Storm/Dry 5-6, SW1-2), and incubation times (Storm/Dry 7-8). We measured (1) inorganic nutrients (nitrate, nitrite, ammonium, phosphate), (2) dissolved organic carbon (DOC), and (3) dissolved organic nitrogen (DON) concentration. Dissolved organic matter (DOM) quality was analyzed with Fourier-transform ion cyclotron resonance mass spectrometry.

This dataset has been carefully reviewed and curated in accordance with PANGAEA's exceptionally high quality standards. However, due to discontinued communication from the authors' side, it did not receive the usual formal approval by the authors and therefore lacks final scientific validation.