Groundwater springs in the German Wadden Sea tidal flat: A fast-track terrestrial transfer route for nutrients and dissolved organic matter

Submarine groundwater discharge (SGD) connects fresh and marine ecosystems conveys terrestrially derived dissolved organic matter (DOM) nutrients from land to sea. The connectivity of terrestrial via SGD depends strongly on local environmental settings. For example, composition is modified its transit through the coastal aquifer, with spring-type highly permeable aquifers presumably being less affected than diffuse systems sedimentary environments. In our study, we investigated near Sahlenburg/Cuxhaven, Northern Germany, which passes fine, unconsolidated tidal sediments before entering ocean. We characterized groundwater, surface water seawater endmembers different seasons assessed potential impacting biogeochemistry “fast-track”, point-source systems. addition physicochemical parameters nutrients, analyzed DOM molecular ultrahigh-resolution mass spectrometry (FT-ICR-MS). Our data revealed a widespread geochemical influence springs flat, producing low salinity carbon (DOC), high nitrate oxygen concentrations not only in springs, but also adjacent porewater. From near- offshore, DOC decreased whereas increased, resembling an inverse estuarine pattern. Furthermore, values suggest anthropogenic sources (e.g., agricultural influence) surrounding watershed may stimulate primary productivity flat. Humic-like fluorescent (FDOM) abundances fingerprints indicated inputs nearshore saltmarsh plants, as well nearby Elbe Weser estuaries. study demonstrated that had strong impact even vicinity large rivers, productive actively hindering sulfate reduction by flushing otherwise anoxic oxygen. posit flats underestimated because it can extend far beyond their visual points.