Metabolic alkalinity release from large port facilities (Hamburg, Germany) and impact on coastal carbon storage

Metabolic activities in estuaries, especially these of large rivers, profoundly affect the downstream coastal biogeochemistry. Here, we unravel the impacts of large industrial port facilities, showing that elevated metabolic activity in the Hamburg port (Germany) increases total alkalinity (TA) and dissolved inorganic carbon (DIC) runoff to the North Sea. The imports of particulate inorganic carbon, particulate organic carbon, and particulate organic nitrogen (PIC, POC, and PON) from the upstream Elbe River can fuel up to 90 % of the TA generated in the entire estuary via calcium carbonate (CaCO3) dissolution. The remaining at least 10 % of TA generation can be attributed to anaerobic metabolic processes such as denitrification of remineralized PON or other pathways. The Elbe Estuary as a whole adds approximately 15 % to the overall DIC and TA runoff. Both the magnitude and partitioning among these processes appear to be sensitive to climatic and anthropogenic changes. Thus, with increased TA loads, the coastal ocean (in particular) would act as a stronger CO2 sink, resulting in changes to the overall coastal system's capacity to store CO2.</p

Total alkalinity (TA) and dissolved inorganic carbon (DIC) in the Ems Estuary in 2020

We measured total alkalinity (TA) and dissolved inorganic carbon (DIC) in the Ems Estuary (Germany). The cruise took place on two consecutive days in June 2020 (11.06.-12.06.2020) on the German research vessel Ludwig Prandtl. We sampled approx. every 20min along the salinity gradient from the Wadden Sea around Borkum island upstream to Papenburg. Two additional samples were collected from shore at Rhede Brücke and weir Herbrum. We took discrete water samples for TA and DIC. Physical parameters (salinity, temperature) were measured in situ with the on board flow-through FerryBox system, for which water was pumped on board from 1.2m below the surface. These data and complementary data for nutrients and stable nitrate isotopes are accessible in: https://doi.org/10.1594/PANGAEA.94222

Recent benthic foraminiferal distribution in the Elbe Estuary (North Sea, Germany): A response to environmental stressors

Highlights • Investigations of the benthic foraminiferal distribution in the Elbe Estuary. • Low diverse assemblages are dominated by Ammonia species. • Low salinities and high-frequency dredging confines foraminiferal proliferation. • Over 40 years, changes in hydrodynamic conditions induced assemblage modifications. Abstract For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to human interventions. In addition, Global Changes are modifying the estuarine physiography, leading to a re-structuration of marginal marine benthic communities. The aim of this study is to document, the modern assemblage composition and the species-environment relations of benthic foraminifera upstream the Elbe Estuary (southern North Sea) and to observe what has changed since the first survey in 1981. For this purpose, a surface sampling was carried out from 22 stations along the transitional area of the Elbe Estuary. Living (rose-Bengal stained) and dead foraminiferal assemblages were analysed as well as hydrological and sedimentological parameters (such as salinity, pH, grain-size, and organic matter). Living faunas are characterized by very low densities and largely dominated by Ammonia species. Dead assemblages are more diverse and dominated by Ammonia aomoriensis, Haynesina germanica, and Cribroelphidium selseyense. Salinity and grain-size seem to be the major factors influencing foraminiferal distributions in the transitional area. Under the ongoing climate changes, future strategies will be taken to foster the application of benthic foraminifera as biomonitoring tool in the Elbe Estuary, via this baseline investigation