Enhanced benthic nitrous oxide and ammonium production after natural oxygenation of long‐term anoxic sediments - Processes and pools in the benthic nitrogen cycle after natural oxygenation of long-term anoxic sediment

In this study, we describe the long-term impact of a natural oxygenation event on the fate of fixed nitrogen in the sediment. We investigated whether the newly oxygenated sediments were sites of efficient removal of fixed nitrogen through denitrification and anammox, which environmental factors affected the division between nitrate reduction processes, and whether nitrate from the water column or sedimentary nitrification was fuelling nitrate reduction processes in the sediment. We conducted three yearly samplings in 2016, 2017, and 2018, where we performed in situ measurements of nitrate reduction process rates and sediment–water fluxes of nutrients, oxygen and dissolved inorganic carbon . We additionally collected sediment samples and measured sediment microprofiles of oxygen, nitrous oxide and hydrogen sulphide to gain further insights into the spatial distribution of the processes in surface sediments. The data set contains 5 files with the following data: - Station information; locations, sediment surface and bottom water conditions - Sediment properties; carbon and nitrogen in the sediment solid phase, porosity, pore water concentrations of NOx and NH4. - Microsensor measurements of O2, N2O and H2S - Sediment-water fluxes of oxygen, dissolved inorganic carbon, NH4 and NOx - Nitrate reduction rates in the sediment Full descriptions of the data can be found in the corresponding readme files accessible from the Data and documentation tab.