=== METHOD === 
Sediment cores were collected with a multiple corer (inner Ø 9.9 cm). The cores were vertically sectioned in 0.5, 1, or 2 cm intervals down to a sediment depth of 20 cm, with highest resolution at the top. 
Samples for analysis of solid-phase carbon (TC) and nitrogen (TN) were freeze dried and homogenized using mortar and pestle prior to analysis. The samples were analyzed on an elemental analyzer (Carlo ERBA N1500g, precision +/- 1%). Sampels for organic carbon (OC) were treated with acid fumes (HCl, 37%) prior to analysis. Due to technical issues, there are no solid phase samples from 2018. 
Sediment cores for pore-water sampling were processed under anoxic conditions in an N2-filled glove bag. Pore water was extracted using Rhizon samplers (Rhizon SMS, Rhizosphere). Samples were stored dark and cold until analysis. Concentrations of NH4+ and NOx- were determined by segmented flow colorimetric analysis (Alpkem Flow Solution IV, OI Analytical). The analytical uncertainties were 0.036 μM for low (0.036– 1.43 μM) and 2.4% for high (> 1.43 μM) concentrations of NH4+ and 0.021 μM for low (0.014–1.43 μM) and 2.5% for high (> 1.43 μM) concentrations of NOx-. The "sediment slice" with depth -0.5 - 0 cm is the bottom water concentration.


 === FIELD EXPLANATION ===
Station - sampling site (A, D, E, F)

Year - sampling year (2016, 2017, 2018)

Depth_top - upper depth of sediment slice (cm)

Depth_bottom - lower depth of sediment slice (cm)

TC - total carbon (% dry weight)

OC - organic carbon (% dry weight)

TN - total nitrogen (% dry weight)

Porosity - porosity

NOx - pore water nitrite + nitrate concentration (µM)

NH4 - pore water ammonium concentration (µM)