Dataset: LI tidal flat pore water analysis

Sediment cores were collected by hand from a bioturbated tidal flat at low tide using clear core tubes. These were sealed at the bottom with rubber stoppers. Overlying water was kept on top and the cores were immediately transported into the lab in buckets. In the lab, pore-water samples were collected using Rhizon samples (Seeberg-Elverfeldt et al., 2015) through pre-drilled holes in the core tubes. Samples were collected in sterile plastic syringes and immediately distributed into different vials for sample preservation. All samples were stored in the fridge. Samples for trace metal analysis were preserved by addition of nitric acid (2% v/v).

Alkalinity was determined spectrophotometrically following the method by Sarazin et al. (1999) using a Spectrostar Nano or Polarstar Omega plate reader (BMG Labtech). Cl- was determined by potentiometric titration with Ag+ using a Radiometer CMT-10 titrator. Iron, manganese and aluminum were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS; Thermo-Finnegan Element 2) following a 1:100 dilution of the samples with In-115, Y-89 and Fe-57 as internal standards. CRM-TMDW-A and in-house standards were used as external reference standards for the ICP-MS analysis.