Sediment cores were collected by divers, sealed in the filed with rubber stoppers and returned to the lab for processing. Pore waters were collected by inserting rhizon samplers (Seeberg-Elverfeldt et al., 2005) through pre-drilled holes in the core tubes.  Samples were collected in gas-tight glass syringes and filtered through 0.45 µm nylon filters into storage vials.  Alkalinity samples were titrated within 12hr of collection; other samples were returned to the lab for analysis, using techniques routinely used in my lab.

Alkalinity and initial pH were determined by Gran Titration using a Metrohm automatic titrator (model 785 DMP Titrino) combined with a Cole-Parmer pH electrode, calibrated using pH 4.00, 7.00 and 10.00 NIST-traceable buffers (Hu and Burdige, 2008).  Sulfate was determined by ion chromatography and conductivity detection with a Thermo-Fisher Dionex ICS-5000 ion chromatograph, while DOC was determined by high-temperature combustion using a Shimadzu TOC-V total carbon analyzer (Burdige and Komada, 2011; Komada et al. 2016).  Ammonium and DIC were determined by FIA analysis using a home-built system consisting of a Rainin Rabbit peristaltic pump and a Dionex CDM-II conductivity detector (Hall and Aller, 1992; Lustwerk and Burdige, 1995).  Total dissolved sulfide was determined spectrophotometrically with an Ocean Optics USB400 UV-Vis spectrophotometer (Cline, 1969; Abdulla et al., in prep.); Total dissolved iron was also determined spectrophotometrically by the ferrozine method using the same spectrophotometer  (Viollier et al., 2000).

Oxygen profiles in the cores were collected with polarographic microelectrodes (Luther et al., 2008) using a DLK 70 WebPstat electrochemical analyzer (AIS, Inc.) and a computer-controlled micro-profiler.