Sediment cores were collected by divers, sealed in the field 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 - Hu and Burdige (2008); sulfate, DIC, ammonium and DOC - Burdige and Komada (2011), Komada et al. (2016); sulfide - Cline (1969), Abdulla et al. (in prep.).

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).

Note: "ns" stands for "samples not collected for this analysis".