Fig. 1: Map of the cores studied in the northern South China Sea and their biogeochemical zonation.
From: Cycling and persistence of iron-bound organic carbon in subseafloor sediments
a Map of cores QDN-G1 and QDN-14B. River systems entering the northern South China Sea are indicated by blue and red lines. b A schematic of biogeochemical zonation, including iron reduction zone (IRZ), sulfate reduction zone (SRZ), sulfate-methane transition zone (SMTZ) and methanogenic zone (MZ), in cores QDN-G1 and QDN-14B inferred by porewater geochemistry. Fe(II) concentration, sulfate concentration, dissolved inorganic carbon (DIC) concentration and carbon isotope ratio of DIC (δ13CDIC) are shown in green, red, blue and magenta lines, respectively. The location of the SMTZ is highlighted in purple. Porewater geochemistry data in QDN-14B are from Niu et al., 2017 and Hu et al., 201928,60. Detailed porewater geochemistry data are plotted in Supplementary Fig. 2 and 3. Source data are provided as a Source Data file.
