Within the south of the marginal sea between Japan and Korea, interstitial water (IW) profiles exhibit a prominent sulfate–methane transition (SMT) in the upper few meters of sediment. As the SMT has become a focus of attention, IW samples were collected at high spatial resolution within shallow sediment at Sites U1426 and U1427 and examined on board the R/V JOIDES Resolution, under the auspices of the Integrated Ocean Drilling Program, for a wide range of dissolved species. However, irregularities were noted for the sulfate (SO42–), Ba, and Fe concentration profiles, each of importance to understanding the SMT. Splits of 134 IW samples, prepared with HNO3 during the expedition, were therefore reanalyzed at Rice University for S, Ba, and Fe, with S as a proxy for SO42–. Results of 134 samples included 29 duplicates with low percent difference (0.01%–34.69%, 0.01%–14.90%, and 0.03%–35.19%) and 6 spiked blanks with low percent error relative to stock solution concentration (1.59%, 2.41%, and 4.11%). The shore-based S and Ba profiles have trends similar to those determined on ship but with obvious offsets. The remeasured Fe profiles are comparable to those measured on ship, albeit with more data points. Although the IW samples were measured between 95 and 113 days after the expedition, the new results have high data reproducibility, render smooth profiles, and give more expected chemistry across the SMTs. For these three elements, we suggest the new results should replace the shipboard data.