Iron Promotes the Retention of Terrigenous Dissolved Organic Matter in Subtidal Permeable Sediments

• DOI: 10.1021/acs.est.3c09531
• Publication Date: 2024-04-01T12:27:10Z
• Authors: Zhe Zhou; Hannelore Waska; Susann Henkel; Thorsten Dittmar; Sabine Kasten; Moritz Holtappels
• Keywords: Terrigenous sediment; Ferrihydrite

Marine permeable sediments are important sites for organic matter turnover in the coastal ocean. However, little is known about their role trapping dissolved (DOM). Here, we examined DOM abundance and molecular compositions (9804 formulas identified) subtidal along a near- to offshore gradient German North Sea. With salinity increasing from 30.1 34.6 PSU, composition bottom water shifts relatively higher abundances of aromatic compounds more highly unsaturated compounds. In bulk sediment, leached by ultrapure (UPW) solid phase 54 ± 20 times abundant than porewater, with H/C ratios terrigenous signature. 0.5 M HCl, amount (enriched oxygen-rich compounds) doubled compared UPW, mainly due dissolution poorly crystalline Fe phases (e.g., ferrihydrite monosulfides). This suggests that promote retention sediments, preferentially terrigenous, fractions. Given intense filtration seawater through posit can serve as an intermediate storage potentially accelerate burial