Influence of Organo‐Mineral Associations on Terrestrial Particulate Organic Matter Dispersal in the Northern Gulf of Mexico

作者：Yord W. Yedema, Francesca Sangiorgi, João Trabucho‐Alexandre, Klaas G.J. Nierop, Jorien E. Vonk, Francien Peterse · 发表于：Journal of Geophysical Research Biogeosciences · 年份：2024 · DOI：10.1029/2024jg008144 · 被引用次数：5 · 研究领域：Atmospheric chemistry and aerosols、Marine and coastal ecosystems、Atmospheric and Environmental Gas Dynamics

Abstract We investigate the influence of organo‐mineral associations on the dispersal of terrestrial organic matter (TerrOM) along a land‐sea transect offshore the Atchafalaya river in the northern Gulf of Mexico (GoM). We analyzed bulk sediment properties, mineral surface area, and clay composition and used lipid biomarkers to distinguish plant‐derived (long‐chain n ‐alkanes and n ‐alcohols) freshwater aquatic (C 32 1,15‐diols) and soil‐microbial (branched glycerol dialkyl glycerol tetraethers (brGDGTs)) OM‐pools in different grain size fractions (≥250, 250–125, 125–63, 63–30, 30–10 and <10 μm) of marine surface sediments. Concentrations and mineral loadings of the targeted biomarkers were highest in the <30 μm fractions, suggesting an affinity with clay minerals. Spatially, concentrations of higher plant‐derived n ‐alkanes remained relatively constant along the transect, whereas those of the other OM‐pools rapidly decreased further offshore. This suggests that the association of plant‐derived OM with mineral surfaces is better maintained than that of freshwater and soil‐microbial OM. In addition, similar distributions among grain size fractions at each site for the C 32 1,15‐diols and brGDGTs suggest that these compounds are likely not associated with mineral surfaces in the marine realm. Furthermore, as TerrOM might be stripped from mineral surfaces upon discharge in the marine realm, the dispersal of TerrOM‐pools could also represent a degradation signal, as n ‐alka...