Composition of Dissolved Organic Matter in Pore Waters of Anoxic Marine Sediments Analyzed by 1H Nuclear Magnetic Resonance Spectroscopy

摘要: Marine sediments are globally significant sources of dissolved organic matter (DOM) to the oceans, but biogeochemical role pore-water DOM in benthic and marine carbon cycles remains unclear due a lack understanding about its molecular composition. To help fill this knowledge gap, we used 1H nuclear magnetic resonance (NMR) spectroscopy examine depth variability composition anoxic Santa Barbara Basin, California Borderland. Proton detected spectra were acquired on whole samples without pre-concentration avoid preclusion any components from analytical window. Broad unresolved (operationally assigned carboxyl-rich alicyclic molecules, or CRAM) dominated all spectra. Most relatively well-resolved peaks (attributed biomolecules their derivatives) appeared at chemical shifts similar those previously reported for literature, different relative intensities. changed significantly within top 50 cm sediment column, where intensity CRAM increased, resolved resonances decreased. The itself also throughout entire length 4.5-m profile, as protons became increasingly aliphatic expense functionalized protons. Given that is generated sedimentary includes pre-aged degraded material, could theoretically be subjected microbial reworking pore waters centuries millennia, these data suggest may compositionally unique upper ocean.