Sediment alkaline-extracted organic matter (AEOM) fluorescence: An archive of Holocene marine organic matter origins

Organic matter (OM) is comprised of a complex mixture of substrates, which are difficult to fully characterize. Therefore a range of analytical approaches is applied to provide a better understanding of the dynamics and biogeochemical cycling of aquatic system. One approach is UV–Visible spectroscopy, which includes measurements of spectral absorption and fluorescence of colored and fluorescent fractions of dissolved OM (DOM, CDOM and FDOM). In this study OM fluorescence is characterized by excitation-emission matrix spectroscopy on alkaline extracted DOM from a Baltic Sea sediment core that spanned 8500 years and fluctuating levels of hypoxia. Our results showed that three underlying fluorescence components had strong correlations with carbon, nitrogen content and δ15N. Our results demonstrate that optical properties of extracted OM from sediments reveal information about OM quality and quantity similar to those of biomarkers, which can be a useful additional tool for investigating OM deposition.