Aromatic carotenoids: Biological sources and geological implications

Abstract

• Aromatic carotenoids are robust biomarkers in reconstructing environments. • Aromatic carotenoids decipher the evolution of microorganisms and ocean chemistry. • Aromatic carotenoids are valid in interpreting on-going diagenetic processes. Aromatic carotenoids have been discovered in geological sections recording mass extinction events, oceanic anoxic events, and other geological abnormalities. Given their conventional biological source attribution to phototrophic sulfur bacteria, aromatic carotenoids have been adopted in interpreting photic zone euxinia (PZE), and encode significant paleoecological and paleoenvironmental information. Nevertheless, the recent detection of aromatic carotenoids in cyanobacteria challenges former assertions. Building on previous studies, this review summarizes the most recent progress on biological sources of aromatic carotenoids and details possible diagenetic processes and how these processes may bias or facilitate our understanding of aromatic carotenoids. This review further expands on typical instrumental and chemical preparative procedures in analyzing aromatic carotenoids. Finally, we illustrate the unique contribution of aromatic carotenoids in characterizing modern and ancient aquatic environments, unrevealing the evolution of microorganisms, and understanding on-going diagenetic processes.