Cohen AB, Christensen LN, Weber F, Yagudaeva M, Lo E, Henkes GA, McCormick ML, & Taylor GT (2024). Preserved particulate organic carbon is likely derived from the subsurface sulfidic photic zone of the Proterozoic Ocean: evidence from a modern, oxygen-deficient lake. Geobiology, 22, e12593. https://doi.org/10.1111/gbi.12593
Summary: Biological processes in the Proterozoic Ocean (2.5 to 0.5 billion years ago) are often inferred from modern oxygen-deficient environments (MODEs) or from stable isotopes in the preserved sediment record. To date, few MODE studies have simultaneously quantified carbon fixation genes and attendant stable isotopic signatures. Consequently, how carbon isotope patterns reflect these pathways has not been thoroughly vetted. Addressing this, we profiled planktonic productivity and quantified carbon fixation pathway genes and associated particulate organic carbon isotope values (δ13CPOC) from meromictic Fayetteville Green Lake, NY (near Syracuse). Results suggest that δ13CPOC values of preserved sediments from Proterozoic Ocean regions with sulfidic photic zones reflect a mixture of alternate carbon-fixing populations exported from the deep photic zone, challenging the paradigm that sedimentary stable carbon isotope values predominantly reflect oxygenic photosynthesis from surface waters.
