Constraining Biomarkers as Dissolved Organic Matter Source Indicators: Past, Present, and Future Directions

Quantifying riverine dissolved organic matter (DOM) sources is crucial toward interpreting reactivity across the terrestrial to marine continuum, yet our current knowledge of riverine DOM sources is largely qualitative. The field has advanced rapidly with regards to high-resolution molecular data and characterization; however DOM source biomarkers such as lignin (a vascular plant marker) and D-amino acids (bacterial markers) remain reliable and promising tools to quantifiably trace DOM origin and fate. In this study, we use molecular biomarkers to calibrate DOM source endmembers by performing microbial incubations of multiple vascular plant leachates in both dark and photo-exposed conditions. We present our results in the context of previous vascular plant incubation studies and natural DOM biomarker yields to assess patterns, deviations, and gaps in constraining riverine DOM source biomarkers.