A hypothesis for the origin of perylene based on its low abundance in sediments of Green Bay, Wisconsin

Perylene, a polycyclic aromatic hydrocarbon (PAH) that is common in sediments, is believed to originate principally from anaerobic diagenesis of organic matter, but its precursor material remains enigmatic. We have investigated the formation of perylene in a dated sediment core from Green Bay, WI. Comparisons of sedimentary profiles of perylene, anthropogenic PAHs, land-plant-derived hydrocarbons, and aquatic contributions of organic matter rule out a specific industrial, terrigenous, or aquatic precursor for perylene. Instead, perylene seems to be formed from any kind of organic matter as a consequence of a specific type of microbial activity in sub-bottom sediments. Despite an abundance of organic matter, the amount of perylene is low in Green Bay and in other organic-carbon-rich lake sediments. The abundant availability of organic matter that stimulates microbial activity in Green Bay sediments would seem to favor perylene formation in such sediments. We therefore hypothesize that the microorganisms responsible for perylene formation do not compete successfully with those that flourish in sediments rich in organic matter. Perylene formation consequently does not become significant until deeper in sediments after the more-reactive types of organic matter have been consumed.