Poly cyclic aromatic hydrocarbons in Recent lake sediments—II. Compounds derived from biogenic precursors during early diagenesis

Abstract

Five groups of polycyclic aromatic hydrocarbons (PAH) thought to be derived by early-diagenetic transformations of biogenic precursors are apparently present in Recent sediments of 4 lakes (Lake Lucerne, Lake Zurich and Greifensee, Switzerland, and Lake Washington, northwest USA). These natural PAH include perylene, an extended series of phenanthrene homologs, retene and pimanthrene derived from diterpenes, a series of tetra- and pentacyclic PAH derived from pentacyclic triterpenes of the amyrin-type and tetra- and pentacyclic PAH formed from pentacyclic triterpenes with 5-membered E-rings. Since these PAH are abundant in very young sediment layers, the transformation reactions involved appear to be faster than previously thought and may be microbially mediated. There is no evidence that anthropogenic or petrogenic sources account for the distributions of these groups of PAH in cores of Recent lake sediments.