Effects of compositions, chemical structures, and microporosity of sedimentary organic matter on degradation of benzo(a)pyrene by hydrogen peroxide.

We investigated how the degradation of 7–14C–BaP aged in sediments by H 2 O 2 treatment was influenced by the chemical structures, compositions, and microporosity of sedimentary organic carbon (SOC). Unstable OC (USOC), stable OC (STOC), mineral-protected OC (MOC), and chemically resistant OC (ROC) fractions were fractionated. The chemical structures and microporosity of the ROC fractions were characterized by 13C solid-state nuclear magnetic resonance (NMR) and CO 2 adsorption technique, respectively. A first-order, two-compartment kinetics model described the degradation process very well (R 2 > 0.980). The BaP degradation ratios increased with the increasing USOC contents and decreased with the increasing ROC contents. The BaP parent compound in the aqueous solution was almost completely degraded. The considerable portions of oxidized intermediates were detected in different SOC fractions, which represented either oxidized intermediates or parent compounds. The very good multivariate regressions among the degradation kinetics parameters, SOC structures and micropore volumes demonstrated that ROC-bulk, aliphatic moieties, and microporosity played crucial roles in protecting sorbed BaP from being degraded by H 2 O 2. The results showed that ROC, aliphatic moieties, and microporosity played vital roles in Bap degradation process in sediments during H 2 O 2 treatment, which is reported for the first time in this study. Image 1 • The BaP degradation changed with the USOC and ROC contents in marine sediments. • The BaP fraction in USOC and aromatic C structures was easily degraded by H 2 O 2. • The BaP fraction in ROC and aliphatic C was hardly degraded by H 2 O 2. • The BaP fraction sorbed in nicropores was not readily released and mineralized. [ABSTRACT FROM AUTHOR]