Distribution of aged 14C-PCB and 14C-PAH residues in particle-size and humic fractions of an agricultural soil.

Organic matter is considered to be the single most important factor limiting availability and mobility of persistent organic pollutants (POPs) in soil. This study aimed to characterize the distribution of 14C−PCB (congeners 28 and 52) and 14C−PAH (fluoranthene and benzo[a]pyrene) residues in an Orthic Luvisol soil obtained from two lysimeter studies initiated in 1990 at the Agrosphere Institute (Forschungszentrum Julich GmbH, Germany). The lysimeter soils contained a low-density OM fraction, isolated during soil washing, which contained a significant fraction (3−12%) of the total 14C-activity. Soils were also fractionated according to three particle sizes:  >20, 20−2, and ( 20 μm) for the PCBs. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20−2 μm > ( (>20 μm) for the PAHs. The distribution of 14C−PCB or 14C−PAH residues in the org...