PYRENE SORPTION BY WATER-SOLUBLE ORGANIC-CARBON

Natural dissolved organic matter (DOM) in soil solution has the potential to facilitate the transport of nonionic organic contaminants (NOC). The interactions between pyrene and ultrafiltration fractions of water-soluble organic carbon (WSOC), humic acid, and fulvic acid were quantified using fluorescence-quenching spectroscopy. Pyrene partition coefficients to the smaller WSOC fractions varied between 4.1 X 1.0(3) and 6.8 X 10(3) L kg-1, while partition coefficients for the largest fraction of WSOC, humic acid, and fulvic acid were 1.5 X 10(4), 1.7 X 10(5), and 1.1 X 10(4) L kg-1, respectively. These results demonstrate that the use of the same (c)K(oc) value to describe NOC partitioning to both immobile organic matter and soil solution DOM will overestimate the ability of DOM to facilitate the transport of NOC. Conversely, pyrene partitioning data to the largest WSOC fraction suggest that the presence of colloidal organic matter suspended in the soil solution may have a large influence on NOC transport.