title: Influence of humic substance adsorptive fractionation on pyrene partitioning to dissolved and mineral-associated humic substances.
abstract: Changes in pyrene binding by dissolved and mineral-associated humic substances (HS) due to HS adsorptive fractionation processes were examined in model environmental systems using purified Aldrich humic acid (PAHA) and Suwannee River fulvic acid (SRFA). For PAHA, carbon-normalized pyrene binding coefficients for nonadsorbed, residual fractions (Koc(res)) were different from the original dissolved PAHA Koc value (Koc(orig)) prior to contact with the mineral suspensions. A strong positive correlation between pyrene log Koc(res) and log weight-average molecular weight (MWw) for residual PAHA fractions was observed, which was relatively independent of the specific mineral adsorbent used and hypothesized fractionation processes. A strong positive correlation between log Koc(ads) and log MWw was also found for PAHA fractions adsorbed to kaolinite at low mass fraction organic carbon levels, although the relationship was statistically different from the one found with residual PAHA fractions. The same trends and correlations found for PAHA were not observed with SRFA, suggesting that the impacts of HS adsorptive fractionation on changes in hydrophobic organic contaminants binding are also influenced by the source and other biogeochemical characteristics of HS.
authors.affiliation: Departments of Environmental Engineering & Science and Geological Sciences, School of the Environment, Clemson University, Clemson, South Carolina 29634-0919, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Hur
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schlautman
mesh_terms: D000327:Adsorption; D001682:Biological Availability; D005591:Chemical Fractionation / Q000379:methods*; D005374:Filtration; D005456:Fluorescent Dyes / Q000737:chemistry; D006812:Humic Substances / Q000032:analysis*; D007700:Kinetics; D008903:Minerals / Q000737:chemistry; D008956:Models, Chemical; D008970:Molecular Weight; D011721:Pyrenes / Q000737:chemistry*; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D005456:Fluorescent Dyes; D006812:Humic Substances; D008903:Minerals; D011721:Pyrenes; D014874:Water Pollutants, Chemical