The effect of humic acids on the water solubility and water - Organic carbon partitioning of fluorene and its NSO-heteroanalogues: Carbazole, dibenzofuran, and dibenzothiophene.

The solubilizing effect of humic acids on fluorene and its NSO analogues ca rbazole, dibenzofuran and dibenzothiophene has been studied. The interactio n between these substances and humic acids was found to depend significantl y on the actual humic acid concentration. A pronounced decrease in the inte raction constant, as well as in the water - organic matter partitioning coe fficient was observed with increasing humic acid concentration. The effects are discussed in terms of concentration dependent macromolecular structura l changes in the humic acids. A linear free energy relation for the interac tion is suggested. (C) 1999 Elsevier Science Ltd. All rights reserved.