SOLUBILIZATION OF PHENANTHRENE BY HUMIC ACIDS

Humic acids has a distinct solubilizing effect on phenanthrene. The ra te constant for the dissolution of solid phenanthrene in synthetic gro undwater is increased by ca. 50% in the presence of 50 mg/L humic acid s. The phenanthrene - humic acid interactions was found to depend sign ificantly on the actual humic acid concentration since a pronounced de crease in the interaction constant, as well as in the water - organic matter partitioning coefficient was observed with increasing humic aci d concentration. The effects are discussed in terms of concentration d ependent macromolecular structural changes in the humic acids, as are effects of varying pH and ionic strength conditions of the aqueous pha se. (C) 1997 Elsevier Science Ltd.