Water-Particle Distribution of Hydrophobic Micro Pollutants in Storm Water Runoff

Abstract

Sorptive behaviors of polycyclic aromatic hydrocarbons (PAHs) as well as other classes of hydrophobic pollutants (i.e., n-alkanes and linear alkylbenzenes: LABs) were investigated for street runoff and for particle-size segregated river water samples. PAHs, except for 3-ring aromatics, were mostly transported with particles >1.2μm. In all the environmental samples PAHs were more hydrophobic than expected from their Kow; whereas vigorous mixing of road dust with water for 24 hours resulted in more desorption of PAHs into the aqueous phase. It indicates that although strongly associated with particles, at least some part of the “particle bound” PAHs could be available for active exchange wirh their dissolved counterparts. As opposed to PAHs, n-alkanes and LABs revealed less hydrophobic nature than expected from Kow, although their majorities were in “particulate form”.

Key Words:

• partition coefficient
• Kow
• Koc
• size distribution
• PAH
• organic colloid