The fate of the aqueous phase polycyclic aromatic hydrocarbon fraction in a detention pond system Kevin Neary a , Thomas B. Boving b, * a State of Connecticut Dept. of Environmental Protection, 79 Elm Street, Hartford, CT 06106-5127, USA b Department of Geosciences Department of Civil and Environmental Engineering, University of Rhode Island, Woodward Hall, Rm 315, 9 E. Alumni Ave, Kingston, RI 02881, USA article info Article history: Received 3 February 2011 Received in revised form 22 April 2011 Accepted 25 April 2011 Keywords: Nonpoint source pollution Organic chemicals Best management practices Stormwater management Runoff PAH abstract The concentration of dissolved polycyclic aromatic hydrocarbons (PAH) in influent, effluent, and within a detention pond system was measured. The "soluble fraction" was operationally defined as the PAHs in solution that passed through a 1.2 mm filter. The results show that influent and effluent PAH concen- trations were similar, indicating that dissolved PAH moved essentially unhindered through the detention pond system. In general, low molecular weight PAH were present at the highest concentrations and the highest PAH concentrations were measured in Summer. Also, year-to-year variations in PAH concen- tration were observed. At the end of sufficiently large storms, the pond was comparably unpolluted. During dry periods, the dissolved PAH concentration rose, possibly due to evapoconcentration and by partitioning of PAH from trapped contaminated sediment in the detention pond system. This study provides evidence that aqueous-phase PAH concentrations in runoff water were relatively unaffected by the passage through a conventional detention pond system. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Storm-generated runoff pollution from impermeable surfaces, such as roads, roof tops, and parking lots, is a non-point source pollution problem. A multitude of organic and inorganic compounds are commonly found in runoff from urban areas (Pitt et al., 2004; Maestre and Pitt, 2005). Problematic contaminants include nutri- ents, pesticides, organic compounds, heavy metals, pathogens, and deicing chemicals. Of particular concern are polycyclic aromatic hydrocarbons (PAH), which originate from numerous, predomi- nantly anthropogenic sources including combustion of fossil fuels, vehicle emissions, and industrial effluent (Björseth and Ramdahl, 1985; Rogge et al., 1993; van Metre, 2000; Shah et al., 2005; Boving et al., 2008). The atmospheric influx of PAHs is another non-negligible factor influencing the quality of runoff in urban environments (Motelay-Massei et al., 2006). Many PAHs are geno- toxic and considered persistent organic pollutants by the United States Environmental Protection Agency (EPA). A toxicological profile of PAHs is provided by the Agency for Toxic Substances and Disease Registry (ATSDR 1995). Urban runoff is primarily comprised of dry-weather base flows, stormwater runoff, combined sewer overflows, and snowmelt. Factors such as land use and climate determine the relative magnitudes of these discharges. For instance, Mahler et al. (2005) showed that runoff from parking lots freshly coated with coal- tar-based sealants can contain PAH concentrations in particulates 65 times higher than those from unsealed concrete and asphalt surfaces. Also, it is estimated that as much as 10 percent of all stormwater discharge systems are contaminated with raw sewage and industrial wastewaters (Pitt et al., 1994). In many urbanized parts of the United States, stormwater runoff from roadways is collected in engineered drainage structures where the adverse effect of roadway runoff on water quality can be minimized through structural and/or non-structural best management practices (BMP) (FHWA, 1999; Yu et al., 1993, 1994; Pitt et al., 1994). According to Conrad and Burch (1995), a BMP is defined as physical, structural, and managerial practices that, when used individually or in combination, prevent or reduce pollution of water and attenuate peak flows and volumes. Examples of structural BMPs are detention ponds and swirl reactors, among other management practices. Structural BMPs operate by physically trapping runoff until contaminants settle out or filter through the underlying soils. Goeble et al. (2007) provides an overview of typical PAH and other contaminant concentrations in stormwater runoff. According to a field study by Hoffman et al. (1984), between 79% and 93% of PAHs were associated with suspended solids. Sedimentation is therefore the most common fate and control mechanism for particle-bound PAHs and a properly functioning detention pond * Corresponding author. E-mail address: boving@uri.edu (T.B. Boving). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2011.04.046 Environmental Pollution 159 (2011) 2882e2890