Watershed‐based sources of polycyclic aromatic hydrocarbons in urban storm water

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds, ubiquitous in the air and water of urban environments, and have been shown to accumulate in coastal estuarine and marine sediments. Although previous studies have documented concentrations and loads of PAHs in urban runoff, little is known about the sources and temporal patterns of PAH loading from storm water. This study characterized the sources and temporal patterns of PAHs in urban storm water by analyzing PAH concentrations and loads from a range of homogeneous land use sites and in-river mass emission sites throughout the greater Los Angeles, California, USA, region. Samples were collected at 30- to 60-min intervals over the course of a storm during multiple storm events over a four-year period in order to investigate PAH sources and inter- and intrastorm patterns in loading. Polycyclic aromatic hydrocarbon storm fluxes ranged from 1.3 g/km2 for the largely undeveloped Arroyo Sequit watershed to 223.7 g/km2 for the highly urbanized Verdugo Wash watershed, with average storm fluxes being 46 times higher in developed versus undeveloped watersheds. Early-season storms repeatedly produced substantially higher loads than comparably sized late-season storms. Within individual storms, PAHs exhibited a moderate first flush with between 30 and 60% of the total PAH load being discharged in the first 20% of the storm volume. The relative distribution of individual PAHs demonstrated a consistent predominance of high-molecular-weight compounds indicative of pyrogenic sources.

Polycyclic Aromatic Hydrocarbons in Urban Stream Sediments

“…Since more than 90% of all stormwater particles are expected in the 1 to 100 µm range and, given the observed higher concentrations of PAHs in the smaller sediment particles, most of the stormwater runoff PAH load would be expected to be associated with the finer particles. This is similar to findings by Stein et al [4], who observed a strong and consistent pattern of high PAH concentrations in dissolved and fine particulate matter. Stein also found that between 30 and 60% of the total PAH load was discharged in the first 20% of the runoff volume for the studied storms and location.…”

“…According to Metre et al [1], PAH levels in urban freshwater sediments in North America have increased over time, indicating additional discharges associated with industrialization and urbanization, including increased use of vehicles and wear and tear of asphalt [1][2][3]. For example, Stein et al [4] found PAHs in storm fluxes ranged from 1.3 g/km 2 for the largely undeveloped Arroyo Sequit watershed to 224 g/km 2 for the highly urbanized Verdugo Wash watershed in California, USA. Similarly, according to Huston et al [5], there is an increase in the PAHs and other contaminant flux in traffic and industrial areas compared to outer suburbs, implicating these developments positively influencing PAHs contribution in the runoff.…”

The Coagulant Type Influence on Removal Efficiency of 5- and 6-Ring Pahs During Water Coagulation Process

“…Despite the fact that there are known over 300 compounds from this group, only 16 of them are designated the most common [11]. PAHs are included into a group of primary environmental pollutants due to the toxic, mutagenic and carcinogenic properties [2,6,13,14]. The occurrence of these compounds in groundwater and surface water has been confirmed by many authors [10,16,17].…”

Estimating the future decline of wild coho salmon populations resulting from early spawner die-offs in urbanizing watersheds of the Pacific Northwest, USA

“…The weight of evidence to date therefore suggests that coho are dying from exposure to chemical pollutants in nonpoint source urban runoff. Urban stormwater contains a very diverse mix of contaminants (Eriksson et al 2007), including metals (Tiefenthaler et al 2008), polycyclic aromatic hydrocarbons (Stein et al 2006), pesticides (Hoffman et al 2000), and other chemicals. The precise agent, whether alone or as a component of a chemical mixture, that causes coho PSM has not yet been identified and is the focus of ongoing investigation.…”