HR: 16:15h
AN: H14A-04    [Abstracts]
TI: Sources and Patterns of Pollutant Washoff in Urban Storm Water
AU: * Stein, E D
EM: erics@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683 United States
AU: Schiff, K
EM: kens@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683 United States
AU: Ackerman, D
EM: drewa@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683 United States
AU: Tiefenthaler, L
EM: lieslt@sccwrp.org
AF: Southern California Coastal Water Research Project, 7171 Fenwick Lane, Westminster, CA 92683 United States
AB: Urban storm water typically conveys a broad spectrum of pollutants that may pose ecologic and human health concerns to downstream receiving waters. Traditional storm water monitoring programs have focused on evaluation of peak flows and mean concentrations, often derived from composite samples, for a limited set of constituents. As the regulatory and management focus on storm water increases, there is an increasing need to understand the sources and temporal patterns of washoff and loading for a broad suite of pollutants. This study investigated washoff of bacteria, metals, nutrients, and organic pollutants from 24 homogenous land use sites and 10 in-river (mass emission) sites in the greater Los Angeles area. Multiple discrete samples were collected over the duration of each storm in order to generate time vs. concentration (i.e. pollutograph) curves. In addition, storms with differing rainfall intensities and antecedent dry periods were sampled to better understand seasonal patterns in washoff. Results show that pollutant runoff generally exhibits intra and inter storm variability. A "seasonal flush" was observed for some pollutants, generally related to the amount of accumulated annual rainfall. For example, PAH mass loading during early season storms was 4-7 times higher than during comparably sized late season storms. For most constituents, concentrations peaked prior to peak flows. Peak PAH concentrations in the Los Angeles River averaged 3,000 ng/L and the peak occurred approximately 5 hours prior to the peak flow. The ability to attribute pollutants to specific land use types varied by constituent. For some constituents, such as zinc and lead, concentrations varied by land-use type: Washoff form industrial land uses had mean zinc concentrations between 2.5 and 5 times higher than other developed land uses. For others, such as PAHs concentrations were similar between land uses, suggesting a consistent regional source. The increased understanding of spatial and temporal patterns of storm water runoff may aid in the development of more refined dynamic models, improved monitoring, and may be used to guide development of management practices.
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2005 Joint Assembly