Predicting runoff induced mass loads in urban watersheds: Linking land use and pyrethroid contamination.

Pyrethroid pesticide mass loadings in the Ballona Creek Watershed were calculated using the volume-concentration method with a Geographic Information Systems (GIS) to explore potential relationships between urban land use, impervious surfaces, and pyrethroid runoff flowing into an urban stream. A calibration of the GIS volume-concentration model was performed using 2013 and 2014 wet-weather sampling data. Permethrin and lambda-cyhalothrin were detected as the highest concentrations; deltamethrin, lambda-cyhalothrin, permethrin and cyfluthrin were the most frequently detected synthetic pyrethroids.

Identification of subwatershed sources for chlorinated pesticides and polychlorinated biphenyls in the Ballona Creek watershed.

Santa Monica Bay forms part of the western border of the greater Los Angeles region. The Ballona Creek watershed is highly urbanized and past studies indicate that Ballona Creek is the largest source for most pollutants to Santa Monica Bay. This study evaluates the contribution of subwatersheds to PCB and chlorinated pesticide loading during wet weather flow.

Characteristics of highway stormwater runoff in Los Angeles: metals and polycyclic aromatic hydrocarbons.

Stormwater runoff from three highway sites in Los Angeles, California, was monitored, during the 2000 to 2003 wet seasons. Correlations among heavy metals, polycyclic aromatic hydrocarbons (PAHs), and storm characteristics were performed using datasets collected for 62 storm events. Statistical correlation analyses of the event mean concentrations (EMCs) and mass first-flush ratios (MFFs) with storm characteristics were conducted to determine if the first flush is related to site or storm characteristics.

Characteristics of highway stormwater runoff.

Highway stormwater runoff was monitored at three highway sites in Los Angeles, California, during the 2000 to 2003 wet seasons. Event mean concentrations (EMCs), partial event mean concentrations (PEMCs), and mass first flush (MFF) factors were calculated for more than 20 water quality parameters for samples from 20 storm events from each site. The early runoff had higher concentrations, as indicated by the PEMCs at 30 and 60 minutes into the storm, which were 1.

Metals and PAHs adsorbed to street particles.

Particles were collected from 18 different city streets adjacent to five different landuses in the City of Santa Monica, California. Landuses were classified as industrial, roads, multifamily residential, commercial and single family residential. Particles were collected using a vacuum cleaner with a 0.

Seasonal first flush phenomenon of urban stormwater discharges.

California's climate, typified by winter and spring precipitation and summer drought, is often called a Mediterranean climate, and creates a long period for pollutant build-up. The initial storms of the winter season usually have higher pollutant concentrations, which is called a seasonal first flush. To investigate the existence of a seasonal first flush, we analyzed four major data sets, collected over the 1999-2000 to 2002-2003 wet seasons.