HR: 1340h
AN: H53A-1199    [Abstracts]
TI: Extraction and Analysis of PAHs in Surface Soils Near Freeways in Los Angeles
AU: * Mannino, I
EM: imannino@altrionet.com
AF: California State University Los Angeles, Department of Civil Engineering 5151 State University Drive, Los Angeles, CA 90032 United States
AB: Large urban areas such as Los Angeles are characterized by high levels of motor vehicle traffic. A by-product of this traffic is the emission of a group of compounds known as polycyclic aromatic hydrocarbons (PAHs). PAHs are a global-scale persistent environmental hazard, many of which are considered to be carcinogenic. This study investigated the prevalence of 16 PAHs in surface soils near major Los Angeles highways. The first phase of the study was the development of a methodology for efficiently extracting PAHs from soil. Preliminary findings suggested that the most efficient extraction method using an accelerated solvent extractor employed a mixture of acetone and hexane and a static extraction time of 5 minutes (completed in 2 cycles). Extraction efficiency was measured by spiking clean sand with a known amount of a PAH standard and extracting and analyzing the sand. The addition of an extra static cycle produced a significant increase in extraction efficiency. For example, utilization of 2 static cycles recovered 99.6% of the spiked phenanthrene compared to a 44% efficiency for the 1 cycle run. Preliminary results from a field sampling campaign indicated that significant concentrations of PAHs are deposited onto and accumulate in surface soils. Specifically, we found 12.13 $\mu$g/kg of anthracene, 15.82 $\mu$g/kg of benzo(a)pyrene, 23.42 $\mu$g/kg of phenanthrene, and 23.43 $\mu$g/kg of pyrene in surface soils, including soils from a public park. These results indicate that background levels of PAHs in soils may pose a significant health risk to humans. For example, the California preliminary remediation goal for benzo(a)pyrene in residential soils is 62 $\mu$g/kg, slightly greater than our reported background values. A more detailed field sampling campaign will be pursued to elucidate the role of different environmental variables (i.e., time of day, sun intensity, traffic congestion, etc.), on the accumulation of PAHs in soils.
DE: 1803 Anthropogenic effects
DE: 1831 Groundwater quality
DE: 1871 Surface water quality
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting