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Title: Determination and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) from Watercraft in Recreational Lakes in Northern Nevada and Eastern California

FOCUS category: WQL

Keywords: Water Quality, water chemistry, mountain lakes/streams, pollutants, recreation, boating, zooplankton

Duration: March 1999 to February 2001.

FY 1999 Federal funds: $ 24,983

FY 1999 non-Federal funds: $ 51,117

Principal investigator(s) name and university: Dr. Glenn C. Miller, University of Nevada, Reno. Mary Miller, Desert Research Institute

Statement of results or benefits:

The focus of the first year of this investigation was to establish PAH emissions profiles for some common recreational watercraft engines and to establish a relationship between watercraft use and the presence of PAH compounds in Lake Tahoe. Emissions profile experiments were conducted in a controlled environment at the California Air Resources Research Facility in El Monte, Ca. during July of 1999. Three different outboard engines; a 90 hp four stroke, a 90 hp direct fuel injected (Ficht technology), a 90 hp carbureted, and a 110 hp personal watercraft were investigated. Data collected were analyzed to determine whether the newer and reportedly “cleaner” engines were capable of contributing significant levels of potentially toxic PAH compounds to recreational waterbodies. Results from this preliminary investigation demonstrated that PAHs exhausted from the carbureted 2-cycle engine and found in the water were

slightly lower that from those of the direct fuel injection (Ficht technology) but did not vary significantly in composition. This suggests that, while the newer technology can be expected to contribute less PAH, the impact may still be significant. The lubrication technology of both types of engines is similar, and the PAH appear to be derived from the oil. The PAH concentrations emitted from the four stroke engines were substantially lower than from the other two engine types and the component profiles were distinctly different.

Volatile samples were collected from each of the engine types, also. These results supported earlier work which indicated that volatiles were greatest from the carbureted engines with the fuel injected and four stroke engines each emitted less. In addition to the emissions profile study, samples were collected on two separate occasions from Lake Tahoe during the summer of 1999, during the Labor Day holiday weekend, a traditionally high use period, and again after the end of the boating season. Phototoxic PAH compounds were found in samples collected in high use areas during the Labor Day holiday weekend but were not detected from mid-lake low use sites. Subsequent samples, collected after the boating season, from both high use and mid-lake sites reveal that PAH concentrations had dropped to non-detect levels. Ambient monitoring of Lake Tahoe for PAH and volatile gasoline constituents was also conducted during the 1999 boating season from near shore sites that included both high use and very low use areas.The volatiles samples were compared to samples taken at the same sites in 1997 prior to implementation of regulations which regulated carbureted two-cycle engines. These results showed that the concentration of volatiles were reduced from 50-90% from pre- to post regulation of these engines.

Nature, scope, and objectives of the research:

The second year of this investigation will continue to focus on PAH contributions to recreational lakes from marine engines. A second series of controlled experiments will be conducted at the El Monte, CA facility and will seek to elaborate the distribution of PAH in the exhaust stream. Samples collected will include both the particulate fraction and dissolved fraction of the exhaust to determine the distribution of potentially phototoxic PAH compounds. Raw gasoline and oil products will also be analyzed in an effort to further differentiate the different marine engine technology. Ambient sampling of Lake Tahoe will resume prior to the 2000 boating season and will be expanded to include Donner Lake and Stampede Reservoir.

As of the 2000 boating season personal watercraft are still permitted on both Donner Lake and Stampede Reservoir and use is anticipated to increase significantly since the 1999 imposition of the ban on two cycle marine engines on Lake Tahoe. Monitoring ambient levels on these lakes and collecting samples during high use periods, will provide relevant data for determining the impacts from different engine technologies on recreational waterbodies.

Additional work will be conducted with gc-ms to confirm which PAH compounds are present in the water from the various engine types.Although most of the compounds have been identified using HPLC with fluorescent detection, these engines emit an unexpectedly complicated array of PAH and not all of the compounds have been identified. We will work with Dr. Barbara Zelinska at DRI to identify these compounds.

Related research:

Ireland, D. S., G. A. Burton, and G. G. Hess. 1996. In situ toxicity evaluations of turbidity and photoinduction of polycyclic aromatic hydrocarbons. Environmental Toxicology and Chemistry. 15:574-581.

Oris, J. T., et al 1998. Toxicity of ambient levels of motorized watercraft emissions to fish and zooplankton in Lake Tahoe, California-Nevada, USA.

Pelletier, M. C., R. M. Burgess, K. T. Ho, A. Kuhn, R. A. McKinney and S. A. Ryba. 1997. Phototoxicity of individual polycyclic aromatic hydrocarbons and petroleum to marine inverebrate larve and juveniles. Environmental Toxicology and Chemistry. 16:2190-2199.

U.S. Department of the Interior, U.S. Geological Survey
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Last Updated: Tuesday November 8, 2005 9:40 AM
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