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Re: E-M:/ Professor Dersch on Two Stroke Marine Engines



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Enviro-Mich message from Chad Bailey <crbailey@umich.edu>
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I understand that MDEQ/Surface Water did a prelimiary assessment of MTBE
in waterways in 1999.  I recall that no MTBE was found in any Michigan
waterways.  This makes sense, as Michigan's summer fuels (June-Sep) are
low-RVP only, and do not have an oxygenate requirement.  Any MTBE in fuel
would be added only for octane-boosting purposes.

As for water quality issues, I'd suggest that the fuel/oil mixture going
through 2-stroke engines is a bigger problem.  A high amount of oil
consumption yields high exhaust concentrations of polycyclic aromatic
hydrocarbons (PAH) which are present in oil and fuel.  As PAHs are
lipophilic, they can biomagnify up through the food chain.  PAHs tend to
be refractory and not burn up in combustion.  Trace metals in oils may
also be contaminants of concern.



> Here is some information worth thinking about in Michigan, where we have
> such a large number of motored watercraft.
>
> Two-stroke engines were banned from Lake Tahoe two years ago.  Water
> quality monitoring studies recently determined that although two-stroke
> engines accounted for only 11 to 12% of the fuel used by boats on that
> lake, they produced 90% of the MTBE (an oxygenate added to gasoline)
> found in the water, and presumably 90% of the gasoline and its other
> additives, such as benzene, toluene, ethylbenzene and xylene.  Amazing!
> They now estimate that 25 to 35% of the fuel that goes into two-stroke
> engines goes directly into the lake without being burned.  (From U.S.
> Water News, July 2001)
>
> Eckhart Dersch
> Professor
> Department of Resource Development
> Michigan State University
>
>
>
>
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