2-stroke engines pollute 2-much

The #1 source of toxic pollution in U.S. waterways

by Russell Long
he two-stroke motor, found on 75 percent of all boats and personal watercraft (jet skis), generates 1.1 billion pounds of hydrocarbon emissions each year. These high emissions are attributed to the design inefficiency of the two-stroke motor, which has remained essentially unchanged since the 1940's.

Consider the following:

• Twenty-five percent of the fuel and required oil that conventional two-strokes use most of it unburned is emitted directly into the water and air. According to the EPA, two-stroke engines discharge as much as 30 percent of their fuel and oil unburned directly into the water.
• In the US, approximately 75 percent of all motorized boats and personal watercraft (14 million units) are powered by two-stroke engines.
• Every year, marine two-stroke motors spill 15 times more oil and fuel into waterways than did the Exxon Valdez.
• The EPA estimates that one hour of operation by a 70-horsepower two-stroke motor emits the same amount of hydrocarbon pollution as driving 5,000 miles in a modern automobile.

Two-strokes pose a serious threat to the marine environment and human health!

On the waterfront

Petrochemicals released from two-stroke motors float on the surface microlayer and settle within the estuarine and shallow ecosystems of bays, lakes, rivers, and oceans, where marine life is youngest and most vulnerable. These areas are the base of the food chain, inhabited by fish eggs, larvae, algae, crab, lobster, shrimp and zooplankton. Research demonstrates that chromosomal damage, reduced growth and high mortality rates of fish occur at extremely low levels of hydrocarbon pollution. Scientists believe that such pollution may bioaccumulate, poisoning much of the marine environment.

According to Michigan State's Dr. John Giesy, one of the world's leading experts on the toxicological effects of marine hydrocarbon pollution, the two-stroke emissions released into the water are up to 50,000 times more toxic under field conditions in the presence of the ultraviolet (UV) light in sunlight. This is due to polycyclic aromatic hydrocarbons (PAHs), substances contained in petrochemicals that form highly toxic and persistent compounds known to be: (1) ubiquitous contaminants that bioconcentrate; (2) carcinogenic to mammals; and (3) acutely photo-toxic to aquatic organisms within minutes or hours.

Through controlled experiments, Dr. Giesy found that it takes .05 ppb (parts per billion) of PAHs in water to cause a 10 percent decrease in zooplankton; as little as 5 ppb (parts per billion) kills all zooplankton in a 30 minute test period. Sampling has found PAH levels substantially in excess of 5 ppb during recreational boating activity. PAH's are considered so dangerous that the N.Y. State Department of Environmental Conservation now regulates PAH's on the same toxicity level as PCB's.

Human health concerns

Seventy-five percent of all of California's reservoirs allow motorized boating. Oil and fuel is being released into municipal drinking water reservoirs from motorized boating activity. Gas and oil contain more than 100 compounds, many of which are listed as toxic by the EPA. These include benzene, known to be carcinogenic to humans, and toluene, which can damage a developing fetus. As a result, dangerous hydrocarbon levels exist in United States and foreign waterways already tested.

Solutions exist

There are four basic types of marine propulsion engines: two-stroke, four-stroke, stern drive, and inboard engines. Four-stroke motors emit less than 4 g/Kwh (grams per kilowatt hour) of hydrocarbons, while two-stroke motors emit more than 150 g/Kwh. Even the latest fuel-injected two-stroke engines (developed for 1998) emit 10 times as many hydrocarbons as do four-stroke engines.

In addition, four-strokes are substantially more fuel efficient and are cost-competitive compared to two-stroke motors.

What can you do to prevent the unnecessary discharge of fuel and oil into our waterways?

1. Don't stop boating shift to four-stroke technologies when possible.

Four-stroke motors, which have been on the marine market since 1972, emit 97 percent less pollution than conventional two-strokes. Four-stroke motors do not mix oil with fuel (no raw petrochemical discharge) and are designed for complete combustion prior to exhausting. Even the latest direct fuel-injected two-stroke motors emit 10 times as many hydrocarbons as four-strokes.

2. Spread the word in the boating community.

Tell your boating friends, marine dealers and engine manufacturers that 2-strokes pollute 2-much and that your next engine purchase will be a four-stroke. Always keep your motor tuned properly, don't idle unnecessarily and don't exceed cruising speeds (as this creates even more excessive pollution).

3. Do the right thing. Recycle.

Call Bluewater Network at (415) 788-3666 ext. 120 for tax-deduction details, or for a discount on a new four-stroke engine in exchange for taking your two-stroke off the water.

Bluewater Network is a coalition of sailors and boaters, fishers, divers, scientists, and other clean water advocates working to reduce the environmental impacts of recreational boating. For further info, contact us at: 300 Broadway, Suite 28 San Francisco, CA. 94133 phone: (415) 788-3666 email: Bluewaterearthisland.org; www.earthisland.org/ei/bw/bw.html.