Emissions from Two Outboard Engines Operating on Reformulated Gasoline Containing MTBE

Abstract

Air and water pollutant emissions were measured from two 9.9 HP outboard engines: a two-stroke Evinrude and its four-stroke Honda counterpart. In addition to the measurement of regulated air pollutants, speciated organic pollutants and particulate matter emissions were determined. Aqueous samples were analyzed for MTBE (methyl tert-butyl ether) and BTEX (benzene, toluene, ethylbenzene, and xylene) emission rates. Compared to the four-stroke engine, the two-stroke had dramatically higher levels of toxic organic and particulate matter emissions. The organic material emitted from the two-stroke engine resembles the test gasoline due to the predominance of unburned fuel. Emission rates for PM10 (particulate matter with a diameter of 10 μm or less) are equal to those for PM2.5, implying that emitted particles are all in the respirable range. Aqueous emissions from the two-stroke are also higher: the two-stroke's BTEX and MTBE emissions are, on average, 5 and 24 times higher, respectively, and 3−10% of the MTBE fed to the engine is emitted to the water. Aqueous emission rates, expressed in brake-specific units, tend to increase with decreasing engine load, as do the atmospheric emission rates.

Nitrate and Phosphate Concentrations in Three Mesotrophic Lakes with Different Boat Propulsion Restrictions

“…These originate primarily from the direct discharge of gasoline into the water from recreational boating, and it has been well documented by others (Reuter et al 1998, Dale et al 2000, Gabele and Pyle 2000.…”

The flushing of pollution from recreational boating in tidal embayments with application to Great Salt Pond on Block Island

“…(1) number of studies on the pollutants associated with marine engine use [8][9][10][11][12][13][14][15][16]. Four of these studies [8,9,10,16] were considered in the analyses reported herein. The pollution is often reported in grams of pollutant per horse-power hour with measurements being carried out for specific engine size and type and operating on specific vessel types and sizes.…”

“…For a particular pollutant of mass, m i , in g/hp-h, the pollution loading factor for an engine type, i, can be defined as Some common pollutant emissions associated with marine engine use computed using data from reference [8]. While other data for gasoline engines [9,10] were considered, only that from [8] were used to obtain these results. .…”

“…Pollutant data was gleaned from a number of studies [8][9][10][11][12][13][14][15][16] and coupled with boat type-and lengthdistributions, the model was expanded to define an appropriate loading factor, k, for the pollutant under consideration. An interface was written to allow for these factors to be changed for different embayments and boating data.…”

Seasonal and daily variations in concentrations of methyl-tertiary-butyl ether (MTBE) at Cranberry Lake, New Jersey

“…Gabele and Pyle [16] found that concentrations of MTBE and BTEX in emissions from outboard engines are higher in two-stroke engines than in four-stroke engines. Also, their study of emissions of engines operating at different rates showed that an engine operating in trolling mode would release more fuel than a speeding engine.…”