Research Notes

Abstracts of 1989 Research Notes

Cotton is the most valuable annual crop grown in California.  In this project, investigators determined whether air- pollution-induced yield losses estimated for cotton on the basis of studies carried out in controlled test atmospheres reasonably represent yield losses that occur in the field.  Cotton plants were exposed to either ambient or carbon- filtered air at four San Joaquin Valley sites representing a range of air pollutant levels. Measured yield losses at three of the sites were similar to expected yield losses.  At the fourth site, measured yield losses exceeded expected losses. This study was performed by the University of California, Riverside.

This research assessed the statewide effect of ambient ozone on the yield of important agricultural crops. Ozone dose- yield loss equations, ozone monitoring data, and county crop production data were used to estimate yield losses for each county and for the state as a whole. The study concludes that, at current air quality levels, several important crops suffer substantial yield losses. Based on these conclusions, an economic modeling study estimated that improving air quality could result in economic benefits of up to $333 million to California growers and consumers.  This study was performed by the University of California, Riverside.

This study estimated the risks of ozone damage to California forests and initiated a database of forest resources for use in future research planning efforts. Using a .045 ppm, 12- hour seasonal ozone standard over 50 percent of the forested areas in 12 California counties, five out of 19 national forests, and 13 California watersheds were found to be at high risk to ozone damage. This study was performed by RCG/Hagler, Bailly, Inc.

This is the first study to measure the spatial and temporal variation of ambient peroxyacetyl nitrate (PAN)-- an air pollutant that damages plants and causes a stinging sensation in the eyes -- in the South Coast (Los Angeles) Air Basin of California. Over 3500 measurements of PAN concentrations were made at various ground sites and aloft on three occasions during the summer and fall of 1987 as part of the Southern California Air Quality Study. This study was performed by Daniel Grosjean and Associates, Inc.

Particulate trap systems were developed to control particulate emissions from diesel-powered vehicles. This study characterized and quantified the criteria pollutants and toxic and mutagenic pollutant emissions from two light- duty diesel vehicles having different kinds of traps. One vehicle was equipped with a catalyzed trap system; the other was equipped with an additive-regenerated trap system. The traps reduced particulate emissions by 79 to 93 percent when the vehicles were subjected to three different test procedures. The traps also reduced mutagenic and other pollutant emissions on a grams-per-mile basis. This study was performed by Southwest Research Institute.

Methanol has been proposed as a clean, alternative vehicle fuel for areas having difficulty attaining air quality standards. This study estimated air quality changes that would result from varying degrees of use of methanol fuel in mobile sources in the South Coast Air Basin. The study found that use of methanol fuel in light- and heavy-duty vehicles would significantly reduce ambient ozone, particulate matter, nitrogen dioxide, nitric acid, and peroxyacetyl nitrate. An air quality simulation model was used to provide these estimates. This study was performed by the Carnegie Mellon University.

In this study, ambient concentrations of polycyclic aromatic hydrocarbons (PAHs) and their nitro-derivatives were determined at selected locations having a high probability of occurrence of these pollutants. Data on daytime and nighttime concentrations, atmospheric reaction and removal processes, and ambient mutagenicity were also obtained.  These data are of interest because earlier studies have shown that some PAH compounds are both toxic and carcinogenic to animals and have been associated with cancer in humans. This study was performed by the University of California, Riverside.