TAILIEUCHUNG - Chemical Composition of Vehicle-Related Volatile Organic Compound Emissions in Central California

In the recharge area, oxidising conditions occur and dissolution of calcium and bicarbonate dominates. As the water continues to move down dip, further modifications are at first limited. By observing the redox potential (Eh) of abstracted groundwater, a sharp redox barrier was detected beyond the edge of the confining layer, corresponding to the complete exhaustion of dissolved oxygen. Bicarbonate increases and the pH rises until buffering occurs at about . Sulphate concentrations remain stable in the oxidising water, but decrease suddenly just beyond the redox boundary due to sulphate reduction. Groundwater becomes steadily more reducing down dip, as. | Chemical Composition of Vehicle-Related Volatile Organic Compound Emissions in Central California Final Report Contract 00-14CCOS Prepared for San Joaquin Valleywide Air Pollution Study Agency and California Air Resources Board Principal Investigator Robert A. Harley Contributing Author Andrew J. Kean Department of Civil and Environmental Engineering University of California Berkeley California 94720-1710 August 2004 1 Acknowledgments The authors thank David Kohler and coworkers at ChevronTexaco for analysis of liquid gasoline samples and James Hesson of the Bay Area Air Quality Management District for analysis of speciated hydrocarbon concentrations in Caldecott tunnel air samples. We also thank Daniel Grosjean and Eric Grosjean for their help with sampling and analysis of tunnel carbonyl concentrations Gary Kendall Daniel Zucker Robert Franicevich and Michelle Traverse of the Bay Area Air Quality Management District for technical support and help with field sampling Juli Rubin of UC Berkeley for assistance with headspace vapor calculations and Caltrans staff at the Caldecott tunnel for site access and help with logistics. Major in-kind support for this research was provided by the Technical Services Division of the Bay Area Air Quality Management District. 2 Abstract Trends in the composition and reactivity of volatile organic compound VOC emissions from motor vehicles are described over a 10-year period between 1991 and 2001. Vehicle emissions were measured at the Caldecott tunnel in the San Francisco Bay area in summers 1991 1994-97 1999 and 2001. Concurrent liquid gasoline samples were collected from service stations in Berkeley in summers 1995 1996 1999 and 2001. Fuel samples were also collected in Sacramento during summer 2001 only. Gasoline headspace vapor composition was calculated using the measured composition of liquid fuel samples and vapor-liquid equilibrium theory. As a result of California s reformulated gasoline RFG program the reactivity of liquid

• Hoá dầu
• Cryopreservation – Equipment
• Overview and Innovation
• Methods of Assessment
• Cryopreserved Semen
• Chemical Features
• Non Conventional Fruits
• Temperature Storage
• Cryopreservation
• Human Spermatozoa
• Vitrification
• Canadian Experience
• Lethal Osmotic