Judy Lloyd
Professor and Chair
• Dept: Chemistry & Physics
• Building: Natural Science Building
• Room: S206
• Office Hours:                  Tuesday, 9:30 - 10:30 
   SPRING 2001             
Thursday 4:00 - 6:00
Other hours by appointment
• Phone: 516-876-2728
• E-mail: lloydj@oldwestbury.edu

Various forms of air pollution - acid rain, tropospheric ozone, visibility-reducing haze - are formed via atmospheric photochemistry, a set of chemical reactions initiated and enhanced by sunlight.  Our environmental chemistry research project is a study of atmospheric free radicals and peroxides that are involved in these processes. 

The free radicals OH, HO₂ and RO₂ feature prominently as atmospheric oxidants.  These radicals are formed during daytime in both remote and urban atmospheres through reactions with water vapor and hydrocarbons, both biogenic and anthropogenic.   Reaction with OH frequently is the first of a series of steps leading to the degradation of volatile organic compounds, and usually results in the formation of an HO₂ or RO₂ free radical.  When the atmosphere also contains high concentrations of NO from high temperature combustion, NO reacts with HO₂ to regenerate OH.  This reaction also forms NO₂.  If NO is not present, HO₂ and RO₂ self-react to form peroxides H₂O₂ and ROOH.

Why are these species - OH, HO₂, H₂O₂ and ROOH - collectively known as odd hydrogen -  important? 
*  The only known source of tropospheric ozone, O₃, is the photolysis of NO₂, formed through the reactions outlined above.  O₃       causes respiratory distress, and damage to natural ecosystems, crops and materials. 

*  Peroxides often dissolve in cloudwater droplets, and may react with dissolved gases such as SO₂ to form acid rain in the form of H₂SO₄ that later is delivered to sites downwind.

*  When clouds evaporate, sulfate salts may be returned to the air as aerosol particles that reduce visibility and participate in further reactions.
 

What are we doing to study this problem?
We are collaborating with scientists at Brookhaven National Laboratory to study these short-lived species.   Our research program has three facets:
*  Method development - design and build new instruments capable of measuring the abundance of these species in the atmosphere.

*  Field measurement - deploy our instrument at surface stations or aboard aircraft for ambient measurements.  Peroxide data from filed measurement campaigns in Nova Scotia (1993), Nashville (1995), New York City (1996), Phoenix (1998), Philadelphia (1999) and Houston (2000) are available upon request from lloydj@oldwestbury.edu. 

*  Analysis and modeling - use the measurements, together with those of other gas species, to better understand atmospheric photochemistry.
 

This work has been sponsored by the U.S. Department of Energy's Atmospheric Chemistry Program (http://gonzalo.er.anl.gov/ACP/) and the National Science Foundation, through their Research in Undergraduate Institutions and Geosciences programs.  We are grateful for this support.  Students who have participated in this project include:
 

RECENT PUBLICATIONS

     Green, R.* and J.B. Weinstein-Lloyd,  Field Measurements of Hydrogen Peroxide, Annual CSTEP Conference, Lake George, N.Y., April, 2000.
     Nunnermacker, L.J., J.B. Weinstein-Lloyd, P.H. Daum, L.I. Kleinman, Y.-N. Lee, S.R. Springston, P.J, Klotz, L. Newman, J. Hubbe, V. Morris, G. Neuroth, P. Hyde,  Trace Gas Measurements in Phoenix, AZ, , Symposium on Atmospheric Chemistry Issues in the 21st Century, 80th Annual AMS Meeting, Long Beach, CA January 2000
     L.I. Kleinman, P.H. Daum, P. Klotz, Y.-N. Lee, L.J. Nunnermacker, S.R. Springston, J. Weinstein-Lloyd, L. Newman (2000)  Ozone Production in the Phoenix Urban Plume, Symposium on Atmospheric Chemistry Issues in the 21st Century, 80th Annual AMS Meeting, Long Beach, CA January, 2000
     T.M. Blackwell* and J.B. Weinstein-Lloyd, Determination of Hydrogen Peroxide and Organic Peroxides in Solution,  New York Chemistry Students' Association (ACS Student Affiliate) 45rd Annual Undergraduate Symposium, New York, NY, May 1997.
     J. B. Weinstein-Lloyd, J.H. Lee, P. H. Daum, B.T. Jobson, D.D. Parrish, Intercomparison of Peroxide Data from the DOE G-1 and NOAA P-3 Aircraft during the 1995 Nashville SOS Study, American Geophysical Union Fall Meeting, San Francisco, CA, December, 1996.
     L.J. Nunnermacker, P.H. Daum, J.B. Weinstein-Lloyd, Y.-N. Lee, S.R. Springston, L. Newman, R.J. Alvarez, A Case Study of Urban Plume Evolution in Nashville, TN, July 3, 1995,  American Geophysical Union Fall Meeting, San Francisco, CA, December, 1996.
     J.H. Lee, P.H. Daum, J.B. Weinstein-Lloyd, L. J. Nunnermacker, S.R. Springston, X. Zhou and L. Newman, An Empirical Study of Indicators for Sensitivity of O3 Formation to NOx and Reactive Organic Gases in the Nashville Urban Plume,  American Geophysical Union Fall Meeting, San Francisco, CA, December, 1996.
     P.H. Daum, L.J. Nunnermacker, L.I. Kleinman, J.H. Lee, S.R. Springston, J.B. Weinstein-Lloyd, L. Newman, Examination of O3 Production efficiencies in the Nashville Urban Plume,  American Geophysical Union Fall Meeting, San Francisco, CA, December, 1996.
     H. G. Woldegaber*, M. Urem* and  J. B. Weinstein-Lloyd, HPLC Analysis of Isomeric Hydroxy and Methoxybenzoic Acids Produced by Fenton Chemistry, 211th Annual Meeting of the American Chemical Society, New Orleans, LA, March, 1996.
     M. Khevelev* and J. B. Weinstein-Lloyd, Reactivity of Chemiluminescence Reagents toward Oxidants, 211th Annual Meeting of the American Chemical Society, New Orleans, LA, March, 1996.