title: Ozone distribution and phytotoxic potential in mixed conifer forests of the San Bernardino Mountains, southern California.
abstract: In the San Bernardino Mountains of southern California, ozone (O(3)) concentrations have been elevated since the 1950s with peaks reaching 600 ppb and summer seasonal averages >100 ppb in the 1970s. During that period increased mortality of ponderosa and Jeffrey pines occurred. Between the late 1970s and late1990s, O(3) concentrations decreased with peaks approximately 180 ppb and approximately 60 ppb seasonal averages. However, since the late 1990s concentrations have not changed. Monitoring during summers of 2002-2006 showed that O(3) concentrations (2-week averages) for individual years were much higher in western sites (58-69 ppb) than eastern sites (44-50 ppb). Potential O(3) phytotoxicity measured as various exposure indices was very high, reaching SUM00 - 173.5 ppmh, SUM60 - 112.7 ppmh, W126 - 98.3 ppmh, and AOT40 - 75 ppmh, representing the highest values reported for mountain areas in North America and Europe.
authors: USDA Forest Service, Pacific Southwest Research Station, Riverside, CA 92507, USA. abytnerowicz@fs.fed.us
authors: Andrzej
authors: A
authors: Bytnerowicz
authors: Michael
authors: M
authors: Arbaugh
authors: Susan
authors: S
authors: Schilling
authors: Witold
authors: W
authors: Fraczek
authors: Diane
authors: D
authors: Alexander
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity; D002140:California; D004784:Environmental Monitoring / Q000379:methods; D005843:Geography; D010083:Oxidants, Photochemical / Q000032:analysis* / Q000633:toxicity; D010126:Ozone / Q000032:analysis* / Q000633:toxicity; D028223:Pinus / Q000187:drug effects*; D012621:Seasons; D014197:Trees / Q000187:drug effects* / Q000254:growth & development; D014481:United States
chemical_list: D000393:Air Pollutants; D010083:Oxidants, Photochemical; D010126:Ozone