Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California.
Two-week average concentrations of ozone (O3), nitric acid vapor (HNO3) and ammonia (NH3) were measured with passive samplers during the 2002 summer season across the central Sierra Nevada Mountains, California, along the San Joaquin River drainage. Elevated concentrations of the pollutants were determined with seasonal means for individual sites ranging between 62 and 88 ppb for O3, 1.0-3.8 microg m(-3) for HNO3, and 2.6-5.2 microg m(-3) for NH3. Calculated O3 exposure indices were very high, reaching SUM00-191 ppm h, SUM60-151 ppm h, and W126-124 ppm h. Calculated nitrogen (N) dry deposition ranged from 1.4 to 15 kg N ha(-1) for maximum values, and 0.4-8 kg N ha(-1) for minimum values; potentially exceeding Critical Loads (CL) for nutritional N. The U.S., California, and European 8 h O3 human health standards were exceeded during 104, 108, and 114 days respectively, indicating high risk to humans from ambient O3.
Cisneros
Ricardo
R
USDA Forest Service, Pacific Southwest Region, 1600 Tollhouse Road, Clovis, CA 93611, USA. rcisneros@fs.fed.us
Bytnerowicz
Andrzej
A
Schweizer
Donald
D
Zhong
Sharon
S
Traina
Samuel
S
Bennett
Deborah H
DH
D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data; D000641:Ammonia / Q000032:analysis*; D002140:California; D017753:Ecosystem; D004784:Environmental Monitoring; D006304:Health Status; D006801:Humans; D017942:Nitric Acid / Q000032:analysis*; D010126:Ozone / Q000032:analysis*; D014887:Weather
D000393:Air Pollutants; D017942:Nitric Acid; D010126:Ozone; D000641:Ammonia