Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California

摘要

Two-week average concentrations of ozone (O_3), nitric acid vapor (HNO_3) and ammonia (NH_3) 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 O_3,1.0-3.8 μg m~(-3) for HNO_3, and 2.6-5.2 μg m~(-3) for NH_3. Calculated O_3 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 O_3 human health standards were exceeded during 104,108, and 114 days respectively, indicating high risk to humans from ambient O_3.