Evidence of Elevated Ozone Concentrations on Forested Slopes of the Lower Fraser Valley, British Columbia, Canada
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- Krzyzanowski, J., McKendry, I.G. & Innes, J.L. Water Air Soil Pollut (2006) 173: 273. doi:10.1007/s11270-005-9072-z
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During the summers of 2001 and 2002, hourly average ozone concentrations were measured at three sites of differing elevation (188, 588, and 1221 m.a.s.l.) on the forested south-facing slopes of the Lower Fraser Valley (LFV), British Columbia. Sites experienced ozone concentrations ranging from 0 to 88 ppb in 2001, and 0 to 96 ppb in 2002. Daily patterns were in agreement with previous studies showing morning increases and late afternoon peaks. Reduced diurnal variation increased the exposure of higher-elevation forested sites. An upper-level ridge coinciding with a thermal coastal trough caused above-average ozone concentrations, and the ‘maximum acceptable’ 1-hour National Ambient Air Quality Objective (AQO) of 82 ppb to be exceeded. Maximum ozone concentrations and AQO exceedance frequency both increased with distance eastward in the valley. A preliminary survey of ozone-like injury symptoms on native shrubs suggested that the elevated ozone levels occurring in the LFV may cause injury to forest plants.