When do high ozone events occur in Great Smoky Mountains National Park?

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:442885

Neufeld, H ^[1]; Joseph, D ^[2]

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1. Appalachian State Univ., Boone, NC (United States)
2. National Park Service, Denver, CO (United States)

In this paper the authors compare ozone dynamics between high and low elevation sites in Great Smoky Mountains National Park for the years 1988--1994. They have shown in earlier studies that high elevation sites have flatter diurnal ozone profiles, and greater total exposures, than low elevation sites, due mainly to elevated ozone concentrations in the nighttime hours. If they define an ozone episode as any period in which the hourly average meets or exceeds 60 ppb, then they find that at the low elevation site, Twin Creeks, 80% of the peak ozone events occur during daylight hours (most between 2--4 pm), whereas at the high elevation site (Cove Mt.), over 60% of the episodes occur at night. At Cove Mt., lower concentrations (40--60 ppb) occur with almost equal frequency at any time. Cove Mt. also has 5X as many episodes, which last up to 2X as long as those at Twin Creeks. Respite periods (ozone concentrations < 60 ppb) are 3X as common at Cove Mt., but last only 1/5th as long as those at Twin Creeks, such that the high elevation site has 41% less respite time between episodes. These patterns have implications for plant response, since plants take up ozone mainly when their stomata are open. Thus, even though ozone exposures are greater at high elevations, and respite times less, the fact that acutely high concentrations of ozone are limited to periods when stomata are normally closed, means that the ozone dose to the leaf (amount actually absorbed) may be lower than expected.

• OSTI ID: 442885
• Report Number(s): CONF-961149--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
AIR POLLUTION MONITORING
DAILY VARIATIONS
ECOLOGICAL CONCENTRATION
LEVELS
NATURE RESERVES
NORTH CAROLINA
OZONE
TENNESSEE