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BACTERIAL FLUX FROM CHAPARRAL INTO THE ATMOSPHERE IN MID-SUMMER AT A HIGH DESERT LOCATION
Citation:
Lighthart, B. AND B. Shaffer. BACTERIAL FLUX FROM CHAPARRAL INTO THE ATMOSPHERE IN MID-SUMMER AT A HIGH DESERT LOCATION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/301 (NTIS PB94190550).
Description:
Estimates of the bacterial flux for a daylight cycle were observed at the Hanford Nuclear Reservation, Richland, WA, during June 1992, using a modified Bowen ratio method. he upward daytime bacterial flux was coupled with the solar radiation/sensible heat cycle, but commenced 2 h later in the morning and ceased 3 h earlier in the afternoon. uring this period, the maximum flux was ca 17,000 Colony Forming Units (CFU) m-2 occurring at solar noon, resulting in a total upward bacterial flux of ca 76,000 CFU m-2 for the time period. uring this same period, the integrated total viable bacterial concentration in the atmosphere was only 0.81%- of total upward bacterial flux. he high temperatures (e.g. 45 degrees C), low relative humidity (e.g. 10%-), and particularly high solar radiation (e.g. 910 W m-2) are thought to be the lethal agents in the high desert atmosphere. he decreasing concentration of bacteria in the atmosphere was found to slow within 30 min of the initiation of the upward flux of bacteria. ven though this upward flux of bacteria decreased after solar noon, the bacterial concentration in the atmosphere continued to increase. resumably, this is due to reduced solar radiation in the afternoon allowing greater survival of the released bacteria and smaller dilution of entering bacteria into the shallow nocturnal mixed layer.