Characterization of regional transport and dispersion using Project MOHAVEtracer data

Perfluorocarbon tracers were released continuously from several surface loc ations and one power plant stack location during the winter (30 days) and s ummer (50 days) intensive studies as part of Project MOHAVE. Tracers were r eleased in winter from the Mohave Power Plant (MPP) and Dangling Rope, UT, located on the shore of Lake Powell near Page, AZ; and in summer from MPP, the Tehachapi Pass between the Mojave Desert and the Central Valley in Cali fornia, and El Centro, CA, on the California-Mexico border. At the Tehachap i tracer release site six-hour pulses of a separately identifiable perfluor ocarbon tracer were released every four days in order to assess the time fo r the tracer to clear the monitoring network. Daily 24-hr integrated sample s were collected at about 30 sites in four states. Limited tracer concentra tion data with higher time resolution is also available. Graphical displays and analyses identify several regional transport paths, including a conver gence zone in the Mojave Desert, the importance of terrain channeling, espe cially in winter, and a relationship between 24-hr maximum influence functi on and distance that may prove useful as a scoping tool and to test regiona l scale air quality models. In winter, Dangling Rope tracer was routinely t ransported through the entire length of the Grand Canyon, while in summer, MPP tracer was routinely transported over most of Lake Mead.