文摘
Attaining the current lower tropospheric U.S. ozonestandards continues to be a difficult task for many areasin the U.S. Concentrations of ozone above the standardsnegatively affects human health, agricultural crops,forests, and other ecosystem elements. This paper describesyear two (1999) of a regional networking of passive andcontinuous ozone monitoring sites in the Dallas-Fort Worth(DFW) Metroplex region. The objectives of the secondyear of study were to (1) validate conclusions of the 1998Passive Ozone Network of Dallas (POND) I study, (2)define the value of taking 12-h diurnal samples in additionto 24-h samples, and (3) add to the scientific knowledgebase of rural/urban ozone comparison studies. Results of thePOND II (1999) study demonstrated that ozone concentrationsexceeding the new 8-h ozone standard could be recordedat least 130 km, or 80 miles, from the DFW Metroplex corein more rural areas. In addition, results of the POND IIstudy indicated that ozone concentrations exceeding the8-h standard probably occurred in areas recording a 12-hdaytime ozone concentration above 60 parts per billion(ppb). The 12-h passive ozone data from POND II also suggeststhe relative magnitude of anthropogenic pollution influencecould be assessed for rural passive ozone sites. Thedata from the POND II study provide modelers a richdatabase for future photochemical subgrid developmentfor the DFW ozone nonattainment area. Indeed, the PONDdatabase provides a great amount of additional ozoneambient data covering 26 8-h and 13 1-h ozone standardexceedance days over an approximate 25 000 km2 region.These data should help decrease uncertainties derivedfrom future DFW ozone model exercises.