An Air Quality Data Analysis System for Interrelating Effects, Standards, and Needed Source Reductions: Part 8. An Effective Mean O3Crop Reduction Mathematical Model

Abstract

A plant injury mathematical model, applied previously to acute and chronic leaf injury data, was used to model National Crop Loss Assessment Network (NCLAN) [USA] data for 15 cv. [corn (''Pag-397'', ''Pioneer''), cotton (''Acala SJ''), kidney bean (''California light red''), lettuce (''Empire''), peanut (''Nc-6), soybean (''Corsoy'', ''Davis'', Essex'', ''Hodgson'', ''Williams''), wheat (''Blueboy II'', ''Coker 47-27'', ''Holly'', ''Oasis'')] and to calculate species parameters from the cultivar analyses. Percent crop yield reduction was estimated as a function of a new parameter, the effective mean O3 concentration: me = [(.SIGMA.ch-1/v)ln]-v, where ch was the hourly average ambient O3 concentration for each daytime hour (defined as 9:00-16:00, always standard time) of data available at an air sampling site for summer (defined as June 1-Aug. 31), n was the total number of such available hours and v was an exposure time-concentration parameter, calculated as .apprx. -0.376. Crop yield reduction for soybean was calculated as z = 0.478 ln (tme2.66)-0.42, where z was the Gaussian transform of percent crop reduction, t was the hours of exposure (525; 7 h/day for 75 days), and ln indicated that the natural log was taken of the quantity within parentheses. Crop yield reductions for 7 plant spp were estimated with similar equations for each of the 1824 site-yr of 1981-1983 hourly O3 concentration data available in the [USA] National Aerometric Data Bank (NADB). County-average effective mean O3 concentrations were indicated by shading on a USA map. State-average O3 parameters and estimated percent crop yield reductions were tabulated. The [USA]National Ambient Air Quality Standard (NAAQS) for O3 specified that, on the average, the 2nd highest daily maximum 1 h average O3 concentration in a year shall not exceed 0.12 ppm. For 1981-1983, 71% of the NADB sites recorded annual 2nd highest daily maximum 1 h average O3 concentrations < 0.125 ppm (for summer daytime hours). Ambient O3 concentrations reduced the total USA crop yield an estimated 5% for 1981-1983. (Summer, daytime and all acronyms were always used).