An analysis of the distribution of surface ozone in Tuscany (central Italy) with the use of a new miniaturized bioassay with ozone-sensitive tobacco seedlings.

An innovative miniaturized kit based on the use of 2-week-old ozone-supersensitive tobacco germlings (Nicotiana tabacum L. cv. Bel-W3) raised in tissue culture plates was utilized, in conjunction with four calibrated automatic analyzers, to monitor the distribution of phytotoxic ground level ozone in Tuscany during the summer of 1993 at 27 sites differing in nature. Germlings of ozone-resistant Bel-B tobacco were also included in the protocol. The intensity of visible injury on the cotyledons of Bel-W3 was linearly correlated with several ozone statistical descriptors. The occurrence of phytotoxic levels of photochemical ozone was detected in all the monitoring sites, which included rural and remote areas, whose local sources of pollution were negligible. The suitability of the new methodology for low-cost, space-saving, user-friendly monitoring of ozone on a large geographical scale is discussed.