Elevated Ozone Levels at the Swedish West Coast and in Southern Sweden (Skåne), using Tobacco as an Indicator Plant

In the summer of 1977, an investigation was carried out to determine occurence of ozone in south-western Sweden, using tobacco plants as ozone-sensitive indicators. Through studying the frequency and intensity of injuries on tobacco at nine localities along the west coast and three localities in the south, an idea was also obtained of potential injury of ozone on natural vegetation, agronomic crops and forest trees. Three varietes of tobacco of differet sensitivity were used, Bel W3, BEl C and Bel B. throughout the investigation period, continous measurements of atmospheric ozone concentration were carried out at a background station on the west coast. Results; 1) Tobacco varieties Bel W3 and Bel C showed injury at all localities. 2) The daily mean value of ozone ranged fron 21 to 77 ppb and the maximum 1-hour mean value ranged from 34 to 102 ppb. 3) No correlation between ozone concentration in the air and degree of inury on tobacco plants was found, but the cause of the injuries was defintitely ozone. 4) Some injury was observed on the ozone-tolerant variety Bel B. This may have been a synergistic effect of sulphur dioxide and ozone. 5) Long-range transported pollutants probably caused the main part of the ozone injuries observed, but there are strong indications that some of them were caused by locally formed ozone. 6) The intensity, frequency and distribution of injury on the tobacco plants indicate that ozone is likely to cause damage also to natural vegetation as well as agronomic crops and forest trees in Sweden

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