Impacts of urban levels of ozone on Pinus halepensis foliage

• Published in: Environmental and experimental botany Vol. 44; no. 1; pp. 69 - 82
• Main Authors: Soda, Costanza, Bussotti, Filippo, Grossoni, Paolo, Barnes, Jeremy, Mori, Bruno, Tani, Corrado
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2000; Elsevier Science
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Cell ultrastructure; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Fundamental and applied biological sciences. Psychology; Italy, Florence; Mediterranean; Pinus halepensis; Sulphur dioxide; Symptomatology; Urban air; Southern Europe; Italy; Europe; Mediterranean; Symptomatology; Urban air; Sulphur dioxide; Cell ultrastructure; Pinus halepensis; Ozone; Plant leaf; Urban area; Anatomy; Sulfur dioxide; Ultrastructure; Softwood forest tree; Gymnospermae; Air pollution; Coniferales; Spermatophyta; Mediterranean region; Chloroplast
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/S0098-8472(00)00055-1

Between May and September, 1996, seedlings of Pinus halepensis were placed at a site adjacent to an automated air pollution monitoring station within the urban area of Florence. Additional ‘control’ plants were placed in chambers ventilated with charcoal/Purafil®-filtered air. All trees were well watered throughout the whole experimental period. During the exposure period, ambient levels of sulphur dioxide were very low, whilst the accumulated hourly exposure to ozone above 40 ppb (i.e. AOT40) exceeded 20 000 ppb h −1 — peak hourly ozone concentrations rising to levels above 100 ppb. Trees exposed to ambient levels of air pollution exhibited typical symptoms of ozone damage (chlorotic mottle) on previous year needles toward the end of the summer. Similar symptoms were not observed on equivalent trees exposed to filtered-air, nor were visible symptoms accompanied by insect or pest infestation. Anatomical and ultrastructural observations made on symptomatic needles revealed degeneration in mesophyll cells bordering sub-stomatal cavities and alterations in chloroplast ultrastructure (fat accumulation, starch and tannin pattern modifications). These observations are consistent with the known effects of air pollutants (namely ozone) recorded in the literature. Findings are discussed in relation to the impacts of ozone on P. halepensis in the Mediterranean region.