title: Harmful effects of atmospheric nitrous acid on the physiological status of Scots pine trees.
abstract: An open top chamber experiment was carried out in the summer of 2003 to examine the effect of nitrous acid (HONO) gas on the physiological status of Scots pine saplings (Pinus sylvestris). Four-year-old pine trees were exposed to two different levels of HONO gas (at ca. 2.5 ppb and 5.0 ppb) and a control (filtered air) from early evening to early morning (18:00-6:00), in duplicate open top chambers. Significant decreases in the ratios of chlorophylls a to b, an increase in the carbon to nitrogen (C/N) ratio, and a reduction of maximum yield of PS II (F(v)/F(m)) in pine needles were also observed after the 2 months' fumigation. Cation contents of pine needles were also decreased by the fumigation with HONO gas. The results could be explained by the harmful effects of OH radicals, generated from photolysis of HONO gas, and/or aqueous phase HONO (NO(2)(-)/HONO), on the photosynthetic capacity of pine needles.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Japan. hsakuga@hiroshima-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakugawa
authors.forename: J Neil
authors.initials: JN
authors.lastname: Cape
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D002244:Carbon / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring / Q000379:methods; D005609:Free Radicals / Q000737:chemistry; D008670:Metals / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009608:Nitrous Acid / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology; D041605:Pinus sylvestris / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*
chemical_list: D000393:Air Pollutants; D005609:Free Radicals; D008670:Metals; D002734:Chlorophyll; C037184:chlorophyll b; D002244:Carbon; D009584:Nitrogen; D009608:Nitrous Acid; D000077194:Chlorophyll A