title: Perchlorate content of plant foliage reflects a wide range of species-dependent accumulation but not ozone-induced biosynthesis.
abstract: Perchlorate (ClO4(-)) interferes with uptake of iodide in humans. Emission inventories do not explain observed distributions. Ozone (O3) is implicated in the natural origin of ClO4(-), and has increased since pre-industrial times. O3 produces ClO4(-)in vitro from Cl(-), and plant tissues contain Cl(-) and redox reactions. We hypothesize that O3 exposure may induce plant synthesis of ClO4(-). We exposed contrasting crop species to environmentally relevant O3 concentrations. In the absence of O3 exposure, species exhibited a large range of ClO4(-) accumulation but there was no relationship between leaf ClO4(-) and O3, whether expressed as exposure or cumulative flux (dose). Older, senescing leaves accumulated more ClO4(-) than younger leaves. O3 exposed vegetation is not a source of environmental ClO4(-). There was evidence of enhanced ClO4(-) content in the soil surface at the highest O3 exposure, which could be a significant contributor to environmental ClO4(-).
authors: Department of Botany and Plant Sciences, University of California at Riverside, Kearney Agricultural Center, 9240 South Riverbend Avenue, Parlier, CA 93648, USA. Electronic address: dagrantz@ucanr.edu.
authors: D A
authors: DA
authors: Grantz
authors: K O
authors: KO
authors: Burkey
authors: W A
authors: WA
authors: Jackson
authors: H-B
authors: HB
authors: Vu
authors: M T
authors: MT
authors: McGrath
authors: G
authors: G
authors: Harvey
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D006801:Humans; D010126:Ozone / Q000633:toxicity*; D010472:Perchlorates / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000393:Air Pollutants; D010472:Perchlorates; D010126:Ozone; C494474:perchlorate
keywords: Air pollution; ClO(4)(−); Crop contamination; Gas exchange; O(3); Oxidants; Ozone; Perchlorate