Project: Potential Effects of Organic Pollutants on Vegetation - Critical Review A61

Reference: STP 14/5/5

Last update: 13/08/2003 14:32:33

Objectives

The objectives are to:

Provide a comprehensive, critical review of the observed and potential effects of VOCs on plants;

Indicate the potential for using plants as bio-indicators of VOC pollution;

Identify a strategy for DETR to establish whether current and future VOC concentrations pose a potential long-term direct threat to plant health, and to the health of herbivores.

Description

Recent measurements have shown that some volatile organic compounds (VOCs) are metabolised by plants at levels close to those in urban air, and that there is some evidence of genotoxicity. Analytical techniques have also progressed to the point where the uptake and fate of VOCs in plants can be reliably measured. The published literature on the potential damage to vegetation from VOCs is fragmentary, and often refers to acute effects at high concentrations rather than to long-term effects of more realistic concentrations. By analogy with knowledge of the effects of inorganic pollutants (sulphur dioxide, ozone) on plants, acute effects are probably not good predictors of chronic effects of low concentrations.

Contractor(s)

Centre for Ecology and Hydrology
Natural Environment Research Council, CEH Directorate, Huntingdon, Cambridgeshire, PE28 2LS
0131 445 4343

Contract details

Cost to the Department: £12,220.00

Actual start date: 01 June 2001

Actual completion date: 31 December 2001

Publication(s)

Potential effects of volatile organic pollutants on vegetation Critical review DEFRA New Horizon Research Programme
Author: J Neil Cape
November 2001

Summary of results

  1. The report concludes that the greatest risk from exposure to VOCs in the UK is likely to be to horticultural crops grown in or close to urban areas, and to garden plants in cities. The most sensitive stage of plant growth appears to be flowering and seed/fruit production. The greatest risk to native plant species and agriculture crop plants is from exposure close to industrial sources or major roads.

    Adverse effects at the ecosystem level are most likely to be caused by the accumulation of VOC metabolites in plants, and consequent effects on the food chain, than by direct effects on plant growth. There have been no relevant experimental studies of the long-term effects of VOCs on plants that include effects on flowering, seed production and viability, and the accumulation of metabolites. Open-top chambers may be used to determine dose-effect relationships by delivering known concentrations of individual VOCs or mixtures, but adequate replication is expensive. Field fumigation experiments are easier to control for VOCs (normally liquids at ambient temperatures) than for inorganic pollutant gases such as ozone, and can be conducted on native vegetation and crops with minimal disturbance to the normal growing environment. Monitoring of the applied VOC concentrations across a gradient of exposure may permit dose-response relationships to be estimated. Several promising biomarkers of VOC exposure have been suggested, but to date no VOC-specific biomarker/ biomonitor has been identified.

Departmental Assessment Status: Project completed prior to the implementation of the Departmental publication scheme.