Arable habitats

Fly ash :: terrestrial ecosystems

Key Concerns:

Fly ash is produced when pulverised fuels are burnt. Like other types of dust, fly ash may affect vegetation by both physical and chemical processes. Physically, particles may cover the leaf surface and reduce the amount of light available for photosynthesis, or may occlude stomata. Occlusion may lead to increased resistance to gas exchange, or may prevent full stomatal closure, leading to water stress. Increased transpiration is a common response to dust exposure. Deposition rates to tall vegetation are greater than to short vegetation.

Cement dusts :: terrestrial ecosystems

Key Concerns:

Cement dusts, like dusts in general, affect vegetation by both physical and chemical processes. Physically, dust may cover the leaf surface and reduce the amount of light available for photosynthesis, or may occlude stomata. Occlusion may lead to increased resistance to gas exchange, or may prevent full stomatal closure, leading to water stress. Increased transpiration is a common response to dust exposure.

Formaldehyde :: terrestrial ecosystems

Key Concerns:

Short-chain alcohols and aldehydes are produced and emitted by some plants. There is evidence that methanol applied to leaves may be beneficially metabolised. Biochemical pathways exist in plants to regulate formaldehyde concentrations, and experiments with trees have suggested that many species are tolerant of high concentrations (microlitre/litre or ppm) on short-term (hours) exposure. See review by Cape(2003).

Additional Comments:

Benzene/Toluene/Xylene :: terrestrial ecosystems

Key concerns:

There is almost no information on the effects of volatile organic compounds (VOCs) on vegetation at concentrations likely to be experienced even in polluted urban air, or over timescales longer than a few hours. The literature has been reviewed (Cape, 2003; Collins & Bell, 2002).

Benzene may accumulate in the leaves and fruit of some species, but is unlikely to be of concern at concentrations typical of rural air (Collins et al., 2000).

Fluoride deposition :: arable ecosystem

Deposition of fluorides increases the fluoride content of vegetation, and eventually soil. Fluoride is very rapidly fixed by mineral soils so even where the concentration increases substantially, there is no increase in uptake by plants. Effects on plants are caused by direct uptake of Hydrogen Fluoride from the air, not by deposition on soil. In arable soils the use of phosphate fertilisers (which contain from 0.5-3% F), are a much more significant source than air pollution. Ploughing mixes deposited fluoride so there is a neglible increase in concentration, even near major sources.

Pages

Subscribe to RSS - Arable habitats

This page was accessed on Saturday, October 20, 2018 05:12