Ecological effects of particulate matter

Atmospheric particulate matter is a mixture of diverse elements. Deposition of particulate matter to vegetated surfaces depends on the size distribution of these particles and, to a lesser extent, on the chemistry. Effects of particulate matter on vegetation may be associated with the reduction in light required for photosynthesis and an increase in leaf temperature due to changed surface optical properties. Changes in energy exchange are more important than the diffusion of gases into and out of leaves which is influenced by dust load, color and particle size. Alkaline dust materials may cause leaf surface injury while other materials may be taken up across the cuticle. A more probable route for metabolic uptake and impact on vegetation and ecosystems is through the rhizosphere. Interception of dusts by vegetation makes an important contribution to the improvement of air quality in the vicinity of vegetation. Although the effect of particulate matter on ecosystem is linked to climate change, there is little threat due to un-speciated particulate matter on a regional scale.

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Ecological effect of airborne particulate matter on plants

Quantitative measures of visible injury are proposed for the protection of the aesthetic acceptability and health of ecosystems. Visible indications of air pollutant injury symptoms can be assessed rapidly and economically over large areas of mixed species such as native ecosystems. Reliable indication requires close attention to the criteria for assessment, species selection, and the influence of other environmental conditions on plant response to a pollutant. The estimation of fluoride-induced visible injury in dicotyledonous species may require techniques that are more varied than the measurement of necrosis in linear-leaved monocotyledons and conifers. A scheme is described for quantitative estimates of necrosis, chlorosis and deformation of leaves using an approximately geometric series of injury categories that permits rapid and sufficiently consistent determination and recognises degrees of aesthetic offence associated with foliar injury to plants.

Rapid quantitative assessment of visible injury to vegetation and visual amenity effects of fluoride air pollution.

The research presented here was the response to an improvement condition issued by the Environment Agency. The aim of the present study was to examine the potential effects of the particulate emissions from an integrated iron and steel works, to an adjacent sand dune ecosystem, identified as a Site of Special Scientific Importance (SSSI) for its flora, fauna and bird life. A monitoring and assessment of the deposition and flux of particulates was undertaken from April 2006 to September 2007 at monitoring sites located on the iron and steel works and in the surrounding area. A passive particulate deposition and flux monitoring study was undertaken at six sites on and surrounding the integrated iron and steel works using Frisbee deposit gauges and sticky pads. The deposition and flux of particulates was significantly higher at the monitoring sites located on or close to the works, and decreased up to 3 km from the works. The particles found on and near the works were predominately iron-rich, and most likely to be a result of emissions from the works. The chemical characteristics of the particles identified further away from the works were more diverse, and a combination of marine, soil, combustion or industrially derived particles. A desk-top review and development of the model scenario was undertaken, to assess the relevance of the modelled scenarios of PM(_10) emissions, to the total dust deposited to the passive deposition gauges. The model scenario was found to be an important qualitative tool, but could not be used to predict quantitative measurements of particulate deposition due to the limitations and uncertainty of modelling. The deposition of particulates to the SSSI was significantly higher at sites located closer to the works, and increased significantly with exposure time. The iron concentration of the soil was found to be significantly higher on the SSSI than at a sand dune ecosystem 3.5 km away. Cleaned leaves of Leymus arenarius and Plantago lanceolata had a significantly higher rate of photosynthesis compared to untreated leaves growing on the SSSI. Therefore at sites where the rate of particulate deposition was relatively higher, and increased soil iron concentration was enhanced in comparison to similar sites, the rate of photosynthesis was significantly reduced in leaves of Leymus and Plantago on the SSSI.

Particulate emissions from a steel works a quantitative ecological assessment

The objective of this discussion is to consider problems involved in the acquisition, interpretation, and application of data collected in studies of air pollutant interactions with the terrestrial environment. Emphasis will be placed on a critical evaluation of current deficiencies and future research needs by addressing the following questions: (1) which pollutants are either sufficiently toxic, pervasive, or persistent to warrant the expense of monitoring and effects research; (2) what are the interactions of multiple pollutants during deposition and how do these influence toxicity; (3) how de we collect, report, and interpret deposition and air quality data to ensure its maximum utility in assessment of potential regional environmental effects; (4) what processes do we study, and how are they measured to most efficiently describe the relationship between air quality dose and ultimate impacts on terrestrial ecosystems; and (5) how do we integrate site-specific studies into regional estimates of present and potential environmental degradation (or benefit).

S. E. Lindberg

Papers

Air pollutant interactions with vegetation: research needs in data acquisition and interpretation