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Magnetic biomonitoring of roadside tree leaves: identification of spatial and temporal variations in vehicle-derived particulates.

Matzka, Juergen and Maher, Barbara A. (1999) Magnetic biomonitoring of roadside tree leaves: identification of spatial and temporal variations in vehicle-derived particulates. Atmospheric Environment, 33 (28). pp. 4565-4569. ISSN 1352-2310

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Abstract

We report here the novel use of rapid and non-destructive magnetic measurements to investigate the spatial and temporal pattern of urban dust loadings on leaves of roadside trees. More than 600 leaves were collected from birch trees and their remanent magnetization (IRM300 mT) determined and normalized for the leaf area. The results show that this normalised 2-D magnetization is dominantly controlled by the tree's distance to the road. The magnetic analyses enabled detailed mapping of the spatial and temporal variations of vehicle-derived particulates. Higher 2D-magnetizations, indicating higher magnetic dust loadings, were measured for leaves collected adjacent to uphill road sections than for those next to downhill sections. This suggests that vehicle emissions, rather than friction wear or resuspended road dust, are the major source of the roadside magnetic particles. Additional magnetic analyses suggest that the particle size of the magnetic grains dominantly falls in the range classified for airborne particulate matter as PM2.5 (<2.5 µm), a particle size hazardous to health due to its capacity to be respired deeply into the lungs. Thus, the leaf magnetizations relate directly to release into the atmosphere of harmful vehicle combustion products. For leaves from individual trees, magnetization values fall significantly from high values proximal to the roadside to lower values at the distal side, confirming the ability of trees to reduce aerosol concentrations in the atmosphere. Magnetic analysis of leaves over days and weeks shows that rainfall produces a net decrease in the leaf magnetic loadings. Key words: Magnetic measurements, vehicle pollution, biomonitoring.

Item Type: Article
Journal or Publication Title: Atmospheric Environment
Uncontrolled Keywords: Magnetic measurements ; vehicle pollution ; biomonitoring.
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 291
Deposited By: Professor Barbara A Maher
Deposited On: 02 Jan 2007
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:48
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/291

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