Rates of particulate pollution deposition onto leaf surfaces: temporal and inter-species magnetic analyses.

Evaluation of health impacts arising from inhalation of pollutant particles <10 microm (PM(10)) is an active research area. However, lack of exposure data at high spatial resolution impedes identification of causal associations between exposure and illness. Biomagnetic monitoring of PM(10) deposited on tree leaves may provide a means of obtaining exposure data at high spatial resolution. To calculate ambient PM(10) concentrations from leaf magnetic values, the relationship between the magnetic signal and total PM(10) mass must be quantified, and the exposure time (via magnetic deposition velocity (MV(d)) calculations) known. Birches display higher MV(d) (approximately 5 cm(-1)) than lime trees (approximately 2 cm(-1)). Leaf saturation remanence values reached 'equilibrium' with ambient PM(10) concentrations after approximately 6 'dry' days (<3 mm/day rainfall). Other co-located species displayed within-species consistency in MV(d); robust inter-calibration can thus be achieved, enabling magnetic PM(10) biomonitoring at unprecedented spatial resolution.