Accumulation histories of magnetic particles on pine needles as function of air quality

Abstract

Atmospheric particulates, especially in the PM 2.5 range, pose a significant threat to human health and require adequate regulation and monitoring. Biomonitoring offers a suitable means to investigate air quality at high temporal and spatial resolution. The accumulation histories of magnetic particulates in the PM 0.1–PM 10 class for 6 sites of different emission background in the Cologne Conurbation, NW-Germany, are described. Five needle cohorts were sampled in triplicate in winter and summer of 2004 for determination of magnetic properties ( χ, IRM and ARM). Variability between sites was found to be significantly higher than within sites. Investigated accumulation rates predominantly reflect anthropogenic emissions. Natural processes are of minor importance, comprising canopy effects and abrasive removal of particles. Emission specific concentrations and grain size distributions can be detected by combination of enviromagnetic parameters and allow for source allocation in highly resolved spatial data sets. For source identification, SEM and Microprobe analyses differentiate fine and coarse PM according to shape and element content. Microscopic analyses are limited with respect to assessment of most health-adverse ultrafine PM, which can be characterised in detail for composition and grain size by enviromagnetic techniques.