Lead‐210 observations within CARBOSOL: A diagnostic tool for assessing the spatiotemporal variability of related chemical aerosol species?

Abstract

We report on observations of atmospheric 210Pb, coregistered with inorganic and organic aerosol species, during 2002–2004 at six European sites. This network reaches from the Azores to the Hungarian plain to represent marine, coastal, mountain and continental conditions. The motivation for observing this natural secondary aerosol tracer was to give insight to what extent it might assist in understanding the more complex aerosol chemistry changes. Synopsis of the 210Pb variability revealed a continental increase, up to a factor of three, from west to east. During the three winter months, we find a variation on nearly the same order in the 210Pb concentration between low‐ and high‐altitude sites. Seasonal 210Pb cycles exhibit summer/winter ratios of around 2–3 at high‐altitude sites, but remain damped at low‐altitude stations. However, all sites show distinct 210Pb changes of around ±50% independent of season on the synoptic timescale. Comparison of concentration variations of organic carbon (OC) and anthropogenic sulphate with the 210Pb variations show largest differences associated with the seasonal cycle at the low‐altitude sites. In contrast, significant covariations of all three components are seen on the synoptic timescale for these sites. At high altitudes, clear covariations of OC and anthropogenic sulphate with 210Pb are seen on both seasonal and synoptic timescales. At two mountain sites with comparable elevation, all three aerosol compounds show strong intersite correlations along with systematic enhancements at the downwind site. Attributing these offsets to a common continental pileup, simple 1‐box model calculations yielded OC‐ and anthropogenic sulphate‐related emission flux densities, which are broadly in agreement with the expected values.