Total gaseous mercury monitoring at Harwell, UK – trends, patterns and a source analysis

Since autumn 2012, total gaseous mercury (TGM) has been monitored at Harwell, Oxfordshire, UK. Harwell is one of the UKs two EMEP supersites (Level II) and is operated by Ricardo-AEA on behalf of the UK Department for the Environment, Food and Rural Affairs. Heavy metals in air monitoring is undertaken at the site as part of the UK rural heavy metals monitoring network run by the UK’s Centre for Ecology & Hydrology. The monitoring site is a semi-rural site, and is located on part of the Harwell Science and Innovation Campus, located at 51.571°N, 1.325°W. Total gaseous mercury (comprising elemental and gaseous oxidised mercury) was monitored using a Tekran 2537A mercury vapour analyser, run at a resolution of 5 minutes, using dual channels allowing for continuous monitoring. The average concentration for December 2012 was 1.34 ng m-3, which is slightly lower than the northern hemispherical background observed in other studies. This poster presents an initial overview of TGM measurements at the Harwell supersite since November 2012. Using wind sector analysis, cluster analysis and air-mass back trajectories in the OpenAir package in the R statistical software, we show how TGM concentrations are influenced by local and regional sources (< 50 km) as well as air masses moving over the UK from continental Europe on easterly winds.