GAS-PHASE MERCURY IN THE ATMOSPHERE OF THE UNITED-KINGDOM

Measurements of total gaseous mercury have been made over a period of 1 yr using a cold vapour atomic fluorescence absorption technique at H arwell, a rural site in central southern England. The mean concentrati on was 1.68 ng m(-3), with a maximum hourly mean concentration of 20.5 ng m(-3) and a minimum hourly mean concentration of 0.26 ng m(-3). Ga seous mercury concentrations are not greatly different from those meas ured at a remote rural site in Ireland, nor other measurements in Euro pe. The data from Harwell show greater variability than those from mor e remote sites but indicate a ''background'' of approximately 1.5 ng m (-3), which is consistent with these other data. The diurnal variabili ty of gaseous mercury at this site suggests a surface source, estimate d to be of the order of 15 ng m(-2) day. Two fossil-fuel combustion pl ants were located in the same 30 degrees wind sector but no clear effe ct of these sources on gaseous mercury concentrations could be establi shed, using sulphur dioxide as a tracer in combination with meteorolog ical data. (C) 1998 AEA Technology plc. Published by Elsevier Science Ltd. All rights reserved.