Characterisation of ambient Total Gaseous Mercury concentrations over theSouth African Highveld

Özet

Mercury is considered a ubiquitous, toxic, and global pollutant. In this study, ambient Total Gaseous Mercury(TGM) concentrations over the South African Highveld are characterised. Studies on ambient mercury in thisregion is important because of various anthropogenic emission sources. In this pilot study, concentrations ofTGM and criteria pollutants (O3,SO2, NO, NO2, and CO) were measured concurrently with meteorologicalparameters at Balfour (BF), Middelburg (MB), and Standerton (ST) from January 2009 to December 2009. Thespatial variation of TGM concentrations ranged from 0.40 to 28.72 ng/m3(1.99 0.94 ng/m3), 0.12–9.91 ng/m3(1.04 0.62 ng/m3), and 0.21–32.10 ng/m3(1.25 1.38 ng/m3), at BF, MB, and ST, respectively. Generally, con-centrations fell within the Northern Hemisphere background range of 1.5–1.7 ng/m3and Cape Point, SouthAfrica background of 1.2–1.4 ng/m3, with the exception of outliers. The outliers were much higher than thebackground values and may be the result of pollution events. Seasonal variation varied with descending orders ofsummer, spring, winter, autumn, at BF; summer, winter, autumn, spring at MB; and winter, spring, summer at ST(no data available for autumn). This study observed no profound diurnal patterns at BF and MB where sparselocal and regional sources appear to have been the predominant sources. An interesting phenomena, however,was observed at ST where the diurnal cycle suggests a potential significant influence from local domesticcombustion sources