70 / 2016-04-30 11:22:22

Atmospheric particulate mercury: effect of meteorological parameters and source analysis

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Measurement of atmospheric particulate mercury (PHg) was conducted at a suburban site in Jinan, China from June 2014 to December 2015. The average PHg concentration with standard deviation was 508.5 ± 402.7 pg m-3. The PHg level in Jinan was of the same order of magnitude as other cities in China but was nearly two orders of magnitude higher than most cities in East Asia, Europe and North America. The average Hg content in PM2.5 (particles with a diameter of 2.5 μm or less) with standard deviation was 6.60 ± 5.82 μg g-1, which was significantly higher than values reported from other cities domestically and abroad.
Correlations between PHg and meteorological parameters were calculated. PHg showed negative links with temperature, relative humidity and wind speed, and a positive link with barometric pressure. The correlations were all significant, although relatively weak which might indicate that atmospheric transformation impacted by meteorological parameters contributed less to PHg contamination than local source emission.
For source identification, the positive correlations with SO2, CO, and NOX were considered, as well as the wind dependence of PHg. These together implied that the potential sources at this site could be coal-fired industries, cement plants, traffic emissions from nearby congested roads and local residential sources. Except the local source emission as the main contributor to PHg in Jinan, the cluster analysis of 36-h backward trajectories implied that PHg in Jinan was less impacted by long-range transport that was originated from dust sources. In contrast, regional transport from the southwestern part of Shandong Province contributed a great deal to the elevated PHg levels.