Tempospatial Variation and Partition of Atmospheric Mercury during Wet and Dry Seasons at Sensitivity Sites within a Heavily Polluted Industrial City

Yi-Hsiu Jen,Cheng-Mou Tsai,Chung-Hsuang Hung,Iau-Ren Ie,Chung-Shin Yuan

doi:10.4209/aaqr.2012.05.0129

Abstract

This study investigated the seasonal variation and spatial distribution of total gaseous mercury (TGM) and particulate mercury (Hgp) in the ambient atmosphere of Kaohsiung City, the largest industrial city in Taiwan, located at the coastal region of southern Taiwan. TGM and Hgp were measured at six sensitivity sites and one coastal background site, from June to December, 2010. Field measurement results showed that the seasonal averaged concentrations of TGM and Hgp were in the range of 2.38–9.41 and 0.02–0.59 ng/m3 with the highest concentrations of 9.41 and 0.59 ng/m3, respectively. Moreover, the partition of atmospheric mercury was found to be 92.71–99.17% TGM and 0.83–7.29% Hgp. As a whole, the concentrations of mercury species in the dry season were higher than those in the wet season, for both TGM or Hgp concentrations. The TGM and Hgp concentrations at the Hsiao-kang site was the highest in Kaohsiung City. Hot spots of atmospheric mercury were found at two regions in Kaohsiung City, including a steel industrial complex in the south and a petrochemical industrial complex in the north. The correlation of atmospheric mercury with meteorological parameters (e.g., ambient temperature, relative humidity, and UV intensity) and air pollutants (e.g., CO, SO2, NOx, and O3) was further discussed. The results indicated that TGM and Hgp concentrations correlated positively with SO2, NOx, CO, ambient temperature, and UVB, and negatively with relative humidity, O3, and wind speed.

Highlights

Mercury is a persistent, toxic, and bio-accumulative heavy metal that exists primarily in three forms in the atmosphere: gaseous mercury including elemental and reactive mercury, and particulate mercury (Schroeder et al, 1998; Lin et al, 1999)
The results showed that total gaseous mercury (TGM) was the main mercury species, accounting for 94.56–99.59% of atmospheric mercury during the wet season, and 92.71– 99.37% of atmospheric mercury during the dry season
The tempospatial variation and partition of gaseous and particulate mercury were investigated in Kaohsiung City

Summary

Introduction

Toxic, and bio-accumulative heavy metal that exists primarily in three forms in the atmosphere: gaseous mercury including elemental and reactive mercury, and particulate mercury (Schroeder et al, 1998; Lin et al, 1999). Some factors (e.g., emission sources, regional atmospheric chemistry, near-ground micrometeorological conditions) may influence the distribution of atmospheric mercury speciation and deposition (Poissant et al, 2004). Gaseous mercury could be transformed back and forth between two gaseous forms (i.e., elemental and reactive mercury), of which gaseous elemental mercury (GEM) is the major species in the atmosphere. Elemental mercury has high volatility, low chemical reactivity, and low solubility in water, which accounts for more than 95% of gaseous elemental mercury (GEM) and Natural mercury sources as arising from changes in the crust, such as volcanic eruptions, rock weathering, forest fires, lakes, mercury mining and evaporation from oceans. The major anthropogenic mercury sources as arising from steel plants, coal-fired power plants, and industrial and municipal waste incinerators.

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