Abstract
Abstract. Total gaseous mercury (TGM) concentrations were measured every 5 min in Pohang, Gyeongsangbuk-do, Korea, during summer (17–23 August 2012), fall (9–17 October 2012), winter (22–29 January 2013), and spring (26 March–3 April 2013) to (1) characterize the hourly and seasonal variations of atmospheric TGM concentrations; (2) identify the relationships between TGM and co-pollutants; and (3) identify likely source directions and locations of TGM using the conditional probability function (CPF), conditional bivariate probability function (CBPF) and total potential source contribution function (TPSCF). The TGM concentration was statistically significantly highest in fall (6.7 ± 6.4 ng m−3), followed by spring (4.8 ± 4.0 ng m−3), winter (4.5 ± 3.2 ng m−3) and summer (3.8 ± 3.9 ng m−3). There was a weak but statistically significant negative correlation between the TGM concentration and ambient air temperature (r = −0.08, p<0.05). Although the daytime temperature (14.7 ± 10.0 °C) was statistically significantly higher than that in the nighttime (13.0 ± 9.8 °C) (p<0.05), the daytime TGM concentration (5.3 ± 4.7 ng m−3) was statistically significantly higher than that in the nighttime (4.7 ± 4.7 ng m−3) (p<0.01), possibly due to local emissions related to industrial activities and activation of local surface emission sources. The observed ΔTGM ∕ ΔCO was significantly lower than that of Asian long-range transport, but similar to that of local sources in Korea and in US industrial events, suggesting that local sources are more important than those of long-range transport. CPF, CBPF and TPSCF indicated that the main sources of TGM were iron and manufacturing facilities, the hazardous waste incinerators and the coastal areas.
Highlights
Mercury (Hg) is an environmental toxic and bioaccumulative trace metal whose emissions to the environment have considerably increased due to anthropogenic activities such as mining and combustion processes (Pirrone et al, 2013; Streets et al, 2011)
In addition to the general background concentration of Hg in the global atmosphere, local Hg emissions contribute to the Hg burden and to the background concentration, much of which represents anthropogenic releases accumulated over the decades (UNEP, 2002)
The average concentration of Total gaseous mercury (TGM) during the complete sampling period was 5.0 ± 4.7 ng m−3. This is significantly higher than the Northern Hemisphere background concentration (−1.5 ng m−3) (Sprovieri et al, 2010) and those measured in China, in Japan and other locations in Korea but lower than those measured at Changchun, Gui Yang and Nanjing in China (Table 1)
Summary
Mercury (Hg) is an environmental toxic and bioaccumulative trace metal whose emissions to the environment have considerably increased due to anthropogenic activities such as mining and combustion processes (Pirrone et al, 2013; Streets et al, 2011). In urban areas in South Korea atmospheric TGM concentrations have decreased over the last few decades due to the reduced fossil fuel (mainly anthracite coal) consumption (Kim et al, 2016; Kim and Kim, 2000). This decreasing trend is inconsistent with steady or increasing global anthropogenic Hg emissions since 1990 in the Northern Hemisphere (Streets et al, 2011; Weigelt et al, 2015; Wilson et al, 2010). While PSCF has been used primarily to identify regional sources, it has been used to identify local sources (Hsu et al, 2003)
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