Characteristics of total gaseous mercury (TGM) concentrations in an industrial complex in South Korea: Impacts from local sources

Abstract

Total gaseous mercury (TGM) concentrations were measured every 5 min in Pohang, Gyeongsangbukdo, 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 ngm-3), followed by spring (4.8±4.0 ngm-3), winter (4.5±3.2 ngm-3) and summer (3.8±3.9 ngm-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 ngm-3) was statistically significantly higher than that in the nighttime (4.7±4.7 ngm-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.