Environmental Engineering Reference
In-Depth Information
value was 15 fg I-TEQ/m
3
(16 fg WHO-TEQ/m
3
). The studies also suggested that
the fluctuations of PCDDs/Fs levels are correlated with minimum relative
humidity, mean temperature, and mean NOx concentration. Abad et al. (2004)
monitored PCDDs/Fs levels in ambient air of 28 different sites (rural, urban,
suburban and industrial) between 1994 and 2002. The mean of TEQ values in
industrial areas, urban and suburban areas and rural areas were 180 fg I-TEQ/m
3
,
80 fg I-TEQ/m
3
, 42 fg I-TEQ/m
3
, respectively. Cheng et al. (2003) reported PCDDs/
Fs levels measured in the ambient air range from 0.058 to 0.127 pg-TEQ/m
3
.
Seoul, the largest city of Korea, has a lot of source of dioxin such as MSWI, a
variety of plants, traffic and etc. Recently, many plants have moved out of the city
but there still remain lots of sources of dioxin in Seoul. The aim of this study was
to determine dioxin levels and to assess temporal trends of the atmospheric
content of these pollutants in Seoul. Moreover, patterns of PCDDs/Fs congeners
have been investigated and the relationship between the level of dioxin in ambient
air and seasonal fluctuation was investigated. Ambient air monitoring for dioxin in
Seoul has been conducted continuously over the 7 years: January 2002 through
December 2008.
2. Sampling and Laboratory Analysis
2.1 Sampling
Air samples for dioxin analysis were collected using high-volume air samplers
equipped with a quartz fiber filter before the PUF (polyurethane foam). An about
450 samples were collected from January 2002 through December, 2008 at three
different sampling locations in Seoul area. Volumetric sampling flow rate was set
on 0.8 m
3
/min.
2.2 Analytical Procedure
The 2,3,7,8-substituted congeners of PCDDs/Fs in samples were determined by
HRGC/HRMS, according to US EPA method TO-9(1999a), 1613b(1994) and
1668a(1999b). Chromatograms were obtained from Gas chromatography electron
impact mass spectrometry (GC-EIMS, a Micromass Autospec Ultima) at a
resolution of 10,000(10% valley) in SIM mode.
