Tracing the origin of dioxins in Baltic air using an atmospheric modeling approach

• Previous work has concluded that the sources of dioxins to the Baltic Sea are dominated by atmospheric deposition. Here, we investigate whether current emission estimates can explain Baltic air levels and deposition fluxes of four selected 2,3,7,8-substituted PCDD/F congeners using an atmospheric modeling approach. The EMEP (European Monitoring and Evaluation Programme) database of emissions for dioxins was used to provide inputs to the selected model (MSCE-POP model) and model predicted levels were compared with measurements of dioxins in air and deposition fluxes at three monitoring stations in Sweden. The model underestimated air concentrations between a factor of 5 and 30, with the level of agreement depending on congener, monitoring station and, importantly, with the compass sector from which the contaminated air mass had arrived. Additional model simulations were undertaken in which emissions were enlarged in some selected areas to optimize agreement between model predictions and measurements. A novel emission adjustment approach is used in an attempt to identify source regions where emissions were in error. The emission adjustment approach improved the agreement between model predictions and measurements for 60% of the measurements within a factor of 3 of model predicted concentrations. However, the agreement was still relatively poor when air masses originated from the SSE and SSW. The model adjustment procedure gives an indication of the magnitude of error in exiting emission estimates, but due to the poor quality of existing emission databases and few quality air monitoring data it is not currently possible to use the emission adjustment approach to accurately identify source regions of error. The approach presented here is promising, however, and could be applied to other substances where better emission and monitoring data are available. (C) Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

Polychlorinated dibenzo-p-dioxin (PCDD)

Polychlorinated dibenzofuran (PCDF)

Baltic Sea

Source

Emission

Applied Environmental Science

tillämpad miljövetenskap

Publikations- och innehållstyp

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art (ämneskategori)